To Better Understand the Various Etiologies of Brown's

Home , Hypertropia, Pediatric ophthalmology, Trochleitis

BROWN'S SYNDROME: DIAGNOSIS AND MANAGEMENT BY Kenneth W Wright, MD'

ABSTRACT Purpose: To better understand the various etiologies of Brown's syndrome, define specific clinical characteristics of Brown's syndrome, describe the natural history of Brown's syndrome, and evaluate the long- term outcome of a novel surgical procedure: the silicone tendon expander. Also, to utilize a computer model to simulate the pattern of strabismus seen clinically with Brown's syndrome and manipulate the model to show potential surgical outcomes of the silicone tendon expander. Methods: Charts were reviewed on patients with the diagnosis of Brown's syndrome seen at a children's hospital ophthalmology clinic from 1982 to 1997, or seen in the author's private practice. Objective fundus torsion was assessed in up gaze, down gaze, and primary position in 7 Brown's syndrome patients and in 4 patients with primary superior oblique overaction. A fax survey was taken of members of the American Association of Ophthalmology and Strabismus (AAPOS) listed in the 1997-1998 directory regarding their results using the silicone tendon expander procedure for the treatment of Brown's syndrome. A computer model of Brown's syndrome was created using the Orbit 1.8 program by simulating a shortened superior oblique tendon or by changing stretch sensitivity to create an inelastic muscle. Results: A total of 96 patients were studied: 85 with Brown's syndrome (38 with congenital and 47 with acquired disease), 6 with masquerade syndromes, 1 with Brown's syndrome operated on elsewhere, and 4 with primary superior oblique overaction in the torsion study. Three original clinical observations were made: 1. Significant limitation of elevation in abduction occurs in 70% of

*From the Department of Ophthalmology, University of California, Irvine College of Medicine and Cedars-Sinai Medical Center, Los Angeles, CA.

TR. AM. OPHTH. SOC. VOL. XCVII, 1999 1024 WVright Brown's syndromie cases surgically verified as caused by a tight superi- or oblique tendon. Contralateral pseudo-inferior oblique overaction is associated with limited elevation in abtductioin. 2. Traumiatic Brown's syndrome cases have larger hypotropias than nontraumatic cases (P<.001). There was no significant hypotropia in primary position in 56 (76%)of 74 congenital and nontrauimatic acquired cases despite severe limitation of elevation. 3. Of 7 patients with Brown's syndrome, 6 had Ino significant fundus torsion in primary position, but had significant (+2 to +3) intorsion in up gaze. Spontaneous resolution occurred in approximately 16% of acquired nontraumatic Brown's syndrome patients. The silicone tenldoil expander was used on 15 patients, 13 (87%) were corrected with 1 surgery and 14 (93%) witlh 2 surgeries. The only failure was a Brown's syndrome not caused by superior obliquie pathology. Five of the silicone tendon expander patients had at least 5 years follow-tip (range, 5 to 11 years). Four (80%) of the 5 patients had an excellent outcome with 1 surgery, final results graded between 9 and 10 (on a scale of 1-10, 10 is best). The fifth patient had a consecutive superior oblique paresis and a good outcome after a recession of the ipsilateral inferior oblique muscle. The AAPOS survey had a mean outcome score of 7.3, with 65% between 8 and 10. There were 9 (6%) complications reported: 4 related to scarring and 5 extrusions of the implant. Three of the 5 extruisions were reported from the same surgeon. The computer model of an inelastic superior oblique muscle-tendon complex best simulated the motility pattern of Brown's syndrome with severe limitation of elevation in adduiction, mild limitation of elevation in abduction, minimal hypotropia in primary position, no superior oblique overactioni, and intorsion in up gaze. Concltusion.s: The presence of mild to moderate limitatioin of elevation in abduction is common, and its presence does not eliminate the diagnosis of Brown's syndrome. The majority of Brown's syndrome patients have a pattern of strabismus consistent with an inelastic superior oblique muscle- tendon complex that does not extend, but can contract normally; not the presence of a short tendon. The presence of inelastic or tethered superi- or oblique muscle-tendon can be diagnosedc without forced duction testing by observing the pattern of strabismus including torsion. Because of the chance for spontaneous resolution, conservative management, not surgery, should be the first line of treatment for acquired Brown's syndromne. If surgery is indicated, a novel procedure, the .silicone tenclon expatndler, is an effective option with excellent long-term outcomes. Brown's Syndrome: Diagnosis and Managenent 1025

INTRODUCTION A small subset of patients presents with an interesting pattern of strabismus, the most prominent feature being restriction of ocular rotations upward and nasally. This distinctive pattern of strabismus has come to be known as Brown's syndrome.'` Much remains to be learned regarding the cause, treatment, and clinical course of this intriguing syndrome. Prior to the present report, there have been no large comprehensive studies on Brown's syndrome since Brown's series published in 1973.5 The goals of this thesis are to better understand the etiology of Brown's syndrome, define specific clinical characteristics of Brown's syndrome, describe the natural history of Brown's syndrome, and evaluate the long-term outcome of a novel surgical procedure, the silicone tendotn expander. This will be accomplished by a literature review, a clinical study on a large number of patients with Brown's syndrome, and postoperative evaluation of patients who underwent the silicone tendon expander procedure for Brown's syndrome. Computer modeling of Brown's syndrome will be used to help elu- cidate the mechanisms and predict the effect of elongating the superior oblique tendon.

BACKGROUND AND HISTORY In 1950, Harold Whaley Brown' first reported on an unusual motility disorder characterized by limited elevation when the eye is in adduction. This was a preliminary report on the clinical features and surgical outcomes of 8 patients. The clinical features were similar to an inferior oblique palsy, but there was little or no associated superior oblique muscle overaction (Fig 1). At surgery, Brown found "their most striking feature a short tendon sheath of the superior oblique tendon that restricts passive movements of elevation in the nasal field." The clinical features of these patients as summarized by Brown are listed in Table I. Brown reported the surgical results on 4 of 8 patients studied." All 4 patients underwent excision of the superior oblique tendon sheath, and 1 patient also had a partial superior oblique tenotomy. He noted that excis- ing the superior oblique sheath improved forced ductions at the time of surgery, but did not significanitly improve postoperative ductions in all 4 cases. Despite these results, Brown attributed the limited elevation to a short or tight ainterior superior oblique tendon sheath and termed this newly discovered syndrome the .superior oblique tendon sheath syndrome. The tight anterior superior oblique tendon sheath theory explained a passive restriction to elevation in adduction found at the time of surgery. Brown demonstrated that the distance from the trochlea to the insertion of the superior oblique tendon normally increases on elevation in adduc- 1026 Wright

FIGURE 1 Composite gaze photograph from Harold Brown's original 1950 article first describing what became known as Brown's syndrome.6 Patient shows a classic right Brown's syndrome with limited elevation in adduction without significant superior oblique overaction. Pafient was noted to have orthotropia in primary position.

TABLE I: CLINICAL FEATURES DESCRIBED BY BROWN 1. The most striking feature is limited elevation in adduction. 2. In straight up gaze there is usually divergence (V-pattern). 3. The degree of limitation is the same on versions, ductions, and forced duction. 4. Usually, there is widening of the palpebral fissure on adduction. 5. Normal or near normal elevation in abduction. 6. Restricted forced ductions to elevation in adduction. 7. Head tilt backwards (compensatory chin elevation for binocular fusion). tion; thus, a short tendon sheath would restrict this movement. He further hypothesized that the short sheath was due to a complete congenital paresis ofthe ipsilateral inferior oblique muscle and secondary sheath contracture because of "a lack of force during its development."6'7 Brown's preliminary report stimulated investigation into this newly identified syndrome.8'14 The syndrome could be acquired, intermittent, and in some cases show spontaneous resolution.l.13 Electrophysiological studies showed that inferior oblique muscle activity was normal and that the muscle was innervated.5'15 Clinical observations also indicated that the pattern of the strabismus of the sheath syndrome was not consistent with an inferior oblique paresis.'6'2' The sheath syndrome is associated with a V-pattern and minimal to no superior oblique overaction, in contrast to inferior oblique paresis that is associated with an A-pattern and marked superior oblique overaction. These findings brought into doubt Brown's original hypothesis that a complete inferior oblique palsy contributed to the elevation deficit and secondary contracture of the superior oblique Brown's Syndrome: Diagnosis and Management 1027 tendon sheath. In 1971, Brown redefined the sheath syndrome and dropped the idea that a congenital inferior oblique paresis was part of the syndrome (later published in 1973).5 He reported on 126 patients and divided them into true sheath and simulated sheath syndromes. True sheath syndrome was defined as "only those cases which have a congenital short anterior sheath of the superior oblique tendon." Simulated sheath syndrome was defined as "all cases with the clinical features of a sheath syndrome caused by an anomaly other than a congenital short anterior sheath of the superior oblique tendon." True sheath syndrome was subdivided into typical and atypical forms based on ipsilateral superior rectus muscle function. Normal superior rectus muscle function indicated the typical form, while "significant coexisting paresis of the homolateral superior rectus muscle" indicated an atypical true sheath syndrome. Brown emphasized that the clinical features of true and simulated sheath syndromes are similar, but true sheath syndrome is always congenital, and constant, and does not show spontaneous recovery. Of 126 patients, 23 were classified as having a simulated sheath syndrome. These patients demonstrated acquired symptoms (5 patients), intermittent symptoms (9 patients), and spontaneous resolution (9 patients).' Brown hypothesized that a thickened posterior superior oblique tendon or firm attachments ofthe posterior tendon sheath to the tendon behind the trochlea caused the simulated sheath syndromes. It was suggested that posterior tendon sheath pathology pre- vented the tendon from passing through the trochlea, thus restricting elevation in adduction. Congenital simulated sheath syndromes were thought to be due to anomalies of the posterior tendon or its sheath, while the acquired form was caused by inflammation from ethmoid sinusitis, a rheumatoid nodule, or idiopathic tendon inflammation. Questioning The Tight Sheath Theorj In his 1971 series, Brown reported on 36 patients who underwent surgery for true sheath syndrome.5 Surgical techniques included sheathectomy, sheathectomy with inferior oblique tuck, and marginal sheathectomy. Brown noted that surgical results were disappointing. Of the 36 patients, 5 achieved full correction, 13 some improvement, 15 no improvement, and 3 an overcorrection. Marginal sheathectomy, with repeated traction tests until the ductions were negative, was reported to be most effective. Brown's summary statement regarding the treatment of this syndrome was, "An operation is not indicated in the absence of a disfiguring head tilt or a vertical tropia."5 Papers by Parks122 and Crawford23 in the mid 1970s dramatically changed the understanding and treatment of the true superior oblique 1028 Wright tendon sheath syndrome. Both authors reported that a tight or short anterior superior oblique tendon sheath was not present. Parks found that of 24 patients with the classic clinical features of a unilateral true sheath syndrome, none had a short superior oblique sheath.' Crawford operated on 28 patients with typical true Brown's syndrome.23 Forced ductions were positive, showing restriction of rotations up and in for each case; however, none had a tight superior oblique tendon sheath. Crawford concluided that the cause of "true" Brown's syndrome was a tight or short tendon. Other reports, including a series reported by von Noorden, confirmed that a tight superior oblique tendon was the cause for what was previously termed true tendon sheath syndrome.242" Terminology Following the reports that questioned the causative role of a short tendon sheath, the term "true sheath syndrome" has, for the most part, been aban- doned in favor of the more general term, "Brown's syndrome." However, confusion ofterms continues. Some authors use the term Brown's syndrome to describe any restriction ofelevation in adduction that conforms to the pattern of strabismus listed in Table I regardless of etiology.2 Alternatively, others use a more narrow definition of Brown's syndrome and limit the term to specifically describe an elevation deficit in adduction associated with trochlear or superior oblique tendon pathology.4 For example, inferior temporal orbital fibrosis that produces the classic signs of limited elevation in adduction could be classified as Brown's syndrome. Under the broad classification it would, yet others might argue that only restriction of elevation caused by abnormalities of the superior oblique muscle, tendon, or trochlea should be called Brown's syndrome. To further complicate matters, the terms true Brown's syndrome and simulated or pseudo-Brown's syndrome are found in current strabismus literature. 2 True Brown's syndrome usually refers to a congenital form with a constant limitation and a positive traction test caused by a tight superior oblique tendon.2427 Simulated or pseudo-Brown's syndrome is a confusing term that represents acquired cases, intermittent cases, or cases not caused by superior oblique muscle-tendon pathology.2s-32 Differing terminology and the various applications of the term "Brown's syndrome" have been a source of confusion for both the novice student and the senior clinician. Differential Diagnosis Despite the ambiguity of terms, there is unanimity on specific diagnoses that should be distinguished from Brown's syndrome. Nonrestrictive causes of limited ocular elevation in adduction, such as inferior oblique muscle palsy or primary superior oblique muscle overaction, are differentiated Brown's Syndrome: Diagnosis and Management 1029 from Brown's syndrome.-4 Superior oblique muscle overaction and relatively free forced ductions are signs of inferior oblique palsy or primary superior oblique overaction, whereas Brown's syndrome is associated with minimal or no superior oblique muscle overaction and markedly positive forced ductions to elevation in adduction.2' Double elevator palsy (monoc- ular elevation deficiency) can also be confused with Brown's syndrome. Strabismus texts stress that the key to a clinical diagnosis of double elevator palsy is limitation of elevation in abduction equal to or more severe than elevation deficit in adduction.- Other causes of restricted elevation in adduction include orbital floor fracture and fat adherence to the inferi- or globe.431.33

Clinical Features of Browvn's Syndrome Since Brown's early clinical description, the reported features associated with Brown's syndrome have not changed significantly. Table II lists Brown's syndrome features recently cited by von Noorden2 and Wilson

TABLE II: CLINICAL FEATURES OF BROWN'S SYNDROME*

CONSISTENT FEATURES 1. Deficient or al)sent elevation in adducetion 2. Normal or miiiinial deficienit elevationi in aldlIuction 3. Mild elevation deficit in primary' position 4. Positive forced (luctions tip and in 5. Minimlal or nio suiperior ol)lique overaction Variable Features 6. Down shoot in aidductioni 7. Divergeince in uip gaze cauising a V-pattern (Y sul)type) 8. Widening of palpebral fissuire in addlletion 9. Anomntalouis head posture (chinl up anid contralateral face tllni) 10. Hvpotropia in primary, position

*Compiled fromivon Noordeu12 aind Wilson et al.2' and associates.4 It is interesting to note how similar they are to the features originally described by Brown (Table I).6 Limited elevation in adduction is the hallmark of Brown's syndrome and is an invariable sign.5 In cases with severe restriction, there can be a down shoot as the Brown's syndrome eye moves nasally. Other signs include full or almost full elevation in abduction, minimal or no superior oblique overaction, and positive forced ductions up and in.i The positive forced duction maneuver is a critical part of the syndrome and equals the limitation seen on ductions 1030 Wright and versions. A hypotropia may be present in primary position, and it has been reported that the size of the hypotropia is proportional to the severity of the restriction.4 Patients with Brown's syndrome often present with a compensatory head posturing, chin up, and a contralateral face turn to avoid the hypotropia that increases in up gaze and gaze to the contralateral side of the Brown's syndrome eye.5 In this position, binocular fusion is obtained and most comfortable.34 A slight head tilt also has been reported to occur in some cases.4 When forced into a gaze that produces a hypertropia, patients rarely complain of diplopia, as most have developed suppression.534 Patients who acquire the strabismus in late childhood or adulthood will experience diplopia when tropic. Some patients with acquired Brown's syndrome present with inflammatory signs including superonasal orbital pain, tenderness, and intermittent limitation of ocular elevation in adduction.542 Another feature often associated with acquired Brown's syndrome is an audible and/or palpable superior nasal click on ocular rotations up and nasal ward.42 Patients also may remark that pain is associated with this ocular movement.5 Often, this click can by felt by palpation or heard with the aid of a stethoscope. Many acquired Brown's syndrome patients will have relatively good ocular elevation in adduction when the eye is rotated around the orbit in a circular pattern, first down, then temporally, then up, and finally up and nasally. In contrast, ocular rotations in the nasal direction then up, or when starting from primary position and going straight up and nasal ward, result in severe restriction. In addition, digital pressure in the area of the trochlea can, in some cases, "unlock" and improve ocular rotations.5 Brown reported higher incidence in females (59%) than males (41%) and a right eye bias with 55% right eyes, 35% left eyes, and 10% bilateral involvement.5 Subsequent series have found an equal male/female, and right eye/left eye distribution.4'5'34434

Congenital versus Acquired Brown's Syndrome A classification of Brown's syndrome can be made on the basis of onset, congenital versus acquired.24 This is a logical distinction, because the cause, treatment, and prognosis are quite different. Congenital Brown's Syndrome. Congenital Brown's syndrome is reported to be a constant restriction that is present at birth.5 There is no associated pain or inflammation, and spontaneous recovery rarely occurs.4 The cause of congenital Brown's syndrome remains controversial. Most experts suggest there is an anomaly of the trochlea and/or superior oblique tendon. This hypothesis is based on the observation that forced ductions usually Brown's Syndrome: Diagnosis and Management 1031 become normal once the tendon is severed.1"2223 It is important to note that forced ductions are not always negative after superior oblique tenotomy. Nonsuperior oblique pathology, specifically congenital bands in the area of the inferior oblique and inferior rectus muscles, have been reported to cause congenital Brown's syndrome."'0 As in other forms of strabismus, the genetics of Brown's syndrome is not well defined.4552 Most cases present without a family history of Brown's syndrome. Of the 26 sheath syndrome cases reported by Brown in 1973,' only 2 had a positive family history for Brown's syndrome. There have been at least 8 reports in the literature of families with Brown's syndrome involving 23 patients.54'5-5 Three of the 8 reports involve monozy- gotic twins with mirror images.47"505' Hamed45 described a sister and 2 brothers in 1 family with bilateral congenital Brown's syndrome. The reported conclusion was that a subset of congenital Brown's syndrome patients may have a strong hereditary basis, transmitted either as an autosomal dominant disorder with decreased penetrance or as an autosomal recessive genetic trait. Acquired Brown's Syndrome. Acquired Brown's syndrome is associated with limited elevation in adduction that occurs after infancy.2'4 In contrast to congenital Brown's syndrome, acquired Brown's syndrome is often intermittent and can be associated with pain or a clicking sensation in the superior nasal quadrant of the orbit.53"42 Spontaneous improvement and even complete resolution have been reported in acquired Brown's syndrome.53 In some cases, acquired Brown's syndrome is idiopathic.5 In other instances, it can be associated with a systemic disease or local orbital pathology.45 Inflammatory diseases, such as rheumatoid arthritis or systemic lupus erythematosus, can cause acquired Brown's syndrome.'14""7 Local inflammation of the superior oblique tendon and trochlea can occur as an idiopathic form without systemic disease.3935"4 Scarring in the area of the trochlea from trauma or from periocular or sinus surgery can also produce Brown's syndrome.?1-7" Disorders that tighten the superior oblique tendon, such as a superior nasal mass that deflects the tendon, a superior oblique tendon tuck, or even thyroid myopathy, are other causes of acquired Brown's syndrome.77'82 A mass under the superior oblique tendon effec- tively shortens the tendon, while a myopathy causes reduced elasticity. Nonsuperior oblique tendon pathology such as a floor fracture or fat adherence secondary to inferior oblique muscle surgery can cause restriction of vertical eye movements and produce a pattern of strabismus consistent with Brown's syndrome.30"34 Even some clinical situations that would seem unrelated to superior oblique function and ocular motility can be associated with acquired Brown's syndrome.'3~'8 For example, Brown's 1032 Wvright syndrome hals been reported to occur after cardiopulmonary resuscitation and even after childbirth."3' Thus, a wide spectrum of systemic and local disorders can cause a similar pattern of strabismus.54'3 Table III lists various forms of acquired Brown's syndrome and associated systemic and local dliseases. Theories regarding possible mechanisms by which these thsorders cause restriction and the clinical featuires of Browni's syndrome are ciscussed in the section titled "Etiology of Brown's Syndrome." Anatomity of the Superior Obliquie Muscle, Tetndon, and Trocllea Understanding theories on Brown's syndrome requires knowledge of the superior oblique muscle-tendon complex anatomy and physiology. The primary function of the superior oblique mnuscle is incyclodluction, but it

