Auditory Brainstem Response Parameters Research Articles

Intraoperative cochlear nerve monitoring in microvascular decompression of hemifacial spasm and resection of vestibular schwannoma

Objective: To analyze the application of direct cochlear nerve monitoring technology-cochlear nerve action potential (CNAP) monitoring in resection of vestibular schwannoma (VS) and to compare with which in microvascular decompression (MVD) of hemifacial spasm (HFS), in order to provide reference for identification of the cochlear nerve during VS resection surgery and predicting postoperative hearing preservation. Methods: From June 2018 to March 2022, patients with facial spasm and vestibular schwannoma who underwent retrosigmoid approach surgery at the Chinese PLA General Hospital were collected. Before surgery, there were a total of 11 HFS patients and 30 VS patients. Before surgery, the former had hearing level of class A(AAO-HNS), while the latter had serviceable hearing (AAO-HNS class A-B), with a maximum tumor diameter of≤20 mm. CNAP combined with Auditory Brainstem Response (ABR) monitoring was performed during surgery. SPSS 23.0 software was used to analyze the differences of ABR and CNAP parameters between the two groups. Results: The preoperative ABR test in the VS group showed that the latency of wave V and I-V interval were significantly prolonged compared to the HFS group (t=8.36, P<0.001; t=4.61, P<0.001).In VS group, all tumors were totally removed with preserved facial nerve function (House-Brackmann grade Ⅰ-Ⅱ). The serviceable hearing preservation rate was 63.3%. In the HFS group, the initial CNAP waveforms were triphasic and biphasic, with N1 wave latency of (4.32±0.37) ms and amplitude of 25.20 [15.63, 35.40]μV. The distribution of CNAP waveforms before tumor resection in the VS group was the same as that in the HFS group, and which in the hearing preservation group after surgery was also the same. Compared with the HFS group, the latency of N1 wave was prolonged (t=2.670, P=0.011;t=4.584, P<0.001), and the amplitude of N1 wavein the VS group before tumor resection was lower (Z=-3.001, P=0.003). The amplitude of N1 wave in the hearing preservation group after surgery was 20.20 [6.23, 40.90] μV,which was significantly higher than that before tumor resection (Z=-2.133, P=0.033), but there was no statistically significant difference compared to the HFS group (Z=-0.495, P=0.621). Conclusions: The reference range of CNAP in normal hearing population can be preliminarily obtained by the analysis of CNAP in MVD surgery. The latency of N1 wave in VS patients is prolonged and the amplitude of N1 wave is decreased due to tumor compression. The CNAP waveform combined with the change of N1 wave amplitude can provide reference for intraoperative mapping of the cochlear nerve and prediction of postoperative hearing preservation.

The human neuroprotective placental protein composition suppressing tinnitus and restoring auditory brainstem response in a rodent model of sodium salicylate-induced ototoxicity

The effect of neuroprotective placental protein composition (NPPC) on the suppression of tinnitus and the restoration of the auditory brainstem response (ABR) characteristics was explored in tinnitus-induced rats. The animals were placed into two groups: (1) the study group, rats received sodium salicylate (SS) at the dose of 200 mg/kg twice a day for two weeks, and then 0.4 mg of the NPPC per day, between the 14th and 28th days, (2) the placebo group, rats received saline for two weeks, and then the NPPC alone between the 14th and 28th days. The gap pre-pulse inhibition of the acoustic startle (GPIAS), the pre-pulse inhibition (PPI), and the ABR assessments were performed on animals in both groups three times (baseline, day 14, and 28). The GPIAS value declined after 14 consecutive days of the SS injection, while NPPC treatment augmented the GPIAS score in the study group on the 28th day. The PPI outcomes revealed no significant changes, indicating hearing preservation after the SS and NPPC administrations. Moreover, some changes in ABR characteristics were observed following SS injection, including (1) higher ABR thresholds, (2) lowered waves I and II amplitudes at the frequencies of 6, 12, and 24 kHz and wave III at the 12 kHz, (3) elevated amplitude ratios, and (4) prolongation in brainstem transmission time (BTT). All the mentioned variables returned to their normal values after applying the NPPC. The NPPC use could exert positive therapeutic effects on the tinnitus-induced rats and improve their ABR parameters.

