Review Article Suprascapular Neuropathy

Abstract Dana P. Piasecki, MD Suprascapular neuropathy is a relatively uncommon but significant Anthony A. Romeo, MD cause of shoulder pain and dysfunction. The follows a tortuous course from the neck to the posterior shoulder. Bernard R. Bach, Jr, MD There are several potential causes of nerve entrapment along this Gregory P. Nicholson, MD path, particularly at the vulnerable suprascapular and spinoglenoid notches, where nerve excursion is limited by bony and ligamentous constraints. Additional extrinsic compression may be caused by glenohumeral joint–related ganglion cysts or soft-tissue masses. Traction neuropathy may occur following excessive nerve excur- sion during overhead sports or as a result of massive, retracted rotator cuff tears in older patients. Diagnosis is based on a careful history, physical examination, focused imaging, and electrodiagnos- tic studies. In the absence of a clear structural compression or overtensioning of the nerve, treatment initially should be nonsurgi- cal, with activity modification and physical therapy. Discrete nerve compression or failure of nonsurgical measures warrants early sur- gical intervention. Arthroscopic alternatives to the traditional open suprascapular and/or spinoglenoid notch decompressions have the benefit of simultaneously diagnosing and addressing intra-articular Dr. Piasecki is Attending Surgeon, and/or subacromial pathology while minimizing morbidity. In most Sports Medicine Division, OrthoCarolina, Charlotte, NC. patients, both open and arthroscopic approaches provide reliable Dr. Romeo is Section Head, pain relief and improvements in function; return of strength and Shoulder and Elbow, Division of muscle bulk is less predictable. Sports Medicine, and Professor of Orthopaedics, Rush University Medical Center, Chicago, IL. Dr. Bach is Claude N. Lambert, uprascapular neuropathy was fraspinatus atrophy will occur with su- MD–Helen S. Thomson Professor of Orthopaedics and Director, Divison Sfirst described by Kopell and prascapular notch involvement, making of Sports Medicine, Department of Thompson in 1959.1 Although it is a the distribution of muscle involvement Orthopaedics, Rush University relatively uncommon cause of shoulder helpful in localizing the site of injury. Medical Center. Dr. Nicholson is Associate Professor of pain and dysfunction, latent suprascap- And because traction injuries typically Orthopaedics, Department of ular neuropathy is common in overhead respond well to nonsurgical manage- 2 Orthopaedics, Rush University athletes, and in some scenarios, nerve ment whereas mass compression usu- Medical Center entrapment and/or injury can contrib- ally responds best to surgical decom- Reprint requests: Dr. Romeo, ute to significant disability. From the pression, the cause of nerve dysfunction Division of Sports Medicine, cervical nerves root to innervation of Department of Orthopaedics, Rush should be determined. University Medical Center, Suite the infraspinatus muscle along the pos- 1063, 1725 West Harrison Street, terior aspect of the , the supra- Chicago, IL 60612. scapular nerve is vulnerable to various Anatomy insults at and between the narrow su- J Am Acad Orthop Surg 2009;17: prascapular and spinoglenoid notches. The suprascapular nerve provides 665-676 The supraspinatus muscle will not be sensory fibers to the coracoacromial Copyright 2009 by the American affected by spinoglenoid notch neu- , acromioclavicular and gle- Academy of Orthopaedic Surgeons. ropathy, whereas both supra- and in- nohumeral joints and, in 15% of the

