PubMed · 6837367
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K Terkildsen, P Osterhammel. 1983. Brainstem electrical response audiometry.. https://doi.org/10.1159/000407486
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Diagnostic audiological tests performed in ten children from 1985 to 1991 showed remarkable differences between the results of behavioral audiometry (free field or pure tone audiometry) and those of auditory evoked response audiometry. Auditory brainstem response (ABR) was absent in seven children with sensory neural hearing loss. Neuropsychological evaluation was performed on four children, neuropsychological observation was performed on two children, pediatric examination was performed on three children and one child showed signs of neuropediatric disorder. The results of neuropsychological evaluation showed moderate to severe learning disabilities (sensory integration disorders, learning disorders) in all four children tested. Available neuropsychological observation also indicated the presence of sensory integration disorders in two children. Two children had multiple handicaps with cerebral abnormalities, two further children were diagnosed as suffering from "minimal cerebral dysfunction," one of which was mentally retarded. The fact that ABRs were absent in seven children indicates that a response desynchronisation in the auditory pathway may exist in these disorders. Thus, ABR might not be a reliable method for audiological testing in children with learning disabilities or other cerebral dysfunctions, but serves as an adjunct to conventional testing methods.
The preservation of hearing is a major aim of contemporary temporal bone surgery. Our present findings demonstrate that intraoperative monitoring is a key method for attaining serviceable postoperative hearing after the removal of an acoustic neuroma. Both electrocochleography (ECoG) and brainstem electrical response audiometry were performed in 96 patients operated on for acoustic neuromas. The specificity of the different monitoring methods was affected by surgical manipulations in addition to such non-specific influences as CSF drainage, core body temperature and anesthesia. In the present study ECoG was found to be more reliable in assessing the intra- and postoperative course with respect to the preservation of cochlear function.
The diagnosis of retrocochlear damage is supported by an increased latency difference between peak I and peak V. In case of high frequency hearing loss peak I is often hard to determine, and peak V latency may be shifted not only by neural delay, but also by missing basal hair cells. The amount of cochlear delay can be estimated by a procedure presented here. High frequency decay was simulated by steep high-pass noise masking. Peak V latency turned out to be established by the highest unaffected frequency components of the click stimulus. Thus, in case of a high frequency gap (with normalization towards higher frequencies) latency may be almost normal. In case of prolonged latency the amount ascribable to the cochlea may be rather precisely be estimated. If the whole lag is explained this way, unnecessary further diagnostics can be avoided.