Recommended Auditory Brainstem Responses to Stimulation and Recording Parameters for Hidden Hearing Loss: A Systematic Review and Meta-Analysis

Although a lesion of hidden hearing loss (HHL) has focused on the sprial ganglion, stimulation and recording parameters for auditory brainstem response (ABR) are not yet specific enough to confirm its dysfunction. In the current review, we identify ABR parameters, especially Wave I, for diagnosing HHL through both a systemic review and meta-analysis of 14 articles retrieved from seven journal data bases. The most commonly used parameters were a click or 4 kHz tone burst as the stimulus at a rate of less than 11/sec at more than 80 dB intensity levels with alternating polarity through the ear canal. For quantitative results, our meta-analysis from eight articles demonstrated a significant difference in the overall effect size for amplitude between HHL patients and their counterparts with normal hearing. For the subgroup and its analysis, tone burst and high intensity level revealed significantly lower effect size in HHL patients compared to the control group, whereas the stimuli rate and electrode montage statstically were not statistical significance. Although we examined a small number of studies and their heterogenity, obtaining ABR Wave I was clinically differentiated when noise-induced HHL was considered. We thus suggest that stimulation and recording parameters should be applied to a large number of patients and thereby standardized as sensitive features for Wave I in the clinic.

Analysis of auditory brain stem response and otoacoustic emission in unilateral tinnitus patients with normal hearing

ObjectiveIn patients with unilateral tinnitus with normal hearing, several studies have compared the ipsilateral and contralateral ears; however, few studies have investigated its relationship with the duration of tinnitus. We compared the auditory brainstem response and otoacoustic emission parameters between ipsilateral and contralateral ears in adults with unilateral tinnitus and normal hearing. MethodsThis retrospective review included 84 patients with unilateral tinnitus and normal hearing who underwent auditory brainstem response and otoacoustic emission; they were categorized according to the duration of tinnitus. The latencies and amplitudes of waves I, III, and V, and V/I ratio of both ears in auditory brainstem response, and the results of distortion-product otoacoustic emission and transient evoked otoacoustic emission were examined. The auditory brainstem response parameters, distortion-product otoacoustic emission parameters, and transient evoked otoacoustic emission parameters between the ipsilateral and contralateral ears along the duration of tinnitus were analyzed. Moreover, the failure rates of both distortion-product otoacoustic emission and transient evoked otoacoustic emission between the ears along with the duration and the effects of the variables on the amplitude and latency of each wave were examined. ResultsIn this study, laterality seemed to have an effect on wave I latency in the multiple linear regression analysis. The distortion-product otoacoustic emission failure rate of the ipsilateral ear was higher than that of the contralateral ear in all patients. However, there was no remarkable difference between the ears in the distortion-product otoacoustic emission and transient evoked otoacoustic emission parameters throughout the duration. ConclusionWe found that outer hair cells and the distal portion of the cochlear nerve are possible pathologic lesions in tinnitus with normal hearing and cochlear synaptopathy could be suspected. Further studies, including those on inner hair cells and higher central cortex, are needed.

Intraoperative Auditory Brainstem Response Results Predict Delayed Sensorineural Hearing Loss After Middle Cranial Fossa Resection of Vestibular Schwannoma.

To identify intraoperative neurophysiologic measures predictive of delayed progressive sensorineural hearing loss in the operative ear after a middle fossa approach (MCF) for resection of vestibular schwannoma (VS). Retrospective review. Academic, tertiary referral center. Subjects with vestibular schwannoma who underwent a MCF microsurgical resection of VS were analyzed for individuals whose hearing was initially preserved but subsequently developed progressive sensorineural hearing loss in the operative ear. Thirty-seven patients were identified for whom audiologic and neurophysiologic data was available. Intraoperative neurophysiologic changes will correlate with delayed sensorineural hearing loss in the operative ear. Audiometric evaluations, intraoperative electrocochleography (ECoG), and auditory brainstem response (ABR) measures. Twenty-five subjects experienced stable hearing or hearing loss in the operative ear comparable to the contralateral ear. Twelve subjects suffered a significant increase in the hearing asymmetry between ears. Deterioration in the amplitude of wave V of the ABR persisting at the close of tumor resection correlated with delayed sensorineural hearing loss in the operative ear (p 0.02, 5% mean improvement in the stable hearing group, versus a 14% decline with progressive asymmetry), but changes in ECoG or other auditory brainstem response parameters (p > 0.05) were not predictive. Persisting amplitude reduction of wave V of the intraoperative ABR best correlates with delayed progressive sensorineural hearing loss in the operative ear. Neither persistent changes in ECoG, other ABR parameters, nor transient changes, correlated with delayed progressive sensorineural hearing loss in the operative ear.

