Comparison of the flexed and extended elbow positions in localizing ulnar neuropathy at the elbow.

Electrophysiologic localization of ulnar neuropathy at the elbow often depends on demonstration of segmental slowing. Based on normative data obtained from 50 control subjects, we compared the utility of flexed and extended elbow positions in demonstrating focal slowing at the elbow as compared to the forearm segment in patients with ulnar neuropathy. We studied 35 patients with ulnar neuropathy with definite electrophysiologic localization to the elbow segment defined by conduction block across the elbow segment or by focal slowing demonstrated either in the flexed or extended position. Applying cutoff values from the control group, all 35 patients demonstrated focal slowing at the elbow in the flexed position, whereas only 5 of 35 (14%) patients did so in the extended position. We conclude that the flexed elbow position is more sensitive than the extended position in localizing ulnar neuropathy at the elbow and should be the preferred method when performing ulnar motor conduction studies.