Background & Aim: Attending to the importance of hearing in development of language skills and the essence of hearing loss in meningitis as an acquired hearing loss, this study focuses on hearing assessment and early diagnosis of hearing loss. The purpose of the present study is to apply EOAE, ABR and behavioral hearing tests to evaluate audiologic condition of infants and neonates suffering from meningitis at the acute and recovery stages.Patients & Method: This cross-sectional study included 40 infants and neonates whose ages ranged from birth to 12 years. These patients, 24-72 hours after diagnosis or starting the treatment, were evaluated using ABR test. This test was also repeated 24 hours before discharge or recovery. 7-14 days after discharge or recovery, all the 40 patients were assessed using EOAE and behavioral tests, which could evaluate choclear function besides confirming the results of ABR test. To analyse the data and draw the charts and diagrams, we profited from SPSS, t-test, Fisher test, and EXCEL.Results: According to the results of ABR test, 24-72 hours after diagnosis, 4 patients (10%) showed bilateral severe to profound SNHL (sensorineural hearing loss) and 1 patient(2.5%) showed unilateral severe to profound SNHL. The same results were observed in re-evaluation 24 hours before discharge using ABR test and also in behavioral test 7-14 days after discharge from the hospital. However, ABR test recognized the rest of the cases (35 patients) as normal regarding their hearing abilities. These 35 patients were diagnosed to have normal hearing sense by EOAE test, which was carried out 7- 14 days after discharge from the hospital, as well. EOAE, however, indicated that three of the five patients suffering from SNHL presented with abnormal choclear function but the two of them remained normal in this respect.Conclusion: SNHL caused by meningitis, which involved 12.5% of our subjects, is detectable at the acute stage of the disease. Moreover, it can be concluded that meningitis can cause damage not only to choclear nerve but probably to choclear function, too. The damage to choclear function may occur in the presence of the damage to choclear nerve or by itself.

Background: Noise induced hearing loss (NIHL) is one of the most important occupational diseases worldwide. NIHL has been found to be potentiated by some of air pollutants. Exposure to noise plus carbon monoxide is common in occupational and environmental settings. This study was performed to evaluate the effect of noise and carbon monoxide exposure simultaneously on rabbits' hearing sySTEM by AUDITORY BRAIN STEM RESPONSE (ABR) assessment.Materials and Methods: In this experimental study, 24 male adult white rabbits were divided to four groups: control group, noise exposure group, noise plus carbon monoxide exposure group and carbon monoxide exposure group. AUDITORY BRAIN STEM RESPONSEs of the four groups were determined: before exposure, 1 hour after exposure and 14 days after exposure by click and tone burst stimulus. Results: The latency mean time of V wave in the ABR test for the group exposed to noise plus carbon monoxide, 1 hour after exposure at 1, 2, 4 and 8 KHz frequency were respectively 5.43±0.08, 5.50±0.07, 5.71±0.07 and 5.75±0.07 millisecond. These values were significantly more than the same values in the other groups. Conclusion: NIHL may be potentiated by carbon monoxide in the simultaneous exposure. Thus, it seems occupational and environmental exposure to noise plus carbon monoxide may increases hearing loss risk.

Hyperbilirubinemia at neonatal period is one of the major deteriorating factors of the AUDITORY sySTEM. If left untreated, it may cause certain cerebral damage. This study aims to evaluate the impact of hyperbilirubinemia on the hearing of neonate. This study was conducted on 35 newborn babies with jaundice (bilirubin more than 20 mg/dL). AUDITORY BRAINSTEM RESPONSE (ABR) and transient evoked otoacoustic emission (TEOAE) tests were performed, after treatment and one year after. ABR test results indicated that 26 children (74.3%) had normal hearing but 9 (25.7%) suffered from an impairment. As for TEOAE test, 30 children (85.7%) passed whereas the remaining (14.3%) seemed to be failures. The comparative results of the two tests pointed to autonomic neuropathy /autonomic dysreflexia symptoms in 5 babies. Due to the high incidence of Autonomic neuropathy/autonomic dysreflexia among hyperbilirubinemic babies, screening in this regard seems reasonable. Our result emphasizes the necessity of more experiments on the afflicted areas.

