CORRELATION OF THE AUDITORY BRAINSTEM EVOKED POTENTIALS AMPLITUDE AND HEARING THRESHOLD SHIFT RELATED TO COCHLEAR INJURY

Abstract

Introduction: We have assessed the effects of the inner ear acoustic trauma on the amplitude of the first (I) and fifth (V) wave of the auditory brainstem evoked response (ABR). The aim was to estimate the diagnostic accuracy of the auditory brainstem evoked potentials amplitude in predicting the hearing threshold. Material and Methods: The ABR and pure tone audiometric recording were taken from 132 patients exposed to acute acoustic trauma. The amplitude of the I and V ABR wave was recorded for 80 dB HL click stimulation. Test of multiple regression was performed to establish the best diagnostic combination of the I, V and V/I ABR amplitude ratio on the hearing threshold prediction at 500Hz, 1 kHz i 2 kHz frequencies. Results and Discussion: The direct correlation was eminent between the hearing threshold and amplitude of the I wave ABR (R=0.065, R=0.048 i R=0.01, p< 0.05) for all of the tested frequencies. The amplitude of I and V wave of ABR significantly predicts haring threshold in cochlear injury related to acoustic trauma (r2=0.057, p< 0.05). Amplitude of the V wave was in reverse correlation to hearing threshold on all of the examined frequencies. Conclusion: The amplitudes of the I and V ABR waves, and V/I ABR wave ratio were significantly correlated with hearing threshold at 500 Hz, 1 kHz i 2 kHz in patients with cochlear damage secondary to acoustic trauma. Inner ear injury results in significant increase of I wave amplitude, yet followed by the decrease in V wave ABR amplitude.