THE EFFECT OF HEARING-LOSS ON ABR INTERPRETATION - USE OF A CORRECTION FACTOR

Patients suspected of retrocochlear disorders often have abnormal ABRs in the presence of high-frequency hearing loss, making clinical decis ions difficult. In a retrospective study of the ABR test results of 15 39 patients, the false-positive and false-negative rates for ABR are p resented as a function of hearing loss at 4000 Hz, both before and aft er using Selters and Brackmann's correction factor for hearing loss. F or patients with more than 50 db HL at 4000 Hz the false-positive and false-negative rates, uncorrected for hearing loss, were 25.0% and 2.9 % respectively, and when the correction factor was used were 12.5% and 5.8%. When hearing loss at 4000 Hz was over 90 dB the ABR was abnorma l in 75% of nontumor patients. Conclusions are that a correction facto r for hearing loss is helpful with reservations, and that ABR is not a useful test when 4000 Hz hearing loss is greater than 90 dB HL and 20 00 Hz is greater than 75 dB HL.