[Auditory evoked potentials from brain stem determined in acoustic nerve neurinomas]

An analysis of the studies of Brain Stem Electric Response Audiometry of patients operated on Bachaumont Clinic or in Cochin hospital in Paris, because of acoustic neurinoma, was carried out. The studies comprised 88 patients divided into groups according to the size of tumour. A group of small intrameatal tumours, a group of up to 2 cm tumours, a group of between 2 and 3 cm tumours and a group of above 3 cm tumours. A control group of examined patients consisted of 20 persons with one-side acoustic impairment or two-side impairment but predominant on one side and patients with one-side tinnitus or two-side tinnitus but predominant on one side. Examinations of these patients made with CT and NMR did not show presence of acoustic neurinoma. BERA's tests did not show a response in case of 22 patients with acoustic neurinoma. In 71% of cases BERA's tests showed an extrahelix type, for which in 50% of cases a prolonged latency on the side of the tumour was found. In 4% of cases Brain Stem Electric Response Audiometry gave results within normal range both with respect to morphology and latency time of each wave. A slight correlation between the size of tumour and type of BERA change was found.