International Journal of Biological & Medical Research

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1 Int J Biol Med Res. 2013; 4(3) : Int J Biol Med Res Volume 3, Issue 1, Jan BioMedSciDirect Publications Contents lists available at BioMedSciDirect Publications International Journal of Biological & Medical Research Journal homepage: International Journal of BIOLOGICAL AND MEDICAL RESEARCH Original Article A comparison of Auditory Brainstem Response obtained using Monaural and Binaural stimulation in normal children and in children with hearing loss. a* b c d e f Shivaji Chalak, Anita Kale, A Rawekar, N Khatib, V Deshpande, D Biswas a* Assistant Professor, Physiology, Jawaharlal Nehru Medical College, DMIMS (Deemed University) India b Professor and head, Biochemistry, Jawaharlal Nehru Medical College, DMIMS (Deemed University) India c,d Associate Professor, Physiology, Jawaharlal Nehru Medical College, DMIMS (Deemed University) India e Director Professor, Physiology, Jawaharlal Nehru Medical College, DMIMS (Deemed University) India f Professor and Head, Physiology, Jawaharlal Nehru Medical College, DMIMS (Deemed University) India A R T I C L E I N F O Keywords: ABR Binaural Monaural Sensory neural Hearing loss A B S T R A C T Objectives: To compare the Auditory Brainstem Response (ABR) obtained using monaural and binaural stimulations in normal children and in children with hearing loss. Methods: This casecontrol experimental study was conducted on 80 children out of whom 40 were apparently healthy and 40 having bilateral symmetrical sensory neural hearing loss. Database wascollected after assessing with otological questionnaire, otoscopic examination and audiometric evaluation. Brainstem Evoked Response Audiometry (BERA) was used as a tool for assessment of hearing loss. Results: Results showed that there was a significant difference between monaurally and binaurally obtained wave V/I amplitude ratios and ABR thresholds. The thresholds obtained by binaural presentation were lower than that by monaural presentation in children of both the groups. It was also found that mode of presentation does not affect the Absolute latencies and Inter peak Latencies in both the groups. Conclusion: Overall it was concluded that binaural mode of presentation improves wave V/I amplitude ratios and thresholds thus proving its accuracy over routinely used monaural mode of presentation in bilateral symmetrical sensory neural hearing loss. The study promotes the use of binaural mode of presentation by neurophysiologists as it not only saves valuable clinical time but also improves the diagnostic accuracy. c Copyright 2010 BioMedSciDirect Publications IJBMR - ISSN: 0976:6685. All rights reserved. 1. Introduction The purpose of BERA assessment is to quantify and qualify hearing in terms of screening and estimating the degree of hearing loss, the type of hearing loss and the configuration of the hearing loss, especially in difficult to test population like premature newborns, mentally retarded child, child with delayed milestones, attention deficits and other sensory or motor impairment.(1,2) To reduce the impact of hearing loss in children as well as, early identification of hearing loss and thus appropriate diagnosis and early intervention is very important. It is now possible to record in humans the electrical activity generated along the auditory pathway in its course from the cochlea to the cortex using surface electrodes.(3) * Corresponding Author : Dr Shivaji Chalak, Assistant Professor, Jawaharlal Nehru Medical College, DMIMSDU, NAAC-A, Sawangi(meghe) Wardha, INDIA: shivajichalak@rediffmail.com c Copyright 2010 BioMedSciDirect Publications. All rights reserved. The binaural mode of presentation for neurological screening or hearing evaluation, in the presence of bilateral symmetrical hearing loss, has not yet achieved widespread clinical application. Monaural mode of presentation still remains routinely used tool for assessment of ABR in unilateral or bilateral disorders. The monaural method is comparatively more time consuming and therefore it faces challenges in assessment of difficult to test population. (4, 5, 6) Recent studies in which comparison has been made between the ABR and the potential recorded directly from different structures of the ascending auditory pathway in man have provided new insights into the neural generators of the human ABR (7, 8, 9). In other studies abnormalities in the ABR patterns of patients with confirmed lesions in the ascending auditory pathways were examined to gain insight into the origin of the ABR. By correlating the location of the lesion with the changes in the ABR, information about the origin of the different components of the ABR can be obtained (10, 11).

