
Diagnosis Definition
- A spinoglenoid notch cyst (SGNC) is a ganglion cyst located in the spinoglenoid notch (between the lateral aspect of the scapular spine and the infraspinous fossa) that most commonly results from a superior labral tear
- It typically occurs in 1) athletic adolescents with traumatic labral tears and 2) adults with chronic degenerative labral tears
- The anatomy of the suprascapular nerve, anchored below the spinoglenoid ligament, renders it susceptible to compression by even small cysts in the vicinity

Imaging Findings
- SGNCs range in size from small and unilocular to large and multiloculated
- They are typically hypointense on T1 and hyperintense on T2-weighted MR images
- Associated acute and subacute compressive suprascapular neuropathy manifests on MRI as hyperintensity of the infraspinatus muscle on T2-weighted images due to denervation myoedema
- Chronic compressive suprascapular neuropathy manifests as infraspinatus atrophy and hyperintense fatty infiltration on T1-weighted images

Pearls
- Proton density fat saturated or T2 fat saturated sequences maximize conspicuity, detection and characterization of paralabral cysts
- Paralabral cysts are indicative of a labral tear until proven otherwise
- SGNCs cause suprascapular neuropathy affecting only the infraspinatus muscle, while supraspinatus notch cysts cause more proximal suprascapular neuropathy affecting both the supraspinatus and infraspinatus muscles
- Labral tear with paralabral cysts may clinically mimic a rotator cuff tear

References
- Pomeranz SJ. Suprascapular Nerve Syndrome. In: Orthopaedic and Sports Medicine MRI: MRI of entrapment neuropathies. MRI-EFI Publications; 2011:14-17
- Stoller DW, Tirman PFJ et al. Labral Cyst, Shoulder. In: Diagnostic Imaging: Orthopedics. Amirsys; 2004:46-49
- Yanny S, Toms AP. MRI Patterns of Denervation Around the Shoulder. AJR 2010; 195:157-163

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