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The Case:

A 50-year-old man initially presented with right shoulder pain and difficulty lifting his arm to chest level. The patient reported no history of trauma. Magnetic resonance imaging (MRI) was performed (Figure 1), and conservative treatment was ineffective. He presented 17 months later with progressive symptoms and a repeat MRI was performed (Figure 2).

Figure 1: Coronal oblique fast spin echo T2-weighted (A) and axial T1-weighted (B) fat-suppressed images obtained through the right shoulder after intra-articular injection of dilute gadolinium mixture. Axial image obtained more superiorly (C).

Figure 2: Coronal oblique fast spin echo T2-weighted fat-suppressed image obtained 17 months later (A). Axial fast spin echo proton density fat-supressed image (B).

Your Diagnosis?

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Diagnosis:

Spontaneous Resolution of a Spinoglenoid Notch Ganglion

This article presents the case of a 50-year-old man who presented with spontaneous resolution of a spinoglenoid notch ganglion, documented on 2 magnetic resonance imaging (MRI) studies obtained 17 months apart. The patient reported long-standing and progressive pain and difficulty lifting his arm to chest level. He reported no history of trauma, and conservative treatment was ineffective.

Although the MRI findings were typical for a spinoglenoid notch ganglion associated with a posterosuperior labral tear, this case was unusual because the ganglion spontaneously resolved without labral repair or decompression by either percutaneous aspiration or surgical means. To our knowledge, only 1 other case of spontaneous resolution of a spinoglenoid notch cyst has been reported in the literature.¹

Clinical Findings

Glenoid paralabral cysts are well-recognized complications of labral tears and are believed to occur by the one-way extension of joint fluid through labrocapsular tears. There have been multiple reports of paralabral cysts (also known as suprascapular notch or spinoglenoid notch ganglia, depending on location) documented by MRI, magnetic resonance arthrography, sonography, and arthroscopy.^2-5

Suprascapular nerve entrapment at the level of the spinoglenoid notch with associated infraspinatus muscular atrophy was first reported in the literature by Ganshorn et al⁶ in 1981. Ganglia are now known to account for most lesions causing entrapment of the suprascapular nerve. Often, there is a history of weight lifting or sport-related shoulder injury. The diagnosis of suprascapular nerve entrapment is usually considered after the development of marked weakness and atrophy of the supraspinatus or infraspinatus muscles. Patients can present with differing symptoms, depending on the location of the paralabral cysts relative to the branches of the suprascapular or axillary nerves.² Ganglia located in the suprascapular notch can compress the suprascapular nervous supply to both the supraspinatus and infraspinatus muscles, whereas spinoglenoid notch ganglia will only affect the infraspinatus muscle. The diagnosis of suprascapular nerve neuropathy can be confirmed with electrodiagnostic testing and imaging. Electromyography (EMG) and nerve conduction studies will demonstrate motor loss in the infraspinatus or both the supraspinatus and infraspinatus muscles, depending on the level of the lesion. If conservative treatment fails, or if there is marked muscle atrophy, surgical decompression is recommended.^5,7

Imaging

Paralabral cysts and their associated labral tears are most commonly identified on MRI or magnetic resonance arthrography (Figure 1), although sonography has also proven to be useful in thin, young patients.⁶ Magnetic resonance imaging series have shown that paralabral cysts are most frequent along the posterior, superior, and anterior aspects of the glenohumeral joint and are uncommon inferior to the joint.³

Figure 1: Spinoglenoid notch ganglion. Coronal oblique fast spin echo T2-weighted (A) and axial T1-weighted (B) fat-suppressed MR arthogram images obtained through the right shoulder after intra-articular injection of dilute gadolinium mixture demonstrating a multiloculated cyst (arrow) extending through the spinoglenoid notch (arrowhead). Axial image obtained more superiorly displaying irregularity of the posterosuperior labrum (small arrow), consistent with labral tear (C).

Labral tears have been identified in 88% of patients with paralabral cysts; therefore, care must be taken to identify the associated labral tears (Figure 2). Compared to conventional MRI technique, magnetic resonance arthrography with an intra-articular injection of gadolinium provides improved visualization of labral lesions.³ This is important, because these cysts will commonly recur if the causative labral tear is not repaired. In addition, a fluid sensitive sequence must be incorporated into the magnetic resonance arthrographic study to increase the detection of the paralabral cysts. Due to the high viscosity of the cysts, intra-articular contrast may not opacify these lesions at the time of imaging (Figure 3). This is particularly true when cysts are small.²

Figure 2: Spontaneous resolution of spinoglenoid notch ganglion. Coronal oblique fast spin echo T2-weighted fat-suppressed image obtained 17 months later demonstrating a type II SLAP lesion (small arrow). In addition, note the partial thickness articular sided supraspinatus tendon tear, superomedial glenoid cartilage loss, and acromioclavicular joint hypertrophic degenerative change (A). Axial fast spin echo proton density fat-supressed image demonstrating resolution of the paralabral cyst that was present on prior MRI, but persistent posterior labral tear (arrow) (B).

Figure 3: Partial opacification of paralabral cyst on magnetic resonance arthrogram. Coronal oblique (A) and axial (B) images in a different patient demonstrate incomplete opacification of a large paralabral cyst (asterisks). Only a small amount of gadolinium (arrows) opacifies the periphery of the viscous collection.

