Reference values of fractionated neurography of the ulnar nerve at the wrist in healthy subjects

Objective: This study is designed to derive a normative database for nerve conduction values of the ulnar nerve in the wrist. Methods: Ulnar nerve study at the wrist (UNSW) was performed in 204 hands of 102 control subjects. The UNSW was composed of motor and sensory tests. Motor UNSW was done with first dorsal interosseous muscle recording. Sensory UNSW was performed antidromically with fifth finger recording. The 3 stimulation points were 2 cm proximal to the pisiform, just lateral to pisiform, and 3 cm distal to the pisiform. Results: Mean latency differences in the proximal and distal segments were 0.4±0.1 and 0.5±0.1 ms in motor UNSW and 0.4±0.1 and 0.5±0.1 ms in sensory UNSW. The 95th percentile values for motor and sensory UNSW were 0.5 ms in the proximal segment and 0.7 ms in the distal segment. Conclusions: When the 95-percentile value was considered as the normal upper limit, the criteria of abnormality for motor and sensory UNSW were greater than 0.5 ms in the proximal segment and greater than 0.7 ms in the distal segment. Significance: The normative values of UNSW may be useful in screening for ulnar neuropathy at the wrist.