November 2009, Vol 17, No 11 665 Suprascapular Neuropathy

Figure 1 of the notch, ranging from a subtle depression to pure bony tunnel with ossification of the overlying liga- ment4 (Figure 2). Although the su- prascapular artery and vein usually pass above the transverse scapular ligament, the nerve passes beneath, limiting its potential excursion within the narrow fibro-osseous tun- nel. On average, the nerve is 3.0 cm medial to the as it passes through the suprascapu- lar notch.6 On exit, it travels pos- terolaterally across the floor of the supraspinatus fossa, providing sev- eral motor branches to the overlying supraspinatus muscle and receiving sensory fibers from the acromiocla- vicular and glenohumeral joints.3,6 These various tethers limit excursion of the nerve to ≤3 cm within the su- praspinatus fossa.3 At the posterolateral corner of the fossa, the nerve reaches the spinogle- Illustration of suprascapular anatomy. After exiting the posterior cervical noid notch, a depression at the lat- triangle, the suprascapular nerve passes through the suprascapular notch, eral base of the scapular spine that across the floor of the supraspinatus fossa, and past the spinoglenoid notch. The suprascapular notch is roofed by the transverse scapular ligament, and occurs 1.8 to 2.1 cm medial to the the spinoglenoid notch is covered by the spinoglenoid ligament; both glenoid rim.3,6 A spinoglenoid liga- structures have the potential to compress the nerve. (Reproduced with ment has been identified with vari- permission from Safran MR: Nerve injury about the shoulder in athletes: Part able frequency coursing over the top 1. Suprascapular nerve and axillary nerve. Am J Sports Med 2004;32: 5 803-819.) of the notch (Figure 3). Recently, Plancher et al7 demonstrated the liga- ment’s presence in all 58 study speci- population, may have a cutaneous through the posterior cervical trian- mens and attributed the variable branch supplying sensation in the gle to reach the suprascapular notch presence reported in prior studies to lateral . Its chief function is that (Figure 1). differences in specimen preparation. of a motor nerve, innervating the su- The suprascapular notch is a bony Histologic analysis confirmed true praspinatus and infraspinatus muscle depression medial to the base of the ligamentous insertional features, and bellies.3 The nerve originates from . Its superior aspect the distance from nerve to ligament the upper trunk of the brachial is enclosed by the transverse scapular was well-conserved across specimens plexus (ie, C5, C6, occasionally C4), ligament. Various morphologies have at a mean of 4.6 mm.7 Because por- from which it courses laterally been described for the bony portion tions of the ligament insert into the

Dr. Romeo or a member of his immediate family has received royalties from, is a member of a speakers’ bureau or has made paid presentations on behalf of, and serves as a paid consultant to or is an employee of Arthrex; has received research or institutional support from Arthrex, Athletico, DJ Orthopaedics, Miomed, and Smith & Nephew; and has stock or stock options held in, and has received nonincome support (such as equipment or services), commercially derived honoraria, or other non–research-related funding (such as paid travel) from, Arthrex. Dr. Bach or a member of his immediate family has received research or institutional support from Arthrex, Athletico, DJ Orthopaedics, Miomed, Ossur, Scheck & Siress, and Smith & Nephew. Dr. Nicholson or a member of his immediate family has received royalties from Innomed and Zimmer; has served as a paid consultant to or is an employee of Zimmer; has received research or institutional support from EBI; and has stock or stock options held in Zimmer. Neither Dr. Piasecki nor a member of his immediate family has received anything of value from or owns stock in a commercial company or institution related directly or indirectly to the subject of this article.

666 Journal of the American Academy of Orthopaedic Surgeons Dana P. Piasecki, MD, et al

Figure 2 Figure 3

Posterior photograph of a cadaver right scapula demonstrating the scapular spine (SS), spinoglenoid ligament (SG), and suprascapular nerve (SN). The spinoglenoid notch is bounded by the glenoid neck inferiorly, the scapular spine medially, and the spinoglenoid ligament superolaterally. (Adapted with permission from Plancher KD, The six types of suprascapular notch: type I, depression (8%); type II, Peterson RK, Johnston JC, Luke shallow V-shaped (31%); type III, U-shaped (48%); type IV, deep V-shaped TA: The spinoglenoid ligament: (3%); type V, type III with partial ossification of the ligament (6%); and type Anatomy, morphology, and VI, complete ossification of the ligament (4%). (Reproduced with permission histological findings. J Joint from Rengachary SS, Burr D, Lucas S, Brackett CE: Suprascapular Surg Am 2005;87:361-365.) entrapment neuropathy: A clinical, anatomical, and comparative study. Part 3: Comparative study. Neurosurgery 1979;5:452-455.)

laris muscle13 may all contribute to posterior capsule, the spinoglenoid omy and nature of the insult. Focal suprascapular notch entrapment. As the nerve passes into the suprascapu- ligament becomes taut in positions of nerve entrapment may occur at any lo- 8 lar fossa, mobility is greater but is adduction and internal rotation, cation along the nerve’s course but is still limited by the nerve’s adherence which corresponds to the follow- most common where mobility is already to the periosteum and by its motor through phase of throwing. It is just limited. Once the nerve reaches the con- branches to the supraspinatus.3 A beyond the spinoglenoid notch that fines of the suprascapular notch, it is scapular fracture malunion, or any the nerve makes an acute medial turn particularly vulnerable. Anything that other space-occupying fossa lesion, around the base of the scapular narrows the notch may injure the nerve. spine, traveling along the scapular may compress the nerve in this re- Fractures involving this region have gion. Likewise, as the nerve turns body and sending two or more mo- been reported to cause neuropathy,10 tor branches into the infraspinatus medially at the spinoglenoid notch and although nerve injury has been muscle.6 These motor branches split and beneath the spinoglenoid liga- attributed to supraglenoid cysts at off the main nerve and travel along ment, it is particularly susceptible to the spinoglenoid notch, paralabral the muscle’s undersurface 2.0 to 2.2 localized compression. Entrapment cysts can extend more medially and cm medial to the glenoid rim.9 caused by paralabral ganglion cysts may affect the nerve at the supra- is now commonly recognized,14 but scapular notch.11 other mass-effect scenarios have been Pathophysiology Anatomic variations also play a reported in recent years, including role. The transverse scapular liga- prominent hardware15 and enlarged Suprascapular neuropathy may occur ment,3 a recently described anterior veins.16 secondary to a variety of mechanisms coracoscapular ligament,12 and fas- In addition to focal nerve entrap- that vary depending on the local anat- cial extensions from the subscapu- ment, neuropathy can follow more

