Painless infraspinatus atrophy due to suprascapular nerve entrapment.

A case of painless suprascapular nerve entrapment, resulting in isolated atrophy and weakness of the infraspinatus, is described. Electromyography was used to confirm the clinical diagnosis. The etiology of this neuropathy ranges from trauma to overexertion of the upper extremity. Consequent entrapment most often occurs at the suprascapular or spinoglenoid notch. Local ganglionic cysts have been found compressing the suprascapular nerve. Conservative management, including "benign neglect," physical therapy, and local injections, is often effective. Surgical decompression may be indicated in refractory or posttraumatic cases.