Is auditory brainstem response a prognostic factor in patients with sudden sensorineural hearing loss?

Background: Serum thyroid hormone levels are closely related to the normal functioning of the cochlea. However, the relationship between initial auditory brainstem response (ABR) results and levels of thyroid hormone remained unclear until we adopted ABR as a prognostic factor in Idiopathic sudden sensorineural hearing loss (ISSNHL) patients.Objective: This investigation aimed to elucidate the association between ABR and outcomes in patients with ISSNHL.Material and methods: Thirty-three patients presenting with unilateral ISSNHL underwent blood sampling and ABR tests on the day of admission. The mean latencies of the ABR results were compared among the groups which were classified by ISSNHL outcome, based on Siegel’s criteria. The association between the ABR results and the thyroid hormone serum levels (TSH, T3, and free T4) were assessed.Results: The overall successful recovery rate was 60.6% (n = 20). The mean latencies of all the ABR parameters were not significantly different between the different treatment outcome groups (Mann–Whitney U test). Wave V latency, III–V interval and I–V interval were negatively associated with T3 serum levels.Conclusion: The results indicate that clinical caution should be exercised when conducting ABR tests without assessing thyroid hormone levels.

Tinnitus Impacts on Speech and Non-speech Stimuli.

To investigate how tinnitus affects the processing of speech and non-speech stimuli at the subcortical level. Cross-sectional analytical study. Academic, tertiary referral center. Eighteen individuals with tinnitus and 20 controls without tinnitus matched based on their age and sex. All subjects had normal hearing sensitivity. Diagnostic. The effect of tinnitus on the parameters of auditory brainstem responses (ABR) to non-speech (click-ABR), and speech (sABR) stimuli was investigated. Latencies of click ABR in waves III, V, and Vn, as well as inter-peak latency (IPL) of I to V were significantly longer in individuals with tinnitus compared with the controls. Individuals with tinnitus demonstrated significantly longer latencies of all sABR waves than the control group. The tinnitus patients also exhibited a significant decrease in the slope of the V-A complex and reduced encoding of the first and higher formants. A significant difference was observed between the two groups in the spectral magnitudes, the first formant frequency range (F1) and a higher frequency region (HF). Our findings suggest that maladaptive neural plasticity resulting from tinnitus can be subcortically measured and affects timing processing of both speech and non-speech stimuli. The findings have been discussed based on models of maladaptive plasticity and the interference of tinnitus as an internal noise in synthesizing speech auditory stimuli.

Is the Auditory Brainstem Response Diagnostic for Vestibular Paroxysmia?

Objectives Vestibular paroxysmia (VP) of the eighth cranial nerve is characterized by recurrent auditory and vestibular disturbances when a proximal part of the eighth cranial nerve is continuously pressed by a vessel. A detailed history and several ancillary diagnostic tools, such as tinnitogram, caloric test, auditory brainstem response (ABR) and magnetic resonance imaging, are used for diagnosis of VP. Among them, although Møller criteria using ABR is a simple method, the previous study is insufficient. Therefore, this study aimed to evaluate ABR’s diagnostic value of VP. Methods ABR records of the 14 patients (patient group) who were diagnosed with VP and 45 patients (as control) who were diagnosed with only tinnitus were reviewed retrospectively. We analyzed the differences in Møller criteria between 2 groups. Results Mean age of the patient group was 52.9 years old and the control group was 55.4 years old. As compared with the control group, there were no significant differences of Møller 3 criteria contents (peak II wave amplitude＜33% [35.7% vs. 15.5%, p=0.133], interpeak latency I–III ≥2.3 msec [42.8% vs. 35.5%, p=0.622]), Contralateral interpeak latency III–V ≥2.2 msec (0% vs. 4.4%, p=1.000) in patient group. Conclusion There was no significant difference of ABR parameters according to the Møller criteria between patient and control groups. Keywords: Vestibular paroxysmia; Auditory brainstem response; Møller’s criteria 중심 단어: í˜ˆê´€ì„±ì‹ ê²½ì••ë°•ì¦í›„êµ°, Møller 진단기준, 청성뇌간반응