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Figure 4 praspinatus motor branch at the su- prascapular notch. Costouros et al21 reported a 38% rate of isolated su- prascapular neuropathy in a series of 26 massive rotator cuff tears and speculated that the nerve may be fur- ther tethered at the scapular spine by infraspinatus retraction (Figure 4). This report documented nerve recov- ery after attempted rotator cuff re- pair. These relationships have led some au- thors to speculate that suprascapular neuropathy may be a significant con- tributor to the pain and muscle atrophy of retracted tears,20 and some now perform routine electromyography (EMG) testing in these patients.21 Iat- rogenic suprascapular neuropathy Illustration of a proposed mechanism for the association between has also been reported following dis- suprascapular neuropathy and massive, retracted rotator cuff tear in which tal resection, spinal position- retraction of the torn tendon bowstrings the nerve against the scapular spine ing, transglenoid stabilization, and (circled area). (Reproduced with permission from Costouros JG, Porramatikul procedures requiring an open poste- M, Lie DT, Warner JJ: Reversal of suprascapular neuropathy following 9,22 arthroscopic repair of massive supraspinatus and infraspinatus rotator cuff rior approach to the shoulder. tears. Arthroscopy 2007;23:1152-1161.) Diagnosis dynamic insults. The identification may affect the nerve indirectly by in- of suprascapular neuropathy in elite ducing intimal damage to the axil- History volleyball players17 and pitchers18 has lary or suprascapular arteries, result- Suprascapular neuropathy causes suggested that a combination of trac- ing in microemboli and secondary pain and spinal weakness in 80% to tion, friction and/or kinking of the ischemia of distal nerve branches.18 100% of patients.23-25 Pain is often nerve at points of tethering may in- Suprascapular neuropathy may also described as a dull, sometimes burn- duce nerve injury. This may be par- accompany other primary shoulder pa- ing, ache in the posterior and lateral ticularly true at the spinoglenoid thology. Nerve compression frequently shoulder regions,25 with occasional notch, a site at which anatomic stud- occurs at the spinoglenoid notch as radiation to the neck or lateral arm. ies have demonstrated an increase the result of paralabral ganglion cysts The pain may be worsened by arm in spinoglenoid ligament tension that develop after a primary labral positions involving cross-body ad- against the nerve in positions that tear establishes a one-way synovial duction and internal rotation8 (Table correspond to the follow-through valve.11,14 Additionally, de Laat et al19 1). This distribution may be ex- phase of throwing.8 Combined scap- reported a 29% rate of suprascapu- plained by the nerve’s sensory contri- ular protraction and infraspinatus lar nerve injury in association with bution to the shoulder and acromio- contraction during this phase may shoulder dislocations and proximal clavicular joints and the known further bowstring the nerve against fractures. Recent focus has tensioning of the spinoglenoid liga- the scapular spine, with acute and/or also turned toward the association ment during adduction and inter- chronic injury resulting.17 Sandow of suprascapular nerve injury with nal rotation maneuvers.8 Subjective and Ilic2 have speculated that the su- massive, retracted rotator cuff tears. weakness during external rotation perior aspect of the infraspinatus Albritton et al20 simulated supra- and/or abduction is more variable may impinge on the nerve at the spinatus retraction in a cadaver and is dependent on the degree and spinoglenoid notch in positions of model and noted that up to 5 cm level of nerve compromise. Isolated abduction and external rotation. In of retraction markedly altered the infraspinatus involvement may not some cases, overuse traction forces course and tension of the first su- be functionally limiting because the

