264 Ann Rheum Dis 1999;58:264–265

LESSON OF THE MONTH Ann Rheum Dis: first published as 10.1136/ard.58.5.264 on 1 May 1999. Downloaded from

An unusual cause of shoulder pain

P Wong, J V Bertouch, G A C Murrell, M Hersch, P P Youssef

A 20 year old man with no significant past active denervation. The left supraspinatus, medical problems presented with a six week biceps, triceps and deltoid were normal. Mag- history of gradual onset diVuse left shoulder netic resonance imaging (MRI) of the left and scapula pain. Two weeks before the onset shoulder region confirmeda2cmby1cm of pain he had started work as a builder, multi-loculated fluid collection at the spinogle- performing heavy lifting. There was no history noid notch causing compression of the inferior of injury or other precipitant. In the week branch of the suprascapular nerve that supplies before presenting, the severity of the pain pre- infraspinatus (figs 2 and 3). There was no evi- vented him from working despite regular anal- dence of more proximal compression of the gesia. He did not complain of upper limb suprascapular nerve. A small tear of the weakness. No constitutional symptoms were posterosuperior glenoid labrum was also iden- present. There was no preceding viral-like tified. illness or vaccination. A provisional diagnosis of a ganglion was On examination, there was left infraspinatus made and the patient was referred to an ortho- tenderness and wasting (see fig 1) with weakness of external rotation of the shoulder. Prince of Wales Power in other muscle groups around the left Hospital, Sydney, New shoulder was normal. All upper limb reflexes South Wales, Australia were present and sensation was normal. P Wong J V Bertouch Examination of the left axilla revealed five P P Youssef small mobile lymph nodes. There was no other lymphadenopathy or splenomegaly.

St George Hospital, Computed tomography (CT) of the left http://ard.bmj.com/ Sydney, New South scapula and axilla was performed to determine Wales, Australia if significant lymphadenopathy was present, for G A C Murrell M Hersch example, because of lymphomatous involve- ment. It showed wasting of the muscles Correspondence to: surrounding the scapula but no mass lesions in Dr P Youssef, Royal Prince the region of the brachial plexus. There were Alfred Medical Centre, Suite

408, 100 Carillon Avenue, non-enlarged lymph nodes in the axilla. on September 27, 2021 by guest. Protected copyright. Newtown, Sydney, New Electromyographic (EMG) assessment re- South Wales, Australia 2042. vealed profuse fibrillations and positive sharp Accepted for publication waves in the left infraspinatus muscle but no Figure 2 Axial (T2 weighted) MRI showing the ganglion 18 January 1999 units under voluntary control, consistent with cyst in the spinoglenoid notch adjacent to the glenoid labrum.

Ganglion cyst

Suprascapular nerve

Figure 3 Diagram showing a ganglion in the spinoglenoid Figure 1 Left infraspinatus wasting. (View from behind the patient). notch causing compression of the nerve to infraspinatus. An unusual cause of shoulder pain 265

paedic surgeon for an arthroscopic ganglion along the path of least resistance, thus resulting drainage and repair of the glenoid labrum. This in a ganglion cyst.1 Tirman et al6 have shown an was successfully performed. Ten weeks after association between ganglion cysts and glenoid the operation, there was significant reduction labrocapsular tears on MRI—as seen in this Ann Rheum Dis: first published as 10.1136/ard.58.5.264 on 1 May 1999. Downloaded from in both shoulder pain and infraspinatus wasting patient. They suggest that detection of a shoul- with only a mild reduction in global range of der ganglion cyst should prompt both a clinical movement. Unfortunately, the patient failed to and MRI evaluation of the glenoid labrum and present for a follow up MRI three months later joint capsule. to assess if there had been a recurrence of the The treatment of this condition is dependent ganglion. upon the extent of pain and the loss of function. In the absence of pain, shoulder Discussion rehabilitation to maximise function is usually With the advent of MRI, suprascapular nerve the only intervention necessary, as the func- compression is becoming increasingly recog- tional deficit is usually mild.1 However, in the nised as a cause of shoulder pain in the presence of persistent or severe pain, as in this orthopaedic,1–4 radiological,56 and sports case, surgery is required. Arthroscopic evalua- medicine8 literature. However, we are unaware tion is often necessary with simultaneous repair of any such reports in the rheumatological of intra-articular pathology to prevent a recur- literature. rence of the ganglion. Traditionally, open gan- The suprascapular nerve arises from the glion excision is performed. However, Iannotti upper trunk of the brachial plexus. It then and Ramsey2 report a series of three cases in traverses the suprascapular notch underneath which suprascapular nerve compression by a the transverse scapular ligament. On entering ganglion cyst was treated by arthroscopic the supraspinatus fossa, it innervates the decompression of the cyst into the shoulder supraspinatus muscle. It then enters the infra- joint. In each of their three cases, the patient’s spinatus fossa via the spinoglenoid notch to symptoms resolved and a postoperative MRI innervate the infraspinatus muscle (fig 3).1 In showed no reaccumulaton of the fluid in the this patient, the ganglion was located at the ganglion. The procedure was well tolerated. spinoglenoid notch, causing only compression Successful ultrasound or CT guided aspiration of the nerve to infraspinatus resulting in weak- of ganglia causing suprascapular nerve com- ness of the infraspinatus muscle. pression has also been reported.4 This patient is noteworthy because of his Overall, in patients with previously normal relatively acute presentation. The usual pre- shoulder anatomy, a successful surgical proce- senting symptom is that of longstanding, deep dure involving decompression of the ganglion and diVuse posterolateral shoulder pain. How- with repair of any underlying labral pathology ever, this man presented with pain of only sev- results in a good long term prognosis. eral weeks’ duration that had worsened over the

