Incidence of bilateral symptoms in carpal tunnel syndrome.

We prospectively studied 266 hands in 133 patients with carpal tunnel syndrome (CTS) in order to evaluate: the incidence of bilateral CTS symptoms; correlation between severity, duration of symptoms and bilateral occurrence of CTS; agreement of clinical and neurophysiological findings; and the neurophysiological findings in asymptomatic hands in unilateral CTS. The incidence of bilateral clinical CTS in our population was 87%. Neurophysiological impairment of median nerve was observed in about half of the asymptomatic hands. Follow-up of patients with unilateral CTS showed that contralateral symptoms developed in most cases. We found a significant positive correlation of bilateral CTS with the duration of symptoms, whereas there was no correlation with the severity of symptoms. Our data suggest that bilateral impairment of median nerve is the rule in patients with CTS and probably it has been underestimated in previous studies.