Brainstem Auditory Evoked Potentials for Detection of Retrocochlear Pathology

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Abstract
Since May 1976 the techniques of brainstem auditory evoked potential (BAEP) testing have been used as a clinical tool in evaluating patients with neurotologic disease in the Department of Otolaryngology and Communicative Disorders at the Cleveland Clinic Foundation. A total of 676 patients was tested using this technique and included patients with primary otologic complaints as well as patients with neurologic disorders. Patients were evaluated with suspected multiple sclerosis, for threshold assessment, children at risk for possible sudden infant death syndrome, brainstem gliomas, systemic neurologic or metabolic disorders, and the final group of 408 patients or 60% were tested for suspected eighth nerve lesions. In the group of patients studied for detection of an eighth nerve lesion, the BAEP test was extremely useful if the result was found to be normal, for at the time of this report, no patient with an eighth nerve lesion, such as an acoustic neuroma, had a normal BAEP test result. However, abnormal results in the BAEP test were found in approximately 34% of patients who underwent Pantopaque® myelography for definitive detection of an eighth nerve lesion in which the myelogram was normal. This unusually high false-positive rate is thought to be the result of testing a different patient population than those that have previously been reported in the literature. There still may be some eighth nerve pathology present; however, the results of the BAEP test which have been suggestive of an eighth nerve lesion remain unexplained at this time. The BAEP test is a very important part of the evaluation of patients with neurotologic disease; however, it is not sufficiently understood to eliminate the need for a complete work-up in patients suspected to have a retrocochlear lesion.