Background: This article presents clinically important details of recording and evaluating ABR details that will eventually be helpful in standardization of our neurophysiology lab, so that ABR recordings on a routine basis will produce better and meaningful results for interpretation.
Aims & Objective: To establish normative data required for recording Auditory Brainstem Response (ABR) using binaural stimulations in children with normal hearing.
Materials and Methods: This study was conducted on 40 apparently healthy children with normal hearing. Database was collected following assessment with otological questionnaire, otoscopic examination. BERA was used as a tool for establishment of normative data. Standard test protocol given by Hall was followed for ABR recordings.
Results: The Interaural latency difference was less than 0.2 ms (milliseconds) and was found to be in normal limit. Normative data was obtained and the mean values of absolute latencies for left ear were 1.77 ms, 3.73 ms and 5.70 ms respectively and for right ear these were 1.77 ms, 3.76 ms and 5.56 ms respectively. Mean values for amplitude of wave I and V for left ear were 0.36 uV and 0.56 uV respectively. For right values were 0.31 uV and 0.52 uV respectively. Mean values of amplitude ratio (V/I) for left and right ears were 3.06 and 1.80 respectively. Mean values of interpeak latencies of wave I-III, III-V, I-V were 2.01 ms, 2.03 ms and 3.89 ms respectively for left ear and for right ear values were 1.98 ms, 2.02 ms and 3.84 ms respectively. Mean values for left and right ear hearing threshold was 26.25 dBnHL.
Conclusion: ABR parameters show 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.
Key words: ABR, Normative data, Binaural. Absolute latency.
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