S106. Normative data of auditory brainstem response in nepalese population

Introduction Auditory Brainstem Response (ABR) is the potential recorded from the ear and the scalp in response to a brief auditory stimulation. It is usually helpful in localizing the lesions in the brainstem. It is useful in diagnosing diseases like intrinsic brainstem tumor, multiple sclerosis, coma, brain death and strokes affecting the brainstem. It can also be used to assess the integrity of auditory pathway. Methods The study was conducted on 30 consenting healthy adult subjects. Auditory Brainstem Response (ABR) was recorded at 60 dB sound intensity. Mean and standard deviation were determined for waveforms I, II, III, IV, and V and interpeak intervals of waveforms I–III, III–V, and I–V. Student t-test was used for statistical analysis. Results In ABR, wave latencies and interpeak latencies were measured. Latencies of wave I [1.85 ± 0.23 ms], wave II [2.99 ± 0.27 ms], wave III [4.21 ± 0.41 ms], wave IV [5.38 ± 0.42 ms], wave V [6.48 ± 0.53 ms] and interpeak latencies I–III [2.35 ± 0.4 ms], III–V [2.28 ± 0.54 ms] and I–V [4.63 ± 0.54 ms]. Conclusion ABR parameters shows variation in values depending upon age, maturation of auditory pathway, environmental factors, laboratory setup. 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.

Auditory system dysfunction in patients with vitiligo: is it a part of a systemic autoimmune process?

Background and aimAssociation of vitiligo with ocular and auditory abnormalities and other autoimmune disorders suggests its systemic autoimmune origin. Therefore, this study was carried out in an attempt to evaluate the effect of melanin deficiency in patients with vitiligo, as regards the extent and duration of the disease on the auditory pathway and to study the associated other ocular and systemic abnormalities in them.Patients and methodsForty patients with vitiligo and 20 normal volunteers were examined. Audiological evaluation including pure-tone audiometry, extended high-frequency audiometry, transient evoked otoacoustic emissions, and auditory brainstem response was carried out. Ophthalmic evaluation including visual acuity, intraocular tension, and fundus examination was carried out. Laboratory investigations including hemoglobin level, random blood sugar, liver, kidney, and thyroid function tests, and autoimmune testing (antistreptolysin O titer, erythrocyte sedimentation rate, rheumatoid factor, and antinuclear antibodies) were carried out.ResultsSensorineural hearing loss was found in 15 (37.5%) patients; 10 (66.67%) of them had bilateral hearing loss and at high frequencies (2–8 kHz) sensorineural hearing loss. Transient evoked otoacoustic emissions were absent or decreased in 67.5%. There were no statistically significant differences in all auditory brainstem response parameters in vitiligo patients compared with the control group. One-fourth (25%) of them had decreased visual acuity, 22.5% had anemia, 12.5% had thyroid dysfunction, 10% had raised random blood sugar, 2.5% had raised liver enzymes, 32.5% had raised rheumatoid factor, 20% had raised antinuclear antibody, and 15% had raised erythrocyte sedimentation rate.

Novel Role of the Mitochondrial Protein Fus1 in Protection from Premature Hearing Loss via Regulation of Oxidative Stress and Nutrient and Energy Sensing Pathways in the Inner Ear.

Acquired hearing loss is a worldwide epidemic that affects all ages. It is multifactorial in etiology with poorly characterized molecular mechanisms. Mitochondria are critical components in hearing. Here, we aimed to identify the mechanisms of mitochondria-dependent hearing loss using Fus1 KO mice, our novel model of mitochondrial dysfunction/oxidative stress. Using auditory brainstem responses (ABRs), we characterized the Fus1 KO mouse as a novel, clinically relevant model of age-related hearing loss (ARHL) of metabolic etiology. We demonstrated early decline of the endocochlear potential (EP) that may occur due to severe mitochondrial and vascular pathologies in the Fus1 KO cochlear stria vascularis. We showed that pathological alterations in antioxidant (AO) and nutrient and energy sensing pathways (mTOR and PTEN/AKT) occur in cochleae of young Fus1 KO mice before major hearing loss. Importantly, short-term AO treatment corrected pathological molecular changes, while longer AO treatment restored EP, improved ABR parameters, restored mitochondrial structure, and delayed the development of hearing loss in the aging mouse. Currently, no molecular mechanisms linked to metabolic ARHL have been identified. We established pathological and molecular mechanisms that link the disease to mitochondrial dysfunction and oxidative stress. Since chronic mitochondrial dysfunction is common in many patients, it could lead to developing hearing loss that can be alleviated/rescued by AO treatment. Our study creates a framework for clinical trials and introduces the Fus1 KO model as a powerful platform for developing novel therapeutic strategies to prevent/delay hearing loss associated with mitochondrial dysfunction. Antioxid. Redox Signal. 27, 489-509.

