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

A total of 49 patients (71 hands) underwent endoscopie carpal tunnel release according to the method of Okutsu [1] 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.