TABLE III: ACQUIRED BROWN'S SYNDROME

Siysteiic Disease Dysthvroid disease Eniteropathlic ar11thropathxv,7 Huirler-Scejiee sxindrome 4 HNv3ogaminaglobulihnemia s5 Juivenile riheuiimatoid artlhritis 1:3''1 (i"".66 Licheni sclerouis et atrophicus - imorphoea Rlheumatiatoi(Iirthiritis, aduilt 3W 57,51, Ifi SI; Sjogren's syndrome Svstemic lipuis ertheflieiatosuS5s.4 6B263 '5,6 Orbital/Octular Disorders Blepharoplastv,F Caniine tootlh syndrome 76, 92 Glaucoma imilplanlt sulperior nasal (jiia(lrant 2, 22 94 NeoplasIml suiper-ior niasal orhit S'6" Orbital floor fracttire 3" Orbital traumiiiia stuperior nasal Peribtilbar ainiestlhesia " Retinal encirclinig hand Sinus sturgery7, "0 475 Sinusitis '7, IWI 101 Suiperior oblique tuick Trochleitis:3s Other Foronis Cyclic Brown's syndrome 192 Idiopathlic 1<5 Inflammatory click syndrome 5S42 Tenosinovitis of the suiperior obli(lle 3 "'3 Cardiopulmonary restsicitationi Postpartum ` Bronwn's Synsdroi-ne: Diagnosis anid AlManagetnetnt 1033 also acts as a depressor (secondary) and an abdnctor (tertiary). The superior oblique muscle origiinates at the orbital apex just above the annulus of Zinn and courses anteriorly between the roof and the medial wall of the orbit. The muscle gradually becomes tendon at the trochlea. Even though the anatomic origin is at the apex of the orbit, the fiunctional origin of the suiperior oblique is the trochlea. After passing througlh the troclhlea, the superior oblique tendon tnrins in a posterior temporal direction to course under the superior rectus muscle, inserting along the temporal bor- (ler of the snperior rectus muscle. This tendon is the longest tendon of the extraocuilar mnscles, measuring 26 mm in length. The tendon insertion fans out broadly under the superior rectuis muscle, extending from the temporal pole ofthe superior rectuis muscle to approximaltely 6.5 mmn from the optic nerve (Fig 2)."'-' The anterior tendon fibers (approximately one tlhird of the tendlon) are responsible for intorsion, wvhile the posteiior fibers produce the abduction and depression functions. Note thalt tension on the posterior tendon fibers pull the back of the eye up and in toward the troclhlea, resulting in depression and abduction of the front of the eve. Trochlea-Tendon Interaction. The trochlea is a cartilaginous "U" shlped structure attached to the periosteum that overlies the trocllear fossa ofthe frontal bone in the superior nasal quiadrant of the orbit. Within the trochlea, a connective tissue wraps around the superior oblique tenedon in an onion-skin configuration ann(iun-ites the tentlon to the surrouniidiing trochlea. This is a vascular structure an(d is referred to as the tendoni slheath. The normal function of the tendoni shealth is to limit the passage of the tendon through the trochlea.

FIGURE 2 Anatomical photograph fromi Finik of broaid inisertioni of suiper-ior oblique ten(don.' 1Note that it extends fromi siperior rectois moiscle to a few miillimieters aniterior- to optic nerve. 1034 Wright The term "trochlea" is Latin for pulley and, until recently, it was taught that the superior oblique tendon moves through the trochlea much like a rope through a pulley. Anatomic studies have shown, however, that tendon movement is not that simple.'05 Through detailed and elegant anatomic study, Helveston showed that tendon slackening distal to the trochlea comes from a telescoping elongation of the central tendon, much like the telescoping movement of a car antenna (Fig 3). Telescoping elongation of the tendon is due to movement of the central tendon fibers that have scant interfiber connections. Sutperior Oblique Tendon Sheath vs Cap.sule. Parks26 makes a distinction

FIGURE 3 Diagraim from Helveston showing telescoping mechanism of superior oblique tendon expan- sionl. Cenitral core tendon fibers are interconnected by a fev connective tissue fibers allow- ing central tendon to move freely in a telescoping manner. between the tendon sheath, a vascular connective tissue that surrounds the superior oblique tendon within the trochlea, and the avascular tendon capsule and intermuscular septum that cover the tendon distal to the trocblea toward the tendon insertion. Helveston"' also has emphasized the highly vascular nature of the sheath of the intratrochlear portion of the superior oblique tendon. Parks' stand on this point is often misunder- stood. It appears that Parks was not objecting to the term "sheath" for the vascular connective tissue within the trochlea, but he did not prefer that term to describe the avascular connective tissue of the anterior tendon.4 Parks refers to the fascia around the superior oblique tendon distal to the trochlea as tendon capsule and describes the intervening connective tissue between the superior rectus and medial rectus muscles that envelopes the superior oblique tendon as intermuscular septum.26 '' This description is Brown's Syndrome: Diagnosis and Management 1035 in contrast to descriptions by Fink,'" who termed the fascial tissue surrounding the tendon at and distal to the trochlea as the tendon sheath. This is an important concept, as "tendon sheath stripping" procedures removed the fascia along the anterior aspect of the superior oblique tendon, namely, the tendon capsule and intermuscular septum, not the tendon sheath, as described by Parks. Etiology ofBrown's Syndrome The cause of Brown's syndrome remains controversial. Etiologies can be divided into two general categories: those that involve the trochlea and superior oblique muscle-tendon complex and those that do not. The most compelling argument that a tight or immobile superior oblique muscle- tendon complex is responsible for Brown's syndrome is the high success rate of improved elevation into adduction after severing the tendon.23 As originally demonstrated by Brown,6 normal elevation of the eye into adduction increases the distance between the trochlea and the superior oblique insertion as the back ofthe eye moves down and out. A tight superior oblique tendon complex would not allow the back of the eye to move down and out and would restrict ocular elevation in adduction. Likewise, disorders that limit the normal movement of the superior oblique tendon would restrict ocular elevation in adduction. Other features of Brown's syndrome, such as divergence in attempted up gaze (V-pattern Y subtype) and down shoot on adduction, can also be attributed to a tight superior oblique tendon, since tension on the posterior fibers results in depression and abduction. Discussed next are theories regarding the causes of a tight or immobile superior oblique tendon associated with Brown's syndrome. Tight or Short Superior Oblique Tendon Theory. It has been suggested that in congenital Brown's syndrome, the tendon may have developed too short or perhaps with less elasticity than normal.2433 A tight superior oblique tendon can be caused by a mass that displaces the tendon, which is analogous to pulling on a bowstring.81'82 An acquired fibrosis ofthe superior oblique muscle, which rarely occurs, is possibly associated with thyroid disease, intramuscular injection of local anesthetic, or, very rarely, with Hurler-Scheie syndrome.7',', Tightening ofthe tendon can also occur after scleral buckling retinal detachment surgery and is often seen after a superior oblique tendon tuck.1'78 Abnormal Telescoping Mechanism. Helveston'05 suggested that limited ocular elevation in adduction associated with Brown's syndrome might be due to reduced telescoping elongation of the superior oblique tendon. Possible vascular dilatation of the tendon sheath vessels or local edema occurring within the confined area of the trochlea could restrict tendon 1036 Wrigfht movement and result in constant or intermittent acquired Brown's syndrome."5 This mechanism could explain acquired Brown's syndrome associated with local tendon inflammation. Congenital Brown's syndrome could be cauised by a developmental abnormality of the elastic cross fibers that normally allow the telescoping movement ofthe central tendon fibers.

Superior Oblique Click Syndro)me. Roper-Hall and Roper-Hall42 described an interesting variation of Brown's syndrome, called the "superior oblique click syndrome." These investigators hypothesized that inflammation produces a nodule on the superior oblique tendon just posterior to the trochlea. The nodule would have difficulty entering the trochlea, thus restricting tendon movement. These authors have found that, at times, patients would have a Brown's syndrome, where at other times they would have a superior oblique paresis. Digital pressure in the area of the trochlea and superior oblique tendon often reveals a bump when the eye moves up and in, usually resulting in pain to the patient. Tendon swelling could occur in association with local or systemic inflammatory disease or as a congenital anomaly ofthe tendon. This theory has been used to explain acquired Brown's syndrome associated with inflammatory conditions such as sinusitis, rheumatoid arthritis, and lupus erythematosus.36'54'

Stenosing Tenosinovitis-Trigger Thumb Analogy Theory. Sanford-Smith3 have theorized that chronic movement of the superior oblique tendon through the trochlea can result in a traumatic tenosynovitis with tendon swelling and stenosis of the surrounding tendon sheath. This would restrict tendon movement and result in limitation of ocular elevation in adduction. This "wear and tear" theory has been used to explain idiopathic acquired Brown's syndrome and those cases associated with a click.37"3 Wilson, Eustis, and Parks4 elaborated that Brown's syndrome may be analogous to congenital trigger thumb. Trigger thumb is a congenital or acquired constriction or stenosis of the fibrous sheath surrounding the tendon and a secondary enlargement of the tendon proximal to the edge of the constriction.'11'7, The combination of sheath stenosis and tendon swelling prevents movement ofthe tendon. Congenital Brown's syndrome could be caused by a similar condition with congenital stenosis of the superior oblique tendon sheath and an enlargement of the tendon posterior to the trochlea.

PeriTrochlear Scarring. Scarring or fibrosis between the trochlea and anterior superior oblique tendon could tether tendon movement and cause Brown's syndrome.729"93 This theory has been used to explain Brown's Syndromle: Diagnosis and Management 1037 acquired Brown's syndrome, especially in cases associated with superonasal orbital trauma.72' Extensive scarring around the trochlea can result in restriction of tendon movement in both ways, resulting in both a Brown's syndrome and a superior oblique palsy."',9' A case report on the histopathology of acquired idiopathic Brown's syndrome, associated with superior nasal pain and a click, revealed normal intratrochlear anatomy and no inflammatory cells within the trochlea or the surrounding tendon fascia.""' The only pathologic finding was circuimferential scarring around the superior oblique tendon anterior to the trochlea. It was concluded that restricted elevation and the pain and click were attributed to movement of the tendon through the surrounding scarred connective tissue."'0 NonSiuperior Oblique Tendon Etiologies. Some patients with Brown's syndrome have restriction of ocular elevation in adduction that is not caused by superior oblique pathology. Severing the superior oblique tendon in these cases does not improve forced ductions.' Inferior orbital fibrous adhesions to the posterior globe can limit elevation in adduction and produce the typical signs of Brown's syndrome.' Causes of inferior adhesions include orbital floor fracture, fat adherence syndrome associated with inferior orbital trauma, and congenital bands.'"'"33 Girard"' reported on a patient with the typical features of Brown's syndrome, but the cause of the restriction was an anomalous check ligament at the insertion of the inferi- or oblique muscle. Parks and Brown2 found that of 24 patients with true sheath syndrome (congenital Brown's syndrome) having "absolute resist- ance" to passive elevation in adduction, only 2 had a taut superior oblique tendon. The other 22 patients with limp superior oblique tendons had all 6 extraocular muscles surgically explored, and the anatomy was normal except for 1 patient with anomalous bands to the inferior rectus muscle. The bands were located 20 mm posterior to the inferior rectus muscle insertion and extended from the orbital floor to the inferior rectus muscle capsule. Severing the bands improved the traction test at the time of surgery but did not improve postoperative ductions. The authors speculated that posterior anomalous bands of the posterior globe in the area of the optic nerve were responsible for the restriction in the 22 cases where the superior oblique tendon was limp. Thus, the clinical signs of Brown's syndrome does not necessarily indicate pathology of the superior oblique muscle-tendon complex or trochlea. Rabb"' reported on an unusual case of Brown's syndrome not truly being a tight superior oblique tendon. This case was caused by an anomalous fibrous band between the superior oblique tendon sheath and the upper nasal intermuscular quadrant. This unusual anomaly resulted in functional shortening of the sheath and resulted in Brown's syndrome. 1038 Wright Management ofBrown's Syndrome Surgical Treatment. A conservative or nonsurgical approach to Brown's syndrome is commonly recommended."' Von Noorden2 suggests that surgery be performed only if there is a hypotropia in primary position, a significant anomalous head posture, and when Brown's syndrome is congenital and constant. The presence of a down shoot alone is not an indication for surgery.2 The major reason for a conservative approach is the relatively poor surgical outcomes.,2,21 " As stated above, removal of the tendon sheath is generally not effective.2223 In an attempt to improve results of removing the sheath, Scott and Knapp"'2 surgically stripped the sheath, then used silk traction sutures to hold the eye up and in for several days. This procedure did not become popular because it was very uncomfort- able for the patients, and it only provided some improvement of ductions in approximately half of the patients. Tenotomy or tenectomy has proven to be much more effective in improving ductions than sheathectomy; however, severing the superior oblique tendon can be an unpredictable procedure, with the major problem being a secondary superior oblique paresis.Y'26'32 The incidence ofpost- operative superior oblique palsy is reported to be between 50% and 85%.241544 This problem is so pervasive that Parks and Eustis added a simultaneous ipsilateral inferior oblique recession along with a superior oblique tenotomy to reduce the incidence of secondary superior oblique palsy. Another strategy designed to loosen the superior oblique tendon without causing a significant superior oblique paresis includes making a suture bridge between the cut ends ofthe tendon after a tenotomy."' Dyer2' suggested the use of a 5 to 6 mm suture bridge to keep the cut tendon ends from separating too much, thus avoiding a consecutive superior oblique paresis. Unfortunately, the suture bridge can act as scaffolding for fibrosis to reunite the cut tendon ends, resulting in undercorrections. Superior oblique recession has been used and described as a procedure that can produce a graded slackening of the tendon."3"'6 Results with this procedure are mixed, as undercorrections are common and limitation of depression a frequent complication.26 Slackening the tendon by removing it from the trochlea has also been reported."9 In that study, 3 of 4 patients with acquired Brown's syndrome showed improvement after superior oblique and trochlear luxation."9 In 1989, the silicone tendon expander procedure was introduced. In this procedure, the superior oblique tendon was elongated by inserting a segment of a silicone retinal 240 band between the cut ends of the tendon.'20"12' Preliminary results were encour- aging but lacked significant follow-up, and only 3 cases of true Brown's syndrome were reported.'22 Clarke and associates'23 reported good results with the silicone tendon expander procedure in 2 patients, one of whom Brown's Syndrome: Diagnosis and Management 1039 had Brown's syndrome. Also, in 1995, Wilson and colleagues'24 reported on 2 patients with postoperative down gaze restriction after placement of a silicone spacer for acquired Brown's syndrome. Medical Treatment ofAcquired Brown's Syndrome. Acquired Brown's syndrome is usually treated conservatively.2'4 If a coexisting local or systemic disease is present, it should be treated.2 It has been reported that treatment of a concurrent sinusitis can cure the associated Brown's syndrome in some cases. Inflammatory diseases, such as rheumatoid arthritis, systemic lupus erythematosus, or superior oblique tenosynovitis, require the use of an anti-inflammatory. Anti-inflammatory treatment includes local steroid injections in the area of the trochlea, systemic nonsteroidal anti-inflammatory (ibuprofen), and oral corticosteroids.2'-' Because ofthe relatively poor results related to surgery and reported cases of spontaneous resolution, many have advocated a conservative approach to acquired Brown's syndrome.2'4'89 Gregersen-3 reported on a longitudinal, long-term study of 10 patients with idiopathic acquired Brown's syndrome arising during the first or second year of life. Patients were followed for an average of 13 years, and each patient had a mean of 9 examinations. Three of the 10 patients showed spontaneous cure while 6 others showed some improvement with reduction of the initial hypotropia, but those patients still showed limited elevation in adduction. One patient showed no improvement. Sensory state at the last examination revealed 4 of 10 with normal binocularity, 2 with peripheral fusion, and 4 with alternating suppression.

METHODS There are 4 major components of the methods in this thesis on Brown's syndrome: 1. Chart review, including review of surgical outcomes. 2. Study of objective fundus torsion. 3. Survey of members of the American Association of Ophthalmology and Strabismus on outcomes of the superior oblique tendon expander procedure. 4. Computer model of Brown's syndrome with clinical correlation.

