Time course changes of nerve conduction velocity in idiopathic carpal tunnel syndrome after endoscopic surgery

A total of 49 patients (71 hands) underwent endoscopic carpal tunnel release according to the method of Okutsu accompanied by electrophysiological studies performed for idiopathic carpal tunnel syndrome at our department between August 1993 and May 1998. Among them, 41 patients (55 hands) who were followed-up for 12 months or more postoperatively were studied. The clinical outcome was favorable in 50 out of 55 hands (90.9%). In the 5 hands showing poor surgical results, distal motor latency or sensory nerve conduction velocity was not recordable before surgery and had not improved at 1 month postoperatively. In the present study, it is highly likely that the long-term prognosis will be poor when distal motor latency or sensory nerve conduction velocity is not recordable at 1 month after surgery as well as preoperatively. It is possible to identify patients with a poor outcome by performing electrophysiological studies at 1 month after surgery.