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Uncommon Compression Syndromes of the Upper Extremity

John D. Lubahn, MD, and Mary Beth Cermak, MD

Abstract

Nerve compression syndromes are a common cause of pain, sensory distur- eighth roots of the . bance, and motor weakness in both the upper and the lower extremities. These fibers course through the Although syndrome is frequently diagnosed and treated surgical- posterior divisions of the upper, ly with success, other compression syndromes are less common and are often middle, and lower trunks, forming best treated nonsurgically. Understanding the anatomy of the major peripheral the posterior cord and, subse- with respect to intermuscular septa, fibrous bands, muscle margins, and quently, the arising internervous planes is crucial to understanding how and where peripheral from the posterior cord. The nerve compression can occur. Some conditions, such as anterior interosseous nerve passes anterior to the sub- nerve syndrome, respond well to nonoperative treatment; others, such as poste- scapularis, teres major, and latis- rior interosseous nerve syndrome, are better treated by surgical intervention. simus dorsi muscles, where the The authors discuss the anatomic and pathologic causes for compression syn- first potential site of compression dromes, as well as guidelines for treatment and outcomes. may occur. Although rare, an J Am Acad Orthop Surg 1998;6:378-386 anomalous muscle, the accessory subscapularis-teres-latissimus, has been reported to cause compres- sion of the radial nerve at this Compression syndromes of periph- nerve may be interpreted as a level.6 Spinner7 has described eral nerves have a number of possi- painful stimulus by the brain. To penetration of the nerve directly ble causes. Pressure on a nerve may describe the extent of compression by the subscapular artery more disrupt either the local blood flow or and/or injury to a nerve, classifica- distally in the axilla, forming a the axoplasmic flow to the nerve. tion systems have been developed neural loop and potentially result- Low blood pressure may diminish by Sunderland4 (Table 1) and by ing in compression. Exiting the the blood supply of peripheral Seddon5 (Table 2). Peripheral axilla, the radial nerve courses lat- nerves and cause the familiar dys- nerve dysfunction secondary to erally, passing through the trian- esthesias, paresthesias, and occa- viral illness or exposure to toxins, gular space and then proceeding sional motor weakness about which such as heavy metals, can mimic through the lateral head of the tri- patients frequently complain. Direct compression syndrome. Patients ceps, where Lotem et al8 and other pressure of 500 mm Hg or more with systemic diseases, such as dia- may cause internal disruption of the betes, may be more susceptible to axons.1 Epineurial scarring may nerve compression. Lifestyle and spontaneously form in peripheral behavioral patterns may also influ- Dr. Lubahn is Chairman, Department of nerves, with resultant symptoms of ence the occurrence of nerve com- Orthopaedic Surgery, Hamot Medical Center, partial or complete compression pression, as in the ÒSaturday night Erie, Pa. Dr. Cermak is Instructor and (Fig. 1).2,3 palsyÓ seen in alcoholics. Orthopaedic Surgeon, Hamot Medical Center. Motor nerves, such as the poste- rior interosseous branch of the Reprint requests: Dr. Lubahn, , Micro- surgery and Reconstructive Orthopaedics, 300 radial nerve and the anterior Radial Tunnel Syndrome State Street, Suite 205, Erie, PA 16507. interosseous branch of the , contain stretch receptors, Pathoanatomy Copyright 1998 by the American Academy of sensory fibers, and motor fibers. The radial nerve is composed of Orthopaedic Surgeons. Therefore, pressure on a motor fibers from the sixth, seventh, and

