Neurinoma of the acoustic nerve is a tumour which attracted for several decades attention of otorhinolaryngologists and neurosurgeons. The number of published papers on the subjects is increasing every year. The increased interest in this tumour is conditioned by the routine use of new examination methods in clinical practice and improving standards of the microsurgical technique. Among tumours of the pontocerebellar angle the neurinoma has the closest relationship with fibres of the acoustic nerve. It is a benign tumour which originates from Schwann cells of the vestibular part of the statoacoustic nerve. Therefore the more accurate term is vestibular schwannoma.The site of origin of the neurinoma is the area of the orifice of the outer auditory meatus, a site where the nerve is still covered by a sheath of Schwann cells.The tumour spreads at first in the direction of the inner auditory meatus and enlarges it , then it grows into the pontocerebellar angle and finally causes compression of the brainstem. House differentiates according to the size and spread of the tumour four clinical stages of the disease.Stage I is a tumour which grows only in the inner auditory meatus , stage II a tumour which spreads already to the area of the orifice of the inner auditory meatus, stage III a tumour which spreads to the pontocerebellar angle, stage IV a tumour causing compression of the brainstem. The incidence of the tumour is some nine cases per 1 million population per year, i.e. ca 0.01 pro mille. At the Clinic of Otorhinolaryngology and Surgery of the Head and Neck and Faculty Hospital, First Medical Faculty Charles University Prague-Motol in 1998 microsurgical operations of neurinomas of the statoacoustic nerve were introduced.Before the operations the patients were subjected to an audiological examination. A group of 23 patients was involved with a diagnosed neurin oma confirmed histologically after operation. The patients were subjected to sound audiometry , examined by suprathreshold tests , clinical tympanometry , incl. examination of the stapedial reflex, verbal audiometry, examination of otoacoustic emissions and acoustically evoked brainstem pontentials. Of thr series of tests examination of acoustically evoked brainstem potentials (BERA-Brainstem Evoked Response Audiometry) proved most useful. In none of the patients a normal BERA record was obtained.Therefore, consistent with the majority of authors concerndc with the given problem we consider BERA examination as one of the decisive methods for assessment of the diagnosis of a vestibular schwannoma.In our group we did not find a statistical relationship between tumour size and the type of record (classification of records according to Maurer). The majority of patients (78.3 %) attended examination only in stage IV of the disease. We assume therefore that the majority of neurinomas of the acoustic nerve is diagnosed late. By detailed audiological examination of every perception hearing disorder it would be possible to detect the disease already in earlier clinical stages and thus improve the perspectives of the patients to preserve the function of the VIIth nerve and of the acoustic part of the VIIIth nerve. In our patients audiological symptoms predominated as the first sign of the disease over neurological symptoms (73.1 %). The presence of a statoacoustic tumour must be taken into account not only in patients with unilateral progressing perception hearing disorders associated with tinnitus but also in patients with an atypical symptomatology ( e.g. sudden hearing disorder, sudden deterioration of an already existing perception defect, dysgeusia , neuralgia of the trigemninal nerve).The suspected presence of a tumour is confirmed unequvically by nuclear magnetic resonance.

        Key words: BERA, neurinoma of the acoustic nerve.