[Audiometry findings, speech, impedance audiometry and BERA in acoustic neurinoma].

Abstract

Audiometric examinations are essential in the diagnosis of acoustic neuroma. Experience with the diagnosis of 41 neurinomas of the acoustic nerve show, however, that the tactics of audiometric examinations vary from one case to the other. The basic examination is in all instances an accurate examination of the threshold of hearing. When the threshold is normal or there are slight or medium severe losses on the side of the lesion, the tympanogram, impedance and speech audiometry and BERA are supreme examinations and all other audiometric examinations are redundant. For BERA alone limiting losses are above 3000 to 4000 Hz. As soon as they pass at the above frequencies the borderline of 60 dB HL in proportion to the magnitude of these losses the amount of falsely positive findings increases rapidly and the importance of BERA in the diagnosis declines. The same applies to impedance audiometry if major losses interfere with medium and lower frequencies. In all these instances the importance of speech audiometry as well as of STAT (Supra Threshold Adaptation Test) increases, i.e. of traditional audiometric examinations, the latter of which can be used successfully also in very high losses round 80-90 dB HL.