Since years bygone, the BRAIN had been the focus of considerable debate and controversy and the fears of declaring death had always been a dilemma. For a long time, this presumption prevailed that the only subtle sign of death was putrefaction and rigor mortis (2). In the presence of cardiac activity, the permanent loss of cerebral function, manifested clinically by the absence of purposeful responsiveness to external stimuli, cephalic reflexes, apnea, and an isoelectic electroencephalogram for at least 30 minutes in the absence of hypothermia and poisoning by central nervous sySTEM depressants indicate cerebral death. The ABR test can be an indicator of preserved BRAINSTEM function in difficult clinical situations and has been utilized in BRAIN-dead patients (3,4). Absence of ABR waves II through V despite a normal wave I indicates a significant lack of function in BRAIN STEM AUDITORY tracts. This clinical trial was conducted on 62 male (30-75 years)who were in comatosed state. The ABR were clear and reproducible in comatosed patients in whom BRAIN death was not documented, whereas these RESPONSEs were not recordable in BRAIN dead-patients.The latter finding was confirmed using preclinical monitors such as EEG, Cerebral angiography and CT Scan.

Background: An increase more than definite limit in sound pressure level is harmful for health, mean while, organic solvents like toluene are used in industrial processes with noise widely. So, this study was going to investigate the relationship between toluene (1000 ppm), noise and toluene along with noise (frequencies 4000 and 8000 Hz) per AUDITORY BRAIN STEM RESPONSE (ABR) on rabbits being exposed to these contaminants.Materials and Methods: This survey was done in experimental method on 48 three months old, male adult white New Zealand rabbits (1800±200 g body weight), in nine groups which were exposed to toluene(1000 ppm), noise (4000Hz), 100 dB SPL, combination of toluene and noise (4000Hz), noise (8000Hz) and combination toluene and noise (8000Hz). ABR test measurement was conducted using click and tone burst stimuli in 110dB sound pressure level. Then the results of ABR test of groups exposed were analyzed by SPSS software. One-way variance (ANOVA) analysis was used to compare the groups and Tukey test was applied as a post hoc test for comparison among the groups. P values were obtained by Tukey test. t-test was conducted for comparison of ABR test results after and before exposing groups. Differences at the level of P<0.05 were considered statistically significant.Results: The results of the study showed that Exposing rabbit's to combination of toluene and noise caused hearing impairment in all of frequencies AUDITORY especially in frequencies 250, 500 and 1000Hz. So that, wave five in ABR test (tone burst stimuli) didn’t formed in 250-1000Hz frequencies. The mean of latency time of V wave (5 wave) were as follows; In control group 4.84±0.07ms, group exposed to toluene 5.18±0.07ms, noise group (4000Hz) 5.5±0.07ms and in combination noise and toluene group (4000Hz) 5.79±0.07 ms. The mean of latency time of V wave in control was compared to that of group noise group P=0.01, toluene group P=0.07 and combination noise and toluene group P=0.0001.Conclusion: According to the result of this study, Both toluene and noise exposure caused the rabbits in hearing impairment but combination of toluene and noise exposure in frequencies of 4000 Hz and 8000Hz was much worse than hearing impairment. So that, the ABR test on rabbits didn't formed V wave in low frequency.

Background and Objectives: Severe hyperbillirubinemia in the neonatal period is a risk factor for hearing loss, and its role is known as a major risk factor for neonatal non-syndromic AUDITORY neuropathy. In this study, the prevalence of hearing loss in term neonates with a history of hyperbilirubinemia was evaluated with ABR test and the results were compared with that of healthy neonates.Methods and Materials: In a cohort study, in the Pediatric Hospital of Tabriz, the hearing loss rate in 102 children who had only severe neonatal Hyperbilirubinemia as deafness risk factor was compared with that of 100 matching healthy neonates without any known deafness risk factors. All subjects were evaluated with AUDITORY BRAIN STEM RESPONSE.Results: All neonates were full term. Fifty-eight of the case group children and 61 of the control group children were boys and 58 of the case group children and 61 of the control group children were girls (P=0.550). Twenty-three neonates with hyperbilirubinemia had an abnormal AUDITORY BRAIN STEM RESPONSE. Seven neonates of the case group patients had mild hearing loss, eight neonates of the case group patients had moderate hearing loss and eight neonates of the case group patients had severe hearing loss. The frequency of abnormal AUDITORY BRAIN STEM RESPONSE in neonates with hyperbilirubinemia was significantly higher than that of the control group neonates (P< 0.001).Conclusion: The mean of bilirubin in the case group neonates was 35.30 ± 5.02. Six-point-nine percent of the case group had mild hearing loss, %7.8 of the case group had moderate hearing loss and %7.8 of the case group had severe hearing loss. The severity of the hearing loss in neonates with hyperbilirubinemia was significantly higher than that of the control group neonates. Twenty-two-point-five percent of the neonates with hyperbilirubinemia had an abnormal AUDITORY BRAIN STEM RESPONSE which was significantly higher than that of the healthy group. It is recommended to evaluate the hearing state in neonates with a history of neonatal hyperbilirubinemia with AUDITORY BRAIN STEM RESPONSE.

