Brain stem electrical responses in cerebello-pontine angle tumours.

Thirty patients with cerebello-pontine angle tumours were studied with brain-stem electrical responses (BSER). Twenty-one of the patients had acoustic neuromas. Two other patients had meningiomas, one a lymphoma, one a chordoma, two patients arterio- venous malformations, and two aneurysms in the cerebello-pontine angle. In eight cases no BSER-waves could be evoked. In 13 cases with a Wave V present this wave was significantly delayed in all cases. The inter-aural time difference (IT5) and the I-V interval was prolonged in all those cases in which these parameters could be estimated, In nine cases, only the earlier components of the BSER (I and III) could be distinguished although Wave II was often missing. In all 30 cases studied the BSER was pathological, indicating a cerebello-pontine angle lesion.