668 Journal of the American Academy of Orthopaedic Surgeons Dana P. Piasecki, MD, et al

Table 1 Figure 5 Common History and Physical Examination Findings for Suprascapular Neuropathy History

Posterolateral and/or superior shoulder pain Mild subjective weakness (abduction, external rotation) Chronic overhead sports or labor History of shoulder trauma or surgery Massive, retracted rotator cuff tear

Physical Examination

Supraspinatus and/or infraspinatus atrophy Tenderness posteromedial to the acromioclavicular joint and/or Photograph of a patient with infraspinatus atrophy. The posterior aspect of posterosuperior joint line the scapula demonstrates atrophy in the region of the infraspinatus fossa. Weakness of external rotation and/or abduction labral pathology. An initial traumatic of the nerve or of surgical incisions event is reported in 40% of pa- consistent with prior spine proce- tients.25 The typical scenario is that dures, open posterior shoulder ap- Table 2 of a chronic, traction-type injury in proaches, rotator cuff repair, or dis- Differential Diagnosis for the younger athlete or laborer who tal clavicle resection should raise Suprascapular Neuropathy places repetitive overhead demands suspicion for the possibility of supra- Rotator cuff pathology (ie, tendinitis/ on the upper extremities during ac- scapular nerve injury. Atrophy of the bursitis, tears) tivity (eg, volleyball, basketball, supraspinatus and/or infraspinatus 17 Acromioclavicular arthritis weightlifting, swimming). However, muscle belly is often evident24 (Figure Adhesive capsulitis suprascapular neuropathy should be 5). Isolated infraspinatus atrophy Labral pathology (eg, SLAP tears, considered in older patients with ro- suggests spinoglenoid notch entrap- 28 Bankart lesions) tator cuff tears and in any patient ment, whereas the presence of both Glenohumeral arthritis with otherwise unexplained shoulder supraspinatus and infraspinatus at- Cervical radiculopathy symptoms after a shoulder operation rophy indicates a more proximal in- Brachial plexitis (ie, Parsonage-Turner or traumatic shoulder injury. The de- jury, typically at the suprascapular syndrome) scribed symptoms may overlap with notch. Atrophy of other periscapular several other potential shoulder pa- SLAP = superior labral anterior-posterior musculature with or without hu- thologies (Table 2). The presence of meral head subluxation may suggest gradually progressive, dull shoulder a more global neurologic injury pat- posterior deltoid and teres minor can pain with isolated weakness in for- tern. Active and passive range of mo- often compensate.17 ward elevation and/or external rota- tion along with careful evaluation of By contrast, nerve compression at tion may help distinguish isolated su- scapular mechanics should be per- the suprascapular notch more often prascapular neuropathy from most formed in all patients to determine causes functional deficits, with up to of these other conditions. the contribution of capsular contrac- 75% loss of abduction and external ture and/or scapular dyskinesis to the rotation strength.26 Symptoms may Physical Examination primary complaint. With suprascap- develop gradually, with or without a Patients with suspected suprascapu- ular notch entrapment, the acromio- preceding injury, and may worsen lar neuropathy should first be exam- clavicular joint and supraspinatus over time to become constant.27 A ined for signs related to prior surgery fossa may be tender to palpation, sense of instability is also frequently and trauma (Table 1). Evidence of whereas spinoglenoid notch com- reported,14 likely in association with penetrating injury along the course pression may cause pain at the pos-

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Table 3 Figure 6 Table 4 Imaging Studies for Additional Diagnostic Tests for Suprascapular Neuropathy Suprascapular Neuropathy Plain Radiographs Suprascapular Nerve Block

Rule out scapular fracture, glenohu- Suprascapular or spinoglenoid notch meral dislocation injection of local anesthetic Consider humeral head position as an indicator of massive rotator cuff tear EMG/NCV Studies Stryker notch view: evaluate suprascap- Must request suprascapular nerve ular notch type, patency evaluation MRI Conduction delays (increased latency) Signs of denervation (fibrillations, sharp Trace nerve’s course, with emphasis on Axial T2-weighted MRI scan of a waves, decreased motor potentials) both notches paralabral ganglion cyst. Cysts Often can localize the site of compres- Assess degree of supraspinatus and typically appear loculated with an sion infraspinatus atrophy increased signal on T2-weighted Look for mass compression (ganglion images. An associated labral tear EMG = electromyography, NCV = nerve cyst) may also be seen. conduction velocity Evaluate rotator cuff and labrum

