Brainstem auditory evoked potentials: correlation between CT midbrain-pontine lesion sites and abolition of wave V or the IV-V complex.

Correlations between CT lesion sites and selective abolition of BAEP wave V or the IV-V complex were made in 16 patients who had discrete midbrain-pontine hemorrhages or tumors. Waves IV and V were consistently abolished by lesions involving the dorsolateral tegmentum of the midbrain-pontine junction area and the upper pons. The abolition of these waves was ipsilateral to the side of the monaural stimulation. Wave V or the IV-V complex was not affected by lesions involving the inferior colliculus, the central pons or the area dorsolateral to the aqueduct. It is concluded that an intact dorsolateral area of the upper pons is a prerequisite for waves IV and V to occur.