Background: Neurogenic thoracic outlet syndrome (NTOS) is attributed to compression of the brachial plexus at the scalene hiatus. Patients with true NTOS (TNTOS) have typical clinical and electrophysiological changes and are considered to respond well to surgical treatment, but patients with nonspecific NTOS (NNTOS) have predominantly sensory signs, not well-defined electrophysiological changes, and are thought not to respond favorably to surgical treatment. The postsurgical outcome of patients with cervicobrachialgia diagnosed as TNTOS and as NNTOS is analyzed. Methods: Seven patients with typical electropbysiological features of TNTOS and 11 with nonspecific signs (NNTOS-extraspinal compression of C5-T1) were treated from 1986 to 2001. Age, duration of symptoms, and follow-up were similar in both groups. All patients underwent unilateral (14) or bilateral (4) supraclavicular decompression of the brachial plexus, for a total of 22 procedures. Clinical outcome was evaluated based on sensory and motor signs and on functional capacity. The Mann-Whitney U test and Fisher exact test were used to compare demographic data and proportions, respectively. Results: Improvement of pain/paresthesias, sensory loss, atrophy, and muscular weakness after surgery was similar in the two groups. Regarding functional capacity, 57.1% of patients with TNTOS and 63.6% of patients with NNTOS became normal or reacquired their previous condition with slight limitation. Surgery-related complications were paresthesias and paresis in the arm, sympathetic dystrophy, pneumothorax, and lymphatic collections, all in patients with NNTOS. Conclusions: Patients with NNTOS with electrophysiological signs of extraspinal radicular impairment had the same chances of improvement after surgical treatment as patients with TNTOS. (c) 2006 Elsevier Inc. All rights reserved.