Brainstem auditory evoked potentials in syndromes of decerebration, the bulbar syndrome and in central death.

The results are reported of serial brainstem auditory evoked potentials recordings in 51 patients with decerebration and bulbar syndrome. In contrast to the stability of latencies of single components of the potential in healthy subjects, patients with decerebration syndromes show considerable instability and an increase in the latency of all the components of the potential. In 34 decerebrate patients the P-I latency and the interpeak latencies for the medullo-pontine and ponto-mesencephalic segments as well as the central conduction time were significantly increased. There was marked reduction of the amplitude of P-V and P-III and deformation of the single components of the potential with widening and smoothing. The amplitude ratios A-V to A-I and A-III to A-I were significantly decreased. The findings are interpreted as due to mesencephalic and pontine functional disturbance during decerebration. The brainstem auditory evoked potential can be used to estimate the time of brain death. Possible causes of misinterpretation are discussed.