CT

Thin cuts: evaluate potential bony sites causes of nerve entrapment and to nerve, sagittal images at the level of of compression assess comorbid shoulder conditions, the lateral scapular spine can be used such as glenohumeral subluxation or to quantify the degree of muscle at- arthrosis (Table 3). The addition of a rophy.29 Compressive lesions such as terosuperior joint line.24 Weakness to Stryker notch view allows visualiza- perilabral ganglion cysts are easily resisted external rotation and/or ab- tion of the suprascapular notch and identified with increased signal on duction will be present in most cas- may demonstrate complete ossifica- T2-weighted images, along with the es.24 Cross-body adduction and inter- tion or near obliteration of its fora- frequently associated labral tears30 nal rotation may elicit pain in the men. Scapular body or neck fractures (Figure 6). Other soft-tissue masses posterior shoulder, probably result- with malunion or fracture callus at may be seen on MRI as well, includ- ing from tensioning the spinoglenoid either notch and the presence of ing lipomas and enlarged spinogle- ligament,8 but the diagnosis should hardware impingement along the noid notch veins.16,31 be differentiated from primary acro- known course of the nerve should be mioclavicular pathology. Likewise, considered. Proximal humeral head Additional Diagnostic Tests given the overlap and frequent coex- migration suggests chronic rotator When a clinical evaluation and routine istence of rotator cuff and labral pa- cuff deficiency and should also be imaging studies do not demonstrate a thology, careful evaluation for supe- recognized. In situations in which os- clear focus of nerve entrapment, the or- rior labral anterior-posterior tears, seous abnormalities are thought to thopaedist may consider additional di- glenohumeral instability, and rotator be the primary cause of nerve injury, agnostic tests (Table 4). An injection of cuff function should be performed. a CT scan may be helpful in appreci- local anesthetic into the suprascapular Finally, a careful neurovascular ex- ating specific regions of likely nerve notch helps to localize the region of en- amination to test specific distal cervi- compression. trapment if pain is relieved.10 Like- cal root function at C5-T1 is critical An MRI study is particularly useful wise, EMG and nerve conduction ve- for ruling out neurologic injury that for quantifying the degree of supra- locity (NCV) studies, with specific is more proximal at the cervical root spinatus and infraspinatus atrophy, attention paid to the suprascapular level or more generally involving the for discerning potential soft-tissue nerve, are routinely obtained to es- brachial plexus. causes of nerve entrapment, and for tablish a baseline before treatment determining the presence of associ- and to localize the site of nerve en- Imaging ated pathology, such as labral or ro- trapment. Increased latency, fibrilla- Routine radiographs should be ob- tator cuff tears. In addition to visual- tion potentials, and diminished am- tained to rule out potential osseous izing the course of the suprascapular plitude suggest nerve compression

670 Journal of the American Academy of Orthopaedic Surgeons Dana P. Piasecki, MD, et al and denervation, although EMG and Figure 7 NCV studies may be falsely negative or positive.18

Treatment

Once the diagnosis of suprascapular neuropathy is made, several treatment options are available. Most patients with an overuse type of neuropathy and no focal mass compression of the nerve will benefit from nonsurgical manage- ment. Those with neuropathy second- ary to a space-occupying lesion or with massive, retracted rotator cuff tears usu- ally benefit most from immediate sur- gical intervention to prevent further nerve injury. Additional considerations include the duration of symptoms, de- gree of muscle atrophy, and associated shoulder pathology. Identifying the re- gion of compression is very helpful for surgical planning, for which open and arthroscopic techniques may be consid- ered (Figure 7). Treatment algorithm for suprascapular neuropathy. EMG = electromyography, Nonsurgical NSAIDs = nonsteroidal anti-inflammatory drugs, PT = physical therapy, SG = spinoglenoid, SS = suprascapular spine Although there are limited data to * An EMG would have been obtained initially to confirm the diagnosis. guide the clinician, most authors agree that an initial nonsurgical ap- proach is prudent for most patients cle bulk and motor strength may be tor cuff tears is unlikely to benefit with suprascapular neuropathy. The irreversibly lost.32 The patient pre- from a prolonged nonsurgical ap- approach includes activity modifi- senting with long-standing (ie, >6 proach.21,33 cations, nonsteroidal anti-inflam- months) symptoms and early muscle The frequently cited scenario of a matory drugs, and a comprehensive atrophy may therefore miss an op- paralabral ganglion cyst is worth program of rotator cuff, deltoid and portunity to regain full function if special mention, given that some au- periscapular stretching and strength- surgery is delayed. Likewise, the pa- thors have recommended immediate ening.25 Depending on the duration tient with structural compression of decompression for this condition to and circumstances of nerve compres- the nerve has been shown to do prevent further nerve injury.32 Al- sion, the recommended length of best after surgical decompression, though this step may be reasonable treatment ranges from 0 to 12 whereas the patient with overuse in many cases, an initial nonsurgical months, underscoring the need to in- neuropathy typically does not im- approach is justified in the patient dividualize a given regimen.25,32 prove with surgery.33 Nonsurgical with a short duration of symptoms, To this end, the duration of symptoms management is therefore indicated in because in some instances a cyst may and the etiology of entrapment are im- most patients who present with su- be incidental or transient. Some au- portant considerations when determin- prascapular neuropathy, particularly thors have reported spontaneous re- ing the length of any initial nonsurgi- in those with an overuse-type etiolo- gression of ganglia, although it is cal treatment. Although pain relief and gy.25 However, the patient with a rare.24 Prior to surgical intervention, restoration of function are reliably long duration of symptoms, muscle additional consideration may also be achieved in most patients,25 once sig- atrophy, entrapment by a mass le- given to CT- or ultrasonography- nificant atrophy has occurred, mus- sion, and/or associated massive rota- guided cyst aspiration. Although

