Ulnar palmar cutaneous nerve and hypothenar sensory conduction studies.

The ulnar palmar cutaneous nerve (UPCN) is potentially useful to the electrodiagnostician. However, no definitive nerve conduction study techniques for the UPCN have been reported. The UPCN supplies sensory innervation to the hypothenar palm. This study describes an orthodromic sensory conduction technique for the hypothenar palm. Data were collected from 20 normal limbed patients (ages 22-58). Potentials were recorded over the ulnar nerve 10cm proximally and at the elbow. Distal latency was 2.19 +/- 0.17msec, and distal amplitude was 12.7 +/- 6.9uv. Additionally, a modified collision technique was used in several subjects to examine the possibility of volume conduction to more than one ulnar nerve branch. The techniques described may be useful in selected cases of distal ulnar nerve pathology. A case is reported in which injury to the superficial sensory branch of the ulnar nerve, with sparing of the UPCN was demonstrated electrodiagnostically. Further study is needed to determine if the UPCN can consistently be electrophysiologically isolated.