378 Journal of the American Academy of Orthopaedic Surgeons John D. Lubahn, MD, and Mary Beth Cermak, MD

and the flexor carpi radialis in the distal third of the to lie superficial and subcutaneous. The deep branch of the radial nerve (the posterior interosseous branch) passes through the so- called radial tunnel, where it once again becomes subject to compres- sion. The radial tunnel is composed of the anatomic structures between the radiohumeral joint and the dis- tal extent of the supinator muscle. Potential sites of compression causing radial tunnel syndrome include the fibrous margin of the extensor carpi radialis brevis mus- cle, fibrous bands at the level of the radiocapitellar joint, the radial Fig. 1 Compressive lesion in the radial nerve. The constriction was intraepineurial, and recurrent artery, the arcade of the patient was treated with epineurolysis. Recovery was slow, and tendon transfers were Frohse proximally as the nerve performed. The lesion resolved over the course of 5 years, with electromyographic evi- passes distally through the supina- dence of return of normal function. (Courtesy of Graham D. Lister, MD, Vero Beach, Fla.) tor muscle, and a fibrous band at the distal margin of the supinator muscle.11,12 Once through the researchers have reported com- and a deep branch. The superfi- supinator, the deep branch of the pression. (Lotem et al correlated cial branch contains sensory fibers radial nerve divides into superfi- the data obtained in cadaveric and continues beneath the bra- cial and deep components. The studies with findings from clinical chioradialis into the forearm, pass- superficial branch courses medial- studies. Surgery was not per- ing between the ly, innervating the extensor digito- formed to verify the exact cause of the compression.) Familial radial nerve entrapment Table 1 has been reported secondary to SunderlandÕs Classification of Nerve Compression4 compression at the lateral head of the .9 A genetic defect in Grade Description Schwann cell myelin metabolism has also been postulated as a cause 1 Interruption of axial conduction at the site of injury. The axon of radial tunnel syndrome.10 Al- remains in continuity; some segmental demyelinization may be though this disorder may be present but not Wallerian degeneration. The condition is reversible. asymptomatic, it can predispose the nerve to intermittent compres- 2 The axon itself is no longer in continuity. The axon does not sion. survive distal to the level of the injury and for a short distance The nerve then courses distally proximal. The endoneurium is preserved. Full recovery may be along the humerus and passes expected. from the posterior to the anterior 3 The axon is severed, and Wallerian degeneration develops. The compartment of the , where endoneurial tube is lost, and the fascicular anatomy is disturbed. yet another potential site of com- Recovery is incomplete. pression, the lateral intermuscular 4 Total destruction of the internal architecture of the nerve. The septum, is found. Following the trunk is intact, but a neuroma will form. Spontaneous recovery deep surface of the brachioradialis is rare. Surgical repair is indicated. and the extensor carpi radialis longus muscles, the radial nerve 5 Loss of continuity of the nerve trunk. Surgical repair is mandatory. bifurcates into a superficial branch

