جستجوی مقالات مرتبط با کلیدواژه « پاسخ شنوایی ساقه مغز » در نشریات گروه « پزشکی »

Neural encoding of sounds starts from the auditory nerve and moves on to the auditory brainstem. What is less defined is how the brainstem responds to complex stimuli. The current study quantified brainstem encoding of fundamental frequencies and first formant amplitude of the spoken syllable /da/ using periodic frequency-following responses. Auditory brainstem responses to spoken syllables in both ears were monaurally presented under quiet conditions for 48 normal adults (25 female) with a mean age of 22.7 ± 2.05 years. The magnitudes of the sustained periodic frequency-following responses (FFR) were assessed by fundamental frequency, first formant amplitude, and higher frequency harmonics of the first formant. Measures of the FFR components of brainstem response to the spoken syllables were robustly obtained. Responses occurred earlier in right ear presentation than those in left, approaching significance for the FFR second peak (p =. 004). A significant difference in interpeak latency of DE was observed (p =. 019), but not for EF interpeak latency. Right ear presentation evoked greater spectral amplitude for F0, F1, and high frequency harmonic ranges than the left ear, but there were no significant differences between ears. Overall, waveform morphology for both sides was quite similar. It is evident that response elements reflecting F0 and F1 are symmetrically processed in the brainstem, suggesting the pathway is not primed for the prosodic elements of speech.

Binaural perception is an important ability in human auditory system in noisy evironment. The human click-evoked binaural interaction component has been known as an index of binaural perception. The purpose of this investigation was to study the stimulus polarity effect on binaural interaction of auditory brainstem response (ABR). ABR’s were recorded monaurally and binaurally in 30 normal adults (12 men & 18 women) using different stimulus polarity. In order to determine binaural interaction component (BIC) from wave V، the binaural response was subtracted from the summed monaural waves (R+L) in each polarity. Repeated measures ANOVA was used to analyze latency & amplitude differences of BIC between the three stimulus polarities. Condensation clicks produced BIC’s with longer latency compared to rarefaction clicks (p˂0. 05). BIC’s amplitude increased by using condensation polarity compared to rarefaction & alternate polarities (p˂0. 001 & p˂0. 01، respectively). Amplitude، latency & morphologic characteristics of BIC were dependent on click polarity. Latency differences have been accounted for by small latency shift of the components of monaurally or binaurally evoked potentials resulting from changes in click polarity. Recognition of BIC was easier using condensation polarity.

While most of the people with tinnitus have some degrees of hearing impairment, a small percent of patients admitted to ear, nose and throat clinics or hearing evaluation centers are those who complain of tinnitus despite having normal hearing thresholds. This study was performed to better understanding of the reasons of probable causes of tinnitus and to investigate possible changes in the auditory brainstem function in normal-hearing patients with chronic tinnitus. In this comparative cross-sectional, descriptive and analytic study, 52 ears (26 with and 26 without tinnitus) were examined. Components of the auditory brainstem response (ABR) including wave latencies and wave amplitudes were determined in the two groups and analyzed using appropriate statistical methods. The mean differences between the absolute latencies of waves I, III and V was less than 0.1 ms between the two groups that was not statistically significant. Also, the interpeak latency values of waves I-III, III-V and I-V in both groups had no significant difference. Only, the V/I amplitude ratio in the tinnitus group was significantly higher (p=0.04). The changes observed in amplitude of waves, especially in the latter ones, can be considered as an indication of plastic changes in neuronal activity and its possible role in generation of tinnitus in normal-hearing patients.

Neonatal hyperbilirubinemia is a common problem that can be potential toxicity effects on the nervous system in infants، especially on the hearing ways. Regarding to hearing impairment leaves so negative effects on speech، language and cognitive development. The aim of this study was the assessment of the incidence of sensorineural hearing loss among icteric infants admitted to the hospitals of Gorgan، Iran in 2012.

In this longitudinal study، 223 infants were recruited by convenience sampling، that OAE screenings at the birth time was normal. Using Automated Auditory Brainstem Response (AABR) was performed for infants at the hospitalization and they were assessed after discharge، and with Auditory Brainstem Response (ABR) were confirmed.

