The risk of hearing threshold estimation by click stimuli auditory brainstem response in children

Abstract

Background: click stimuli auditory brainstem response (ABR) test is commonly used in the audiology centers for confirmation of hearing loss as well as hearing threshold estimation for hearing aid fitting in children.Aim: To compare hearing threshold evaluation by behavioral pure tone audiometry with that by click stimuli auditory brainstem response audiometry.Patients & Methods: The study includes 82 children with bilateral hearing loss and no ABR or behavioral responses (164 ears), ranged in ages between 1 and 8 years. These children were referred for hearing threshold estimation as a pre requisite of hearing aid fitting. 16 children (32 ears), aged 4 years and greater, which forms about 20 % of cases were selected for comparison of the results of pure tone audiograms with their auditory brainstem response results, because by the age of 4 years and greater, the pure tone audiometry with headphones can be measured reliably. Results: The mean age of auditory brainstem response testing was 2.81 years (SD 1.56) and most of the children`s hearing is diagnosed in the 2nd, 3rd and 4th year of age with percentages of 38, 18 and 24 respectively, males (48) more than females (34). Whereas the mean age of ABR for those 4 years and greater is 2.9 (SD 1.3) and ranged in ages between 1.5 and 6 years. The mean age of pure tone audiogram tests was 5.4 (SD 1.1), and ranged between 4 and 8 years. The pure tone audiograms of the 31 ears with no click ABR responses revealed a wide range of dynamic hearing in the frequencies 250, 500, 1000, 2000, 4000, and 8000 Hz with figures of 40-100 (mean 65), 50-100 (mean 75), 70-115 (mean80), 75-120 (mean100), 75-120 (mean105), and 80-120(mean110) respectively. Conclusion: the study indicated that the Clicks stimuli auditory brainstem response is not a good predictor of behavioral hearing threshold in children, and there is great delay in the age of hearing loss estimation and that will results in delay and inappropriate hearing aid fitting and its consequences on speech development. This raises more attention to be paid on proper behavioral testing, and reliance more on battery of tests by combining click stimuli ABR with other frequency specific tests such as tone pips auditory brainstem response and auditory steady state response for hearing aid fitting and confirmation of hearing loss, and the use of single hearing test for assessing children`s hearing should be discouraged.