Vol 6, No 6, November/December 1998 379 Nerve Compression in the Upper Extremity

well established. Treatment may Table 2 include rest, stretching exercise, 5 SeddonÕs Classification of Nerve Compression and splinting.14,15 If symptoms have not improved after 6 to 12 Type Definition weeks, a corticosteroid injection carefully placed adjacent to, but Neurapraxia Pressure on the nerve with resultant dysesthesias but no loss not within, the nerve is an accept- of continuity able therapeutic option.14,15 Axonotmesis The neural tube is intact, but the internal axons have been Surgical intervention may be disrupted considered if the symptoms are not Neurotmesis The nerve itself has been completely divided relieved by rest, activity modifica- tion, nonsteroidal medication, or a cortisone injection. Before consid- ering surgical treatment, precise rum, the extensor digiti minimi, extension and forearm supination localization of the pain to the and the extensor carpi ulnaris against resistance may also repro- region directly over the radial muscles. The deep branch contin- duce the pain.11 However, this nerve within the radial tunnel must ues distally to supply the abductor maneuver (among others) will also be confirmed. Lister et al11 have pollicis longus, the extensor polli- cause pain with lateral epicondyli- recommended decompression of cis brevis, the extensor indicis pro- tis. Forearm pain may be produced the radial nerve through a trans- prius, and the extensor pollicis by resisted supination with the verse incision at the level of the longus. elbow extended or by resisted supinator when the surgeon is extension of the middle-finger absolutely certain that the site of Clinical History and Symptoms metacarpophalangeal joint with the compression is the supinator. If Pain is the most common prima- elbow extended and the forearm doubt exists because of tenderness ry presenting symptom in radial supinated. These maneuvers pur- proximally over the radial nerve, a tunnel syndrome. There is some portedly produce compression of more extensile, bayonet-shaped controversy concerning the exis- the nerve by the fibrous arch of the incision beginning at the level of tence of this syndrome because it is supinator and extensor carpi radi- the lateral epicondyle and extend- based essentially on the presence alis brevis muscles, respectively. ing in a curvilinear fashion distally of localized pain without objective Electrodiagnostic evaluations are across the supinator muscle is nec- findings. It is the only nerve com- negative in most cases of radial essary. Care should be taken to pression syndrome in which the tunnel syndrome, but are positive identify all potential sites of com- signs and symptoms are not based in the presence of posterior interos- pression and to release the entire on the nerve distribution.13 A seous nerve syndrome. supinator, including its distal point of maximal tenderness is edge.12 present at the site of compression, Management Postoperative management in- usually located over the anterior Nonoperative treatment is im- cludes use of a long-arm posterior radial neck, in contrast to tennis portant, and every effort should be splint with the wrist in neutral po- elbow, in which pain is at the ori- made to modify patient activity to sition. A gradual range-of-motion gin of the extensor carpi radialis avoid provocative positioning of exercise program is begun at 1 brevis muscle. Compression of the the arm. For example, if the pa- week, with stretching exercise for Òmobile wadÓ may also cause pain, tientÕs job requires elbow exten- the extensor muscles of the fore- as can resistance to active exten- sion, forearm pronation, and wrist arm. Return to unlimited activities sion of the middle finger. Roles flexion repetitively or for long peri- can take 6 to 12 weeks, depending and Maudsley14 were the first to ods of time, an ergonomic evalua- on job requirements. Patients who describe radial tunnel syndrome in tion should be completed, and are receiving workerÕs compensa- a patient with resistant tennis every effort should be made to tion should be managed proactively elbow. modify the task or change the job. with job modification. When time At any of the potential sites, Symptomatic treatment should off work or operative treatment is compression of the radial nerve is be attempted in all nerve compres- required, it is important to establish most significant with the elbow sion syndromes, including radial agreement between patient and extended, the forearm pronated, tunnel syndrome, although the effi- employer on a gradual return-to- and the wrist flexed. Active wrist cacy of such management is not work program.