Electrophysiological Evidence for Central Neuroplasticity of the Contralesional Ear in Patients with Unilateral Vestibular Schwannoma

Objective: Vestibular schwannomas (VS) are often associated with tinnitus of the affected ear. The current pathophysiological concept of tinnitus involves neuroplasticity in auditory structures due to sensory deafferentation resulting in an increase of central gain. While idiopathic tinnitus usually occurs suddenly, a VS is a slow growing process enabling neuroplastic adaptation and compensation of the ipsi- and contralesional auditory system. In the present study, we describe electrophysiological findings in patients with unilateral VS indicating an adaptation of central auditory gain of the contralesional ear. Methods: The presented retrospective study enrolls 250 patients scheduled for microsurgical resection of a unilateral VS. Electrophysiological and clinical pre- and postoperative evaluation included auditory brainstem responses (ABR), speech discrimination score (SDS) and pure tone audiometry (PTA) of both the ipsilesional (IL) and contralesional (CL) ears. Patients were classified by the presence of tinnitus (TN+ and TN-) and hearing loss according the Gardner-Robertson (GR) score. Statistical analysis was based on multivariate generalized linear modelling (SPSS 22.0). Results: TN+ had significant stronger hearing impairment of the affected IL ear in comparison to TN- patients. There was no difference in hearing of the healthy CL ear. There was no difference between TN+ and TN- in any IL ABR parameters except for wave V latency. In contrast, for the healthy CL ear there was a significant increase of wave V and I-III, I-V latencies as well as a decrease of wave V amplitudes in TN+ compared with TN- patients. Conclusion: Our electrophysiological results indicate that in patients with unilateral VS the present of ipsilesional tinnitus leads to an increase of contralesional ABR latencies and the reduction of wave V amplitudes. For the first time, we provide evidence for an adaptation of the healthy auditory system to the increased central auditory gain in unilateral VS.

정상청력인 이명 환자에서의 청성뇌간반응 검사

Background: The aim of our study is to evaluate the auditory nerve and auditory brainstem function of the normal hearing individuals with tinnitus and without tinnitus using auditory brainstem response (ABR). Methods: Twenty three individuals with tinnitus (study group) and 23 without tinnitus (control group) were participated in the study. The ABR parameters [latency of waves l, lll, V; interpeak intervals l-lll, lll-V, l-V; amplitude of wave l, lll, V; amplitude ratio between wave V and I (V/I), wave III and I (III/I)] were compared between two groups. Results: The ABR results from the normal-hearing individuals with and without tinnitus were within normal limits. However, the study group showed the tendency of prolongation in latencies of waves l, lll, V; interpeak interval of l-lll, lll-V, l-V, even though it was not statistically significant. In addition, the amplitude of wave V and V/I amplitude ratio in the study group were significantly larger than those in the control group. Conclusions: Our results suggest that the origin of tinnitus in normal hearing can be auditory brainstem, even though more investigations are needed. Therefore, ABR might contribute to the workup of normal hearing patients with tinnitus. (J Clinical Otolaryngol 2015;26:202–207)

Auditory pathway maturational study in small for gestational age preterm infants.

To follow up the maturation of the auditory pathway in preterm infants small for gestational age (SGA), through the study of absolute and interpeak latencies of auditory brainstem response (ABR) in the first six months of age. This multicentric prospective cross-sectional and longitudinal study assessed 76 newborn infants, 35 SGA and 41 appropriate for gestational age (AGA), born between 33 and 36 weeks in the first evaluation. The ABR was carried out in three moments (neonatal period, three months and six months). Twenty-nine SGA and 33 AGA (62 infants), between 51 and 54 weeks (corrected age), returned for the second evaluation. In the third evaluation, 49 infants (23 SGA and 26 AGA), with age range from 63 to 65 weeks (corrected age), were assessed. The bilateral presence of Transient Evoked Otoacoustic Emissions and normal tympanogram were inclusion criteria. It was found interaural symmetry in both groups. The comparison between the two groups throughout the three periods studied showed no significant differences in the ABR parameters, except for the latencies of wave III in the period between three and six months. As for the maturation with tone burst 0.5 and 1 kHz, it was found that the groups did not differ. The findings suggest that, in the premature infants, the maturational process of the auditory pathway occurs in a similar rate for SGA and AGA. These results also suggest that prematurity is a more relevant factor for the maturation of the auditory pathway than birth weight.