I. CHART REVIEW A chart review of Brown's syndrome patients was performed, including patients seen between 1982 to 1997 at a children's hospital ophthalmology outpatient clinic and patients seen in private practice by the author. A card file listing all consecutive Brown's syndrome cases seen at the chil- 1040 Wright dren's hospital outpatient clinic consisted of 59 patients. After approval from the hospital's Institutional Review Board, charts were retrieved from the medical records department, and the chart review was performed on the hospital grounds; charts were not removed from the premises. Of the 59 charts, 54 were available for review and 49 of those charts contained enough information to complete the data sheets created for this review. The patients from the children's hospital card file were seen by designat- ed professionals: the author (approximately 75% of patients), a senior orthoptist, or a pediatric ophthalmology staff physician. In addition, 47 patient records were obtained from the author's private practice files on Brown's syndrome. Patients with iatrogenic Brown's syndrome after a superior oblique tendon tuck were excluded, as the diagnosis was obvious. Patients were categorized by onset of Brown's syndrome according to history provided by the patients or patients' parents. Patients with an onset at less than 1 year of age were considered congenital and all others considered acquired. Patients with congenital Brown's syndrome were further subdivided into 4 groups: nonsurgical, silicone tendon expander surgery, superior oblique tenotomy, and torsion study. Patients diagnosed as having acquired Brown's syndrome were divided into 6 separate categories: 1. Accidental orbital trauma. 2. Periocular surgery. 3. Sinusitis 4. Pain and click. 5. Idiopathic acquired Brown's syndrome. 6. Idiopathic acquired Brown's syndrome who underwent superior oblique expander procedure. Clinical descriptions of duction limitations were rated on a scale of -1 to -4, with -4 being the most limited, as the eye could not move past midline. Superior oblique function was graded on versions and rated on a scale of -4 to +4. The -4 rating means maximum underaction where the eye does not depress past midline when the contralateral eye is abducted and depressed, and +4 means maximum overaction where the eye overdepresses maximally when the contralateral eye is in straight abduction. A- and V-patterns were assessed clinically, with an A-pattern being more divergence in down gaze by at least 10 prism diopters (PD) and a V- pattern being more divergence in up gaze by at least 15 PD. These clinical descriptions are published elsewhere.44"'5 Strabismus measurements were taken using prism and alternate cover testing. Stereoacuity was obtained using the contour figures by the Titmus stereoscopic fly, animals, or circles. Brown's Syndrome: Diagnosis and Management 1041 Surgical Outcomes The author performed the silicone tendon expander on 15 patients from 1987 to 1997 for Brown's syndrome.'26 Data on these patients were obtained from chart review as described above. In 1998, patients were called by telephone to obtain a current follow-up examination. Data on 6 Brown's syndrome patients who had undergone superior oblique tenotomy also was obtained by chart review. Of the patients who underwent a superior oblique tenotomy, 1 patient (C28, Table VI ) was operated on by the author and the others by local pediatric ophthalmologists. Silicone Tendon Expander Technique. The silicone tendon expander procedure consists of elongating the superior oblique tendon by performing a tenotomy and then inserting a segment of medical grade silicone 240 retinal band between the cut ends of the tendon (Fig 4). Critical to the success of this procedure is placing the silicone implant within the tendon capsule without disrupting the floor of the tendon capsule. Disruption of the tendon capsule floor can result in postoperative adherence of the silicone to sclera. A conjunctival incision is made temporal to the superior rectus insertion point. A second incision is made through the intermuscular septum. The superior rectus muscle is then hooked from its temporal border, and the eye is retracted inferiorly. The conjunctival incision is then retracted nasally to expose the nasal intermuscular septum. A small Desmarres retractor is placed within the conjunctival incision, and the conjunctiva is retracted posteriorly to expose the nasal aspect ofthe superior rectus mus-

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FIGURE 4 Silicone tendon expander procedure: Diagram shows a segment of silicone 240 retinal band being sewn to cut ends of superior oblique tendon. A tenotomy and placement of silicone implant is done 3 mm nasal to the superior rectus muscle. 1042 Wright cle. The nasal intermuscular septum is left intact. By direct visualization and palpation, the superior oblique tendon is identified on the nasal aspect of the superior rectus muscle. Using a fine forceps, the superior oblique tendon capsule is elevated, and the Westcott scissors are used to open the tendon capsule. The superior oblique tendon fibers are then identified and a Steven's hook is passed behind the tendon fibers. The tendon is elevated into the surgical field. A second Steven's hook is used to pass under- neath the superior oblique tendon without violating the floor of the tendon capsule. Two Steven's hooks are then separated to expose the superi- or oblique tendon. Three millimeters nasal to the superior rectus border, a 5.0 Mersilene suture is passed through the superior oblique tendon with locking bites placed at each edge of the tendon, and the Mersilene is tied together to secure the tendon. A second Mersilene suture is placed in an identical manner 2 mm nasal to the first suture. Westcott scissors are used to perform a superior oblique tenotomy. Exaggerated forced ductions, described by Guyton,127 are then performed to make sure that the entire tendon has been transected. The preplaced Mersilene sutures attached to the cut ends of the tendon are then sutured to each end of a segment of silicone 240 retinal band using a horizontal mattress suturing technique. The silicone is tied in place, bringing the ends of the tendon against the ends of the silicone segment. The tendon capsule is then closed using 6.0 plain gut sutures on the nasal aspect of the superior rectus muscle. The temporal intermuscular septum and conjunctival incisions are also closed with 6.0 plain gut interrupted sutures. Corticosteroid-antibiotic ointment was placed in the eye postoperatively. Description of Superior Oblique Tenotomy. The superior oblique tenotomy was performed on the nasal side ofthe superior rectus muscle in each case.'26

II. OBJECTIVE FUNDIS TORSION A subgroup of study patients was examined specifically for the pattern of fundus torsion. The subgroup included 7 Brown's syndrome patients and 4 patients with primary superior oblique overaction. Using indirect oph- thalmoscopy, the author examined all patients in the fundus torsion study. Objective fundus torsion was assessed after full pupillary dilatation was done during the patient's routine ophthalmic examination. Patients were examined for fundus torsion in primary position, up gaze, and down gaze, and measurements were recorded on a work sheet. Normally, the fovea is aligned with the lower third of the optic disc (direct fundus view).62s Intorsion is identified if the fovea is located above the lower third of the optic disc.-2' The scale is 0 for no torsion to +4 for intorsion, which means the fovea is higher than the superior pole of the optic disc.'28 Extorsion, Brown's Syndrome: Diagnosis and Management 1043 recorded as a minus sign (-), is noted when the fovea is below the inferior pole of the optic disc. In one patient (C36), fundus photographs were taken to document objective retinal torsion.

III. SURVEY OF AAPOS MEMBERS ON SILICONE TENDON EXPANDER A survey form was faxed to all AAPOS members listed in the 1997-1998 directory with an operating fax number regarding their use of the silicone tendon expander; 120 members responded to the survey by returning the form. The form included questions regarding preoperative ductions, postoperative ductions, length of follow-up, complications, and overall assessment of outcome on a 1 to 10 ranking, with 10 being best. It also asked for incidences of subsequent superior oblique palsy. A section was provided for comments on complications and overall impression of the procedure. The fax form specifically did not have a place for the member's name so that the form could be returned anonymously. The results were tabulated using Microsoft Excel.

IV. COMPUTER SIMULATION OF BROWN'S SYNDROME Computer simulation of Brown's syndrome was created using the Orbit 1.8 Program.'29'l34 Orbit 1.8 is a computer simulation program that uses math- ematical analysis oforbital and muscle anatomy and physiology to simulate eye movements.'29'130 The Orbit 1.8 program was run on a Power Macintosh 7200/120. Orbit 1.8 is written in SQUINT computational code and Lancaster chart analyses were printed on a Epson Color Stylus 850 printer. Brown's syndrome was simulated by shortening superior oblique tendon length or by changing stretch sensitivity to create a stiff, inelastic muscle. The tendon length was shortened from the normal 32 mm to 22 mm. Stretch sensitivity is a measure of muscle stiffness and was increased from the normal value of 100% to 200%, 225%, 250%, 275%. Lancaster chart printouts reflected the simulated strabismus created by changing either the tendon length or stretch sensitivity. These Lancaster charts were used to compare the computer model to the pattern of strabismus seen in patients with surgically verified superior oblique caused Brown's syndrome. Surgical treatment of Brown's syndrome was simulated in the altered stretch sensitivity simulations by progressively elongating the tendon until a superior oblique paresis was created.

RESULTS

I. CHART REVIEW A total of 96 patients were retrospectively studied: 38 with congenital Brown's syndrome, 47 with acquired Brown's syndrome, 6 with masquer- 1044 Wright ade Brown's syndrome, 1 with postoperative complications of the silicone tendon expander, and 4 with primary superior oblique overaction (Tables IV through XIX). The 6 patients with masquerade Brown's syndrome were initially identified as having Brown's syndrome but at surgery were found to have negative forced ductions. The patient with postoperative complications of the silicone tendon expander procedure was operated on elsewhere for Brown's syndrome, not primarily seen by the author. Four patients with primary superior oblique overaction were included in the torsion study for comparison to Brown's syndrome patients. Thus, of the 96 patients studied, 85 were classified as having Brown's syndrome (Tables IV through XIII). These 85 patients showed a relatively even sex distribution, with 41 males and 44 females. There was a slight bias for right eyes, with 46 right eyes, 35 left eyes, and 4 bilateral. The slight bias for right eyes was not statistically significant (P<.50). Limitation of elevation in adduction ranged from -1 to -4 (scale, 0 to -4), with 78 of 85 (92%) demonstrating a severe deficit of -3 or -4. Only 1 patient (A16) had -1 limitation of elevation, and this patient's presenting symptom was pain on attempted elevation in adduction. Elevation in abduction was rated in 83 patients and, of these, 35 (42%) were rated as full, 28 (34%) as -1, 15 (18%) as -2, and 5 (6%) as -3. Superior oblique function was documented in 79 patients. Superior oblique function was minimal (within ±1) in 70 of 79 patients (89%); 6 patients had -2 superior oblique underaction, and 3 patients showed +2 superior oblique muscle overaction. Ofthe 85 Brown's syndrome patients, 81 had statements regarding the presence of an A- or V-pattern. Twenty- four patients (30%) showed a V-pattern, 1 patient (<1%) an A-pattern, and 56 patients (69%) showed no significant pattern. Amblyopia was uncommon and found in only 3 (4%) ofthe 85 Brown's syndrome patients studied. In 2 congenital cases (C22 and C26), amblyopia was attributed to anisometropia, and in one acquired case (All), to strabismic amblyopia, as this patient had a history of infantile esotropia.

CONGENITAL BROWN'S SYNDROME Thirty-eight patients were classified as having congenital Brown's syndrome with age at onset less than 1 year (Tables IV through VII). Thirty- six patients had unilateral involvement (22 right eyes and 14 left eyes), and 2 patients had bilateral involvement (C4 and C14). In 31 of 38 patients (82%), the onset was recorded as occurring at birth. Of the 38 congenital Brown's syndrome patients, 26 had a notation regarding family history, and in 9 (35%), a relative was noted to have amblyopia or strabismus. One of these patients (C12) had a sibling with Brown's syndrome. Stereoacuity results were obtained in 26 of 38 patients, with 21 (81%) Brown's Syndrowne: Diagnosis and Management 1045 demonstrating stereopsis ranging from 40 to 3,000 seconds arc. The deviation in primary position was documented in all 38 patients. Of these, 15 (39%) were orthotropic, 6 (18%) had a horizontal strabismus of greater than 10 PD (range, esotropia [ET] 35 to extropia [EX] 30 PD), and 5 (13%) had a vertical deviation greater than 5 PD (range, 0 to 15 PD). Limitation of elevation in adduction ranged from -2 to -4. Only 1 patient (3%) had a -2, 5 patients (13%) a -3, and 32 patients (84%) had a -4. In each patient, the hypotropia was much greater in up gaze than in primary position or down gaze (Fig 5).

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FIGURE 5 Left coingeniital Brown s syndrome (patient C23). Note dowvn shoot of left eye in right gaze and marked limaitation of left eye to elevation in addtiction. There is + 1 pseudoinferior obliqnie overactioni, right eye. Note, psetdo-esotropia in up gaze as patient is looking to right.

Twenty-two of the 38 congenital Brown's syndrome patients did not have strabismus surgery. Follow-up between 12 and 60 months (mean, 30 months) was obtained on 5 of these patients (Cl, C4, C6, C14, and C16). All 5 patients continued to have significant limited elevation in adduction at the last examination. Four of the 5 patients had -4 limitation on the last examination, and one (C14) with bilateral congenital Brown's syndrome demonstrated constant ratings of -4 in the right eye, but variable ratings in the left eye of -1 to -4 during the follow-up period of 48 months. The last examination at 7 years of age showed limited elevation in adduction of -4 right eye and -2 left eye. Other clinical findings included one patient (C2) with an ipsilateral superior oblique paresis in conjunction with the Brown's syndrome, and one patient (C5) had a cerebral arterial venous malformation that required neurosurgery. 1046 Wright

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ACQUIRED BROWN'S SYNDROME Forty-seven patients were classified as having acquired Brown's syndrome, 11 associated with trauma (accidental or surgical) and 36 without trauma (Tables VIII through XIII). Age at onset ranged from 6 to 65 years (mean, 29 years) for 10 patients in the trauma group (one did not have a specified age), and from 1 to 13 years (mean, 3.7 years) in 23 patients of the non- trauma group whose parents could provide a specific age at onset. Non- trauma cases were classified into the following groups: sinusitis, pain and click, idiopathic acquired Brown's syndrome, and idiopathic Brown's syndrome that underwent silicone tendon expander procedure. Stereoacuity was recorded on 36 of 47 acquired Brown's syndrome patients, and 26 (72%) demonstrated stereopsis between 40 and 3,000 seconds arc. Only one of the 47 acquired Brown's syndrome patients had strabismic amblyopia associated with coexisting infantile esotropia. Seven acquired Brown's syndrome patients had a computer tomo- graphic scan (CT) or magnetic resonance imaging (MRI) that indicated the following: one sinusitis, 1 an enlarged superior oblique tendon, 1 fat enhancement around the trochlea, and 4 negative scans.

Trauma Group Accidental Orbital Trauma. Six patients had accidental trauma associated with acquired Brown's syndrome (Table VIII). Canine tooth syndrome was diagnosed in 3 patients, with 2 caused by a metal hook injury to the superior oblique tendon (Al and A2) and 1 from a dog bite (A3). Patients with canine tooth syndrome all had small deviations in primary position of 5 PD or less and demonstrated a coexisting ipsilateral superior oblique paresis (-2). Rectus muscle surgery was performed on all 3, but ductions did not significantly improve. Blunt orbital trauma occurred in 2 patients (A4 and A6), and 1 patient (A5) sustained a penetrating injury to the inferior orbit. Patient A6 had an acquired Brown's syndrome after surgical reduction of a frontal sinus fracture and had the largest hypertropia (left hypertropia [LH] 30 PD) of the Brown's syndrome patients. Patient A5 had infraorbital adhesions in the area ofthe inferior rectus and inferior oblique muscles that were the cause of the Brown's syndrome. Periocular Surgeny. In 5 patients, Brown's syndrome was acquired after peri-ocular surgery: one from a 3600 scleral buckle, one after a reoperation upper lid blepharoplasty (Fig 6), one from an inferior oblique weakening procedure, and 2 from glaucoma implants (Table IX). This group had a large deviation in primary position, with 3 of 5 having a significant horizontal deviation (XT, 15-45 PD) and all 5 showing a significant vertical deviation (right hypertropia [RH], 10-20 PD). Patients A7 and A8 had 1050 Wright o WK C)C _a

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FIGURE 7 Patient (A8) wvith left Molten(o implant, left superior nasal (lladranit, anid left acquired Brown's syndrome. A, In right gaze, there is a left hypotropia. anid oni clinlical examiinlationi, left eye does not elevate well inl adduictioni. B, Large bleb over Molteno implant cauising a inass in suiperior nasall (iliadrant. 1052 Wright

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o 1- oo (0- Brown's Syndromne: Diagnosis and Management 1053 scarring and adhesions to the globe, approximately 8 to 10 mm from the limbus. Approximately one third of the inferior oblique muscle was scarred to anterior sclera about 10 mm posterior to the limbus. Ductions improved after removal of scar and the inferior oblique muscle from the sclera.

Non Trauma Group Sinusitis. Four patients had acquired Browni's syndrome associated with sinusitis (Table X). In one case (A14), the Brown's syndrome was bilateral and symmetric. The deviation in primary position was small, with 3 of the 4 patients being orthotropic and one (A12) having a left hypertropia (LHT) 2 PD. Follow-up was obtained in 3 of the 4 patients and ranged from 3 to 24 months. Patient A13, a 46-year-old, did not have direct follow-up but, by history, has lived with Brown's syndrome since childlhood. Only patient A12 demonstrated some improvement of ductions, going from -4 to -3 over a 24-month period. This patient's parents gave a clear history of an acute onset of Brown's syndrome along with acute sinusitis. Patient A15 might have worsened slightly over a 12-month period, going from a -3 to -4.

Pain and Click. Seven patients had either superonasal pain on eye movements (4 patients), a click on ocular rotation up and nasal (1 patient), or both click and pain (2 patients) (Table XI). Onset ofthe Brown's syndrome varied between 1 year and 13 years of age (not necessarily coincidental with the painl or click). Treatmnent included, as needed, oral nonsteroidal anti-inflammatory drugs, such as ibuprofen, and in one patient, a course of oral corticosteroids. Follow-up was obtained for 4 of the 7 patients and ranged from 24 to 48 months, with a mean of 37.5 months. Of these, 2 showed significant improvement over time, with patient A21 showing duction improvement and resolution of pain over 48 months. Patient A22 experienced spontaneous resolution of pain and duction restrictions from -3 to -1 over a 30-month period. Virtually all gave a history of variable or intermittent symptoms (Fig 8). Idiopathic Acquiired Brown's Syndrome. Twenty-five patients were classified as having idiopathic acquired Brown's syndrome (Tables XII and XIII). Onset ranged between 1 and 8 years of age, with 13 of 15 patients (87%) noting a history of a specific onset between 1 and 3 years of age. The vertical deviation in primiary position ranged between 0 and 10 PD. Only 2 of 25 patients (8%) had a deviation greater than 5 PD, and 17 of 25 (68%) were orthotropic. Three patients had esotropia associated with hyperopia. Four of the 21 patients underwent surgery with the silicone tendon expander procedure. Of the 21 who did not have surgery, 6 had 1054 Wright

FIGURE 8 Patient (A17) with acquired intermittent left Brown's syndrome. Left photograph shows relatively good elevation to adduction left eye. Right photograph was taken a few minutes later and shows left eye now with significant limitation of elevation to adduction. This child had an intermittent acquired Brown's syndrome with pain in superior nasal quadrant. follow-up ranging from 6 to 84 months. Improvement of ductions was recorded in 3 patients (A31, A42 and A43), and 2 of these showed complete spontaneous resolution without treatment. Patient A42 had -4 limitation to ocular elevation in adduction at age 3 years of age, then gradually improved to normal ductions spontaneously at 5 years of age (Fig 9). Patient A43 had acute onset of Brown's syndrome with -4 limitation of ocular elevation in adduction after bilateral lower limb fractures sustained when the patient was run over by a car at 8 years of age (Fig 10). The Brown's syndrome remained stable for approximately 8 months and then resolved spontaneously at 10 months without treatment.

