Natural history of carpal tunnel syndrome according to the neurophysiological classification.

Although many studies on carpal tunnel syndrome (CTS) have been reported, few data on the natural history of CTS are available. Knowledge of the natural course of the disease has significant clinical and therapeutic value. We prospectively followed up 80 cases of untreated CTS. The evaluation was based on self-administered questionnaires and on neurophysiological investigation. According to the neurophysiological classification, cases of CTS were divided into six groups on the basis of impairment severity: negative, minimal, mild, moderate, severe, and extreme. Disease worsening was inversely related to severity of nerve entrapment. On the contrary, improvement was proportionally related to nerve function impairment (except for extreme cases that never improved), and about one-third of mild and moderate cases improved. Most minimally cases remained neurophysiologically unchanged. We hypothesize that in a good percentage of CTS cases, nerve impairment is self-limited. Our data suggest the utility of further studies on the natural course of this common disease.