2 3454 Rationale of the study: The fact that the binaural response recorded is not the same as the sum of monaural responses, indicates that there are differences in the response of the auditory system in binaural versus monaural modes of presentations. Also, no studies so far have looked forward to evaluate the effect of two types of modes of stimulations on ABR in Indian subjects with hearing loss. Hence it is necessary to empirically determine so as to how ABR data obtained for monaural presentation compares to data obtained with binaural presentation using insert earphones and by giving click stimuli on ABR thresholds, latency and amplitude ratios. This study will benefit neurophysiologists in terms of selection of mode of presentation while BERA assessment especially in patients of bilateral symmetrical sensory neural hearing loss. Hence, this study was conducted with the following objective: To study the effect of monaural and binaural presentation on the various parameters of the ABR waveforms in normal children and in children with hearing loss. II. Materials and Methods 2.1 Study settings: This study was conducted in neurophysiology department of 850 bedded tertiary care hospital of Datta Meghe Institute of Medical Sciences University (NAAC Accredited Grade A), Wardha. 2.2 Study duration: December 2008 to December Ethical committee clearance: Approval and clearance was obtained from institutional ethical committee. 2.4 Study design: Present study is a case control experimental study. 2.5 Research plan: Sampling included control and study groups. Total recruitment of 80 children was done. Mean age for control group was 7.62±2.39 yrs and for study group was 6.57±2.92 yrs. Both sexes participated with 70% males and 30% females. All the patients were selected from OPD and IPD of ENT and Paediatrics departments for BERA assessment. 2.6 Evaluation: The participants were evaluated according to predesigned protocol, after their due consent and data was collected using structured interview information related to presence of ear diseases and other otological disorders. The examination of each patient was carried out once using an otoscope to verify the condition of external ear for BERA assessment. 2.7 Study instrument: BERA assessment was done using multichannel polyrite system. Silver chloride disc electrodes were used on standard scalp locations. (12) 2.8 Recordings: Evoked potentials were recorded after sedating the apprehensive patients with oral Triclofos syrup and testing them in quiet and relaxed test environment. (13) ABR recordings by monaural presentation were obtained first by following test protocol given by Hall. (14). A total of 2000 stimulations were averaged and all the parameters were compared at 70 db stimulus intensity level. Other technical specifications were kept constant for both recordings. Masking with white noise was given in non test ear for monaural recordings only. (15) 2.9 Statistical analysis: Results were analyzed by Statistical Package for Social Sciences (SPSS) software, version 7 and graph pad prism 4, the following tests were used: Descriptive analysis was done to find out mean, standard deviation and standard error of mean. Z-test was applied to compare between means and for testing the significance of difference of each parameter between the control and study group because n>30. III. Results: Out of 125 participants who came, 80 were included in the study, 45 participants were excluded from the study on account of having asymmetrical hearing loss, otological disorders, impacted wax in external ear and aural discharge. In the following pages, the results pertaining to the two groups of subjects will be presented. All the parameters pertaining to ABR recordings were evaluated and compared for right and left ear separately. 3.1 The age and sex wise distribution: Baseline characteristics of the subjects in both groups are reported in Table 1. Table 1: Age and sex wise distribution of patients in both the groups. Figures in the Parentheses show values in percentage. 3.2 Interaural latency difference in controls and study group: is depicted in Table 2 Table 2: Interaural Latency difference in the control and Study group. (in milliseconds)

3 Shivaji Chalak Int J Biol Med Res. 2013; 4(3):

4 3456 In this study, we investigated the mean values of the Interaural difference of absolute latencies for wave I, III and V by using monaural and binaural modes of presentation as depicted in Table 2 were found to be within normal limit(<0.2 milliseconds) which means that there was no asymmetry of absolute latencies between right and left ears in controls. The Interaural difference in study group was also within normal limit which indicates that the hearing loss was symmetrical in both ears. The values obtained from Table 3 and 4 indicate that p value is significant for monaurally and binaurally obtained wave V absolute latencies when compared among controls and study group for left and right ears respectively at 70 dbnhl. There is no effect of presentation mode on absolute latencies of wave V. Fig 1 shows the mean values for absolute latencies of wave V at 70 db for both modes of presentation. These findings rule out the experimental errors amongst the two procedures. Ainslie and Boston et al reported in their study that absolute latencies were not affected by the two modes of presentations. (16) The values obtained from Table 5 and 6 indicate that there is significant difference between monaurally and binaurally obtained wave V/I amplitudes ratio when compared among controls and study group. The reason is due to wide variation of amplitude ratio in study group subjects. (Due to the variability of amplitudes) There is an effect of presentation mode on wave V/I amplitudes ratio. Binaural wave V/I amplitude ratio is greater than that obtained using monaural stimulation. Fig 2 shows the mean values of wave V/I amplitudes ratio at 70 db for both the modes of presentation. These findings report that waveform morphology and diagnostic criteria become more accurate when binaural stimulation was used as compared to monaural method. Riedel and Kollmeier et al found in their study that wave V/I amplitude ratios were significantly larger for chirps than for clicks for all conditions. (17) The values obtained from Table 7 and 8 indicate that there is significant difference between monaurally and binaurally obtained ABR thresholds when compared among controls and study group.

