Tone Pip Elicited BER's

Abstract

Since the initial work of Jewett and Williston in 1971, a remarkable degree of quantification and confirmation of brainstem evoked response data has been published. The consensus of findings has led to the clinical acceptance of BER as an intricate test in the diagnostic assessment of both normal and pathological subjects. BER studies continue to demonstrate that the BER technique does provide an objective means for assessing hearing, especially among infants and difficult-to-test patients. The principle underlying BER is the same as that used for any evoked potential study. Basically, EEG changes resulting from auditory stimuli are recorded by scalp electrodes. The result is a specific wave form which may be recorded and the latency of each wave peak can be accurately measured. All in all, there are seven different wave peaks that are available to use as measurement points, some more stable than others, each reflecting different areas of neural activity in the auditory pathways through the brainstem. The individual peaks reflect changes in the auditory pathway that occur within the first 10 msec after the onset of the auditory stimulus. Each of the seven different waves has its own Roman numeral designator and anatomical location. In brainstem evoked response audiometry, Wave V has been found to be the most diagnostically useful waveform. Accurate estimates of thresholds have been made from the curves described by the latency values of the Wave V's of BER's elicited by click stimuli. These thresholds refer to intensity only and lack the frequency specificity required for audiological assessment. Speculation exists that other stimuli, especially more frequency-specific stimuli, might provide additional frequency-specific information. The purposes of our study were 1) to obtain Wave V latency curves for selected tone pip frequencies; 2) to compare the frequency-specific curves with previously obtained tone pip curves from other studies; and 3) to determine, if possible, the clinical utility of the selected procedure.