MMP-9 gene ablation mitigates hyperhomocystenemia-induced cognition and hearing dysfunction.

Hyperhomocysteinemia (HHcy) is associated with cognitive decline and hearing loss due to vascular dysfunction. Although we have shown that HHcy-induced increased expression of matrix metalloproteinase-9 (MMP-9) is associated with cochlear pathology in cystathionine-β-synthase heterozygous (CBS(+/-)) mice, it is still unclear whether MMP-9 contributes to functional deficit in cognition and hearing. Therefore, we hypothesize that HHcy-induced MMP-9 activation causes vascular, cerebral and cochlear remodeling resulting in diminished cognition and hearing. Wildtype (WT), CBS(+/-), MMP-9(-/-) and CBS(+/-)/MMP-9(-/-) double knock-out (DKO) mice were genotyped and used. Doppler flowmetry of internal carotid artery (ICA) was performed for peak systolic velocity [PSV], pulsatility index [PI] and resistive index [RI]. Cognitive functions were assessed by Novel Object Recognition Test (NORT) and for cochlear function Auditory brainstem response (ABR) was elicited. Peak systolic velocity, pulsatility and resistive indices of ICA were decreased in CBS(+/-) mice, indicating reduced perfusion. ABR threshold was increased and maximum ABR amplitude and NORT indices (recognition, discrimination) were decreased in CBS(+/-) mice compared to WT and MMP-9(-/-). All these parameters were attenuated in DKO mice suggesting a significant role of MMP-9 in HHcy-induced vascular, neural and cochlear pathophysiology. Regression analysis of PSV with ABR and cognitive parameters revealed significant correlation (0.44-0.58). For the first time, MMP-9 has been correlated directly to functional deficits of brain and cochlea, and found to have a significant role. Our data suggests a dual pathology of HHcy occurring due to a decrease in blood supply (vasculo-neural and vasculo-cochlear) and direct tissue remodeling.

Brainstem response to speech and non-speech stimuli in children with learning problems

Neuronal firing synchronization is critical for recording auditory responses from the brainstem. Recent studies have shown that both click and/da/synthetic syllable (speech) stimuli perform well in evoking neuronal synchronization at the brainstem level. In the present study, brainstem responses to click and speech stimuli were compared between children with learning problems (LP) and those with normal learning (NL) abilities. The study included 49 children with LP and 34 children with NL. Auditory brainstem response (ABR) to 100-μs click stimulus and speech ABR (sABR) to/da/40-ms stimulus were tested in these children. Wave latencies III, V, and Vn and inter-peak latency (IPL) V–Vn in click ABR and wave latencies I, V, and A and IPL V–A in sABR were significantly longer in children with LP than children with NL. Except IPL of I–III, a significant positive correlation was observed between click ABR and sABR wave latencies and IPLs in children with NL; this correlation was weaker or not observed in children with LP. In this regard, the difference between correlation coefficients of wave latencies I, III, and V and IPLs I–V and V–Vn/V–A was significant in the two groups. Deficits in auditory processing timing in children with LP may have probably affected ABR for both click and speech stimuli. This finding emphasizes the possibility of shared connections between processing timing for speech and non-speech stimuli in auditory brainstem pathways. Weak or no correlation between click and speech ABR parameters in children with LP may have a clinical relevance and may be effectively used for objective diagnoses after confirming its sufficient sensitivity and specificity and demonstrating its acceptable validity with more scientific evidence.

Binaural recordings of Auditory Brainstem Response for establishment of normative data and its application in screening patients with symmetrical hearing loss

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.

Auditory Brainstem Responses and EMFs Generated by Mobile Phones.