380 Journal of the American Academy of Orthopaedic Surgeons John D. Lubahn, MD, and Mary Beth Cermak, MD

Posterior Interosseous palsy. The wrist extends and devi- ment and may influence the pre- Nerve Syndrome ates radially because it is not dictability of a successful outcome. opposed by the extensor carpi A recent Mayo Clinic study cited a Pathoanatomy ulnaris and extensor carpi radialis 51% success rate for surgery for Posterior interosseous nerve brevis, which insert at more ulnar radial tunnel syndrome and cited syndrome is the result of pressure sites in the base of the small-finger difficulty in differentiating radial on the nerve with secondary loss of and long-finger metacarpals, re- tunnel syndrome from lateral epi- motor function. Typical causes are spectively. condylitis as the reason for their elbow synovitis caused by rheuma- Posterior interosseous nerve mediocre results.17 In our experi- toid arthritis and benign tumors, compression may coexist with lat- ence, while considerable improve- such as ganglions (Fig. 2) and lipo- eral epicondylitis. As part of the ment is often noted in selected mas. When compression within clinical history, other potential patients, few return to work at their the radial tunnel is sufficient to causes of peripheral neuritis, such preoperative level, and none return cause paralysis but there is no as polyarteritis, rheumatologic dis- to physically demanding jobs. palsy, the condition is termed pos- orders, and postÐsystemic illness Late return of function was a terior interosseous nerve syn- angioneuropathy, should be con- feature of the patients in the initial drome, rather than radial tunnel sidered. description of the condition. With syndrome. early diagnosis (within 3 months of Management onset of symptoms), a higher rate Clinical History and Symptoms Initial nonoperative treatment of spontaneous recovery can be Partial lesions occur when only should include rest, activity modi- expected. When an underlying one nerve branch is involved. fication, and use of a wrist cock-up cause, such as a lipoma or gan- Compression of the superficial or splint. A cortisone injection should glion, is suspected, a magnetic res- medial branch causes paralysis of also be considered. Regular gentle onance imaging study (Fig. 2) may the extensor carpi ulnaris, extensor stretching of the wrist extensor confirm the diagnosis, and surgical digiti quinti, and extensor digito- muscles with the elbow held in full decompression of the nerve, with rum communis. Compression of extension is begun after a sponta- removal of the lesion, is indicated. the lateral branch causes paralysis neous recovery. When no obvious anatomic lesion of the abductor pollicis longus, If no improvement is seen with- exists, decompression of the poste- extensor pollicis brevis, extensor in 90 days, spontaneous recovery is rior interosseous nerve by release pollicis longus, and extensor indicis unlikely, and surgery should be of the supinator and the arcade of proprius. Compression of the performed. If the condition per- Frohse may be considered if spon- superficial branch affects the exten- sists for 18 months or more, muscle taneous return of function does not sor communis, extensor digiti mini- fibrosis occurs, creating an irre- occur by 6 months. In the case of mi, and extensor carpi ulnaris. Ex- versible condition.16 In late cases, older patients and patients for tensor carpi radialis longus func- tendon transfers will be necessary. whom recovery is less likely (those tion is preserved even in a complete There have been no long-term with no return of function after 18 prospective outcome studies com- months or more), tendon transfer paring operative and nonoperative should be performed. treatment for either radial tunnel or posterior interosseous nerve entrap- ment. Lister et al11 reported im- Pronator Syndrome provement in 19 of 20 patients with radial tunnel syndrome who were Pathoanatomy followed up 9 months to 4 years The median nerve is composed after surgical release. The outcome of fibers from the roots of the fifth, was particularly dependent on the sixth, seventh, and eighth cervical correct preoperative diagnosis. nerves and the first thoracic nerve. Therefore, the surgeonÕs familiarity To reach the median nerve, fibers with the diagnosis and treatment of from these nerve roots must pass radial tunnel syndrome, lateral epi- through the anterior divisions of Fig. 2 This ganglion cyst in the proximal forearm resulted in posterior interosseous condylitis, and posterior interos- the upper, middle, and lower nerve palsy. seous nerve syndrome is critical in trunks and the lateral and medial patient selection for surgical treat- cords of the brachial plexus. The

