Objective
Patients with carpal tunnel syndrome are often refered for electrophysiologic evaluation of postoperative residual symptoms. We performed this prospective study to assess changes of the electrophysiological parameters after carpal tunnel release.

Method
Fifty-four hands of 29 patients with electrodiagnostically confirmed carpal tunnel syndrome underwent surgical release of the transverse carpal ligament. Serial electrophysiological evaluation of the median nerve performed at 2 weeks, and 1, 3, 6 months after surgery in all patients. All the tests were performed by one electromyographer using Dantec Counterpoint machine. Median motor and sensory responses were obtained from abductor pollicis brevis and 3rd digit respectively. Repeated measure ANOVA test was done to observe the changes in each parameter on serial examination.

Results
The median motor latency (ML), motor amplitude (MA), sensory latency (SL) and sensory amplitude (SA) were as follows: preoperative ML (6.1⁑0.2 ms), MA (7.3⁑0.5 mV), SL (5.1⁑0.2 ms), SA (6.8⁑1.0 uV); postoperative week 2, ML (5.5⁑0.2 ms), MA (6.9⁑0.5 mV), SL (4.5⁑0.2 ms), SA (11.4⁑1.3 uV); postoperative month 1, ML (5.1⁑0.2 ms), MA (7.1⁑0.5 mV), SL (4.1⁑0.2 ms), SA (13.0⁑1.3 uV); month 3, ML (4.6⁑0.1 ms), MA (7.2⁑0.1 mV), SL (3.8⁑0.2 ms), SA (15.4⁑1.4 uV); month 6, ML (4.6⁑0.2 ms), MA (7.4⁑0.5 mV), SL (3.5⁑0.1 ms), SA (16.5⁑1.4 uV).

Conclusion
Improvement was gradually seen up to the postoperative 3 months. However, the least amount of improvement was observed in the postoperative 3 to 6 month period.