New near-nerve needle nerve conduction technique: Differentiating epicondylar from cubital tunnel ulnar neuropathy

At the elbow, the ulnar nerve is compressed most commonly either in the epi condylar groove or at the cubital tunnel. While conventional electrodiagnos is may localize an ulnar neuropathy to the elbow, separating epicondylar sy ndrome (tardy ulnar nerve palsy) from cubital tunnel syndrome is more diffi cult. We describe a new method using a near-nerve needle technique for dist inguishing these two types of ulnar neuropathy at the elbow. We placed thre e active needle electrodes across the elbow: the first was 4 cm above, and the second and third were 1.5 cm and 6 cm below the medial epicondyle, resp ectively. The latter two points were chosen because of the presence of the cubital tunnel in this segment, Sensory, motor, and mixed nerve conduction studies (NCS) were performed on these two segments (elbow segment and cubit al tunnel segment) in 26 normal nerves and normal data were established. We also present 7 cases of epicondylar ulnar nerve palsy and 1 case of cubita l tunnel syndrome in which we were able to confirm the diagnosis with the p resent method, In 3 cases of epicondylar ulnar nerve palsy, the present met hod accurately localized the lesion when other methods failed. We believe t hat this method will be helpful in distinguishing cubital tunnel syndrome f rom epicondylar ulnar nerve palsy, especially in early ulnar neuropathy in which only sensory fibers are involved. (C) 1999 John Wiley & Sons, Inc.