The ulnar nerve may be compressed either in the retrocondylar groove or at the cubital tunnel and optimal surgical therapy should be directed at the specific site involvement. Although routine electrodiagnosis may localize an ulnar neuropathy to the elbow, reliably separating retrocondylar lesion from cubital tunnel compression is more difficult.

The purpose of the study was to evaluate the difference in conduction times and amplitudes of the compound muscle action potentials of the hypothenar muscle. Differences in short segment responses was determined by stimulation in the ulnar nerve at 2 cm intervals across the elbow in 30 normal adult. The maximum conduction time in a 2 cam segment was 0.62 msec.