CONTRALATERAL PSEUDO-INFERIOR OBLIQUE OVERACTION Apparent contralateral inferior oblique overaction was seen in patients with limitation of elevation in abduction and specifically in patients C18, C21, C23, C42, and A43 (Fig 5, 9A, lOB, llA, and 12A). Apparent infe-

FIGURE 9 Three-year old child (A42) with acquired right Brown's syndrome and spontaneous resolution. Left, Marked limitation of elevation in adduction right eye. There is pseudo-overaction of left inferior oblique. Right, Six years later, child has normal eye movements, no Brown's syndrome. Mother notes that Brown's syndrome improved over a 2-year period. Brown s Syndromne: Diagnosis and Management 1055

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FIGURE 10 Eight-year old boy (A43) sustained bilateral lower extremnity fractures when his legs were run over by a car. Left, A few weeks after the injury, parents nioted new oniset of a cihin elevatioll. Note marked clhinl elevation in this plhotograph taken wvlile the patient wvas still in leg casts. Right, Examination a few weeks after the injury showed a left Brown's syndronme. Note marked limitation of elevation in adduietion, left eye, and(I inild limitationi ofelevation in abduction thalt causes a pseudo-overaction of right inferior ol)li(que. Brown's syn-drome remained stable for approximately 8 months anid, at 10 months, post-injury resolved spolntaneously. rior oblique overaction disappeared postoperatively in patients C18, C21, and C42 who underwent the silicone tendon expander procedure, reliev- ing the superior oblique restriction (Fig 9B, lIB, 12C).

MASQUERADE BROWN'S SYNDROME Six patients underwent strabismus surgery for limited ocular elevation with the diagnosis of possible Brown's syndrome, but forced ductions at the time of surgery were negative, indicating a nonrestrictive strabismus. Subsequent to the surgical findings, 3 patients were diagnosed with unilateral inferior oblique paresis (Table XIV) and 3 patients with bilateral superior oblique overaction (Table XV). All of the bilateral cases and 2 of the unilateral cases had an A-pattern lambda subtype. The unilateral cases had large hypertropias in primary position measuring 16 to 25 PD. Superior oblique overaction of +2 to +4 was present in each case (Fig 13). Head tilt testing was not recorded.

SILICONE TENDON EXPANDER RESULTS The silicone tendon expander procedure was performed on 15 Brown's syndrome patients by the author (Tables V, XIII, and XVI). The length of the silicone implant ranged from 5.5 to 7.0 mm, with 11 of 15 implants measuring 6 mm. Patient C22 also underwent a contralateral lateral rec- Brown 2s Syndrome: Diagnoqsi.s atnd Managemnent 1059

TABLE XIV: NMASQUERADE BROWN'S SYNDRONIE - UNILATERAL INFERIOR OBLIQUE PARESIS

CODE DEV PRIMI DEV EL SO PATTERN FD UP DEV DOWN ADD FUNC lOP I LH16 LHl15 XiO0 LH30 X20 -2 +4 A-Lamb nieg IOP 2 RH25 X5 lRHI-i X3 RH18 X4 -4 +4 nione ineg IOP 3 LH20 XIO LI112 XIO X20( -4 +2 A-Lamiib neg A-Lamiib, A patterii lambda stubty,pe; Dev clown, deviation in dovnigaze;Dev tup, (le-viation in nipgaze; IOP, unilateral iniferior obliqnie palsy; LH, left hvlpertropia; RH, rigbt bvpertropia; SO, suiperior olblique foiniectioni; X, extropia.

TABLE XV: MIASQUERADE BROWN'S SYNDROME - BILATERAL SUPERIOR OBLIQUE OvERACTION

CODE DEV PRINI DEV EL EL SO PATTERN FD UP DEV DOWN ADD ABD FUNC

BSO 1 E30 E:30 oi-tbo -3/-3 -1/-1 2/3 A-Lamab Neg BSO 2 E20 E18 ortbo -3/-3 NA 3/3 A-Lamlb Neg BSO 3 X5 X 10 X40 -3/-4 -(/-0 4/4 A-Lam-b Nec A-Lamnb, A patterni lamiibda subtypc; BSO, bilateral superior obli(que overation; Dev down, deviation in d0xow17 gaze; Dev primii, deviation in primllary positionl; Dev uip, dexiation in upgaze; E, esotropia; El al)d, elevation ill ablduction; El add, elevation in addntictioni; FD, forced due- tionis; Ortbo,ortbotropia; SO. sliperior oblique funcltstion; X, exotropia. tuis muscle recession to treat a coexisting exotropia. Ten patients had congenital Brown's syndrome, and 5 had acquired Brown's syndrome. One of the acquired cases was secondary to orbital trauma, and the other 4 were idiopathic. None of the acquired Brown's syndrome patients had evidence of inflammation. Indications for surgery in the congenital grouip included correction of compensatory head posturing in 9 cases and establishment of fuision in 1 patient with a large hypertropia. Indications for surgery in the 5 patients of the acquired group included diplopia in 1, compensatory head posturing in 3, and establishment of fusion in 1 patient with a large hypertropia. Preoperative ocular elevation in adduiction was -4 in 14 patients and -3 in 1 patient. Follow-up after surgery ranged from 1 month to 134 miioniths (11 years), with a mean of 35 months. Follow-up was at least 10 mionths for 11 of the 15 patients, more than 5 years for 5 patients. Forced Dulction.s In each of the 15 cases, forced (luctions performed prior to superior oblique tenotomy were positive for restriction of ocular rotation up and nasal and matched the preoperative clinical limitation of ductions. In 13 1060 Wright

FIGURE 11 This patient (C21) has longest follow-up of silicone tendon expander group at 11 years. A, Preoperative composite photograph of eye movements showing fight Brown's syndrome. Note severe limitation of elevation of fight eye in adduction and down shoot in straight left gaze. Patient underwent silicone tendon expander, 6 mm, fight eye. B, Postoperative photograph 3 years after surgery showing full ocular motility. C, postoperative photograph 11 years after surgery showing continued normal ocular motility.

FIGURE 12 Right congenital Brown's syndrome (C18) that demonstrated late improvement after silicone expander procedure. A, Preoperative composite photograph showing severe limitation ofelevation in adduction, right eye. Also note down shoot of right eye in straight left gaze. Patient underwent 6 mm silicone tendon expander, right eye. B, Postoperative 2 months, note significant residual right Brown's syndrome. The down shoot in adduction has improved. C, Postoperative 7 months, elevation in adduction has improved greatly, almost normal versions. Brown's Syndrome: Diagnosis and Management 1061

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FIGURE 13 Bilateral primlary stiperior obli(ltie overactioin anid limited elevationi in addoletioin (patienit BSO 3). This case was initially diagniose(d as bilateral Brown's syvndroine. Suiperior obliquie overactioni is so severe, the ncasal eye disappears on1 versions(dowvni anid to either side. of the 15 cases, the restriction was released, and forced dnctions became free after the superior oblique tenotomy part of the procedure. In 2 patients (C24 and A6), however, forced ductions remained positive even after a complete tenotomy, indicating a nonsuperior oblique contribution to the etiology of the Brown's syndrome. Silicone Tendlon Expander Clinical Outconme Elevation of ocular rotation in adduction improved from -4 to normal or + 1 in 10 of the 15 patients. Abnormal versions (more than + 1) were secondary to undercorrection in 3 patients and to a consecutive superior oblique paresis with +2 inferior oblique muscle overaction in 2 patients. An inferior oblique muscle recession was subsequently performed on one of the patients with a superior oblique paresis (C23), resulting in -1 inferior oblique muscle underaction. Of the 3 undercorrected patients, 2 patients (C24 and A6) had nonsuperior oblique causes for the restriction, as forced ductions were not free after tenotomy. Patient C24 underwent a second operation to explore for residual superior oblique tendon fibers that might be responsible for the undercorrection. No residual tendon fibers were found; the silicone was removed and a superior oblique tenectomy performed. Forced ductions remained restricted even after tenectomy, and the patient continued to have postoperative limitation of elevation in adduiction (Fig 14). The cause ofthe restricted eye movements was thought to be an inferior orbital adhesion, although this was not substan- tiated. Patient A6 sustained a frontal fracture, and after repair of the injury, the patient developed a large left hypotropia of 30 PD. Superior oblique tenotomy improved ductions at the time of surgery, but they were not normalized. Postoperatively, the vertical deviation improved, as the patient only had a right hypertropia of 5 PD; elevation in adduction, however, remained restricted because of orbital scarring. The preoperative vertical deviations ranged from 0 to 30 PD, with 10 Brown's Syndromle: Diagnosis and Alatangemenet1t1063

FIGURE 14 Patient (C(24) Nith aI nonstiperior obliquie tein(lon cattiuse of Browns svnldrolme in riglht eve. Tlhis patienit haid persistent positive force(d duictions eveni af'ter superior ohlique tenotoniv. Cause of linilite(l elevation in a(ldllction was never (leteriiniile(l. of 15 patients measuring 4 PD or more; only 3 had no vertical deviation in primarv position. Postoperative vertical alignment improved to a range letween 0 and 1(0 PD, with 10 of 15 patients having a deviation of 2 PD or less, incluiding 9 with no vertical deviation in primary position. Postoperative stereoacuity was recorded in 11 of the 15 congenital Brown's syndrome patients, and all but 2 demonstrated stereopsis ranging from 40 to 400 seconds arc. The 2 without stereoacuity did not have stereopsis preoperatively. In each case, postoperative stereoacuity was equal to, or better than, the preoperative stereoacuity, except for patient C20, who had 40 seconds arc preoperatively and was not tested postoperatively. This patient had an excellent outcome, being orthotropic, and was asymptomatic without a face turn. It is highly likely, therefore, that stereopsis was maintained. A face turn or chin elevation was present preoperativelv in 9 of 10 congenital Brown's syndrome patients who had the silicone tendon expander procedure. Eight of 9 had improvement of abnormal head posturing, with 6 showing complete resolution. The final overall result for the 15 patients who underwent the silicone tendon expander procedure averaged 8.3, graded on a scale of I to 10, with 10 being best (Fig 11). Of these 15 patients, 13 (87%) were corrected with a single suirgery and 14 (93%) were corrected by 2 surgeries with a final result score of 7 or better.

Late Imjprovement After Superior Oblique Expan'ider The postoperative course was interesting, as an initial undercorrection followed by improvement was the rule. Follow-up ranged from 1 month to 11 years, with a mean follow-up of 35 months. Ten of the 15 patients had at least 11 months of follow-up. An initial undercorrection occurred in each patient, and 6 showed -2 to -3 during the first 4 months after surgery, then duictions improved over a 4- to 6- month period (Fig 12). Two 1064 iVright patients eventually developed a consecutive superior oblique paresis and inferior obli(lue overaction (C19 and C23). The superior obli(ue paresis occurred at approximately 12 to 24 months for patient C19 and at 4 months for patient C23. Figure 15 shows the postoperative change in elevation in addtuction for the 9 patients with at least 2 examinations during the first 6 months and at least 11 months of follow-up.

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Five patients had more than 5 years of follow-up. Of these 5 patients, 4 (80%) had an excellent long-term outcome (final result, 9 to 10) with a single operation, and all 5 had a good outcome (final result, 7 to 10, mean, 9.2) with 2 surgeries. There were no long-term complications, including no extrusions, no restriction of ocular rotations, and no infections.

SUPERIOR OBLIQUE TENOTOMY RESULTS Six patients with congenital Brown's syndrome were surgically treated with a superior oblique tenotomy (Table VI and XVII). Only one was operated on by the author (C28). Three of the 6 patients had an associated horizontal strabismus (C30, C31, and C32). Of 5 patients with recorded preoperative primary position measurements, 2 had a vertical deviation (C28 - RH4 and C30 - RH5). Postoperatively, 5 of 6 patients had vertical deviations greater than 5 PD, ranging from 6 to 15 PD. Postoperative elevation in adduction was within + 1 of normal in only 1 of 6 patients. Ofthe 5 patients with abnormal postoperative versions, 2 patients had significant residual restriction (-3 and -4), and 3 were overcorrected, resulting in + 2 inferior Brotnn's Synfdrotwte: Diagnosis anld Mlanagement 1065

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POSTOPERATIVE COMPLICATION OF SILICONE TENDON EXPANDER One patient, not included in the 15 patients operated on by the author, was referred for management of complications from the silicone tendon expander procedure after surgery elsewhere for Brown's syndrome. Preoperative records could not be obtained, so the patient is not in the for- mal study, but the case is includled becauise it demonstrates an important complication of superior oblique surgery and, specifically, the silicone expander procedure. The patient had uindergone a right silicone tendon expander by a nonpediatric ophthalmologist. Postoperatively, there was mcarked limitation of movement of the right eye to depression, elevation, and addluction, with underaction of the ipsilateral superior oblique muscle (Fig 16A). A reoperation performed by the author revealed positive forced ductions up and nasal ward and into adduction. The silicone implant was scarred to superior nasal sclera and the superior rectus muscle, and there was extensive fat adherence (Fig 16B). The silicone implant was removed and the scar excised until forced ductions improved. This resulte(d in improved motility, but a significant restriction persisted. This is an example of postoperative restriction that can occur if orbital fat is surgically exposed and Tenon's~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~..capsule is violated..... FIGURE 16 Patient ill(lersveint right siliconie tendon expander procedure elsewhere. Left, Patienit is seeni postoperatively after silicone expander procedure with restricted eye imovemnenits to depres- SiOIi, elev'tion and(I adduction, right eye. Right, Reoperationi several imioniths after the siliconie tenidoni expanider proceduire revealed scarring alonig nasal aspect of stiperior recttus mnuscle, inicluiding area of suiperior oblique tenldoni. Superior obli(lule tendoni and siliconie implant were i(leutifie(I in a mass of' scar adherent to suiperior recttus muiiscle and nasal sclera. Stuperior oblique tenidon is shown on Steven's hook, with silicoiie banid eniclosed in a capsule. Brow n's Syndrome: Diagnosi.s and Managemwnt 1067

II. OBJECTIVE FUNDUS STUDY The indirect ophthalmoscope was used to judge fumndus torsion on 7 Brown's syndrome patients, 6 presumed secondary to a tight superior oblique tendon and one (A5) surgically verified to be caused by an scarred inferior oblique muscle, not due to a tight superior oblique tendon (Table XVIII). In all 7 patients, there was no significant torsion in primary position or down gaze. In up gaze, however, 6 of 7 patients demonstrated sig-

TABLE XVIII: TORSION IN BROWN'S SYNDROME

CODE EL SO TOR TOR TOR ADD UP PRIM DOWN

C34 -4 0 0/+2 0/+1 /0 C:35 -4 0 +2/() 0/0 0/A G:36 -3 0 0/+:3 0/M 0/0 C:37 -4 0 +2/() 0/0) /0 C38 -4 0 0/+2 0/) 0/0 A5 -4 0 -1/0 A/0) /+1 A43 -4 1 0/+3 0/+1 0/0 +, intorsion; -, extorsioni; El add, elevattion in addulction; SO, superior olblique futnctioni; Tor down, torsion in down gaze; Tor priimi, torsion in primiary gaze; Tor uip, torsioni in tip gaze. nificant intorsion of + 2 to +3. Figure 17 shows positions of gaze and fundus photographs from a representative Brown's syndrome patient (C36). Four patients with the classic pattern ofprimary superior oblique overaction (2 bilateral and 2 unilateral) were also examined for comparison (Table XIX). These patients all deinonstrated no torsion in up gaze, and 3 of 4 had + 2 to + 3 intorsion in down gaze. Minimal torsion was present in primary position measuring between 0 and +1.

III. AAPOS SILICONE TENDON EXPANDER SURVEY A fax survey was sent to all full members ofthe AAPOS who had a fax number listed in the 1997 - 1998 directory. Pediatric ophthalmologists were asked to answer questions regarding their experience using the silicone tendon expander for Brown's syndrome. Of 450 faxes sent, 176 physicians responded with the following information: 122 did not use the procedure, 15 used the procedure but did not include patient data, and 39 responded with patient data. All forms containing patient data were included in the study. The 39 pediatric ophthalmologists reported on 140 patients who had 1068 Wright

FIGURE 17 Congenital Brown's syndrome, left eye (patient C36). Left, Composite photographs showing left Brown's syndrome with marked limitation of elevation in adduction. Right, Fundus torsion (direct view). Bottom set of fundus photographs represents down gaze, center photographs primary position, and top photographs show up gaze. Note that in top set of photographs, left fundus is intorted as foveal fixation point is slightly ahove top of optic disc. Compare this to right eye in up gaze and to either eye in primary position (center pair), and down gaze (hottom pair), where fundus torsion is normal. With normal fundus torsion, fovea is aligned writh lower third of optic disc (direct fundus view).

