Ganglion causing paralysis of the suprascapular nerve. Diagnosis by MRI and ultrasonography.

A 26-year-old man had a right infraspinatus muscle weakness and aching of the shoulder due to suprascapular nerve entrapment confirmed by electromyography. MRI revealed a well-defined area of increased signal intensity over the suprascapular notch. An ultrasonogram showed a homogeneous hypoechogenic area at the base of the scapular spine. A diagnosis was made of a ganglion compressing the inferior branch of the suprascapular nerve. After removal of several ganglia, the patient had immediate pain relief, and normal electromyographic findings were obtained 5 months postoperatively.