[Changes in short latency SEPs (S-SEPs) to median nerve stimulation in brain dead patients].

Short latency SEPs (S-SEPs) to median nerve stimulation consist of positive waves of P1, P2, P3 and P4, followed by negative waves of N 16 and N 19. These potential reflect activities of peripheral nerve, dorsal column of the cervical cord and medial lemniscus. The origins of these waves are considered as follows, P1--peripheral part of the brachial plexus, P2--the entry into the spinal cord or the dorsal column, P3--dorsal column nucleus or upper cervical cord, P4--the medial lemniscus, N 16--rostral brain stem or the thalamus, and N 19--thalamocortical projection or the cortex. The purpose of the present study is to elucidate changes of S-SEPs in brain dead patients. Fifteen brain dead patients were examined with S-SEPs. In addition to that, thirteen cases with lesions of subcortical or the brain stem but not in the state of brain death were studied for the controls. S-SEPs with non-cephalic references, conventional SEPs with earlobe reference and the evoked potentials at the Erb's point were recorded in all these cases. Serial recordings were performed in six brain dead cases during the process of rostro-caudal deterioration of the brain stem functions due to cerebral herniation. In the state of brain death, only P1 and P2 were recorded in eleven cases, and in three cases, only P1 was recorded. The other case with anoxic brain damage showed flat S-SEPs and the evoked potentials at the Erb's point could merely be obtained by the supramaximal stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)