TABLE XI[X: TORSION IN PRIMARY SUPERIOR OBLIQUE OVERACTION

CODE DIAGNOSIS EL SO TOR TOR TOR ADD UP PRIM DOWN TSO1 BSO full +.3/+2 0/0 +1/0 +3/+2 TS02 LSO -4 3 0/0 0/0 0/+2 TS03 LSO -1 2 0/0 + 1/0 0/+2 TS04 BSO full +3/+3 0/0 0/0 +1/+1 + intorsion; BSO, bilateral superior oblique averaction; LSO,left superior oblique overaction; Tor down, torsion in down gaze; Tor prim, torsion in primary gaze; Tor up, torsion in up gaze. undergone the silicone tendon expander procedure. There were 5 acquired and 135 congenital Brown's syndrome cases. Postoperative follow-up ranged from 1 month to 72 months (mean, 20.2 months). A list of the 140 patients is presented in Table XX. The number in the "Type" column marks the start of a different surgeon's patients. Summary of results calculated from data on these patients are listed in Table XXI. Limitation of elevation in adduction improved significantly after surgery, with mean preoperative limitation of -3.6 and postoperative limitation of only -1.01. The overall outcome as judged by the surgeon on a scale of 1 to 10 (10 being best) was 7.26. Twenty-six surgeons rated 91 patients (65%) at 8 to 10, and 14 surgeons rated 18 patients (13%) between 1 to 3. BrowtU s Syjudro,nie: Diagnosis an2d Anlalagewent 1069

TABLE XX: AAPOS* SILICONE TENDON EXPANDER SURVEY

TY'PE PRE OP PO DUCT F/U RESULT SOP COMPLICATIONS DUCT DUCT CHANCE (10=BEST)

1 1 Cong -4 -2 2 24 6 N o No 2 Cong, -:3 -1 2 34 8 No No :3 Colng -2 -1 1 18 8 No No 4 Cong, -:3 -1 2 21 8 No No 5 Con(e -3 -2 1 30 5 No No 6 Coln -4 -1 3 26 6 No No 7 Colg -:3 -1 2 19 7 No No 8 Cong -4 -_9 2 17 4 No N o 9 Colln -:3 -2 1 14 5 No No 1(0 2 Cong -4 -1 3 6 9 No No 1 I Colng -4 -:3 1 36 2 No nIo 12 Conig -4 -:3 1 36 4 No N o 1:3 Con,g -:3 -1 2 30 8 No No 14 Cong -4 -1 :3 24 6 No N o 15 3 Cong -4 -1 :3 5 8 No No 16 Con,g -4 -2 2 12 8 No No 17 4 Con,9 -:3 3 12 1 No No 18 5 Intlaom -:3 -2 1 6 3 No restrictioni, subse(lleuntly remove(d 19 (Co(nI(e -:3 -2 1 6 7 No No 2() 6 (Conig -4 4 65 1 No No 21 Cong -4 4 65 8 Y n1o 22 Conog -4 () 4 65 8 71Y o 23 Congr -4 4 65 8 Y I() 24 Con(g -4 4 65 8 Y No 25 Con(g -4 4 6(0 9 No No 26 Coig,, -4 -1 :3 50 9 No No 27 Congr -4 -1 3 50 9 No No 28 Cong' -4 -1 3 50 9 No No 29 Cong -4 -1 3 50 9 No No :30 Con(g -4 -1 3 :30 9 No No

:31 CoIng( -4 - 1 3 20 8 No No :32 Cong(r -4 -1 3 2(0 8 No No

:33 Cong(, -4 - 1 3 20 8 No No :34 Cong -4 -1 :3 2(0 8 No No :35 Cong("I -4 - 1 :3 15 4 No extrnision (1 111111 sili coIne) :36 Cong -4 -1 3 15 8 No No 37 Congr -4 -1 :3 25 9 No No :38 Cong -4 -1 :3 3(0 9 No No :39 Cong(r -4 -2 2 12 7 No No

40 (TCon7 -4 -_ _ 1 8 N o N o 41 8 Cona -4 -2 2 24 6 No No 1070 Wright

TABLE XX (CONTINUED): AAPOS SILICONE TENDON EXPANDER SURVEY

TYPE PRE OP PO DUCT F/U RESULT SOP COMPLICATIONS DUCT DUCT CHANGE (10=BEST)

42 Conig -3 -1 2 34 8 No No 43 Conig -2 -1 1 18 8 No No 44 Conig -3 -1 2 21 8 No No 45 Cong -3 -2 1 30 5 No No 46 Conig -4 -1 3 26 6 No No 47 Conig -3 -1 2 19 7 No No 48 Coing -4 -2 2 17 4 No No 49 Cong -:3 -2 1 14 5 No No 50 Cong -4 -1 3 6 9 No No 51 9 Conig -4 0) 4 15 7 No No 52 10 Conig -3 -2 2 20 8 No No 53 Cong -3 -1 2 8 9 No No 54 Cong -4 -2 2 12 8 No No 55 C,ong -3 -1 1 9 8 No No 56 11 Conig -4 -1 3 24 5 No No 57 12 Conig -4 -2 2 6 9 No No 58 Cong -4 -1 3 14 9 No No 59 Cong -3 0) 3 26 9 No No 60 Conig -4 0) 4 24 9 No No 61 13 Conig -4 0) 4 34 10 No No 62 Cong -3 -1 2 26 9 No No 63 Cong -3 -1 2 20 9 No No 64 Conig -4 -2 2 12 3 No No 65 14 SO Tick -3 0) 3 72 10 No No 66 15 Conig -4 0) 4 48 10 No No 67 Conig -3 0 3 44 9 No No 68 Cong -3 0) 3 36 10 No No 69 Conig -3 0 3 30 10 No No 70 Conig -3 0) -3 28 10 No No 71 Cong -4 -2 2 24 3 No No 72 Cong -4 -3 1 18 2 No No 73 Acq -4 0 4 16 10 No No 74 Conig -4 0) 4 12 10 No No 75 Conig -4 0) -4 12 10 No No 76 16 Conig -4 -1 3 53 8 No No 77 Conig -4 -4 0 7 1 No No 78 17 Conig -4 0) 4 4 8 No No 79 Cong -4 0) 4 4 8 No No 80 Conig -4 -2 2 12 7 No No 81 18 Conig -4 0 4 8 8 No No 82 Conig -4 -2 2 4 4 No No 83 19 Conig -2 0 2 36 10 No No 84 Conig -4 0) 4 6 10 No No 85 Acq -4 -4 0 3 1 No No 86 20 Conig -3 0 3 24 9 No No Brown's Syndromle: Diagnosis and Management 1071

TABLE XX (CONTINUED): AAPOS SILICONE TENDON EXPANDER SURVEY

TYPE PRE OP PO DUCT F/U RESULT SOP COMPLICATIONS DUCT DUCT CHANGE (10=BEST)

87 Coing -4 -1 3 27 8 No No 88 Conig -4 4 23 8 No extruision 89 Conig -3 0 3 6 8 No No 90 Conlg -4 4 27 9 No No 91 21 Cong -4 -2 2 4 8 No No 92 22 C,ong; -4 0 4 72 9 mild No 93 Conig -4 -1 3 36 8 No No 94 Conig -4 -1 3 28 9 No No 95 Conig -3 -1 2 3 7 No No 96 23 Conig -3 -_ 1 14 :3 No No 97 Coing -4 -2 2 20 3 No No 98 24 Coing -3 -2 1 2 6 No No 99 25 Cong -4 -2 2 2 10 No No 100 Colng -3 -1 2 2 1() No No 101 Colng -4 0 4 2 8 No No 102 Conig -3 -2 1 2 10 No No 103 Conig -3 -1 2 2 10 No No 104 26 Conig -3 -4 -1 1 1 No scarring, reel)oved sili coi)e 105 27 Conig -4 -1 3 24 7 No No 106 Conig -3 -1 2 12 8 No No 107 Conig -4 -1 3 6 7 No No 108 28 Conig -4 -1 3 4 8 No No 109 Cong -3 -1 2 4 8 No No 110 Cong -3 -1 2 4 8 No No 111 Conig -4 -1 3 4 8 No No 112 Conig -4 -1 3 4 8 No No

113 Conig -3 - 1 2 4 8 No No 114 Conig -2 0 2 4 8 No No 115 29 Coing -4 0 4 24 I inarked No 116 Cong -4 -1 :3 6 8 No No 117 Cong -4 0 4 12 10 No No 118 Cong -4 0 4 12 10 No No 119 30 Cong -3 -1 2 12 6 No No 120 31 Conig -4 -:3 1 15 1 No No 121 32 Conig -4 -2 2 3 1 No silicoC)e removed

122 Conig -4 - 1 :3 6 1 No silicoC)e remCioved 123 33 Conig -4 0 4 3 10 No extruided 124 Coing -4 0 4 12 10() No extni(led 125 Conig -4 4 12 1 () N)o extrl(lced 126 34 Acq -4 0 4 62 8 No No 127 Conig -4 4 29 8 No No 1072 Wright

TABLE XX (CONTINUED): AAPOS SILICONE TENDON EXPANDER SURVEY

TYPE PRE OP PO DUCT F/U RESULT SOP COMPLICATIONS DUCT DUCT CHANGE (10=BEST)

128 35 Cong -4 -1 3 6 8 No inflammation, scarring, sili coone removed 129 Cong -4 -1 3 8 8 No No 130 Cong -4 -2 2 10 1 No No 131 Cong -4 -2 2 10 1 No No 132 36 Cong -4 -2 3 36 1 No searring, restriction, sili conie removed 133 37 Cong -3 -2 1 12 4 No No 134 38 Coing -3 0 3 6 10 No No 135 Cong -2 0 2 12 10 No No 136 Cong -2 0 2 18 10 No No 137 Cong -2 0 2 6 10 No No 138 39 Cong -4 0 3 12 9 No No 139 Conig -3 -1 2 6 7 No No 140 Cong -3 0 3 3 8 No No *AAPOS, American Association of Ophtlhalmology and Strabismus.

TABLE XXI: AAPOS SILICONE TENDON EXPANDER SURVEY RESULTS ON 140 PATIENTS

Preoperative: Elevation in adduction -3.6 (imeani) Postoperative: Elevation in adduietion -1.01 (imiean) Change in dcictioni 2.5 (meain) Outcome (1-10; 10 is best) 7.26 (Ineani) Postoperative: superior oblique paresis 6/140 (4%) Complications 9/140 (6%)

AAPOS, American Association of Ophthalmology an(d Strabismuis.

Complications were recorded on 9 patients (6%) and included scarring and restriction with removal of silicone implant in 4 and spontaneous extrusion in 5. Three ofthe 5 spontaneous extrusions came from the same surgeon. Another surgeon used a 10 mm implant that extruded. Silicone implants from 2 additional patients (121 and 122) were removed because of undercorrected ductions; this was not considered a complication of the silicone implant by the surgeon. Each surgeon was asked to comment on the procedure (Table XXII). These comments ranged from excellent to Brown's Syndrome: Diagnosis and Management 1073

TABLE XXII: AAPOS SILICONE TENDON EXPANDER SURVEY COMMENTS

SURGEON OVERALL IMPRESSION AND COMMENTS

1 Excellent 2 Unpredictable, less thani satisfactory resuilts 3 Best option not perfect, A delayed reaction 4 No a(dvantage unpredictable 5 Unpredictable 6 Very effective early uindereorrections that improve, 8mm max. 7 Excellent results, mild tindercorrects likely to caautious 5.0mm silicolne expander 8 Excellent 9 Generally good 10 Excellenit results 11 Better supraductioni btit inot perfect solution 12 It works great 13 Works well; proceduire is very techni(lue dependent 14 Excellenit long termn resuilt 15 Abouit 80% successftl 16 More suiecess with chicken stutture 17 Very good results 18 Good restults but it cani take some time for elevation to improve 19 Mixed-done 3 cases: 2 fabulous, one useless 20 Excellent restults 21 Oncee in a child 18 moniths old worked well 22 Hlappy, dooi't uinderstanid ouir one failure. We feel 5mm is eniouigh. No extnmsion yet. 23 Not halppy with results 24 Tend(Is to undercorrect prolblems 25 Excellenit procedure, Vast imiiprovement over free tenotomny 26 WVorks well with SOOA but cauitious with Brown's 27 Not suire if better thani more simple recession 28 Excellent restults for Brown's synidrome 29 Good , not great still can overcorrect, more precise than tenotomny 30 Have a lot of diffictulty closing Tenons capsule in separate layers 31 lad(l little affect on alignmiienit or ductions 32 Poor, both improved post remiioval of spacer followed by tenotomy 33 All lbad good responise initially. All did well after extruded expanlder removed. 34 Best of proceduires, Most predictable, less chanice of getting secondary OA of IO. 35 I did 4 eyes before encouniiterin-g a severe bilateral orbital inflamllmllation. 36 I rani into scarring of the SR with limitation of movemnent 37 Undercorrection of Brown's 38 It's great! 39 Works well, I have had l(o comiiplications from the expander. AAPOS, Amiierican Association of Ophtlalmology and Strabismus. poor, with 23 positive (59%), 12 negative (31%), and 4 mixed (10%). IV. COMPUTER SIMULATION OF BROWN'S SYNDROME 1074 Wright There are 3 parts to the computer simulation: 1. Shortening the tendon. 2. Increasing muscle stiffness (stretch sensitivity). 3. Lengthening a stiff muscle as a treatment model. Deviations are recorded in degrees; to convert to prism diopters, multiply by 2. Shortening the Superior Oblique Tendon Decreasing the superior oblique tendon length from 32 to 28 mm did not limit elevation in adduction significantly. At a tendon length of 25 mm, there is an ipsilateral -1 limitation of elevation in adduction on the Lancaster chart; however, a 22 mm superior oblique tendon created a -4

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limitation to elevation in adduction, similar to what is seen clinically in Brown's syndrome (Fig 18). A 22 mm tendon induced a primary deviation of 5i40 (11 PD) hypotropia and 3.80 of intorsion. In down gaze, the hypotropia persisted at 3.50 (7 PD) and intorsion increased to 5.70. Comparison of primary position to up gaze showed only a slight decrease of hypotropia to 5.20 (10.5 PD) and a decrease of intorsion to 2.70.

Increasing Superior Oblique Muscle Stiffness Muscle stretch sensitivity (muscle stiffness or inelasticity) was progres- Brown's Syndrome: Diagnosis and Management 1075 sively increased by 25% intervals starting at 200% and going up to 275%. The best simulation of Brown's syndrome was obtained with 250% stretch sensitivity, producing a -4 limitation of adduction and -1 limitation of elevation to abduction by Lancaster chart (Fig 19). This induced a

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hypotropia in primary position of 1.30 (2.6 PD) and no significant torsion. In down gaze, there was no deviation. The largest deviation was in up gaze: a 5.80 (11 PD) hypotropia, 3.10 of intorsion, and an exotropia of 3.80 (8 PD). Lengthening an Inelastic Superior Oblique Muscle The 250% stretch sensitivity model was used to test the treatment effect of elongating the tendon on Brown's syndrome patients. Tendon elongation was induced at 1 mm intervals from 4 mm to 10 mm. The 5 and 6 mm lengths worked best for revising the limitation of elevation without induc- ing a significant superior oblique muscle paresis. A 6 mm elongation resulted in full elevation with negligible paresis of the ipsilateral superior oblique muscle (Fig 20). The deviation in primary position was a hypertropia of4 PD and extorsion 1.40. An elongation greater than 6 mm resulted in a significant ipsilateral superior oblique muscle paresis with an 8 PD hypertropia in downgaze. 1076 Wright

DISCUSSION

MALE-FEMALE RATIO AND LATERALITY The clinical characteristics of Brown's syndrome patients in our study group is similar to Brown's classic study of 126 patients.5 In the present study of 85 Brown's syndrome cases, 52% were female (Brown, 59%), 54% were right eyes (Brown, 55%), and 5% were bilateral (Brown, 10%). Wilson and others423'343 concluded that the male-female sex distribution is equal, on the basis of a combination of reports that included 36 females and 40 males. The current study found 41 males and 44 females in the general group of Brown's syndrome patients. Using the Z-statistic, if44/85 differs from 50%, the P-value was nonsignificant (P> .50). Analyzing different subgroups of Brown's syndrome yielded interesting results. The distribution was almost identical in congenital Brown's syndrome patients, 20 females and 18 males. Not unexpectedly, there was a predominance of males in the traumatic acquired Brown's syndrome group: 9 of 11 (82%). When idiopathic acquired Brown's syndrome patients are considered sep- arately, females outnumber males: 20 females and only 12 males (63% females). This approaches, but does not reach, statistical significance (P>0.10). Series from Parks and Eustis44 and von Noorden and Olivey-5 support a female bias, with 19 females versus only 6 males (76% female). One possible explanation for the preponderance of females with idiopathic acquired Brown's syndrome is that inflammatory diseases such as myositis, scleritis, Sj6gren syndrome, rheumatoid arthritis, and lupus erythematosus are more common in females.'35 A report by Tychsen and associates, on trochleitis with superior oblique myositis, found 9 of 13 patients (69%) studied were female. Imaging studies have confirmed the presence of inflammatory changes in patients with acquired Brown's syndrome involving the area of the trochlea and anterior superior oblique tendon.29 140 Perhaps some of the acquired Brown's syndrome cases represent an inflammatory process of the superior oblique tendon or trochlea. Because females generally have a higher predisposition to idiopathic inflammation, they tend to be more frequently involved than males.

INHERITANCE Prior to this study, there have been at least 8 reports of Brown's syndrome pedigrees in the literature.5','5- In Brown's study of 126 patients, only 2 (2%) had a family history of Brown's syndrome.5 The present study con- curs, as only one (C12) of 38 (3%) congenital Brown's syndrome patients had a family member (a sibling) with Brown's syndrome. Even though familial Brown's syndrome appears to be rare, it is interesting that 35% of patients with congenital Brown's syndrome had a family member with Brown's Syndrome: Diagnosis and Management 1077 amblyopia or strabismus. It appears that a subgroup of familial Brown's syndrome does exist, but the majority present without a family history of Brown's syndrome. The relatively high incidence of family members with strabismus might indicate the presence of an underlying genetic trait for Brown's syndrome, perhaps either an autosomal recessive or an autosomal dominant with incomplete penetrance.

PAlTERN OF STRABISMUS Ipsilateral Limitation ofElevation in Abduction Descriptions of Brown's syndrome emphasize that elevation in abduction is full to nearly full.2'4'5 The present study, however, finds that limitation of elevation in abduction occurs quite frequently. Of 13 patients with a surgically verified tight superior oblique tendon at the time of the silicone expander procedure, 9 patients (69%) showed -2 to -3 limitation of elevation in abduction preoperatively. In each case, there was also limitation to elevation in primary position, with the limitation significantly worse in adduction (Fig 5, 9A, lOB, llA, and 12A). The limited elevation in abduction and adduction resolved after the superior oblique was surgically lengthened (Fig llB and 12C). Thus, an extremely tight superior oblique muscle will limit elevation in primary position and even in abduction. Mild limitation in abduction is also seen in the computer model of an inelastic superior oblique muscle (Fig 19). The presence of limited elevation in abduction should not preclude the diagnosis of Brown's syndrome. It is the difference between elevation in adduction versus elevation in abduction that differentiates Brown's syndrome from disorders such as double elevator palsy, where elevation is worse in abduction. Contralateral Pseudo-Inferior Oblique Overaction Limitation of elevation in abduction provides an explanation for contralateral inferior oblique overaction that has been reported to be associated with unilateral Brown's syndrome."4'," The contralateral inferior oblique overaction is considered pseudo-overaction due to limited elevation in abduction ofthe Brown's syndrome eye. Hering's law states that both eyes will receive equal innervation. Limited elevation in abduction caused by the Brown's syndrome results in increased innervation to the ipsilateral superior rectus muscle and the contralateral inferior oblique muscle. The ipsilateral eye is restricted, but the contralateral eye overelevates in adduction, thus showing pseudo-inferior oblique overaction. Apparent contralateral inferior oblique overaction can be seen in virtually all patients with limitation of elevation in abduction (Fig 5, 9A, lOB, 11A, and 12A). Apparent inferior oblique overaction disappears postoperatively when the superior oblique restriction is relieved (Fig 9B, llB, 12C). 1078 Wright Ipsilateral Superior Oblique Overaction A hallmark of Brown's syndrome is restricted elevation of the eye in adduction with minimal or no superior oblique muscle overaction.25 The present study verifies this finding. Of 13 patients with surgically identified superior oblique tendon associated Brown's syndrome, 12 patients had no superior oblique overaction and one had a +1 overaction. In contrast, of 6 masquerade syndrome patients with inferior oblique paresis and superi- or oblique muscle overaction, all had +2 to +4 superior oblique overaction. These data suggest that the presence of even mild superior oblique overaction should be regarded with suspicion as not being consistent with Brown's syndrome of superior oblique tendon etiology. V-pattern Another finding of Brown's syndrome often quoted in the literature is the frequent presence of a V-pattern.2'4 The V-pattern has the form of the letter Y with most of the divergence occurring from primary position to up gaze.4 In the present study, less than one third ofthe patients (30%) exhib- ited V-patterns, most patients (69%) did not have a significant pattern, and one patient (<1%) had an A-pattern. This A-pattern patient also had an esotropia and did not have surgery to verify a tight superior oblique tendon. In contrast, 2 of 3 patients with unilateral inferior oblique muscle paresis and 3 of 3 patients with bilateral superior oblique muscle overaction had an A-pattern.

