Brain-stem auditory evoked potential abnormalities with unilateral brain-stem lesions demonstrated by magnetic resonance imaging
O. N. Markand, M. R. Farlow, J. C. Stevens and M. K. Edwards
Department of Neurology, Indiana University School of Medicine, Indianapolis.
We correlated the brain-stem auditory evoked potential (BAEP) abnormalities
in 24 patients with discrete unilateral brain-stem lesions demonstrated by
magnetic resonance imaging. In 18 patients who had BAEP abnormalities
either confined to or more severe on stimulation of one ear, the lesion on
magnetic resonance imaging was in the brain stem ipsilateral to the
corresponding ear. Mesencephalic lesions produced amplitude abnormalities
of the IV/V complex while pontine lesions resulted in abnormalities of
earlier components (wave II and/or III). Prolongation of the I-III
interpeak latency tended to occur with pontine lesions and of the III-V
interpeak latency with mesencephalic lesions. Unilateral brain-stem
lesions, particularly at the mesencephalic level, often produced BAEP
abnormalities on both ipsilateral and contralateral monaural stimulation.