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Figure 8 rior portal, the arthroscope is redi- rected into the subacromial space, and a subacromial bursectomy is per- formed. Following bursectomy, the arthroscope is repositioned into a lateral portal and a shaver or radio- frequency device is introduced through an accessory anterolateral portal to expose the coracoacromial ligament medially to the coracoid process.34 Further medial dissection is performed to the coracoclavicular ligament origins on the coracoid base, 15 mm medial to the acromio- clavicular joint.36 Just medial to these , the lateral margin of the transverse scap- ular ligament can be identified. To Illustration of open suprascapular notch decompression. The most frequently used open approaches to the suprascapular notch involve a superior, expose and instrument the supra- trapezius-splitting exposure or one that elevates the trapezius off the scapular notch, additional portals scapular spine. (Reproduced with permission from Romeo AA, Rotenberg are required between the clavicle and DD, Bach BR Jr: Suprascapular neuropathy. J Am Acad Orthop Surg 35 1999;7:358-367.) the scapular spine. Bhatia et al de- scribe placing two portals along a line bisecting the angle created by the roughly half of cysts can be expected split in line with its fibers, the su- clavicle and scapula (Figure 9). An 14 to recur following this intervention, praspinatus is retracted posteriorly, initial medial portal is placed 30 to symptom relief after aspiration can and the notch is identified medial to 35 mm medial to the angle, through be helpful diagnostically in the pa- the coracoid base. The transverse which a probe and/or elevator is tient who has multiple potential scapular ligament is localized, ex- used to bluntly expose the transverse sources of pain. tending over the top of the notch, af- scapular ligament and subsequently ter which the suprascapular vessels retract the , vein, Surgical (above the ligament) and nerve (be- and nerve. A “suprascapular portal” In the patient for whom nonsurgical low the ligament) are exposed and is then established 5 to 10 mm lat- treatment fails, particularly the pa- protected as the ligament is released. eral to the medial portal, through tient with a reversible, structural If the nerve continues to be con- which arthroscopic scissors are used cause of entrapment, surgical inter- strained by the bony notch, its me- to perform the actual decompression vention is warranted, with the goal dial border may be carefully widened (Figure 10). A similar approach is of eliminating compression of the with a burr. Dissection can be per- described by Lafosse et al,34 with the nerve. Ideally, the surgeon would ap- formed posterior to the supraspina- addition of occasional bony notch preciate a specific locus of nerve en- tus muscle when simultaneous spino- resection in cases in which ligament trapment such that surgical decom- glenoid notch decompression is release does not adequately mobilize pression may be targeted. desired. After adequate decompres- the nerve. The most common sites of nerve sion, repair of the trapezius is fol- Open decompression of the spinogle- compression are the suprascapular lowed by a standard closure. noid notch is usually accomplished and spinoglenoid notches. The su- Several authors have described ar- through a posterior approach, using a prascapular notch has traditionally throscopic techniques for suprascap- longitudinal incision 3 cm medial to the been decompressed through an open ular notch decompression.34,35 In posterolateral corner of the trapezius-splitting approach,32 using these reported procedures, the pa- (Figure 11). After subcutaneous flaps either a saber or transverse incision tient is positioned in the beach-chair are developed, the deltoid fascia is di- along the scapular spine (Figure 8). position with34 or without35 traction. vided and the muscle split in line with Following mobilization of subcuta- After a diagnostic glenohumeral ar- its fibers, with care taken to avoid dis- neous flaps, the trapezius muscle is throscopy through a standard poste- section more than 5 cm below the

