Chronic Infraspinatus Muscle Denervation from Spinoglenoid Notch Paralabral Cyst
Imaging Findings:
 • T2-hyperintense diffuse intramuscular signal of the infraspinatus with concomitant T I-hyperintense intramuscular signal.
 • Circumscribed T 2-hyperintense mass extends medially from the posterior glenoid labrum into the spinoglenoid notch.
 • Blunted morphology and intermediate signal within the posteroinferior glenoid labrum.
Case description:
 • Chronic posterosuperior labral tear with a septate paralabral cyst extending into the spinoglenoid notch.
 • Secondary denervation edema (T2 signal) of the infraspinatus with fatty atrophy (T1 signal) suggesting chronicity.
 • Cyst compresses the suprascapular nerve within the spinoglenoid notch distal to the supraspinatus branches.
Differential diagnosis:
1. Suprascapular notch cyst: compresses the suprascapular nerve proximal to branching and denervates the infraspinatus and supraspinatus.
2. Parsonage-Turner viral neuritis: appx 90% involves the supraspinatus and infraspinatus, but also commonly deltoid.
3. Venous varices in spinoglenoid notch can lead to similar denervation of cuff musculature.

Dr. Donald von Borstel @DrvonBorstel

#Infraspinatus #Denervation #Paralabral #Cyst #clinical #mri #clinical #Radiology #diagnosis #msk