Surgical prognosis in carpal tunnel syndrome: usefulness of a preoperative neurophysiological assessment.

In this study 37 CTS hands underwent pre- and post-operative (15 days 2 and 6 months) evaluation of median nerve distal motor latency (DML) and sensory nerve conduction velocities (SNCV: I digit and III digit-wrist). Pre-operatively, CTS hands were classified as mild (decreased SNCV, normal DML), moderate (decreased SNCV, increased DML) or severe (absent sensory nerve action potentials, increased DML). Post-operatively, all hands presented clinical and neurophysiological improvement. The three groups of patient showed different clinical and neurophysiological responses to nerve decompression: we observed a rapid restitutio ad integrum in mild group, an improvement with normalisation in about 50% of the hands in moderate group, and a high percentage of restore of the sensory responses with no normalisation in severe group. A marked improvement of sensory symptoms was observed in all cases, but some degree of motor and/or sensory deficit was still present six months after surgery in more advanced cases. Preoperative electrophysiological assessment of median nerve function in CTS hands have an important role in predicting the outcome of surgical decompression.