Vol 6, No 6, November/December 1998 381 Nerve Compression in the Upper Extremity median nerve is formed anterior to nerve and innervate the pronator GantzerÕs muscle, which is an the third portion of the axillary teres.19 anomalous flexor pollicis longus), a artery. It enters the upper arm Entering the forearm, the nerve palmaris profundus muscle, and a behind the pectoralis major muscle, is subject to potential compression flexor carpi radialis brevis mus- lateral to the brachial artery. The by the lacertus fibrosus. The medi- cle.16 Anomalous arteries, such as nerve passes with relative freedom an nerve then passes beneath the an aberrant , or an through the upper portion of the humeral head of the pronator teres. enlarged bicipital bursa, may also arm, with the only potential sites of In 6% of patients, the ulnar head is cause pressure on the nerve. compression being the pectoralis absent20; however, compression Pronator syndrome is the result minor muscle, anomalous muscles from the humeral head is still possi- of compression of the median or blood vessels, and the deltopec- ble. The nerve then passes beneath nerve between the two heads of the toral .18 the proximal fibrous arch of the two . Pronator Distally in the arm, a supracondy- muscular heads of the flexor digito- syndrome commonly occurs with loid process (located medial and rum superficialis, where compres- strenuous activities such as weight proximal to the medial epicondyle) sion is also possible. The median lifting and in occupations requiring and associated ligament of Struthers nerve continues distally in the fore- repetitive pronation of the forearm is a potential compression site. In arm between the flexor digitorum with the elbow extended. 1% of upper extremities, a supracon- sublimis and the flexor digitorum dyloid process (Fig. 3) exists where profundus. The anterior interos- Clinical History and Symptoms the ligament of Struthers origi- seous nerve, which is the last major Pronator syndrome can be con- nates.16 More commonly, the liga- branch of the median nerve in the fused with , ment of Struthers originates from the proximal forearm, supplies the flex- as both may cause numbness and humerus at the site where the supra- or pollicis longus, the flexor digito- paresthesias in the median nerveÐ condyloid process may occur and rum profundus to the index and innervated digits, weakness of the inserts in the medial epicondyle. long fingers, and the pronator thenar muscles, and pain in the There are no branches of the median quadratus. wrist and forearm. Unlike carpal nerve in the arm, except possibly a Additional sites of compression tunnel syndrome, there is no Tinel separate fascicular bundle that may of the median nerve in the forearm sign at the wrist. Dysesthesias are leave the main trunk of the median include anomalous muscles (e.g., present in the palmar triangle or in the skin overlying the thenar emi- nence, as this is innervated by the palmar cutaneous branch of the median nerve, which originates proximal to the transverse carpal ligament. Furthermore, pronator syndrome does not produce noctur- nal symptoms.21 However, carpal tunnel syndrome and pronator syn- drome may coexist, and the examin- er should carefully evaluate the patient for the simultaneous presen- tation of both conditions.

Management Although the diagnosis is rarely made, once it is established, surgi- cal intervention is usually not nec- essary. The condition is typically treated with activity modification. When nonoperative treatment fails or when space-occupying Fig. 3 Anteroposterior radiograph shows a characteristic supracondyloid process (arrow). When this appearance is seen in a symptomatic patient, removal of the supra- lesions exist, surgery may be indi- condyloid process and the associated ligament of Struthers should be considered. cated. In a review of the long-term results of surgical treatment of