preceding week, raising the possibility of http://ard.bmj.com/ brachial neuritis. The lessons This case demonstrates that EMG and nerve x Suprascapular nerve entrapment must be conduction studies are useful in localising the considered in the diVerential diagnosis of a site of nerve compression. They distinguish painful shoulder, particularly in the presence nerve entrapment at the suprascapular notch, of supraspinatus or infraspinatus weakness. which produces denervation of both suprasp- x The most appropriate investigation is MRI inatus and infraspinatus, from that at the of the shoulder girdle. However, EMG and on September 27, 2021 by guest. Protected copyright. spinoglenoid notch, which results in infrasp- nerve conduction studies can be useful in inatus weakness only. In addition, they exclude determining the site of nerve compression more widespread pathology, for example bra- and the degree of nerve dysfunction. chial neuritis. Nevertheless, MRI is the imaging modality 1 Fehrman DA, Orwin JF, Jennings RM. Suprascapular nerve of choice for defining the lesion because of its entrapment by ganglion cysts: A report of six cases with arthroscopic findings and review of the literature. Arthros- excellent resolution of soft tissue. In this case, it copy 1995;11:727–34. would have been preferable to perform MRI as 2 Iannotti JP, Ramsey ML. Arthroscopic decompression of a ganglion cyst causing suprascapular nerve compression. the initial investigation, thereby negating the Arthroscopy 1996;12:739–45. need for EMG and nerve conduction studies. 3 Ogino T, Minami A, Kato H, Hara R, Suzuki K. Entrapment neuropathy of the suprascapular nerve by a However, MRI is not readily available in our ganglion. J Bone Joint Surg Am 1991;73:141–7. unit. Hence, this patient had initial EMG and 4 Ganzhorn RW, Hocker JT, Horowitz M, Switzer HE. Suprascapular nerve entrapment. J Bone Joint Surg Am nerve conduction studies to delineate the neu- 1981;63:492–4. rological abnormality. 5 Fritz RC, Helms CA, Steinbach LS, Genant HK. Supras- capular nerve entrapment: Evaluation with MR imaging. This case also demonstrates many of the Radiology 1992;182:437–44. typical features of this condition. It is mostly 6 Tirman PFJ, Feller JF, Janzen DL, Peterfry CG, Bergman AG. Association of glenoid labral cysts with labral tears and seen in men for two reasons. Firstly, there is an gleno-humeral instability: Radiologic findings and clinical association with weight lifting.47Secondly, the significance. Radiology 1994;190:653–8. 7 Neviaser TJ, Ain BR, Neviaser RJ. Suprascapular nerve spinoglenoid ligament is absent in 50% of denervation secondary to attenuation by a ganglion cyst. J women compared with 13% of men.9 Bone Joint Surg Am 1986;68:627–8. 8 Ferrick MR, Marzo JM. Ganglion cyst of the shoulder asso- The pathogenesis of this condition is uncer- ciated with a glenoid labral tear and symptomatic tain. It is believed that trauma results in tearing glenohumeral instability. Am J Sports Med 1997;25:717– 19. of the posterior capsulo-labral complex. This 9 Kaspi A, Yanai J, Pick CG, Mann G. Entrapment of the dis- allows synovial fluid to leak out of the joint tal suprascapular nerve. Int Orthop 1988;12:273–5.