Establishment of Normative data for Monaural Recordings of Auditory Brainstem Response and its Application in Screening Patients with Hearing Loss: A Cohort Study.

OBJECTIVES To establish normative data required for recording Auditory Brainstem Response (ABR) using monaural stimulations in children with normal hearing. METHODS This study was conducted on 40 apparently healthy children. Database was collected after assessing with otological questionnaire, otoscopic examination and audiometric evaluation. Brainstem Evoked Response Audiometry (BERA) was used as a tool for establishment of normative data. ABR recordings by monaural presentation were obtained by following the standard test protocol given by Hall. RESULTS ABR parameters like Absolute latencies, amplitudes, amplitude ratios, Inter- peak latencies and thresholds were assessed for their normative values which are required to establish a baseline data. The Interaural latency difference was less than 0.2 ms (milliseconds) and was found to be normal limit. Mean values of absolute latencies for left ear were1.66 ms 3.68 ms and 5.64 ms respectively and for right ear these were 1.66 ms, 3.65 ms and 5.59 ms respectively. Mean values for amplitude of wave I and V for left ear were 0.32 uV and 0.41 uV respectively. For right values were 0.31 uV and 0.36 uV respectively. Mean values of amplitude ratio (V/I) for left and right ears were 1.81 and 1.74 respectively. Mean values of interpeak latencies of wave I-III, III-V, I-V were 2.02 ms, 2.02 ms and 3.92 ms respectively for left ear and for right ear values were 2.04 ms, 1.98 ms and 4.03 ms respectively. Mean values for left and right ear hearing threshold was 25.25 dBnHL. CONCLUSION ABR parameters shows variation in values depending upon age, myelination process, maturation of auditory pathway, environmental factors, laboratory setup etc. Hence it is concluded that each laboratory should have its own normative data which can be used as a baseline data for screening of patients with hearing loss.