Carpal tunnel syndrome: median nerve stress test.

The purpose of this study was to determine the effect of wrist position on distal sensory and motor latencies of the median nerve. An orthosis was devised to maintain the wrist either in extension or in flexion while measuring these latencies. Fourteen patients with presumptive carpal tunnel syndrome (CTS) and 12 control subjects were evaluated following extension or flexion of the wrist for 5 and 10 minutes. Results showed an increase in distal latencies for both groups; the highest increment was found among CTS patients following 5 minutes of wrist flexion. Since it is not uncommon for patients to present with classical CTS symptoms but without electrodiagnostic findings in support of such diagnosis, it is suggested that such patients be reevaluated after 5 minutes of wrist flexion (median nerve stress) test.