Sympathetic skin response before and after surgical release of carpal tunnel syndrome

Sympathetic skin response (SSR) was performed before and 1 year after surgi cal release of the median nerve in 20 subjects (mean age 52.8 years) with u nilateral idiopathic carpal tunnel syndrome (CTS). SSR was evoked by stimul ation of the ulnar nerve at the wrist contralateral to the side with CTS, r ecording from the palm, third (M3) and fifth fingers, and from the third fi nger contralateral to the side of CTS (M3c). Before surgery, anomalies of M 3 SSR were found in 8 hands (40%): M3 SSR was absent in 1 hand; and the M3c /M3 SSR largest area ratio was abnormal in 7 hands, 3 of which also had abn ormal mean differences between M3 and M3c SSR latencies. M3 SSRs were not s ignificantly modified after surgery. The absence of postsurgical improvemen t may be due to the poor reinnervation capacity of sympathetic fibers. (C) 2001 John Wiley & Sons, Inc.