Gender differences in carpal tunnel relative cross-sectional area: a possible causative factor in idiopathic carpal tunnel syndrome.

UNLABELLED: Previous research has not established a consistent difference in hand size or carpal tunnel cross-sectional area between patients with and without carpal tunnel syndrome. We tested the hypothesis that there would be no difference in relative carpal tunnel sizes between men and women. We defined relative carpal tunnel size as the cross-sectional areas at the inlet (level of the pisiform) and outlet (level of the hook of the hamate) of the carpal tunnel divided by the length of the capitate (as a measure of hand size). We made the measurements on the magnetic resonance imaging scans of 50 men and 50 women taken for symptoms unrelated to carpal tunnel syndrome. The mean relative cross-sectional area was appreciably smaller in women than men (p < 0.05). This suggests that the carpal tunnel cross-sectional area relative to the size of the hand is constitutionally smaller in women than in men. This could in theory be a significant factor in patients developing carpal tunnel syndrome. LEVEL OF EVIDENCE: V.