Brain-stem auditory evoked potential monitoring. Variations of stimulus artifact in brain death

Brain-stem auditory evoked potentials (BAEPs) were recorded in 20 subjects with brain death (mean age, 33.2 +/- 15.1 years) and 20 healthy volunteers (mean age, 29.8 +/- 6.8 years). Brain death was due to head injury (n = 14), encephalitis (n = 3), brain-stem hemorrhage (n = 1), cerebellar hemorrhage (n = 1) or cerebral infarction (n = 1). The presence, latency and amplitude of the individual BAEP components and variations of the stimulus artifact were evaluated. The mean (+/- S.D.) amplitude of the stimulus artifact was 0.26 +/- 0.12 microV in the brain-dead subjects and 0.09 +/- 0.05 microV in the control group (P < 0.001, t test). The causes of the phenomenon of increasing stimulus artifacts in the evolution of brain death remain unclear.