Prognostic factors for postsurgical hearing and facial nerve function in cases of cerebellopontine angle-tumours. The meaning of brain stem evoked response audiometry (BERA).

Presurgical and postsurgical brain stem evoked response audiometry (BERA) examinations were done in patients with tumours of the posterior cranial fossa. A correlation exists between the extent of presurgical BERA-alterations and postsurgical hearing-power and facial nerve function. Small tumours (less than 1 cm) correlate generally with small BERA-alterations and show a good prognosis. Conservation of hearing in cases of larger tumours can only be expected when BERA-alterations are small. Prognosis is generally bad in cases of big tumours (greater than 3 cm). BERA-alterations on the contralateral side point to an additional brain stem compression which can normalize after surgery.