Interrater Repeatability of Motor Nerve Conduction Velocity of the Ulnar Nerve.

OBJECTIVE The purpose of this study was to obtain data on interrater repeatability of the motor nerve conduction velocity (NCV) of the ulnar nerve of different segments, ulnar distal motor latency (DML), and compound muscle action potential (CMAP) amplitudes. DESIGN Twenty-four healthy volunteers were examined in consecutive order. Ulnar motor NCV of different segments, ulnar DML, and CMAP amplitudes were determined. Based on a randomization list of various combinations and sequences, 1 of 3 examiners performed the first measurement. A second examiner repeated the evaluation within half an hour. RESULTS There were no significant differences between the first and second measurements for all parameters. For the ulnar motor NCV of the different segments, the intraclass correlation coefficient (ICC) ranged from 0.38 to 0.51, and the coefficient of repeatability (CR) ranged from 8.0 to 11.6 m/s. For the ulnar DML, the ICC was 0.44, and the CR was 0.49 millisecond. For the CMAP amplitudes at the different stimulation sites, the ICC ranged from 0.53 to 0.76, and the CR ranged from 1.5 to 2.3 mV. CONCLUSIONS A moderate amount of interrater variability of the ulnar motor NCV must be taken into account. Compared with the CMAP amplitudes, the interrater repeatability of the ulnar motor NCV is poorer.