Normative data for lateral femoral cutaneous nerve SEPs.

AIMS OF THE STUDY: To determine normative values for somatosensory evoked potentials (SEPs) of the lateral femoral cutaneous nerve (LFCN). METHODS: The LFCN was stimulated at two points, one located 1 cm lateral to the midpoint of a line joining the anterior superior iliac spine (ASIS) and the patella (31 subjects), and the other one located 12 cm distal to the ASIS (24 subjects). Recordings were performed at Cz' (2 cm behind Cz)-Fz. RESULTS: Reproducible SEPs were obtained in all but one of the 31 subjects to ASIS-patella midpoint (mean P1 latency: 33.2+/-3.5 ms, mean side-to-side difference: 2.0+/-1.6 ms) and in all but three of the 24 subjects to stimulation 12 cm distal to the ASIS (mean P1 latency: 30.9+/-3.3 ms, mean side-to-side difference: 2.2+/-1.7 ms). CONCLUSIONS: Reliable SEPs can be obtained to LFCN stimulation. It is easier and, therefore, more convenient to stimulate the ASIS-patella midpoint.