382 Journal of the American Academy of Orthopaedic Surgeons John D. Lubahn, MD, and Mary Beth Cermak, MD pronator syndrome in 5 patients, rior interosseous nerve syndrome, Johnson et al22 noted relief of pain the surgeon should consider a more in 4 (80%). In a Mayo Clinic study proximal cause of nerve compres- of 36 patients treated surgically, 8 sion, such as pronator syndrome, had excellent results, 20 had a good brachial , or a tendon outcome, and 5 had only fair rupture, as occurs in patients with results; the condition of the remain- rheumatoid arthritis. ing 3 patients was unchanged.21 Management Reports in the neurologic litera- Anterior Interosseous ture indicate that anterior interos- Nerve Syndrome seous nerve syndrome resolves spontaneously. In one series,23 all Fig. 4 Patients with anterior interosseous Pathoanatomy and Diagnosis nerve palsy are asked to position their patients recovered without surgical hand as shown. Those with absent profun- Anterior interosseous nerve syn- intervention. Miller-Breslow et al24 dus and flexor pollicis longus activity flex drome was first described by Tinel believe that the condition is a neu- only the interphalangeal joint of the index finger and the metacarpophalangeal joint in 1918 and was further delineated ritis. Regardless of the cause and of the thumb. by Kiloh and Nevin in 1952. In management of the neuropathy, if contrast to pronator syndrome, motor function does not recover, pain may be elicited by resisted tendon transfers will restore func- flexion of the flexor digitorum sub- tion satisfactorily. es of the median nerve arise on its limis of the long finger and may Anterior interosseous nerve syn- ulnar side at this level, the most also be present at rest and on local drome usually resolves with time, notable exception being the anteri- palpation of the nerve. When the particularly if the lesion is sec- or interosseous branch, which orig- syndrome is complete, denervated ondary to neuritis. Observation for inates on the radial side. In severe muscles include the flexor pollicis 3 to 6 months is favored before sur- cases, neurolysis and pronator teres longus, the two radial profundus gical treatment. Strengthening of lengthening may be required.28 tendons, and the pronator quadra- remaining muscles and, occasional- tus. No sensory changes occur, ly, modalities such as heat and and the hand assumes a character- stretching are useful in most cases. Quadrilateral Space istic posture such that the patient is If no improvement is noted, or if a Syndrome unable to position the thumb and space-occupying lesion is present, index finger in the shape of a six surgical release is recommended. Pathoanatomy and Diagnosis (Fig. 4). The profundus tendon to If no improvement occurs after The axillary nerve originates the long finger is not always solely decompression, tendon transfer from the C5-6 nerve roots and pro- innervated by the median nerve, should be performed.25 ceeds through the posterior divi- and the posture of the fingers in Surgical exposure of the median sion of the upper trunk, coursing to making a fist may resemble that nerve and its anterior interosseous the posterolateral aspect of the pos- seen with an isolated flexor digito- branch is through an S-shaped inci- terior cord. In approximately 72% rum profundus avulsion or lacera- sion that extends proximal to the of cases, the axillary nerve sepa- tion of the index profundus. elbow to allow exposure of the rates from the posterior cord at the Association with absent flexor median nerve at the ligament of level of the coracoid, and the poste- pollicis longus function establishes Struthers if necessary.26 The nerve rior cord becomes the radial the diagnosis of anterior interos- is then traced distally, passing nerve.29 The axillary nerve then seous nerve syndrome. The prona- beneath the lacertus fibrosus27 and travels with the posterior circum- tor quadratus may be tested with then between the humeral and flex humeral artery through the the elbow held in a flexed position ulnar heads of the pronator teres. quadrilateral space, which is to neutralize the humeral head of The humeral head is taken down bounded by the long head of the the pronator teres muscle. Electro- and tagged for later lengthening or triceps medially, the proximal myographic (EMG) and nerve- reattachment. The median nerve humerus laterally, the teres major conduction studies are often helpful may actually penetrate the prona- inferiorly, and the teres minor in establishing the diagnosis. If the tor teres muscle. The safer ap- superiorly. findings from electrodiagnostic proach to the median nerve is from Idiopathic quadrilateral space studies are not consistent with ante- the radial side, as nearly all branch- syndrome is very uncommon.29,30

