Figure 38-10 Short-latency somatosensory evoked potentials are produced by stimulation of the median nerve at the wrist. The ability to identify each of the labeled peaks shown in the tracing from the awake patient is compromised by the anesthetic state and use of different recording electrode locations. Corresponding tracings are labeled with the same letter. (Adapted from Chiappa KH, Ropper AH: Evoked potentials in clinical medicine. N Engl J Med 306:1205, 1982.)