Assessment of sensory nerve conduction in carpal tunnel syndrome before, during and after operation.

Sensory conduction velocities of the median nerve before, during and after operation were compared in nine patients with carpal tunnel syndrome and four controls, in order to evaluate the prognostic value of the pre-operative and intra-operative findings. Sensory conduction velocity was higher after operation than before in all patients (mean difference 31.33%), but not in control subjects. One patient showed a dramatic increase of 157% immediately after decompression. Comparing the intra-operative with the post-operative findings all patients but one showed an increase of antidromic sensory conduction velocity (mean 44.37%), while in control subjects again minimal changes were found (mean -4.25%). The study confirms the high diagnostic value of the pre-operative antidromic sensory conduction velocity findings. However, the prognostic value of both pre-operative and intra-operative ASCV findings is low.