[Aspects of early somatosensory and auditory evoked potentials in neurologic comas and brain death].

Following stimulation of the median nerve at the wrist, SEPs, BAEPs and EEG activity were recorded during the same session in 20 comatose patients (13 head injuries, 6 comas of vascular origin, 1 anoxic coma). Patients were classified according to clinical data. In traumatic comas with clinically preserved brain stem reflexes (5 patients), BAEPs were all present, with preserved cervical N14 and scalp recorded P15 SEPs; the parietal N20 SEP was either present on both sides or unilaterally absent in case of hemispheric, possibly EEG silent, traumatic lesion. In comas with a reactive EEG and absent brain stem reflexes (8 patients), N14 and P15 SEPs were present when the parietal N20 component was absent on both sides. In these patients various aspects of BAEPs were observed, but in most cases (7 out of 8) either the BAEPs were completely absent or only peaks I or I and II were present. In brain-dead patients (7 cases) the cervical N14 was recorded in all cases, the P15 SEP was inconstant and the parietal N20 component was constantly abolished on both sides; in most cases (5 out of 7) all the BAEPs were absent. The practical use of evoked responses for the survey of comatose patients is discussed.