Hypotropia in Primary Position Another interesting clinical finding of the present study was the lack of a significant hypotropia in primary position in nontraumatic Brown's syndrome cases. Comparison of the vertical deviation in the congenital group (n=38), acquired nontraumatic group (n=36), and traumatic group (n=11) showed a statistically significant larger hypotropia in the traumatic group (P<.001 using square root transformation). Of 74 patients with congenital and acquired nontraumatic Brown's syndrome, 56 (76%) had essentially no vertical deviation in primary position (O to 2 PD), and only one (1.4%) had a vertical deviation greater than 10 PD (C23 had 15 PD hypotropia). In contrast, Brown's syndrome associated with trauma (periorbital surgery or accidental trauma) had much larger hypotropias. Of 11 traumatic Brown's syndrome patients, 7 had vertical deviations in primary position of 10 PD or greater (range, 0 to 30 PD). The 2 largest deviations were caused by a superior orbital mass associated with a glaucoma implant and an inferior and frontal fracture with surgical repair. Patients in the masquerade group with a unilateral inferior oblique palsy also had large vertical deviations in primary position. The 3 patients with inferior oblique paresis in the pres- Brown's Syndrome: Diagnosis and Management 1079 ent study had vertical deviations ranging from 12 to 17 PD. Astle and associates,"3 in a report on inferior oblique palsy and Brown's syndrome, listed the vertical deviations in primary position. Three of 5 inferior oblique palsy patients had deviations between 14 and 25 PD, while Brown's syndrome patients measured between orthotropia and hypertropia of 12 PD. The computer simulation of Brown's syndrome demonstrated that an inelastic superior oblique muscle-tendon complex produced a pattern that best matched minimal to no hypotropia in primary position even with very restricted ductions (Fig 19). A shortened tendon, on the other hand, resulted in a relatively large hypotropia in primary position even when ductions were only mildly affected (Fig 18). Our study supports the presence of an inelastic muscle-tendon complex as the cause for Brown's syndrome in the majority of cases, as 9 (69%) of 13 patients with surgically verified tight superior oblique tendons had hypotropias of <5 PD or less despite severe limitation of elevation (Fig 11A). Lack of a significant vertical deviation in primary position, despite severe limitation of elevation, has not been well-defined in the literature. Most reports on Brown's syndrome emphasize the limited ductions, but few state the preoperative vertical deviation in primary position.5"23,25"443 This point, regarding the relatively small vertical deviation in primary position of Brown's syndrome caused by an inelastic superior oblique muscle- tendon complex, is clinically useful. If the vertical deviation in primary position is greater than 10 to 12 PD, the ophthalmologist needs to be sus- picious that the diagnosis is not a simple Brown's syndrome caused by an inelastic superior oblique tendon. Instead, consider an inferior oblique palsy, severe periocular scarring, or a superior nasal mass. Objective Fundus Torsion Objective fundus torsion is frequently associated with oblique muscle dysfunction."18 Guyton reported 2 patterns of torsion associated with Brown's syndrome: 1 with intorsion in primary position and 1 with no torsion in primary position but intorsion in up gaze.'28 He suggested that a short tendon would cause intorsion in primary position, and an inelastic tendon would produce intorsion in up gaze but not primary position. The present study's computer model verified Guyton's hypothesis. An inelastic superi- or oblique muscle produced no torsion in primary position and down gaze but significant intorsion in up gaze, while the short tendon induced intorsion in primary position (Fig 18 and 19). In the present study, 7 patients with Brown's syndrome were specifically studied for fundus torsion: 5 had no torsion, and 2 had +1 intorsion in primary position or down gaze. Six of 7 patients had intorsion that increased to +2 to +3 in up gaze. Only patient A5 did not have intorsion in up gaze, but this patient had restric- 1080 Wright tion caused by scarring and adhesions around the inferior oblique and inferior rectus muscles, not a tight superior oblique tendon. Intorsion in up gaze occurs in patients when there is a stiff or tight superior oblique muscle-tendon complex because the superior oblique muscle is an intor- tor, and the leash effect is encountered in up gaze. In contrast to Brown's syndrome, patients with primary superior oblique overaction demonstrated no torsion in up gaze, but had +1 to +3 intorsion in down gaze. Thus, superior oblique overaction is associated with intorsion in the field of action of the superior oblique muscles (down gaze), whereas in Brown's syndrome, secondary to a tight superior oblique tendon, intorsion occurs as the eye moves up and encounters the tight tendon. The presence of intorsion in up gaze can help substantiate the diagnosis of Brown's syndrome caused by an inelastic superior oblique muscle- tendon complex.

DIAGNOSING BROWN'S SYNDROME WITHOUT FORCED DUCTIONS Properly diagnosing Brown's syndrome and the presence of a tight superi- or oblique muscle-tendon complex is important because it directs the surgical plan and provides a prediction postoperatively regarding prognosis. Ifthe cause ofthe Brown's syndrome is a tight or inelastic superior oblique tendon, then a tendon-lengthening procedure is indicated, and the outcome is likely to be good barring surgical complications. If the superior oblique muscle-tendon complex is not the cause, then surgical correction must be directed elsewhere, such as the possibility of inferior temporal adhesions. The prognosis is poor in these cases because the cause of the restriction is often impossible to find, as in case C24 of this study, and cases descried by Parks.' The proper diagnosis of Brown's syndrome can also be difficult in masquerade syndromes. Superior oblique overaction or inferior oblique palsy can be mistaken for Brown's syndrome. Forced ductions are often suggested as a way to make the definitive diagnosis of Brown's syndrome; however, in many patients, especially children, it is difficult and sometimes impossible to obtain forced duction testing. In addition, a positive forced duction test does not, by itself, diagnose a tight superior oblique muscle-tendon as the cause of Brown's syndrome. Non-superior oblique restrictions, such as inferior orbital adhesions, can restrict ocular elevation in adduction. Surgical release ofthe restriction by superior oblique tenotomy is needed to document that the tight superior oblique tendon is responsible for the restriction. Since most Brown's syndrome cases are followed conservatively without surgery, forced duction testing results are usually not available. In most cases, careful attention to the clinical features of the strabismus can make the appropriate diagnosis without forced duction testing. Brown's Syndrome: Diagnosis and Management 1081 For example, if a patient has marked unilateral limitation of elevation that is worse in adduction with the combination of superior oblique muscle overaction, A-pattern, and a large vertical deviation (>10 PD) in primary position, this pattern rules out Brown's syndrome. Add the presence of fundus intorsion that increases in down gaze, and it categorically rules out Brown's syndrome even without forced duction testing. Instead, this configuration indicates inferior oblique muscle paresis or primary superior oblique overaction. Likewise, ifthere is marked limited elevation worse in adduction, with a small vertical deviation in primary position (< 10 PD) and no superior oblique overaction, then the diagnosis is probably Brown's syndrome secondary to an inelastic superior oblique tendon. If the observer can also demonstrate normal fundus torsion in primary position and intorsion on up gaze, the diagnosis of Brown's syndrome caused by an inelastic muscle tendon complex is verified. There may be cases that are not clearly defined, but careful clinical examination of the pattern of strabismus can, in most cases, establish the diagnosis without forced duction testing. The clinical characteristics of Brown's syndrome, inferior oblique paresis, and superior oblique muscle overaction are compared in Table XXIII.

SENSORY STATUS AND AMBLYOPIA The literature states that Brown's syndrome patients, in general, have good binocular fusion with many adopting a compensatory face turn and/or a chin elevation.25'5 Clarke and Noel4 described the fusion status of 28 patients with Brown's syndrome, reporting 72% with binocular fusion and those with a relatively high incidence of amblyopia (25%). Brown5 found only 15 (12%) patients with a tropia in all fields of gaze and no significant incidence of amblyopia or refractive errors. The current study identified only 3 (4%) of 85 patients with amblyopia. The cause of amblyopia was anisometropia in 2 patients and strabismic amblyopia in a third patient having coexisting infantile esotropia. Very little has been written on stereoacuity in Brown's syndrome; even the paper by Clark and Noel4 on fusion status, and Brown's large series5 did not report on stereoacuity. In the current study, 62 patients (26 congenital and 36 acquired) had stereopsis recorded with 47 (76%) having measurable stereoacuity to Titmus testing. This study indicates that amblyopia can occur in patients with Brown's syndrome, but the incidence is low with most patients showing good binocular function.

SPONTANEOUS RESOLUTION Spontaneous resolution of both congenital and acquired Brown's syndrome has been reported.5'8'9' """4 Kaban and associates"" reported on the natural history of presumed congenital Brown's syndrome and stated 1082 Wright

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0 0~~~~~~~~~~~~0VE V 0Z C'o 3 - 4 0 QQ CZ > A ~ -dC ~~~~ 0 ~~~~~~~~~~~~~oT Brown's Syndromte: Diagnosis and Managemnent 1083 that 6 (10%) of 60 patients experienced a complete spontaneous resolution between 4 and 15 years of age. Brown recorded spontaneous recovery in 9 (7%) of 126 sheath syndrome cases. One patient he reported was observed from age 5 to 1 lyears without change, then returned at 18 years of age with full spontaneous recovery. Gregersen and Rindziunski53 published one of the longest follow-up studies on Brown's syndrome. These were patients with acquired Brown's syndrome who were followed between 7 and 19 years, with a mean follow-up of 13 years. Of the 10 patients studied, 3 showed complete spontaneous resolution. Unfortunately, the article did not specify when the improvement of ductions occurred. The present study found 5 (6%) of 85 Brown's syndrome patients experienced spontaneous recovery to within -1 limitation of elevation in adduction. All spontaneous resolutions occurred in nontraumatic acquired Brown's syndrome cases, 2 with pain and click and 3 being idiopathic. This represents 16% of the 32 nontraumatic acquired Brown's syndrome cases. Spontaneous recovery in these cases occurred over a period of 6 months to 48 months. Follow-up on 5 congenital Brown's syndrome patients over a 12 to 60 month period was obtained, and all showed persistent -4 limitation of elevation at the last follow-tip visit. In the patient (C14) with bilateral Brown's syndrome, one eye showed improvement from a -3 to a -2 over a 48 month period, while the other eye remained at -4. The literature and the present study agree that spontaneous resolution of Brown's syndrome does occur in probably 6% to 7% of cases, and improvement can be draimatic as seen in Fig 9. Spontaneous recovery appears more likely to occur in acquired Brown's syndrome cases. Because of the possibility for late spontaneous recovery, a conservative approach to management is justified, especially for patients with acquired Brown's syndrome.

MEDICAL EVALUATION OF BROWN' S SYNDROME Patients who present with acquired Brown's synidrome without an obvious cause should be evaluated for an associated disease. Sinusitis, adult or juvenile rheumatoid arthritis, systemic lupus erythematosus, and even a metastatic tumor to the superior oblique tendon can be associated with Brown's syndrome.'3' 4154,i6696 Despite the many case reports on systemic disorders associated witlh acquired Brown's syndrome, the vast mnajority will be idiopathic. In the presen-t study, there were 47 acquired cases, with only 4 being associated with sinusitis and none with rheumiatoid disease or autoimmune syndromes. These findings are interesting, considering that more than half ofthe studly patients were derived from a chart review from a children's hospital. Of 32 patients with acquired Brown's syndrome of unknown cause (Table XI through XIII), 11 (32%) had a systemic disorder, 1084 Wright but in almost every case it was not apparently directly related to the Brown's syn-drome. Systemic disorders included crainiosynostosis, coarc- tation of the aorta, brain arterial venous fistula with hemiparesis, developmental delay, hydrocephalus, patella loose knee menisenescus, growth hormone deficiency, caf6 au lait spots, and lower extremity fracture. One could speculate as to the reasons these disorders might cause Brown's syndrome; perhaps patients with the lax knee cartilage also have an abnormality of the trochlea cartilage, or the crainiosynostosis patient might have an abnormal trochlea in addition to cranial bone abnormalities. Even though a coexisting systemic disease is not common, a systemic evaluation should be considered. The minimum workup is a thorough history and physical examination by a pediatrician or internist aware of the systemic disorders associated with acquired Brown's syndrome. Consider an MRI of the orbits and rheumatologic studies if there is pain, discom- fort, signs of inflammation, or if the pattern of strabismus is atypical.29"140,'46 In general, present data do not support the routine use of imaging techniques in every Brown's syndrome patient. In the present study, 7 acquired Brown's syndrome patients had a CT scan or MRI, and results showed 1 sinusitis, 1 large tendon, 1 fat enhancement, and 4 negative scans. Imaging studies may, in some cases, identify pathology in the area of the trochlea, but this does not usually change the treatment plan.

SURGICAL TREATMENT Standard Surgical Approach Superior oblique tenotomy and tenectomy are popular procedures used to elongate the superior oblique tendon.232425-'2614" These procedures have been relatively successful in treating primary superior oblique overaction associated with horizontal strabismus in nonfusing patients where small postoperative vertical deviatioins are not important. Patients with bifoveal fusion, on the other hand, do not tolerate small induced postoperative cyclovertical deviations, and tenotomy in this group has been less than successful."I"19'15122 A major problem of tenotomy and tenectomy is the uncontrolled separation of the tendon ends. In some cases, the tendon end will separate widely, causing consecutive superior oblique paresis; in other cases, the cut ends may reunite and scar back together, producing an undercorrection. Unpredictable results of tenotomy and tenectomy for the management of Brown's syndrome are well known, with the major problem being postoperative superior oblique muscle palsy.24'5-26,44,143 Sprunger, von Noorden, and Helveston'43 reported on 38 Brown's syndrome patients treated with the superior oblique tenectomy from 2 institutes. One half of these tenectomy patients developed consecutive superior oblique paresis that required additional strabismus surgery. Brown's Syndrome: Diagnosis and Management 1085 Dyer2' suggested the use of a 5 to 6 mm suture-bridge between the cut ends of the superior oblique tendon to avoid exaggerated tendon separation and a consecutive superior oblique paresis. Unfortunately, the suture- bridge can act as scaffolding for fibrosis to reunite the cut tendon ends, resulting in undercorrections. Another procedure designed to avoid superior oblique paresis and maintain the integrity of superior oblique tendon is the split tendon lengthening procedure.26'"2 Parks26 reported on 16 patients with a split tendon lengthening procedure: 7 obtained a good result, 6 patients were significantly undercorrected, and 3 developed secondary inferior oblique muscle overaction or a superior oblique palsy. Parks also pointed out the difficulty of the Z tenotomy, which would frequently become an unplanned complete tenectomy. The superior oblique tendon does not have substantial transverse connections between tendon fibers, and because Z lengthening procedures overlap marginal cuts oftwo thirds tendon-width, they often result in a free tenotomy.26 Superior oblique muscle recession has also been touted as a procedure that produces a graded slackening of the tendon.'3""'5 The problem with recessing the superior oblique muscle, however, is that it dramatically changes the superior oblique tendon insertion characteristics and can result in postoperative complications such as limited depression.-6 151 Superior oblique recession collapses the broad posterior insertion of the superior oblique tendon and moves the insertion to an anterior nasal position. Moving the superior oblique tendon insertion alters its functional mechanics, changing it from a depressor and abductor to an elevator and adductor. A more desirable procedure would be one that maintains the normal physiology ofthe broad superior oblique tendon insertion and sim- ply lengthens the tendon. In response to the high incidence of consecutive superior oblique paresis after tenotomy or tenectomy, Parks and Eustis' studied adding a simultaneous inferior oblique recession to the superior oblique tenotomy. In their series of 16 eyes, reoperation for overcorrection was not necessary. Performing a simultaneous inferior oblique recession with the superior oblique tenotomy did reduce the consecutive superior oblique paresis; however, 12 (75%) of 16 eyes showed significant inferior oblique underaction in the early postoperative period. Seven (44%) of 16 eyes had -2 to -3 limitation of elevation at the last visit (mean follow-up, 19 months). Figure 21 shows the postoperative course on Parks and Eustis' patients having superior oblique tenotomy with inferior oblique recession with at least 10 months follow-up.44 Note the significant undercorrection as late as 10 to 24 months after surgery. In the present study, 6 patients underwent superior oblique tenotomy. In general, the results of superior oblique tenotomy were poor, with only 1086 WHuht 1 patient having a good outcomne. Of the 6 patients studied, 2 were significantly uindercorrected (-3 and -4 elevationi in adductioni), and 3 had marked postoperative superior oblique palsies. In one case (C33), the surgeon hadl tried to reunite the cut ends of the tendon becauise there was superior ol)lique underactioin and cyclovertical diplopia in down gaze. The Silicone Tenidoni Expatn(ler Procedture Becauise of the difficuilties with conventional strabismus surgery in treating Brown's syidrome, a nlew procedure to lengthen the suiperior obliquie tendoni was developed, the .silicone tendon expancler proceduire. 12' This procedure has the theoretical advantage of providing a grade(i lengthening of the superior oblique tendon. The silicone retinal band material used in the procedure is Iigid enouglh to keep the cut tendoln ends apart, produicing a graded lengtlheninlg of the tendcon. Thus, the silicone tendon expanlder was developed to elongate the suiperior oblique tenidon while maintaininig the physiology of the superior obliquie tendon insertion. 121"2-3 As shown in the comiputer muodel, if ani inelastic superior oblique tendon causes Browvn's syndromne, then lengtheninig the tendon 5 to 6 mm should theoretically solve the problemn (Fig 20). In the cturrenit study, 15 patients undlerwent the silicoone tendon expander proceduire for Brown's syndrome. The Laverage final result graded oni a scale of I to 10 (10 being best) was 8.3. Of these 15 Brown's syndrome patienits, 13 (87%) were corrected with a single surgery, and 14 (93%) were corrected with 2 surgeries, achieving a f'inal resuilt score of 7

