Comparison of nerve conduction parameters in canine studies using recording needle and surface electrodes

Surface electrodes have been used in electromyography and nerve conduction studies in human and veterinary medicine, but comparisons have not been made between surface and needle electrode recordings in dogs. Our aim in this method comparison study was to determine whether surface electrodes captured larger compound motor action potentials (CMAP) than needle electrodes. Tibial nerve CMAP from 25 dogs with normal limb function was acquired using both surface and needle recording electrodes; the stimulus was elicited with monopolar concentric needles. Paired Wilcoxon signed rank test (if data was not normally distributed) or a paired two tailed t-test was used if data were normally distributed; significance was set at P<0.05. Mean CMAP amplitude (P=0.009), area (P=0.045) and latency (P=0.02) recorded with needle electrodes were larger compared with surface recording. CMAP duration was not significantly longer when recorded with surface electrodes (P=0.898). Needle electrode recordings are suitable for canine studies, although surface electrodes could also be considered. Low CMAP amplitudes recorded with surface electrodes should be verified with needle electrodes.