The study of wrist position effect on conduction velocity of the ulnar nerve

Across the elbow ulnar nerve conduction velocity (NCV) has been shown to be significantly influenced by the elbow position, so that, ulnar NCV increases in elbow flexion. This is because of buckling of the ulnar nerve upon itself in elbow extension and unfolding of the nerve in elbow flexion. Some studies have been done with the effects of wrist position on ulnar NCV. They compared wrist flexion against extension, but their results were contradictory. In order to clarify this difference and confirm one of them, this investigation was carried out on 40 healthy subjects without signs of ulnar neuropathy. Effects of wrist flexion (F), extension (E) and neutral position (N) on ulnar NCV were determined. The mean across elbow ulnar NCV’s in positions of F, N and E were 59.3, 59.4 and 59.8 m/s respectively, that were not significantly different (P = 0.3). Forearm (below elbow to wrist) mean NCV’s in these positions were 62.6, 61.8 and 61m/s respectively, that were significantly different (p=0.02), but when corrected for distance, mean NCV´s were not significantly different (p=0.3). It was found that the skin traction and wrist position did not affect the calculated across elbow and also across forearm ulnar NCV's significantly. Thus, during individual electrodiagnostic evaluation consistent wrist position is necessary.