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0de-. 2 2 I 2 .03 -0. 2 3 20 3 dog lyp-d-ev 28. 2.0 -0.6 30 3 Z.3 0.7 dog 06 e6 00 0.3 3.0 3.2 dg 30 Ol 30 30' Ol 30' FIGURE 20 C,omiputer siioo,ilattiool of inoelastic right suiperior obli(cl(' miuiscle with stretch sensitivity of 250% and1 stliperimpol)(s(dl elongation of suipenor obliqoe tenidoni, 6 nmm. Note that motilitv is almiiost ormali, \\it1h onlv a trace riglit stipenior obliqe )paresis. Brown's Syndrome: Diagnosis and Management 1087 or better. In 13 of the 15 cases, a tight superior oblique tendon was the sole cause of the restriction. Of the other 2 cases, one was associated with a frontal bone fracture and surgical repair that caused orbital scarring and a tight superior oblique tendon, and the other had a non-superior oblique etiology that could not be identified at the time of surgery. In no patient could a tight or short superior tendon sheath be implicated as causing the restriction. Considering the 13 Brown's syndrome cases caused solely because of a tight superior oblique tendon, 10 (77%) showed essentially normal versions (no more than ± 1) postoperatively. Of the 3 patients with abnormal postoperative versions, 2 had +2 inferior oblique overaction associated with a moderate superior oblique paresis, and 1 had -2 residual restriction of elevation in adduction. One of the patients with a consecutive superior oblique paresis was treated with inferior oblique recession and had an excellent outcome. Postoperative vertical deviation in primary position ranged from 0 to 10 PD in all 15 cases, with 10 of 15 patients having 2 PD or less. Postoperative stereoacuity was maintained in all patients who had preoperative stereopsis. A preoperative face turn or chin elevation was present in 12 of 15 patients. All 12 showed postoperative improvement, with 10 showing no abnormal head posturing. Follow-up ranged from 1 month to 11 years, with a mean follow-up of 35 months. Ten of 15 patients had at least 11 months of follow-up, and 5 patients had more than 5 years offollow-up. Ofthe 5 patients with at least 5 years of follow-up, 4 (80%) had an excellent long-term outcome (final result, 9 to 10) with a single operation, and all 5 had a good outcome (final result, 7 to 10, mean 9.2) with 2 surgeries. The postoperative course of 9 patients with at least 11 months offollow-up and 2 examinations in the first 6 months are diagrammed in Fig 15. Note the long-term stability after the initial 6 months of follow-up. Every patient showed an initial undercorrection and then demonstrated improvement over the first few months. Comparison of the simultaneous superior oblique tenotomy and inferior oblique recession to the silicone tendon expander procedure shows the expander procedure to have quicker recovery to normal ductions (Fig 15 and 21). No long-term complications ofthe silicone implant were found. In no case was there an infection, extrusion, or complication secondary to the silicone implant. The patients could not feel the implant, there was no secondary ptosis, and there was no limitation of depression as previously described in 2 cases.124 Only 1 patient (C24) in the present study had the silicone implant removed because of an undercorrection, but this patient did not improve even after removal of the implant and tenectomy. Although it was determined that the Brown's syndrome was not due to a tight superior 1088 Wright

-4

A 4 --- A. * Is a a a 4 5 s

FIGURE 21 Line graph showing change in ductions over time after suiperior oblique tenotomy with ipsilateral iniferior oblique recession. Note delayed imuprovement. Even 12 months after surgery, patients show residual limitation of elevation in adduction. Mocdifefld fromii Parks andl Eustis 1987.44

oblique tendon, the exact cause of the restriction remains unknown. To determine the efficacy of the silicone tendon expander procedure in a large population ofpediatric ophthalmologists, a survey of the AAPOS membership was performed. Members responded by filling out and returning the data sheets, providing information on 140 patients. Preoperative limitation to elevation in adduction averaged -3.6, and postoperative restriction averaged only -1.01. The overall outcome as judged by the surgeons, on a scale of 1 to 10 with 10 being best, was a mean of 7.26. The results from AAPOS members were similar to that of the author's (a mean of 8.3). Complications of this procedure, including scarring and restriction, occurred in 9 patients (6%) resulting in removal ofthe implant in 4 patients and spontaneous extrusion of the implant in 5. The same surgeon operated on 3 of the 5 patients who had spontaneous extrusion, and another surgeon used an oversized implant (10 mm) that subsequently extruded. These results indicate that the silicone tendon expander is effective for treating Brown's syndrome in the hands of most pediatric ophthalmologists, but complications can occur, probably most often due to problems with surgical technique. The silicone implant length in the present study ranged from 5 to 7 mm. It is interesting that the optimal length determined by the computer model to correct a -3 to -4 limitation in elevation caused by an inelastic muscle was between 5 and 6 mm. A 6 mm tendon elongation of a computer-simulated Brown's syndrome (-4 restriction), secondary to an inelastic superior oblique muscle (stretch sensitivity 250%), results in almost complete correction of the strabismus (Fig 20). Based on the outcomes of Brown's Syndrome: Diagnosis and Matnagemnent 1089 the present study, the recommended silicone implant length for the treatment of a -3 to -4 Brown's syndrome is 5.5 to 6.0 mm. A patient in the current study was referred to the author after having the silicone tendon expander procedure done by a surgeon not experienced with oblique muscle surgery. This patient developed severe postoperative restriction of elevation and depression (Fig 16A). The author performed a reoperation, and the silicone implant was found scarred to sclera and the superior rectus muscle, with extensive fat adherence in the superior nasal area (Fig 16B). Removal of scar and the silicone implant improved motility, but residual restriction persisted postoperatively. This particular case exemplifies the importance oftechnique in the silicone tendon expander procedure. Wilson and associates'24 reported on 2 patients who developed a restrictive down gaze deficit after silicone tendon expander procedure for acquired Brown's syndrome. Adhesions were present in both cases and, in one case, adhesions to the superior rectus muscle were specifically noted. Adhesion of the capsule surrounding the silicone to the nasal aspect of the superior rectus muscle and sclera produces a new insertion anterior and nasal to the original insertion and defeats the purpose of the silicone tendon expander procedure. This new insertion is anterior to the equator of the eye and changes the superior oblique muscle from a depressor to an elevator, thuis causing down gaze restriction. This complication can be avoided by placing the silicone implant 3 mm nasal to the superior rectus muscle and by care- frilly placing the implant within the tendon capsular bag. 26 The silicone tendon expander procedure requires a different surgical approach from the standard tenotomy and tenectomy techniques. Extreme care must be taken to preserve intermuscular septum and tendon capsule integrity so the silicone implant can be placed within the tendon capsule bag. An intact intermuscular septum and floor of the tendon capsule provides a barrier to avoid adhesions of the silicone to sclera. Fig 22

FIGURE 22 Intraoperative photograph of silicone tenidon expacnder proceduire after placement of tendon sutures anid tenotoynv. Note suitures attached to emit ends of tendon, anid floor of tendon cap- stile is inltact. 1090 Wright is an intraoperative photograph taken during a silicone tendon expander procedure after the tenotomy part of the procedure. Two sutures were placed prior to the tenotomy to elevate the cut ends of the superior oblique tendon. Note that the nasal intermuscular septum and the floor of the tendon capsule are intact. To keep the superior nasal intramuscular septum intact, the conjunctival incision must be made temporal to the superior rectus muscle, even though the tenotomy and placement of the silicone is nasal to the superior rectus muscle. As Parks'52 emphasizes, the temporal incision is important, because it leaves the nasal intermuscular septum and superior oblique tendon capsule intact. Figure 23 shows an intraoperative photograph of a reoperation on a patient who had the silicone tendon expander procedure by the author to correct superior oblique overaction. The silicone was appropriately placed in the tendon capsular bag, and the intermuscular septum was left intact. The reoperation was indicated for ipsilateral dissociated vertical deviation. At surgery, the silicone implant was explored and found to be freely mobile and encapsulated within the superior oblique tendon capsule without adhesion to sclera or the superior rectus muscle. This case demonstrates that proper placement ofthe silicone within the tendon capsular bag results in a free and mobile tendon preserving the original insertion. The silicone implant should not be used if the intermuscular septum and superior oblique tendon capsule floor are violated. Finally, it is critical to preserve Tenon's capsule, the barrier to orbital fat. Once orbital fat is exposed, fat adherence syndrome can result, often causing a postoperative result worse than the preoperative strabismus. The present long-term follow-up study of the silicone tendon expander procedure has demonstrated that the procedure is safe and effective for the treatment of Brown's syndrome caused by an inelastic superior oblique muscle-tendon complex. The AAPOS survey has demonstrated that a wide range of different pediatric ophthalmologists can successfully perform the

FIGURE 23 Reoperation on silicone tendon expander that was placed by author within tendon capsular bag. Note intact tendon capsule encloses silicone implant. Implant was free and mobile without adhesions to selera or superior rectus muscle. Brown's Syndrone: Diagnosis and Management 1091 procedure. However, it is not as easy to perform as tenotomy or tenectomy and requires special surgical techniques. Much like the learning curve when intraocular lenses were first introduced, learning the silicone tendon expander procedure requires a significant investment of time and effort.

TERMINOLOGY, CLASSIFICATION, AND CAUSES OF BROWN'S SYNDROME This author agrees with the recommendation of Wilson, Eustis, and Parks,4 suggesting the term "Brown's syndrome" be reserved for a restrictive inability to elevate the eye into adduction specifically caused by an abnormality of the superior oblique muscle-tendon-trochlea complex. Some might argue that the term "Brown's syndrome" should be more encompassing and apply to any restrictive cause of limited elevation in adduction, even if the superior oblique muscle-tendon complex was not involved. This argument, however, is counter to Brown's original description and premise that this syndrome of limited elevation in adduction was caused by an abnormality of the superior oblique muscle-tendon complex. The present study and the literature support Brown's premise, since the vast majority of cases with the features described by Brown are caused by an abnormality of the superior oblique muscle-tendon-trochlea complex.23'25 26-122 Furthermore, a broad classification would be ambiguous, as it wouild not provide information about the underlying cause of Brown's syndrome. In addition, the present author suggests that those cases caused by non-superior oblique pathology, such as a floor fracture or inferior orbital adhesions, should be termed pseudo-Brown's syndrome. If the clinical or surgical characteristics of a case do not clearly indicate the cause of the Brown's syndrome, then perhaps the designation of presumed Brown's syndrome should be used. Following is a proposed classification of Brown's syndrome and a description of the cause of each type of Brown's syndrome. This classification is derived from a literature review and data from the present study.

