Intersession stability of somatosensory evoked potentials

Upper and lower limb nerve somatosensory evoked potentials (SEPs) were recorded from a group of normal adults in order to assess their intersession stability. Median, peroneal and sural nerve SEPs were recorded from each subject on 3 successive occasions at weekly intervals. For median nerve SEPs, the intrinsic variability was more pronounced for interpeak latencies (N9-N20, N13-N20) than for the latencies of individual components. Their inherent fluctuation was not, however, notably greater for the primary cortical response (N20) than for the more caudally generated components (N9 and N13). These relationships were not so apparent for lower limb SEPs where intersession variability was markedly greater overall than for upper limb SEPs.