5 3457 There is an effect of presentation mode on ABR thresholds. The binaural thresholds are 3 db and 8 db lower in controls and study group respectively as compared with monaural thresholds. Fig 3 shows the mean values of ABR thresholds at 70 db for both the modes of presentation. These values indicate that accuracy of hearing thresholds is better by binaural as compared to monaural presentation. Conijn et al also reported lower (better) thresholds obtained by binaural method than monaural. (18) The available literature implies that there are differences in ABR latencies and amplitudes for monaural versus binaural stimulation in normal hearing subjects as well as persons with hearing loss. However, these studies are often only small sample studies and have used varied methodologies. Also, most of the reported studies on persons with hearing loss are done on persons having high frequency sloping hearing loss. Very few studies that have addressed differences in ABR threshold and wave morphology for monaural and binaural stimulation have been conducted and reported on Indian subjects. We hypothesized that amplitude ratios of wave V/I and the thresholds obtained by binaural system of assessment will have more accuracy and reliability, the results showed that the entire test hypothesis set up at the beginning of the study was correct. 5. Conclusion: Overall it can be concluded that binaural presentation improves amplitude ratio of wave V/I, and threshold in subjects with and without hearing loss (In controls and study group). Mode of presentation does not affect wave V latency; in either of the subject groups. Implications of the study: The main findings of this study are: a) Normative data for Multichannel POLYRITE-AD, software system could be established for the study group children. b) The findings indicate that binaurally evoked ABR gives better amplitude ratio and lower threshold than monaurally evoked ABR thus proves to be more accurate and saves valuable clinical time. The study will raise awareness among neurophysiologists about implementation of binaural method of assessment. c) Latency difference was not observed for both the modes of presentation hence binaural ABR can save time without influencing the results (threshold). Limitations 1. Study comprised of child population only. 2. Only bilateral symmetrical moderate hearing loss was studied. 6. Acknowledgement: During this work, I have collaborated with many colleagues, for whom I have a great regard, and I wish to extend my warmest thanks to all the teaching, and non teaching staff of Physiology department who gave me support throughout this study. 7. References: [1]. Biswas A. clinical audio-vestibulometry for otologists and neurologists. 4th ed. Mumbai: Bhalani Medical Book House; P , [2]. Mishra UK, Kalita J. Clinical neurophysiology: nerve conduction, electromyography, evoked potentials. 2nd ed. N. Delhi: Reed Elsevier India Private Ltd; P. 1-9, , [3]. Jewett, D. L., & Williston, J. S. Auditory evoked far fields averaged from the scalp of humans. Brain, 1971, 4, [4]. Starr, A., Picton, T., Sininger, Y., Hood, I., & Berlin, C. Auditory neuropathy. Brain; 1996, 119: [5]. Hood, L. J. Clinical applications of the auditory brainstem response, 1998, p San Deigo: Singular Publishing Group, Inc. [6]. Dobie, R. A., & Berlin, C. I. Binaural interaction in human auditory evoked responses. Archives of Otolaryngology, 1979, 105, [7]. Moller, A. R., & Jannetta, P. J. Compound Action potential recorded intracranially from the auditory nerve in man. Journal of Experimental Neurology, 1981, 74, [8]. Moller, A. R., & Jannetta, P. J. Auditory evoked potentials recorded from the cochlear nucleus and its vicinity in man. Journal of Neurosurgery, 1983, 59, [9]. Moller, A. R., & Jannetta, P. J. Monitoring auditory nerve potentials during operations in the cerebellopontine angle. Otolaryngology Head and neck Surgery, 1984, 92, [10]. Stockard, J. J., & Rossiter, V. S. Clinical and pathological correlates of brainstem auditory response abnormalities. Neurology, 1977, 27, [ 1 1 ]. S o h m e r, H., Fe i n m e s s e r, M., & S z a b o, G. S o u rc e s o f electrocochleargraphic responses as studied in patients with brain damage. Electroencephalography and Clinical Neurophysiology, 1974, 37, [12] Yumnam A, Neelam V, O.P. Tandon & Madhu. Functional Status of Auditory Pathways in Hypothroidism: Evoked Potential Study. Indian J Physiol Pharmacol 2006; 50 (4); [13] Holmes GL, Jones HR Jr, Moshe SL. Clinical neurophysiology. 5th ed. Edinburg: Churchill Livingstone (Elsevier); 2005.p [14] Hall, J. W. III. handbook'of auditory evoked responses, Allyn and Bacon. 1992, (118) [15] Bhatia M, Kumar A, Kumar N, Pande RM and Kochupillai V. Electrophysiologic evaluation of sudarshan kriya: An EEG, BAER, P300 Study. Indian J Physiol Pharmacol 2003; 47(2): [16] Ainslie, P. J., & Boston, J. R. Comparison of brain stem auditory-evoked potentials for monaural and binaural stimuli. Electroenchalography and clinical Neurophysiology, 1980, 49(3-4), [17] Riedel, H., & Kollmeier, B. Comparison of binaural auditory brainstem response and the binaural difference potential evoked by chirps and clicks. Hearing Research, 2002, 169(1-2), [18] Conijn, E. A., Brocaar, M. P., van Zanten, G. A. Monaural versus binaural auditory brainstem response threshold to clicks masked by high-pass noise in normal-hearing subjects. Audiology, 1990, 29(1), c Copyright 2010 BioMedSciDirect Publications IJBMR - ISSN: 0976:6685. All rights reserved.