[Somatosensory evoked potentials in comatose patients: comparison with clinical findings, EEG and prognosis]

21 comatose patients were examined by somatosensory evoked potentials (SSEP). The findings were correlated with the stage of brainstem herniation, the EEG and the outcome. We evaluated the early components of the SSEP (N10, N13, N14, P15, N20) in view of presence, latency and interpeak-latency of the potentials. In most cases the percentage of abnormal SSEP increased from caudal to rostral registration sites, but the potential P15 and N20 were equally abnormal. The progression of herniation correlated with increasing abnormality of the potentials. SSEP over the scalp (P15, N20) could not be registered in patients without any EEG-activity (isoelectric). Mean values of latencies and the interpeak-latencies were significantly prolonged in all cases with fatal outcome. Our findings suggest SSEP as a useful tool in the evaluation of brain-dysfunction in comatose patients.