672 Journal of the American Academy of Orthopaedic Surgeons Dana P. Piasecki, MD, et al

Figure 9 Figure 10

Arthroscopic view of the suprascapular notch at the shoulder. Scissors have been introduced through one of the accessory suprascapular portals to resect the ligament. L = superior transverse scapular ligament; Co = coracoid, N = suprascapular nerve. (Reproduced with permission from Bhatia DN, de Illustration demonstrating technique for arthroscopic suprascapular notch Beer JF, van Rooyen KS, du Toit decompression, requiring additional portals for exposing and instrumenting DF: Arthroscopic suprascapular the notch. The angle that the scapular spine and acromion (AC) makes with nerve decompression at the the clavicle is bisected (line x-x). An initial medial portal (B) and a suprascapular notch. Arthroscopy “suprascapular portal” (A) are placed along line x-x. (Adapted with 2006;22:1009-1013.) permission from Bhatia DN, de Beer JF, van Rooyen KS, du Toit DF: Arthroscopic suprascapular nerve decompression at the suprascapular notch. Arthroscopy 2006;22:1009-1013.) the scapular spine and retracting the supraspinatus posteriorly to ac- cess the suprascapular notch, then acromial border to prevent axillary combined with effective arthroscopic anteriorly to access the spinoglenoid nerve injury. Retraction of the deltoid decompression of the cyst through notch. facilitates identification of the superior the tear37 (Figure 12). When no la- One preliminary report describes border of the infraspinatus, which is bral tear is present, the cyst may be an all-arthroscopic technique for de- subsequently mobilized inferiorly to re- decompressed via a small capsulot- compressing both notches. Soubeyr- veal the scapular spine. Dissection is omy just posterior and medial to the and et al38 successfully decompressed then carefully performed above the lat- posterosuperior labrum. Other au- both notches using a series of arthro- eral extent of the spine to release the thors have described intra-articular scopic portals along the scapular spinoglenoid ligament and underlying labral repair followed by a more spine, through which the plane be- nerve. complete cyst decompression from neath the supraspinatus was devel- Arthroscopic spinoglenoid notch the subacromial space.37 When a oped. Preliminary results were de- decompressions have been reported, single locus of compression is not scribed as good in three patients, but usually in association with the man- obvious but clinical and MRI evi- further study is needed to justify the agement of paralabral ganglion dence of both supra- and infraspina- potential morbidity associated with cysts.37 The high frequency of labral tus denervation is seen, it is not clear this approach. tears in association with ganglion if both notches should be decom- The coexistence of massive re- cysts at the spinoglenoid notch has pressed, although some authors have tracted rotator cuff tears has recently led many authors to suggest the ad- reported good results after doing so. received increased attention. Several dition of glenohumeral arthroscopy Sandow and Ilic2 reported excellent recent preliminary studies docu- to the management of this scenar- results in eight volleyball players mented the association of suprascap- io.11,14 Arthroscopy allows identifica- treated with an open posterior ap- ular neuropathy in 28% to 100% of tion and repair of labral pathology proach, elevating the trapezius off massive, retracted rotator cuff

November 2009, Vol 17, No 11 673 Suprascapular Neuropathy

Figure 11

Open decompression of the spinoglenoid notch. A, Illustration of an oblique incision starting 4 cm medial to the posterolateral corner of the acromion. B, Exposure of the notch is then possible after splitting the deltoid and retracting the infraspinatus inferiorly. C, In this intraoperative photograph, after the notch is exposed, a spinoglenoid ganglion is visualized. D, Finally, the spinoglenoid ligament is released.

Figure 12 ing of suprascapular neuropathy in patients with massive rotator cuff tears may lower the threshold for surgical intervention.