Background and Objectives: Sever neonatal hyperbilirubinemia, is a major risk factor for AUDITORY neuropathy and hearing lost. Here we studied the prevalence of hearing loss in a group of child who had a history of hyperbilirubinemia.Materials and Methods: In this study, we evaluated the rate and severity of hearing lost in a group of children who had a history of severs neonatal Hyperbilirubinemia. The results were compared with a matched group of healthy neonates, without a history of neonatal Hyperbilirubinemia. Levels of hearing lost were evaluated with AUDITORY BRAIN STEM RESPONSE (ABR).Results: In this study we entered 102 child (M/F=58/44, mean age=24.5±8.9 months) with history of Hyperbilirubinemia (35.30±5.02 mg/dl). Our control group consisted of 100 healthy child (M/F=61/39, mean age=23.6±8.61 months). Abnormal BRAIN AUDITORY RESPONSE was detected in 23 patients in case group. It was mild, moderate and sever in seven (%6.9), 8 (%7.8) and 8 (7.8%) child succeedingly. Non of individuals in control group had abnormal ABR result and hearing lost.Conclusion: It is recommended to evaluate hearing state in child with history of neonatal hyperbilirubinemia.

Objectives: The aim of this study was comparing ABR in normal and down children.Materials & Methods: This study was performed between 1388 to 1391 at Akhavan rehabilitation center of University of Social Welfare and Rehabilitation Sciences Tehran and Babol Amir Kola hospital. Forty five 3-6 year-old boy with Down’s syndrome and forty five normal children were selected from available population.After case history, otoscopy and basic hearing tests, ABR test was performed. In ABR absolute latencies, interpeak latencies and amplitude ratio of V/I were analyzed. For analyzing data, parametric independent t test was selected.Results: Latencies and inter-peak latencies of I-III, I-V (P-value<0.001), III-V (P-value=0.01) and V/I amplitude ratio (P-value<0.001) were shorter than normal. Children with Down syndrome had significantly higher threshold than normal children (P-value<0.001).Conclusions: Peripheral AUDITORY sySTEM development is delayed and BRAINSTEM function in children with Down’s syndrome is abnormal.Early diagnosis of hearing impairments and intervention in these children is very important because it affects communication skills.

Background: Increase in mobile phone users cause extensive consideration of researchers to biological effects of mobile phone waves. As the mobile set, is held near the ear and temporal lobe, and whereas distance of antenna from the inner ear is few centimeters, this study is the first research in our country to assess potential changes in AUDITORY BRAIN STEM RESPONSE of rabbit after exposure to mobile phone waves from a simulator.Materials & Methods: This study is experimental. In conducting the experiment, were used male rabbits. The method used was, AUDITORY BRAINSTEM RESPONSE (ABR), which is the usual method in detecting changes in retrocochlear and acoustic pathway. Before and after animal's exposure (one and two weeks), latency time of the fifth wave of ABR were measured and recorded with two stimuli, click and tone burst (at different frequencies) in two intensities of 70 and 100 dB.Results: At the end of first week the latency time of wave V (ms) increased for all the frequencies of the experiment, especially at the (2000-4000 & 8000Hz). An increased of more than 0.2 ms was noticed. It was caused at least 10 dB deficiency in hearing. But at the end of second week of exposure, the latency time of wave V, at the frequencies of 500 and 1000 Hz, was almost unchanged but at the frequencies of (2000-4000 & 8000 Hz) was decreased more than 0.2 ms and was nearly the amount of pre-exposure. Statistical analysis of results has not shown significant changes between latency time of wave V (ms), in pre and post exposure (p>0.05).Conclusion: This decrease in 2000-8000 Hz frequencies at the end of second week can be viewed as adaptation of animal's hearing at high frequencies. Although for confirm it need to research more and longer.