Abnormal brainstem auditory evoked potentials and neuropathology in "locked-in" syndrome

Brainstem auditory evoked potentials (BAEPs) were studied in a "locked-in" syndrome resulting from multiple occlusions of paramedian pontine arteries. Abnormality of BAEPs (first recorded 10 days after infarction) indicated that brainstem damage extended beyond the basis pontis, where, typically, interruption of corticospinal pathways results in the "locked-in" syndrome. Later, partial BAEP recovery suggested that the technique can be used to distinguish between permanent and transient brainstem involvement. Autopsy examination revealed close correspondence between permanent brainstem damage and persistent BAEP abnormalities. Persistent abnormal prolongation of III-V conduction time and aberration of wave IV were associated with damage near the lateral lemniscus contralateral to the stimulated ear.