Carpal tunnel syndrome surgery: identification of a neurophysiological high-risk category

Abstract

Surgical decompression of the median nerve is a standardized treatment for carpal tunnel syndrome. After surgery a clinical and neurophysiological improvement is observed also on severe cases. We report 4 cases of carpal tunnel syndrome (CTS) in the hands of 3 patients with prolonged median wrist-thenar distal motor latency (longer than 10 ms, normal values < 4.0 ms) and absence of digit-wrist sensory responses. In these patients surgery caused complete loss of median nerve function. Such a marked increase of median distal motor latency (DML) is rare (0.6% in 500 CTS hands consecutively examined in our laboratory) and suggests the presence of a chronic condition with severe disruption of the myelin. On the basis of these anecdotal observations, we suggest that patients with median DML of 10 ms or more be considered at high risk for CTS surgery failure.