[Brain stem auditory evoked potentials in various tumors in the cerebellopontine angle]

Abnormalities of brainstem auditory evoked potentials of 63 patients with tumours in the pontocerebellar angle were classified in 7 types and correlated by size and nature of tumours. Types A and B brainstem responses are characteristic for small tumours up 20 mm and are indicated for computed pneumocysternography in spite of the negative CT of the brain. Type C is statistically more frequently found than larger tumours over 22 mm in size. Other types of responses which are more characteristic for tumours which are not neurinomas are described. Auditory evoked potentials are the most reliable neuro-otologic methods in detection of PCU tumours and their careful analysis provides valuable data both about the size and nature of tumours.