The mean age of the infants on admission was 3. 84±4. 58 days and 55. 6% of them were female. The mean birth weight was 3431±218 grams and the mean gestational age was 39±1. 3 weeks. Serum total bilirubin levels in 61. 4% of infants were between 12-20 mg/dL and of 38. 6% were higher than 20 mg/dL. 13. 0% received conventional phototherapy، 72. 6% intensive phototherapy and 14. 3% of patients had exchange transfusions. Totally، 8 (3. 6%) of infants in admission had disturbance waves in AABR. Subsequent studies have shown improvement in 7 patients، but one patient problem still remains، and from other patients with normal admitted AABR in following 6 infants was impaired in ABR. Finally، 7 (3. 1%) of hearing loss were remains. There was a statistically significant difference between the hearing loss، serum total bilirubin level and total AABR impairment result on admission and final result (p<0. 05)، but there was no significant difference with variable of gender and kind of delivery (p<0. 05).

This study indicated that hyperbilirubinemia in the neonatal period can cause sensorineural hearing loss. Hence، regular screening in icteric newborns seems to be necessary.

Studies have shown that long-term use of monaural hearing aid in symmetrical hearing losses may lead to physiological changes. In this research، the possibility of plasticity occurrence in bilaterally hearing impaired listeners fitted with only one hearing aid was investigated. Our study was carried out on 12 elderly listeners with a mean age of 61. 92 years who had symmetrical moderate to severe sensory neural hearing loss in both ears. All of the participants had minimum monaural hearing aid experience of 2 years. We used auditory brainstem response (ABR) testing in order to compare absolute latency and amplitude of wave V between the two ears of cases. Air conduction click stimuli were presented monaurally at 80، 90 and 100 dB nHL. Despite the shorter absolute latency of wave V in the fitted ear، no significant difference was found between the two ears (p>0. 389). The difference between wave V amplitude of both ears was greater in 90 dB nHL level (p=0. 043). Women showed shorter mean latency than men and the mean amplitude of women was greater than men. Significant gender difference was observed in absolute latency of wave V (p<0. 037). Our findings indicate that the use of monaural hearing aid in symmetrical hearing losses can induce neural plasticity within auditory brainstem pathways which can be displayed by auditory brainstem response test.

Preterm birth is one of the risk factors need comprehensive audiological assessment. In this study، the effect of sex and rate of stimulation on response of children with history of preterm birth was investigated by auditory brainstem response (ABR). This cross-sectional study was conducted using convinience sampling. Click-evoked a uditory brainstem response test with both low (21. 1 c/s) and high (51. 1 c/s) stimulus rates was recorded in 30 children with a history of preterm birth and 30 ones with history of term labor، as controls. Significant differences were observed in inter-peak latencies of I-III in both rates، III-V in the low rate، I-V in the high rate، and absolute latency of III wave between high and low stimulus rates (p<0. 05 for all). Rate of stimulus affect on auditory brainstem response of preterm birth group was more than controls. Sex also affected on some parameters of auditory brainstem response test. Preterm birth group showed longer latencies than normal group in both rates. Rate of stimulus had significant effect on results of children with history of preterm birth compared normal group. These findings may reflect the negative effect of preterm birth on neural synchronization function in response to transient stimuli.

Multiple sclerosis is one of demyelinating disorder of CNS that is an uncommon cause of the sensorineural hearing loss. This study was done to determine the hearing loss in multiple sclerosis patients. This case-control study was performed on 60 (44 women, 16 men) multiple sclerosis patients and 38 (27 women, 11 men) normal subjects by pure tone audiometery, otoacustic emissions and auditory brainstem responses in Gilan provine, Iran during 2010-11. Data was analyzed by using SPSS-17, Chi-Square and Fischer tests. 12.5% of case and 3.9% of the control ears had abnormal pure tone audiometery (P<0.05). The frequencies of abnormal HF-pure tone audiometery and two modalities of otoacustic emission did not show any significant differences in two groups. Abnormal autidory brainstem response of ears were observed in 20% and 9.2% of cases and controls, respectively (P<0.05). 20% of case and 9.2% of the control ears had abnormal auditory brainstem response (P<0.05). The absolute latencies of waves I, II and V had not significant differences between two groups. Inter peak latencies of I-III and III-V waves were observed in 10% and 11.7% in cases ears and 1.3% and zero percent in controls, respecticely. 6.7% of cases and 2.6% of control ears had retrocochlear abnormality. Hearing loss detected by pure tone audiometery and auditory brainstem response is more common in multiple sclerosis compared to normal population.