Results

Nonsurgical Martin et al25 reported on a series of 15 patients with suprascapular neuropa- thy. MRI studies were obtained in only a small subset; no mass lesions were seen. Treatment consisted of activity modifications and physical therapy to improve range of motion and strengthen the rotator cuff and deltoid. Arthroscopic images of surgery for spinoglenoid notch compression caused by a ganglion cyst. The procedure should include an evaluation of the joint. After a minimum of 6 months, 80% of Because of the frequency of associated labral tears, most authors patients had achieved a good or excel- recommend cyst decompression through the labral tear, followed by labral lent clinical result with improvement in repair. A, Labral tear. B, Appearance following cyst decompression and labral pain and function. However, although repair. (Reproduced with permission from Youm T, Matthews PV, El Attrache NS: Treatment of patients with spinoglenoid cysts associated with superior most patients were unrestricted in the labral tears without cyst aspiration, debridement, or excision. Arthroscopy use of their pathologic shoulder, persis- 2006;22:548-552.) tent atrophy and mild weakness on iso- kinetic testing was common. In the sub- tears.21,28 Nerve recovery was seen af- contributing to muscle atrophy. Al- set of patients who had posttreatment ter attempts at tendon repair, and though further study is needed to EMG studies, persistent deficits were was correlated with clinical improve- clarify the potential role of isolated seen in roughly half. This would sug- ment, suggesting that tendon retrac- nerve decompression in the setting of gest that nonsurgical management pro- tion (presumably bowstringing of the irreparable tears or the addition of vides benefit mostly through compen- nerve at the two notches) might be focused neurolysis at the time of at- satory muscle action, and less so causing the neuropathy and could be tempted rotator cuff repair, the find- through nerve recovery.

674 Journal of the American Academy of Orthopaedic Surgeons Dana P. Piasecki, MD, et al

Surgical derwent partial repair in the series of 21 References The reporting of outcomes follow- Costouros et al, EMG/NCV studies performed 6 months after surgery ing surgical management is limited. Evidence-based Medicine: References demonstrated significant nerve re- Most published studies are case re- 19, 26, 29, and 32 are level II stud- covery that correlated with pain re- ports or small case series in which it ies. References 5-9, 12, 13, 20, 24, lief and functional improvement. is difficult to ascertain the extent of 27, 36, and 40 are level III studies. denervation before treatment and/or The remaining references are level IV the potential coexistence of other Summary studies. sites of compression. However, most Citation numbers printed in bold appropriately selected patients can Suprascapular neuropathy is an un- type indicate references published expect an improvement in pain and common but potentially significant within the past 5 years. function, although preoperative mus- cause of shoulder pain and dysfunc- cle atrophy, particularly in chronic tion that can result from a variety of 1. Kopell HP, Thompson WA: Pain and the 32 frozen shoulder. Surg Gynecol Obstet situations, may never resolve. static and dynamic insults along the 1959;109:92-96. Kim et al23 reported long-term pain path of the suprascapular nerve from 2. Sandow MJ, Ilic J: Suprascapular nerve relief and strength improvements in neck to shoulder. It should be sus- rotator cuff compression syndrome in nearly 90% of 31 patients at a mean pected in patients with recurrent volleyball players. J Shoulder Elbow Surg 1998;7:516-521. 18-month follow-up after open su- shoulder symptoms after more com- prascapular notch decompression. 3. Warner JP, Krushell RJ, Masquelet A, mon conditions have been ruled out, Gerber C: Anatomy and relationships of Good preliminary results have also particularly in overhead athletes and the suprascapular nerve: Anatomical been reported arthroscopically. A constraints to mobilization of the those with traumatic shoulder inju- supraspinatus and infraspinatus muscles case series on arthroscopic supra- ries and/or massive, retracted rotator in the management of massive rotator- cuff tears. J Bone Joint Surg Am 1992; scapular notch decompression by cuff tears. 34 74:36-45. Lafosse et al demonstrated excel- Most patients with an overuse type lent results in a prospective cohort of 4. Edelson JG: Bony bridges and other of neuropathy will benefit most from variations of the suprascapular notch. 10 patients. At a mean 15-month extended nonsurgical management; J Bone Joint Surg Br 1995;77:505-506. follow-up, all patients had signifi- those with reversible, structural causes 5. Rengachary SS, Burr D, Lucas S, cant improvement in pain and func- Brackett CE: Suprascapular entrapment of nerve compression will improve with tion, with normalization of EMG neuropathy: A clinical, anatomical, and surgical intervention. Given evidence comparative study. Part 3: Comparative findings in seven of the eight tested. study. Neurosurgery 1979;5:452-455. that chronic denervation may be irre- Open spinoglenoid notch decom- versible, the duration of symptoms and 6. Bigliani LU, Dalsey RM, McCann PD, pression has been reported in concert April EW: An anatomical study of the degree of muscle atrophy may be im- with arthroscopic management of as- suprascapular nerve. Arthroscopy 1990; portant considerations in choosing 6:301-305. sociated labral tears. Fehrman et al39 treatment options. Nerve decompres- 7. 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November 2009, Vol 17, No 11 675 Suprascapular Neuropathy

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676 Journal of the American Academy of Orthopaedic Surgeons