PMC

A, Skin erosions are visible on the distal pulp of the second and third fingers. B, Bilateral ulcerations are visible on the second fingers in a patient with bilateral carpal tunnel syndrome.

Box plot showing the relationship between age in decades and body mass index for women with carpal tunnel syndrome and those without. Younger women with carpal tunnel syndrome have a higher body mass index than those without carpal tunnel syndrome

Evoked responses in healthy controls and carpal tunnel syndrome. (A) Healthy controls (HV) and subjects with carpal tunnel syndrome demonstrated M20 and M30 S1 peaks. Longer latency peaks at ∼60 and ∼100 ms were also present. Significantly larger M30/M20 ratio was also present for Digit 3 versus Digit 5 (paired tests, P < 0.04) in carpal tunnel syndrome. (B) Healthy controls showed no significant difference in M20 latency between median and ulnar nerve-innervated digits. However, in carpal tunnel syndrome, Digits 2 and 3 responses were slightly longer than those of Digit 5 (*P < 0.002, **P < 0.008). Thus, delayed signal transmission at the periphery leads to delayed onset of central responses at the level of S1. (C) For contralateral S2, Digit 2 response was larger than Digit 3 in healthy controls at ∼55–125 ms and in carpal tunnel syndrome at ∼75–110 ms (P < 0.005). Additionally, in carpal tunnel syndrome, Digit 5 response was greater than that of Digit 3 and also Digit 2 at ∼75–125 ms and ∼205–220 ms, respectively (P < 0.005). No significant differences were found between groups. Thus, evoked S2 response is not likely to be a consistent marker for median nerve abnormality in carpal tunnel syndrome.