Diagnosis of ulnar neuropathy: A new approach

Conventional electrodiagnosis used to detect an ulnar neuropathy at the elb ow depends on accurate determination of ulnar nerve length across this segm ent. We present a new approach, using the difference in latency of the comp ound nerve action potentials (CNAPs) of the ulnar and median nerves elicite d by stimulation at the wrist and recorded 10 cm above the elbow. Sixty nor mal controls were examined in order to determine the normal upper limit (1. 4 ms) of the difference in CNAP latency of the ulnar and the median nerves (Dlat index). Values obtained in 10 patients with ulnar nerve lesions are d iscussed. This test was shown to be both sensitive and specific, was indepe ndent of ulnar nerve length, and was easy to perform. (C) 2000 John Wiley & Sons, Inc.