Vol 6, No 6, November/December 1998 383 Nerve Compression in the Upper Extremity

Vague discomfort and can produce considerable postoper- Clinical History and Symptoms pain with fatigue occur when the ative pain.30 The posterior ap- Patients normally complain of a patient holds the arm above shoul- proach is made under the lower dull aching pain over the posteri- der level. The pain of axillary nerve edge of the deltoid. Both transverse or lateral aspect of the shoulder. compression is poorly localized to and vertical incisions have been de- This pain may radiate up the neck the shoulder. Paresthesias are pres- scribed. This approach exposes the or down the lateral aspect of the ent in a nondermatomal pattern. main area of compression in the arm. The etiology of suprascapu- Discrete tenderness to palpation in posterior aspect of the space and is lar nerve entrapment is varied the quadrilateral space and deltoid the preferred approach. Fibrous and may include sports activities weakness are present. Objective bands or an anomalous head of the such as weight lifting, volleyball, evidence of compression is demon- triceps is usually responsible for the and baseball. Other causes in- strated by an arteriogram indicat- compression.31 clude soft-tissue growths, such as ing compression of the posterior The patient may begin active ganglion cysts, and iatrogenic circumflex humeral artery during range-of-motion exercises as early injury during rotator-cuff surgical abduction of the shoulder.31 Dop- as postoperative day 7. According mobilization for tears greater than pler studies may obviate the need to Dellon and Mackinnon,20 this 3 cm.35 for an arteriogram. The EMG find- promotes axillary nerve gliding Clinical diagnosis is difficult ings are also diagnostic. From ErbÕs and prevents scarring. In one when muscle atrophy is not evi- point distally, distances of 15 to 18 study, Cahill and Palmer30 found dent. Tenderness on palpation of cm should have an average latency that 89% of patients showed im- the notch, differential injections, of 4.3 msec.32 Any latency longer provement of symptoms postoper- and the cross-body adduction test than 5 msec should be considered atively. of the arm may help establish the abnormal. The differential diagno- diagnosis. Electromyographic and sis includes thoracic outlet syn- nerve-conduction studies are re- drome, suprascapular nerve entrap- Suprascapular Nerve quired and will be diagnostic. ment, disease, and C5, Entrapment Magnetic resonance imaging will C6, and C7 . help rule out a rotator-cuff disorder Pathoanatomy and may reveal a ganglion cyst in Management The suprascapular nerve is a the notch.36 Initial treatment is conservative, mixed motor and sensory nerve with muscle relaxants, nonsteroidal that originates from the upper Management anti-inflammatory medication, rest, trunk of the brachial plexus. It Treatment usually begins by and cortisone injections. If there is leaves the trunk 3 cm above the eliminating the activity associated no improvement after 3 to 6 clavicle and passes deep to the with the problem. Nonsteroidal months, operative treatment may trapezius and omohyoid muscles anti-inflammatory drugs, analgesic be considered. A positive EMG, on its way to the suprascapular agents, and trapezius-strengthening Doppler, or arteriographic study is notch. In the notch, the supra- exercises are encouraged. Cor- also an indication for operative scapular nerve passes beneath the tisone injections are also used. If 3 treatment. superior transverse scapular liga- to 6 months of conservative thera- Three surgical approachesÑ ment, and the suprascapular artery py fails or if the initial EMG study anterior, axillary, and posteriorÑ and vein pass above the ligament. is positive, demonstrating muscle are available. The anterior ap- The nerve supplies one or two fibrillation, operative intervention proach through the deltopectoral branches to the supraspinatus mus- is warranted.29 Three operative interval is not helpful in compres- cles and then passes into the infra- approaches to the suprascapular sive cases because only the anterior spinatus fossa by proceeding nerve are available. The posterior portion of the space can be visual- around the lateral margin of the approach is generally used in cases ized. The anterior approach is use- scapular spine.33,34 of muscle atrophy or underdevel- ful when there has been penetrating Suprascapular nerve entrapment oped muscle. Otherwise, the mus- trauma and when space-occupying is a cause of shoulder pain to be cle covers the notch and is difficult lesions are present anteriorly. The considered in the differential diag- to retract.37 axillary approach is excellent for nosis with rotator cuff disease, The cranial approach exposes exposure; however, care must be impingement syndrome, acromio- the notch well, but distal dissection taken to avoid the intercosto- clavicular joint arthritis, and cervi- is difficult. Hadley et al34 de- brachial cutaneous nerve, as injury cal . scribed a third approach midway

384 Journal of the American Academy of Orthopaedic Surgeons John D. Lubahn, MD, and Mary Beth Cermak, MD between the clavicle and the spine controversial. Murray37 has stated Summary of the scapula through the trapez- that osseous overgrowth may occur ius muscle. The upper border of if the notch is resected, but Vas- The ability to identify potential the scapula is palpated, and the tamŠki and Gšransson38 recom- causes of appendicular pain in the notch is identified. Although expo- mend bone resection if the notch is musculoskeletal system is crucial sure is difficult, the omohyoid narrow. to the practicing orthopaedist. muscle leads directly to the medial Postoperatively, the pain should Although radicular pain from the margin of the notch. Care must be be greatly diminished or complete- cervical spine is a common cause of taken to avoid the suprascapular ly relieved.38 Muscle atrophy and extremity pain and dysfunction, artery and vein above the notch. weakness improve very slowly peripheral nerve compression with The transverse scapular ligament is with physical therapy. The patient secondary dysfunction in the ex- then transected, and the nerve is should begin active motion within tremity should be considered in the explored. Resection of the notch is 2 weeks after surgery. differential diagnosis.

References

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