There has been a manifold increase in the number of mobile phone users throughout the world with the current number of users exceeding 2 billion. However this advancement in technology like many others is accompanied by a progressive increase in the frequency and intensity of electromagnetic waves without consideration of the health consequences. The aim of our study was to advance our understanding of the potential adverse effects of GSM mobile phones on auditory brainstem responses (ABRs). 60 subjects were selected for the study and divided into three groups of 20 each based on their usage of mobile phones. Their ABRs were recorded and analysed for latency of waves I-V as well as interpeak latencies I-III, I-V and III-V (in ms). Results revealed no significant difference in the ABR parameters between group A (control group) and group B (subjects using mobile phones for maximum 30min/day for 5years). However the latency of waves was significantly prolonged in group C (subjects using mobile phones for 10years for a maximum of 30min/day) as compared to the control group. Based on our findings we concluded that long term exposure to mobile phones may affect conduction in the peripheral portion of the auditory pathway. However more research needs to be done to study the long term effects of mobile phones particularly of newer technologies like smart phones and 3G.

Effect of hormone replacement therapy on the auditory brainstem response of postmenopausal women.

To investigate whether hormone replacement therapy modifies the auditory brainstem response in postmenopausal women. Nineteen postmenopausal women received hormone replacement therapy (study group) and 25 received no treatment nor placebo (control group). In both groups, age ranged from 45 to 60 years and pure-tone sensitivity was 25 dB or better at frequencies between 500 and 2000 Hz. Auditory brainstem response was evaluated before and after 3 months of hormone use in the study group. The control group was also evaluated at the same periods. The following auditory brainstem response parameters were compared between the two groups: latencies of waves I, III, and V; I-III, III-V, and I-V interpeak intervals. Mean age did not differ between groups (study group: 51.5 ± 0.7 years; control: 52.9 ± 0.6 years). No significant differences in wave latencies, or interpeak intervals were observed between the two groups (p > 0.05).

Electrophysiological differences in sensorineural hearing loss patients with and without problem-tinnitus

EnAbstract Objects Problem-tinnitus refers to tinnitus that is sufficiently severe to produce a major disruption in the patient’s life; tinnitus of such severity involves a number of regions of the auditory system and other brain systems may also play an essential role. Auditory brainstem responses (ABR) and event-related potentials (ERP) were recorded from sensorineural hearing loss (SNHL) patients with problem-tinnitus and were then compared with responses from normal hearing and hearing loss tinnitus-free patients. Aim To study whether differences exist in ABR and/or ERP parameters in SNHL patients with and without problem-tinnitus when matched as closely as possible for hearing loss, age, and sex to investigate the mechanism responsible for tinnitus. Materials and Methods Ninety participants were included in this study. They were divided into two groups: the study group included 66 participants with bilateral symmetrical SNHL that did not exceed a moderate degree. The study group was divided into two subgroups: 36 patients had problem-tinnitus and 30 patients were tinnitus-free (SNHL, age, and sex matched). Participants in each of these subgroups were compared with each other and were also compared with 24 healthy individuals in the control group (age and sex matched with the study group). All participants were subjected to a basic audiological evaluation and electrophysiological tests (ABR and ERP). Results This work had shown a higher prevalence of ABR abnormalities in tinnitus patients in comparison with either the control group or the SNHL tinnitus-free group. Statistically significant differences were found in III–V and I–V interpeak latencies and in the VI amplitude ratio in problem-tinnitus female patients compared with tinnitus-free female patients. Meanwhile, in problem tinnitus male patients when compared with tinnitus-free male patients at III–V interpeak latencies and at VI amplitude ratio. As regards the results of ERP in this work, an increase in latency and amplitude reduction were found. Statistically significant differences were observed regarding both the mean latency values of waves N1, P2, and P300 and the amplitude mean values of P2 and P300 when we compared the problem-tinnitus subgroup with either the tinnitus-free subgroup or the control group (both female and male patients. Conclusion A variety of ABR and ERP components are altered in tinnitus patients; this would indicate impairment in both the central auditory pathway and central auditory processing. Thus, it is suggested that this form of ABR, ERP testing could be considered as an objective measure to complement behavioral, audiologic, and other physiologic methods of assessing tinnitus, rather than a single definitive tinnitus measure in an attempt to supplement and thereby extend knowledge of the nature and origins of tinnitus. Furthermore, these results provide the basis for future neurofeedback-based tinnitus therapies aiming at maximizing the ability to shift attention away from the tinnitus.