[Compression syndromes of the shoulder and their differential diagnosis].

Compared to other painful conditions on the shoulder suprascapular nerve entrapment is an obscure and uncommon syndrome causing severe shoulder pain and disability, and is easily cured if only it is recognized. The condition was described by Thompson and Kopell in 1959, Schilf reported a case of isolated suprascapular entrapment in 1952. The nerve passes through the suprascapular notch, the roof of the notch is formed by the transverse scapular ligament. The shape of the suprascapular notch may be guilty for entrapment symptoms. Suprascapular nerve compression may result of acute trauma, of transmitted forces, fracture of collum scapulae, of kinking or traction of the nerve over the edge of the foramen, of sling effect, of compression by ganglia, or its cause may be idiopathic. The hallmark of suprascapular nerve entrapment is a deep and poorly delineated pain, localized to the posterior and lateral aspect of the shoulder. Atrophy and weakness of the supraspinatus and infraspinatus may be noted. Adduction of the extended arm across the body tenses the nerve, increasing the pain. Blocking the nerve by local anesthetic a dramatic, but not long lasting pain relief may be achieved. Electromyographically a decrease in the amplitude or marked polyphasicity of evoked potentials is significant as well as an increased latency time, indicating an impaired conductibility. A surgical release is indicated in case of constant pain and pathological changes of EMG-patterns. From a postero-superior approach decompression of the nerve is performed by simple removal of the transverse scapular ligament.