Most paralabral cysts are often incidentally discovered on MRIs of the shoulder, and do not result in compression neuropathies.³ However, ganglia expanding into the suprascapular notch can lead to denervation changes and atrophy of both the supraspinatus and infraspinatus muscles. Alternatively, ganglia isolated to the spinoglenoid notch (located between the scapular spine and glenoid cavity) may have isolated atrophy of the infraspinatus muscle. Studies have shown that compression neuropathy is more likely to occur if the cysts are large (mean size in any single dimension of 3.1 cm) or located next to the posterior or inferior labrum.²

On MRIs, muscle denervation is indicated by diffuse abnormal signal intensity in the affected muscle with or without muscle atrophy. With clinical recovery of motor function, signal intensity returns to normal.^5-7 Our patient, however, had no nerve compression or associated muscle atrophy.

Treatment Options

Treatment options for spinoglenoid notch ganglia vary and can be handled by conservative, minimally invasive, and operative means. Surgical decision making is first dependent on whether or not a cyst is causing suprascapular nerve compression. Conservative treatment options for compression of the suprascapular nerve include rest, nonsteroidal anti-inflammatory medication, and physical therapy. Percutaneous aspiration can be used as a temporizing measure until definitive labral repair, by means of computed tomography or sonographic or magnetic resonance guidance (Figure 4).^7,8

Figure 4: Percutaneous needle aspiration of paralabral cyst. Sagittal fat-supressed proton density image through the shoulder in a different patient delineates an anterior paralabral cyst (arrows) extending along the base of the coracoid process (A). CT fluoroscopic image obtained during percutaneous aspiration of the dominant cystic component (B).

Surgical treatment options include open excision of the cyst, arthroscopic decompression of the ganglion, and repair of the posterior-superior capsulolabral complex tear.^9-12 Decompression of paralabral cysts about the shoulder without addressing the intra-articular pathology has been associated with a failure rate of 50%.¹⁰ Ninety percent of ganglion cysts about the shoulder that cause suprascapular nerve compression are associated with labral tears. It is thought that these cysts persist and may enlarge over time. Arthroscopic management of a superior labral anterior to posterior (SLAP) lesion as the cause of cyst formation, and the drainage of the ganglion is an effective way with low surgical morbidity that shows good postoperative results.

Although our patient had spontaneous resolution of his paralabral cyst without percutaneous or surgical cyst decompression, he had persistent pain which prompted arthroscopic surgery. As a result, he underwent repair of his confirmed SLAP II labral tear, debridement of his partial thickness rotator cuff tear, distal clavicular resection, and subacromial decompression.

References

1. Davidge CM, Walker R, Brett K, Boorman RS. Spontaneous resolution of a spinoglenoid notch cyst and associated suprascapular nerve palsy: a case report. J Shoulder Elbow Surg. 2007; 16(3):4-7.
2. Tung GA, Entzian D, Stern JB, Green A. MR imaging and MR arthrography of paraglenoid labral cysts. AJR Am J Roentgenol. 2000; 174(6):1707-1715.
3. Tirman PF, Feller JF, Janzen DL, Peterfy CG, Bergman AG. Association of glenoid labral cysts with labral tears and glenohumeral instability: radiological findings and clinical significance. Radiology. 1994; 190(3):653-658.
4. Fritz R, Helms C, Steinbach L, Genant H. Suprascapular nerve entrapment: evaluation with MR imaging. Radiology. 1992; 182(2):437-444.
5. Lee BCS, Yehappan M, Thiagarajan P. Suprascapular nerve neuropathy secondary to spinoglenoid notch ganglion cyst: case reports and review of literature. Ann Acad Med. 2007; 36(12):1032-1035.
6. Ganzhorn RW, Hocker JT, Horowitz M, Switzer HE. Suprascapular-nerve entrapment. J Bone Joint Surg Am. 1981; 63(3):492-494.
7. Winalski CS, Robbins MI, Silverman SG, Davies JAK. Interactive magnetic resonance image-guided aspiration therapy of a glenoid labral cyst: a case report. J Bone Joint Surg Am. 2001; 83(8):1237-1242.
8. Martinoli C, Bianchi S, Pugliese F, et al. Sonography of entrapment neuropathies in the upper limb (wrist excluded). J Clin Ultrasound. 2004; 32(9):438-450.
9. Tashjian RZ, Burks RT. Arthroscopic aspiration and labral repair for treatment of spinoglenoid notch cysts. Am J Orthop. 2009; 38(2):94-96.
10. Schroder CP, Skare O, Stiris M, Gjengedal E, Uppheim G, Brox JI. Treatment of labral tears with associated spinoglenoid cysts without cyst decompression. J Bone Joint Surg Am. 2008; 90(3):523-530
11. Werner CM, Nagy L, Gerber C. Combined intra- and extra-articular arthroscopic treatment of entrapment neuropathy of the infraspinatus branches of the suprascapular nerve caused by a periglenoidal ganglion cyst. Arthroscopy. 2007; 23(3):328.
12. Park JH, Lee YS, Park JW, Yoo JC, Kang JW, Park JS. Effective arthroscopic treatment of large, anteriorly extended spinoglenoid cysts [published online ahead of print September 12, 2009]. Arch Orthop Trauma Surg. doi:10.1007/s00402-009-0970-1.

Authors

Mr Ayyagari is from Florida Hospital and Dr Bancroft is from the Department of Radiology, University of Central Florida, Florida State University, Orlando, and Dr Jablonski is from Jewett Clinic, Winter Park, Florida.

Mr Ayyagari and Drs Bancroft and Jablonski have no relevant financial relationships to disclose.

Correspondence should be addressed to: Laura W. Bancroft, MD, Florida Hospital, Department of Radiology, 600 E Rollins, Orlando, FL 32803.

doi: 10.3928/01477447-20091020-29