[Evaluation of electrophysiological neuromonitoring in the diagnosis of brain death: Part I. Brainstem auditory evoked potentials].

Electrophysiological neuromonitoring of brainstem auditory evoked potentials (BAEP), short-latency somatosensory evoked potentials (SSEP) and compressed spectral array (CSA) EEG can provide precise and immediate information concerning functional integrity of the brain, brainstem and upper spinal cord of severely brain-damaged patients. We applied this neuromonitoring system in the cases of 154 severely brain-damaged patients in order to evaluate its reliability in the diagnosis of brain death. In particular, this study considers the relationships between BAEP and neurological findings, conventional EEG findings and factors affecting final BAEP findings. As a result, we evaluated the significance of BAEP in the diagnosis of brain death. A total of 109 brain-dead patients were divided into two groups: group A with 48 patients determined brain dead neurologically and by EEG prior to BAEP monitoring, and group B with 61 patients who had undergone automatic BAEP monitoring every 10 to 30 minutes before and/or after determination of clinical brain death. A third group, C, included 45 non brain-dead patients subjected to neuromonitoring, and served as a comparative group. Brain damage was caused by subarachnoid hemorrhage in 50 patients, intracerebral hemorrhage in 36, cerebral infarction in 8, head injury in 47, meningitis in 3, brain tumor in 3 and anoxia in 7. There were no significant differences in causes among the three groups (chi 2 = 20.3). The mean ages in the three groups were 50 (ages 10-91) in group A, 51 (14-86) in group B, and 50 (5-87) in group C. There were no significant differences in age distribution among the three group (chi = 25.0). The last BAEP findings of the 109 brain-dead patients indicated loss of all waves in 99 (91%), the presence of wave I in 9 (8%), and the presence of waves I and II in one patient (1%) (Table 1). Only three of the 45 group C non brain-dead patients indicated loss of all BAEP waves within one month after onset (Table 1). The one demonstrated loss of all BAEP waves 17 days after her accident, with recovery of waves I to V three months later. The temporal relationships in group B patients of the course of BAEP findings and the time of neurological brain death diagnosis are shown in Table 2 and Fig. 1. All but two of the 61 patients were followed up until final loss of BAEP waves (Fig. 1).(ABSTRACT TRUNCATED AT 400 WORDS)