Occurrence of bifid median nerve in healthy and carpal tunnel syndrome patients.

We investigated the possible association between median nerve morphology and carpal tunnel size, hand side and nerve conduction measurements. The study included a patient group (n = 58; 44 women) with idiopathic carpal tunnel syndrome (CTS) in 100 hands and a control group of healthy volunteers (n = 56, 112 hands; 44 women). The following data were recorded: (1) median and ulnar motor and sensory nerve conduction parameters (2) ultrasonographic dimensions of the carpal tunnel inlet area (CTAin ) and inlet area of the median nerve. The prevalence of bifid median nerve was 19% in the CTS hands and 13.3% in the control group. Bilateral bifid nerve was detected in 7 subjects and unilateral in 23, with no side or sex preponderance. The median nerve area was larger in the participants with single than those with bifid median nerve. No correlation was found between CTAin and median nerve area for single or bifid nerves in controls or patients. It was concluded that bifid median nerve was not a rare variation. We could not, however, support its etiological relation to CTS. Ultrasonographic examination of the carpal tunnel region supplementing neurophysiology provided a reliable means to detect median nerve size and morphology.

CLINICAL TRIAL REGISTRATION NUMBER: 84; 5/3/15.