Electrocochleography (ECochG) and brain stem evoked response recordings (BSER) in the diagnosis of acoustic neuromas.

Evaluation of the auditory evoked responses has hitherto been the most important otoneurological method for early diagnosis of acoustic neuromas. ECochG enables to recognize serious damage to the first neurone. Criteria are: increased latency of the action potential (N1) and a low amplitude of the action potential relative to a high amplitude of the microphonic potential. BSER is a more sensitive indicator for functional deficiency in the first neurone, especially by evaluating interaural differences of the interpeak intervals (IPI) I-V and I-III. Problems arising when wave I cannot be clearly detected can be overcome by combining ECochG and BSER and evaluating the latency N1-V or perhaps in a better way by applying derivation of BSER between promontory and vertex. In 24 of 25 patients with indistinctly defined wave I in the standard recording, evaluation was possible in promontory BSER.