Abstract

The suprascapular nerve may rarely be entrapped in the suprascapular notch. This causes weakness of the supra- and infraspinatus muscles and pain in the glenohumeral and acromioclavicular joints, which are innervated by this nerve. The entrapment syndrome may result from direct or indirect trauma, fracture of the neck of the scapula, kinking or traction on a sling affecting the nerve, from the shape of the notch, compression by a ganglion, or its cause may be idiopathic. Diagnosis of the syndrome is based upon deep unceasing pain reported at the postero-lateral shoulder, atrophy of the supra- and infraspinatus muscles, and impaired shoulder external rotation and a lidocaine test. The final proof is taken from polyphasic EMG potentials which are decreased in amplitude and increased in distal latency. Initially the entrapment neuropathy may be treated by immobilization, analgesics, and physiotherapy. A tear of the rotator cuff as well as a frozen shoulder have to be excluded by arthrography. In persistent cases of pain and pathologic EMG findings surgical decompression of the nerve should be done. The trapezius muscle is approached by a postero-superior incision. Via the suprascapular fossa the notch may be reached. Then the nerve is decompressed by removing the transverse scapular ligament. Reports of the cases operated so far are promising, though their number is small.