Sensory nerve recovery following median nerve provocation in carpal tunnel syndrome.

The purpose of this study was to evaluate the recovery of median nerve sensory nerve action potentials (SNAP) following median nerve provocation in hands with carpal tunnel syndrome (CTS). Repeated nerve conduction measurements were performed before and after wrist flexion combined with resisted finger flexion in 35 hands with a clinical diagnosis of CTS and in 25 asymptomatic control hands. Orthodromic sensory median nerve potentials were recorded over an 8 cm segment between the palm and wrist. Hands with CTS had significant reductions in nerve potential amplitude and latency following median nerve provocation. Hands with mild to moderate CTS, had the greatest reductions in nerve potential amplitude and the longest amplitude recovery times following median nerve provocation. Determination of changes in amplitude and amplitude recovery time of the median nerve SNAP following median nerve provocation has the potential to improve the accuracy of the electrophysiological diagnosis of CTS.