CONGENITAL BROWN'S SYNDROME Despite the many causes of congenital Brown's syndrome, recent reports have documented that the majority of cases are caused by a tight superior oblique tendon. Eustis and Parks-" in 1987 reported on 13 patients who uinderwent superior oblique tenotomy with simultaneous inferior oblique recession. A tight superior oblique tendon was found to be the cause in each case; there was no mention of non-superior oblique tendon causes. Sprnnger, von Noorden, and Helveston'43 in 1991 reported results on 38 patients who underwent surgery for Brown's syndrome from 2 institutes. Again, a tight superior oblique tendon was the cause of each case, and there was no mention of non-superior oblique tendon causes for the 1092 Wright Brown's syndrome.'43 The current study describes 11 patients with congenital Brown's syndrome operated on by the author, and 10 were caused by a tight superior oblique tendon. Only one patient (C24) had a non- superior oblique tendon cause for the limited elevation in adduction. With the combined experience of the literature and the data from the present study, it is clear that a congenitally tight superior oblique muscle- tendon complex causes the majority ofcongenital Brown's syndrome cases. The pattern of strabismus in Brown's syndrome is interesting. The superior oblique muscle function is essentially normal, and in primary position there is only a minimal hypotropia, with no significant torsion, despite severely limited elevation of the eye in adduction and intorsion in up gaze. This pattern suggests a mechanism of an inelastic superior obliquie muscle-tendon complex that would allow tendon retraction and normal superior oblique muscle function, combined with a tether that limits extension of the superior oblique tendon. The stretch sensitivity computer model verifies that an inelastic muscle-tendon complex will produce a pattern of strabismus that matches congenital Brown's syndrome (Fig 18). The model of a short superior obliquie tendon, however, is not com- patible with the pattern of strabismus associated with congenital Brown's syndrome (Fig 19). A possible cause of a congenitally inelastic muiscle-tendon complex is congenital fibrosis of the superior oblique muscle. An alternate explanation could be an abnormality of the tendon and/or trochlea that would limit the extension of the superior oblique tendon while maintaining the ability of the tendon to pull and retract. This one-way restriction could be caused by congenital abnormalities of the superior oblique tendon telescoping mechanism.'05 Perhaps a mechanism similar to the congenital trigger thumb syndrome, as described in the introduction, plays a role, allow- ing the tendon to pull but not extend.437"03"0708 Although the cause of the restricted extension of the superior oblique muscle-tendon complex remains unknown, it apparently is not due to a congenitally short tendon in the majority of cases. Congenital Pseudco-Brown's Syndrome. Congenital onset of limitation of elevation in adduction with a pattern of strabismus consistent with Brown's syndrome may be due to non-superior oblique pathology such as congenital bands in the inferior orbit connected to the inferior oblique and inferior rectus muscles.""' These cases are rare, but identification is important because superior oblique surgery will not improve this condition. To distinguish this non-superior oblique cause of limited elevation in adduction, this author prefers the term congenital pseudo-Brown's syndrome. Brown's Syndromne: Diagnosis and Management 1093 Acquired Brown's Syndrome. A great variety of disorders can cause acquired Brown's syndrome. It is difficult to develop a classification system based on the mechanism of the acquired Brown's syndrome, because in many cases, the mechanism causing the restriction is unknown, even when an associated disease has been identified. The fact that a case of acquired Brown's syndrome is associated with rheumatoid arthritis, for example, does not identify the specific mechanism that is causing the restriction. With these difficulties acknowl- edged, a breakdown of different types acquired Brown's syndrome follows. Peritrochlear Scarring. Surgical or accidental trauma to the area of the trochlea has been reported to cause acquired Brown's syndrome.69"-4" Chronic inflammation caused by sinusitis can result in inflammation that, over time, can lead to chronic scarring.4" In the present study, 4 patients had a strong history of sinusitis associated with the Brown's syndrome. Two persons had follow-up of 12 and 24 months, and the Brown's syndrome did not resolve. Patient A12 is especially interesting in that there was an acute onset of sinusitis associated with acute Brown's syndrome. The patient was treated with antibiotics, and follow-up 2 years later showed only slight improvement of the Brown's syndrome. Perhaps secondary scarring in the area of the trochlea contributed to the limited elevation in adduction and lack of improvement even after the sinusitis resolved. It is likely that fibrosis in the area of the anterior trochlea would inhibit the normal telescoping mechanism of the superior oblique tendon. A study of the superior oblique tendon and trochlear pathology in a patient with chronic inflammatory Brown's syndrome revealed peritrochlear adhesions around the superior oblique tendon as it exits the anterior trochlea.""3 Scarring around the tendon could inhibit expansion of the tendon but would not necessarily limit contracture of the tendon, thus preserving superior oblique function. Severe scarring of the tendon and trochlea, however, limits movement of the tendon in both directions, resulting in a Brown's syndrome with a superior oblique paresis. This disorder has been called "canine tooth syndrome" or Knapp type 7 classification.".12 Three patients in the present study (Al, A2, and A3) had canine tooth syndrome with both restrictive elevation in adduction and a superior oblique palsy. All 3 cases presented with severe trauma to the trochlear area, 2 by metal hooks and 1 from a dog bite. Management of these cases could be extremely difficult, as reconstructive surgery in the area of the trochlea can lead to further scarring. In the acute phase immediately following trauma, local corticosteroid injection might help reduce secondary fibrosis.69 Initial management is conservative because spontaneous improvement may occur.72 If the deviation persists after 6 months, then 1094 Wrzght surgical correction can be considered. In these cases, it is best to correct the strabismus by operating on extraocular muscles rather than trying to remove fibrosis in the trochlear area.73'74 Fibrosis in the area of the trochlea can also occur secondary to systemic disease. Oliver and Laidler93 reported a case of lichen sclerosus et atrophicus and morphoea, resulting in an acquired Brown's syndrome. This disease involves the skin and subcutaneous tissue. It is characterized by subcutaneous fibrosis with infiltration of fibrosis deep into the subder- mal fat. This penetration of fibrosis is the morphoea component of the combined skin disease. The patient in this case report had skin lesions over both superior nasal quadrants involving the area of the trochlea and demonstrated bilateral Brown's syndrome, right eye more involved than left eye. The authors postulated that fibrosis penetrated the area of the anterior trochlea, resulting in restriction of tendon movement. Another cause of peritrochlear scarring may be periocular surgery, as upper lid blepharoplasty has been associated with acquired Brown's syndrome.89"9' In the present study, patient A10 had a repeat upper eyelid blepharoplasty and noted double vision immediately after the procedure. The blepharoplasty included removal of periorbital fat with cautery. At 4 months follow-up, the patient continued to have a severe Brown's syndrome and was compensating with a chin elevation. Acute onset of the Brown's syndrome immediately after surgery is indicative of contracture of peritrochlear connective tissue. It is likely that cautery in the area of the trochlea caused contracture of connective tissue surrounding the superior oblique tendon, restricting the tendon extension. Tendon-Trochlear Inflammation and Edema. Local inflammation in the area of the superior oblique tendon and trochlea is a well-known cause of acquired Brown's syndrome. Inflammatory diseases such as juvenile rheumatoid arthritis, adult rheumatoid arthritis, systemic lupus erythematosus, trochleitis with superior oblique myocitis, and entropathic arthropathy have all been associated with acquired Brown's syndrome.1338415559-61,66,67 It is interesting, however, that of the 47 patients with acquired Brown's syndrome in the present study, none were associated with systemic inflammatory disease despite the fact that the chart review included records from a large children's hospital. Data from the present study suggest that the association of acquired Brown's syndrome with systemic diseases such as juvenile rheumatoid arthritis, adult rheumatoid arthritis, and systemic lupus erythematosus is uncommon. Other previously reported causes of local inflammation associated with acquired Brown's syndrome include pansinusitis and blunt trauma to the superior nasal quadrant even without fracture or skin penetration.7"' Brown's Syndrome: Diagnosis and Management 1095 Perhaps Helveston has the best explanation as to how these inflammatory processes and blunt trauma ofthe anterior aspect ofthe superior nasal orbit produce limited elevation in adduction.'"5 Helveston hypothesized that local inflammation, caused by blunt trauma or inflammatory disease, could produce edema and swelling of the vascular connective tissue that surrounds the superior oblique tendon within the trochlea. Congestion in the tight constraints within the trochlea would result in restriction of tendon movement. Idiopathic inflammatory Brown's syndrome can present in association with superior nasal pain or a click sensation in the superior nasal quadrant. 5,37,42 It has been reported that many of these acquired inflammatory Brown's syndrome cases spontaneously resolve over time.2'4'5'8'53 The present study substantiates spontaneous improvement, especially in the group ofpatients with symptoms ofpain and/or a click. Three of 7 patients in the pain and click group improved over a period of months to several years. MRI and CT scanning have been useful in identifying edema and tissue swelling in the area of the trochlea.-29'3855101,140"146 MRI and CT scans performed on patients with pansinusitis, entropathic arthropathy, and trochleitis with superior oblique myositis show enhancement in the area of the trochlea and enlargement of the anterior aspect of the superior oblique tendon.3- il In the present study, 7 patients had imaging studies, 2 with positive findings in the area of the superior oblique tendon and trochlea. One patient (A18) with superior nasal orbital pain showed fat enhancement in the area of the trochlea, and the other patient (A14) with sinusitis demonstrated enlargement of the superior oblique tendon. As discussed previously, inflammation in the area of the trochlea could cause swelling of the tendon, interfering with movement. In addition, swelling of peritrochlear tissue could also limit tendon movement. Superior Nasal Orbital Mass. A mass in the superior nasal orbit can produce Brown's syndrome. Acquired Brown's syndrome is a well-known complication of a glaucoma drainage implant placed in the superior nasal quadrant.288294 Patients A7 and A8 from the present study had superior nasal quadrant glaucoma implants that resulted in large hypotropias in primary position and limited elevation in adduction (Fig 7). Because of the high risk of acquired Brown's syndrome, it is recommend that glaucoma implants not be placed in the superior nasal quadrant.28 A neoplasm in the superior nasal quadrant can also cause limited elevation in adduction.8'897 Biedner and associates8' described a case of frontal sinus osteoma that extended into the orbit. This resulted in diplopia and downward displacement of the globe. Removal of the osteoma 1096 wVriaht returned octular motility to normal. At least two mechanisms contribute to the restrictive eye movements associated witlh a superior nasal mass of the anterior orbit. First, the mass can push on and deflect the superior oblique tendon, functionally shortening the tendon. Second, a mass can crowd the anterior orbit, thus inhibiting ocular rotation up and nasal ward. In contrast to Brown's syndrome, whiclh is associated with an inelastic tendon or a restriction at the trochlea-tendon junction, patients with superior nasal mass usually demonstrate large vertical deviations in primary position, often associated with an exotropia. The 2 patients in the present study with glaucoma implants both had a large exotropia and vertical deviation of 18 to 20 PD. This is a striking contrast to the small vertical deviation usually associated with nontraumiatic acquired or congenital Brown's syndrome. Tight or Inelastic Superior Obliquie Muscle. Acq.uired loss ofelasticity ofthe superior oblique muscle can result in the classic strabismus pattern of Brown's syndrome. Hughes and associates-' reported a case of dysthyroid eye disease associated with acquired Brown's syndrome. Review of the composite gaze photographs in this case showed the classic findings of Brown's syndrome: severe limitation of elevation in adduction, normal superior obli(lue function, and minimal vertical deviation in primary position. CT scans and MRI revealed the presence of swelling of the ipsilateral superior oblique muscle. This case of acquired Brown's syndrome, catused by an inelastic superior oblique muscle, matches the pattern of strabismus pre(licted by the computer model of Brown's syndrome (Fig 19). Acquired Brown's syndrome may also occur after peribulbar anesthesia. Erie9' reported on a patient with peribulbar anesthesia for cataract surgery. The anesthesiologist injected 5 mL of lidocaine and bupivacaine mixture in the inferior temporal orbit and 3 mL of the same mixture in the superior nasal orbit at a depth of approximcately 2.5 cm. The patient did not have diplopia on the first day after surgery, and ocular rotations were reported to be normal. Subsequently, the patient developed limited elevation in adduction and showed the classic pattern of Brown's syndrome. The authors attributed this to scarring within the trochlea and tendon sheath. The present author has an alternative explanation. Perhaps superior oblique muscle fibrosis occurred secondarily to an inadlvertent intramuscular injection of anesthetic. Late intramuscular fibrosis and restriction of eye movements is a well-known complication of intramuscular injection of lidocaine and bupivacaine.'53-'55 It is possible that an inad- vertent injection of local anesthetic into the superior oblique muscle produced intramuscular fibrosis resuilting in an inelastic muscle, similar to the case associated with thyroidI disease. Brown's Syndrome: Diagnosis and Managemnent 191097 An unusual cause of a tight or stiff superior oblique muscle-tendon complex is Hurler-Scheie's syndrome.5 This is a mucopolysaccharidosis disease associated with contracture of hips, knees, elbows, and fingers. Bradbury and associates" reported on a 5-year-old girl with Hurler- Scheie's syndrome who developed limited elevation in adduction consistent with Brown's syndrome. They hypothesize that Hurler-Scheie's syndrome may be associated with widespread shortening of the tendons and that possibly, in this case, the superior oblique tendon became shortened. This case was not a pure Brown's syndrome, since the patient had an A- pattern esotropia measuring 20 PD in primary position, 35 PD in up gaze, and only 4 PD in down gaze. It is likely that other extraocular muscles were involved with the tendon contracture. Acquired inelastic superior oblique muscle is rare and there was none in the present study. However, these cases are important because they are examples of a pathologic mechanism that may operate in many congenital cases. A shortened superior oblique tendon is another cause of acquired Brown's syndrome. As already discussed, a superior nasal mass can fuinc- tionally shorten the superior oblique tendon. Another common cause of tendon shortening is a superior oblique tuck.'"5' Like Brown in his classic papers, the present author has not included these in this study as the diagnosis and mechanism are obvious.5X7620 A short tendon gives a different pattern ofstrabismus than an inelastic tendon (Figs 18 and 19). As describe previously, a short tendon induces a significant hypotropia with intorsion in primary position. An inelastic tendon, on the other hand, does not significantly affect primary position, but does affect up gaze. The pattern of strabismus in most Brown's syndrome patients is more consistent with an inelastic muscle-tendon complex or a tethered tendon, not a short tendon. Idiopathic Acquired Brown's Syndrone. In the majority of acquired Brown's syndrome patients, no specific cause of the restriction can be identified. Patients with signs of inflammation, such as pain or tenderness in the superior nasal orbit, are usually classified as inflammatory Brown's syndrome as already discuissed. In the present study, 36 patients were given the diagnosis of nontraumatic acquired Brown's syndrome. Four cases were associated with sinusitis, 7 were associated with a pain and a click sensation, and 25 (70%) were classified as idiopathic. One theory regarding the cause of idiopathic acquired Brown's syndrome is low-grade local inflammation or edema in the area of the trochlea and superior oblique tendon.53,4- "3 Swelling of the tendon within the trochlea would restrict tendon movement. Imaging studies have verified enhancement and tendon swelling in the area of the trochlea in some cases; however, 2 patients with idiopathic acquiired Brown's syndrome in the present stud(y 1098 Wright had orbital CT scans, and both were negative.2- "4 Negative orbital imaging does not necessarily eliminate an inflammatory cause of idiopathic Brown's syndrome, because it is possible the scans were not sensitive enough to identify inflammation within the trochlea. Local tendon inflammation or edema may help explain why acquired Brown's syndrome occurs in association with seemingly unrelated disorders. Trauma distant from the trochlea has been associated with an acquired Brown's syndrome. For example, Brady and Hiles` reported a case of acquired Brown's syndrome as a complication of cardiopulmonary resuscitation (CPR). This was a 2-year-old who developed a typical Brown's syndrome after a near-drowning accident and CPR. The Brown's syndrome resolved without treatment over 18 months. In the present study, an 8-year-old boy (patient A43) was run over by a car, causing fractures of both legs (Fig 10A). Soon after the accident, the patient noted double vision, and a left Brown's syndrome was diagnosed (Fig lOB). This case also resolved spontaneously over a 12-month period. Perhaps emboli from the leg fractures or from CPR obstructed small vessels of the connective tissue surrounding the superior oblique tendon, resulting in local ischemia, inflammation, and edema. This edema in the area of the trochlea could cause a temporary restriction of the normal telescoping of the superior oblique tendon. Postpartum acquired Brown's syndrome has also been reported. In this case, hormonal changes could have caused local edema in the area of the trochlea, resulting in restriction of tendon movement."4 These theories attempt to explain how such remote events could cause a local restriction of elevation in adduction. The exact mechanisms that cause acquired Brown's syndrome in these cases are unknown, but it is likely that local edema and/or inflammation in the area of the trochlea plays a role. Acquired-Pseudo Brown's Syndroine (Non-superior Oblique Causes) Acquired Brown's syndrome can be caused by restriction located away from the trochlea and superior oblique tendon. For example, a floor fracture can result in a vertical strabismus that mimics Brown's syndrome.:" The present study included 2 patients with non-superior oblique acquired Brown's syndrome, both involving the inferior oblique muscle. In 1 patient (All), the inferior oblique muscle was inadvertently anteriorized between the lateral and inferior rectus muscles, approximately 6 mm from the limbus, during an attempted inferior oblique muscle recession. This case also had fat adherence and scar in the inferior temporal quadrant. Removal of the fat adherence and plication of the inferior oblique muscle resulted in much improved ductions. The other patient (A9) had a 3600 retinal buckle that entrapped and anteriorized the inferior oblique muscle. Brown's Syndrome: Diagnosis and Management 1099 Again, there were adhesions in the inferior temporal quadrant. Releasing the inferior oblique muscle and adhesions improved ocular motility, but significant restriction persisted. Adhesions to the inferior temporal quadrant of the globe and inferior oblique muscle can result in the pattern of strabismus of Brown's syndrome.

PROPOSED CLASSIFICATION OF BROWVN'S SYNDROME Table XXIV summarizes the classification proposed by this author.

CONCLUSIONS REGARDING TREATMENT Congenital Brown's Syndrome Congenital Brown's syndrome is unlikely to improve spontaneously, so surgery is an important option to consider. The most important indication for surgery is the presence of a face turn or chin elevation that significantly interferes with the patient's quality of life. Head posturing indicates that a vertical deviation is present in primary position. The presence of limitation in adduction alone is not an indication for surgery. Surgery is usually considered after the child is old enough to cooperate with optotype visual acuity, usually at 3 years of age or older. The author's procedure of choice is the silicone tendon expander. Patients and/or parents should be informed that most, but not all, congenital Brown's syndrome cases are caused by a tight superior oblique muscle-tendon complex. In those cases not caused by a tight tendon, a tendon-lengthening procedure will not improve the condition. In many of these non-superior oblique cases, the cause of the restriction cannot be determined. The silicone tendon expander procedure works well, but there is approximately a 15% chance that further surgery will be required usually for an overcorrection (ie, a superior oblique paresis). Patients must have a full ophthalmic examination, including a cycloplegic examination, and be followed closely before and after surgery for amblyopia. Acquired Brown's Syndrome As discussed previously, acquired Brown's syndrome patients should be medically evaluated for coexisting systemic disease. If a disorder such as rheumatoid arthritis or sinusitis is identified, then it should be treated. Once systemic disease is ruled out, acquired Brown's syndrome patients with signs of inflammation (ie, pain or tenderness) can be treated with anti-inflammatory medication. Oral ibuprofen is a good first-line choice. If this does not sufficiently relieve symptoms, then local corticosteroid injections can be administered.35 Some authors have also advocated the use of oral corticosteroids.' Patients with inflammatory Brown's syn- 1100 Wright

TABLE XXI\': CLASSIFICATION OF BROWN'S SYNDROME

I. CONGENITAL ONSET a) Congeoital Brown s syncirooze i) Inelastic niiuscle-tenidoni comiiplex ii) Aniomialies of the stiperior oblique tendoni fibers b) Cotigeotital Psetido-Brotcnls syndromne i) Aniomlalous inferior orbital adhesions ii) Posterior orbital banids II. ACQUIRED ONSET a). Acqutired Brown's syndrome i) Peri-trochlear secarrin;g an,ld adhesionis (1) Chronic sinutisitis (2) Traumiiia - stuperior temiiporal orbit (3) Blepharoplasty & f'at removal (4) Licheni sclerostus et atrophicits anid morphoea ii) Tendon-trochlear inflaiimmationi and edemi.a (1) Idiopathic inflammatory (pain and click) (2) Trochleitis witlh stuperior oblique myocitis (3) Actute sinusitis (4) Adtult rheumiiatoid arthritis (5) Juvenile rheumatoi(d arthritis (6) Systemic luipus erylthemlatostus (7) Possibly distanit traumiiia (CPR anid lonig bone fracttures) (8) Possibly hormiionial chalinges postpartum iii) Suiperior nasal orbital milass (1) Glauconia implant (2) Neoplasnm iv) Tiglht or inelastic superior obli(lue muiiiscle (1) Thyroid disease (inelastic mutscle) (2) Peribulbar anesthesia (inelastic tenldoll) (3) Hurler-Scheies syndrome (inelastic tendoin) (4) Superior oblique tuick (short tenidoni) v7) Idiopatlhic b) Acquired Pseudo-Browns syndrome i) Floor fracture ii) Retinal band arouniid iniferior obliquie mutiscle iii) Illf'erior temporal aldhesionis drome often show spontaneous resolution once the inflammatory disease process is controlled. Inflammatory Brown's syndrome cases are best managed medically, and surgery should be deferred. Idiopathic Brown's syndrome should be observed for as long as possible, because spontaneous resolution is known to occur in some patients over a period of months to years. It is probably prudent to be conservative in regards to surgery in these cases. Some patients will, however, require surgery because of an unacceptable face posturing. In these cases, a reversible procedure such as silicone tendon expander or tenotomy with suture bridge is preferred. Brown's Syndrome: Diagnosis ancd Matnagemnent 1101

SUMMARY

The present study included 96 patients, 4 with primary superior oblique overaction for the torsion study and 92 with a diagnosis of Brown's syndrome. Of the 92 patients with Brown's syndrome, 6 were masquerade syndromes, 1 was unspecified Brown's syndrome not seen preoperatively, and 85 were Brown's syndrome study patients (38 congenital onset and 47 acquired). The percentage of right eyes versus left eyes and males verses females were similar for the entire Brown's syndrome group. A moderate female bias was identified in the acquired Brown's syndrome group, which had 63% females (P<0.1). As reported previously, the present study found that Brown's syndrome is rarely familial, as only one of 85 Brown's syndrome patients studied had a family member with Brown's syn-drome. A new finding from the present study, however, is that 35% of congenital Brown's syndrome patients had a family history of strabismus or amblyopia. In general, Brown's syndrome patients had equal vision and good binocular fusion, with 76% demonstrating stereoacuity and only 3 (4%) of 85 having amblyopia. Spontaneous resolution occurred in 5 of 85 patients (6%). All 5 were nontraumatic acquired Brown's syndrome cases representing 16% of this group. Recovery occurred over a 6 to 48 montlh period. Included with the 5 cases of spontaneous recovery is a unique case of transient acquired Brown's syndrome associated with traumatic long bone fractures of both legs. The pattern of strabismus previously described for Brown's syndrome was confirmed by the current studly. In addition, three new clinical observations were realized: 1. A limitation of elevation in abduction is commuon in Brown's syndrome caused by a tight or inelastic superior oblique tendon; this occurred in approximately 70% of surgically verified cases. Computer simulation demonstrated that limitation of elevation in abduction is a feature consistent with the presence of an inelastic ipsilateral superior oblique muiscle. This study also showed that apparent contralateral inferior oblique overaction is associated with limited elevation in abduction, and both disappear after the superior oblique is surgically lengthened. 2. The hypotropia in the traumatic Brown's syndrome cases is significantly larger than in the nontraumatic cases (P<.001). Congenital and nontraumatic acquired Brown's syndrome are associated with little or no vertical deviation in primary position, even when severe limitation of elevation in adduction is present. There was no significant hypotropia in primary position in 56 (76%) of 74 non-traumatic cases despite severe limitation of elevation (-3 to -4), and only one (1.4%) had a 1102 Wright hypotropia greater than 10 PD. 3. The pattern ofobjective fundus torsion in Brown's syndrome is little or no torsion in primary position and down gaze, and significant intorsion in up gaze. Of 7 patients with Brown's syndrome, 6 had no significant fundus torsion in primary position but had significant (+2 to +3) intorsion in up gaze. The one patient that did not have this torsion pattern had inferior oblique muscle scarring as the cause of Brown's syndrome, not a tight superior oblique tendon. The computer model for an inelastic superior oblique muscle showed no significant hypotropia or torsion in primary position, but intorsion was present in up gaze. In contrast, a short tendon creates a significant hypotropia and intorsion in primary position. The majority of congenital and nontraumatic acquired Brown's syndrome cases have a pattern of strabismus consistent with the computer simulation of an inelastic superior oblique muscle or a tethered tendon that cannot extend but contracts normally. Simulation of a short superior oblique tendon does not match the pattern of strabismus seen clinically in most Brown's syndrome patients. The diagnosis of Brown's syndrome caused by a tight or inelastic superior oblique muscle-tendon complex can be made by the pattern of strabismus, even without forced duction testing. The pattern of marked limitation of elevation in adduction, no superior oblique overaction, a small vertical deviation (<10 PD) in primary position, and intorsion present only in up gaze is indicative of a superior oblique-related Brown's syndrome. Conventional surgery, such as tenotomy and tenectomy, has not been effective in treating Brown's syndrome, producing a high incidence of either overcorrections or undercorrections. The silicone tendon expander procedure was found to be very effective in treating Brown's syndrome. Of 15 patients operated on by the author, 13 (87%) were corrected with one surgery and 14 (93%) with 2 surgeries. The only failure was a patient with non-superior oblique Brown's syndrome. Long-term follow-up of over 5 years was obtained on 5 patients, with one followed for 11 years. Four (80%) of the 5 patients with long-term follow-up had an excellent outcome with 1 surgery, having final results graded between 9 and 10 (scale of 1 to 10, 10 is best). The remaining patient had a good outcome after a second surgery. The AAPOS survey showed good results in most of the 140 cases. The final outcome ranked by the 39 surgeons averaged 7.3, with 65% scoring between 8 and 10. There were 9 (6%) complications reported, 4 related to scarring and 5 being extrusions of the implant. Complications seem to be related, at least in part, to the individual surgeon's technique, as 3 ofthe 5 extrusions were from the same surgeon. As determined by the computer model and clinical experience with the sili- Brown's Syndrome: Diagnosis and Managenent 1103 cone tendon expander procedure, a silicone implant length of 6 mm is recommended for the majority of Brown's syndrome cases. When compared to the traditional surgical techniques of superior oblique tenotomy and tenectomy, the silicone tendon expander procedure appears to yield more favorable results in the treatment of Brown's syndrome.

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