Across-elbow ulnar nerve sensory conduction technique.

Compression of the ulnar nerve across the elbow is one of the most common of the entrapment syndromes. The usual method of electrodiagnostic evaluation is to determine the motor nerve conduction for this nerve segment. Normal values for sensory conduction and amplitude changes for this nerve segment have been rarely reported, and clinical usefulness of the sensory techniques remains unclear and controversial. This study reports an ulnar nerve sensory technique for the across-elbow segment. Normal data with the elbow flexed to 90 degrees and for a 10-cm nerve segment were 1.8msec, mean +2SD for sensory latency measured to onset and 1.9msec to peak. Comparable motor latency was 2.0msec. Sensory amplitude decrement across the elbow was 41% mean +2SD and 7.6% for the comparable motor amplitude decrement. Three cases of ulnar nerve compression at the elbow are reported, exemplifying that this technique appears to be useful particularly in patients with sensory, as opposed to mixed (sensory and motor), clinical abnormalities.