[The diagnostic significance of additional electrophysiological studies in suspected neurogenic thoracic outlet syndrome].

The neurogenic thoracic outlet syndrome (TOS) is a controversial clinical entity, since unambiguous diagnostic criteria are lacking and abnormal findings are absent in many patients. To evaluate electrodiagnostic methods a retrospective analysis was done comprising all 75 patients with suspected TOS who had been examined electrophysiologically in our laboratory in the last 5 years. 35 of the 75 patients were finally diagnosed as having TOS, but only 10 of them had a corresponding electrophysiological pathology. 6 had "classic" TOS with clinically obvious sensorimotor deficits, whereas in 4 the electrophysiologic findings were the only abnormalities (in 3 of 4, only minor neurographic anomalies were found). Proximal motor stimulation techniques did not improve the diagnostic yield. We conclude that electrodiagnostic methods are of little value in the diagnosis of TOS if there are no clinical abnormalities. The electrophysiological examinations did however reveal distal entrapment neuropathies in 15 of 75 patients (12 carpal tunnel syndromes). The frequent detection of such neuropathies in our patients is interesting and it justifies per se electrodiagnostic examination of the patient with suspected TOS.