A study of cases with partial disappearance of the waves in the auditory brain stem response.

Twenty cases which showed partial loss of ABR waves were reported. Only wave I was recorded in 18 ears tested. Wave I and II; I-III; and I-IV responses were observed in four, eight, and five ears tested, respectively. Cases included pontine glioma (8), acoustic tumor (4), West syndrome (2), leukodystrophy (2), facial neurinoma (1), epidermoid tumor (1), pontine bleeding (1), and unknown cause (1). Fourteen of 20 were tumor cases. This fact indicates that if the ABR shows partial loss of waves, the examiner should first suspect the space-occupying lesions of the brain stem.