High incidence of speech disorders in children with cerebral palsy could be related to a deficiency in processing of auditory stimuli. So it is vital to check out any peripheral or central disorders in auditory system using behavioral and electrophysiological auditory tests.

In a cross-sectional study, 15 children with spastic diplegia, mean age 5.77, SD 2.26 years, and 15 normal children, mean age 5.33, SD 1.80 years, were tested using pure tone audiometry, immittance and auditory brainstem responses. The results were compared between the two groups.

Hearing thresholds and middle ear status were in normal range in all participants; however, contralateral acoustic reflex thresholds were mostly elevated. Comparing absolute latency and interpeak latency intervals of auditory brainstem responses between the two groups, absolute latency interval of later waves, and in specific the V wave, was significantly longer in diplegic children (p=0.04) resulting in a longer III-V interpeak latency intervals (p=0.02).

Neurological disorders in ponto-reticulo-spinal pathway, pontine reticular nuclei and upper pons which are adjacent to auditory nuclei of lateral leminiscus and inferior colliculus result in auditory dys-synchrony and increased latency intervals in latter waves of auditory brainstem responses. This could also attributed to functional disorders in wave-generating sites in these patients.

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. 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). 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. It is recommended to evaluate hearing state in child with history of neonatal hyperbilirubinemia.

Autism is a neurodevelopmental disorder of the brain,which occures in first few years of life, and characterized by symptoms such as qualititative impairments in verbal and non verbal communication, reciprocal social interactions, inability to communicate with others, stereotyped patterns of behavior, loss of eye contact and inappropriate facial expressions. Its prevalence is 2-5 in 10000 children and is greater in boys. Due to retarded language development, differential diagnosis other than those used with communication, behavioral and sensorial deficits should be made with Sensorineural or conductive hearing loss. The aim of this study was to determine whether children with autism have abnormalities affecting the cochlear nerve or auditory pathway in brainstem. In this case – control study, auditory brainstem responses were recorded from 12 autistic children and 12 normal children aged 3-12 years in rehabilitation Zafar central in Tehran – Iran during 2005. Absolute latency values of waves I, III and V and interpeak latencies of I-III, III-V and I-V were compared with the results of 12 normal children as control group. Wave V could be traced down to 25 dB nHL in both normal and autistic groups. Absolute latency of Wave V and Interpeak latencies of III-V and I-V were significantly prolonged in Autistic children in comparison with control group. This study showed a slowing in nerve conduction in auditory pathway in brainstem of autism patients. The brainstem lesion may be a part of neurological damage in autistic children that accounts for deviant language, cognition and social development. Prolongation of wave V, III-V and I-V IPLs can be a marker for early diagnosis of autism.

One of the most important problems of children who suffer from autism is abnormality in receiving and integrating sensory inputs, especially hearing input. It has been shown that brainstem has a key role in receiving, encoding and integrating hearing input. Auditory brainstem response (ABR) is a tool by which we can evaluate this function. The purpose of this study was to assess and to compare autistic and normal children brainstem hearing function.

This case-control study was conducted on thirty (58 ears) autistic and thirty (57 ears) normal 6-12 years old children. The children with autism were divided into slight and severe subgroups according to Autism Diagnostic Interview-Revised questionnaire. Click-evoked ABR was recorded and compared between groups.

There was significant difference between two groups V and III wave latencies and I-III and I-V interpeak latencies (p<0.05). In fact, comparison of the results of autism subgroups with normal children indicated that the latencies of the severe subgroup significantly prolonged.

Increasing latencies of ABR waves in severe subgroup maybe due to abnormality in low level of brainstem. Brainstem abnormality may result in exacerbating the symptom of autism. It is therefore suggested that ABR is included in diagnostic test batteries for these patients.

Physiologic measures of cochlear and auditory nerve function may be of assis¬tance in distinguishing between hearing disorders due primarily to auditory nerve impairment from those due primarily to cochlear hair cells dysfunction. The goal of present study was to measure of co-chlear responses (otoacoustic emissions and cochlear microphonics) and auditory brainstem response in some adults with auditory neuropathy/ dys-synchrony and subjects with normal hearing. Patients were 16 adults (32 ears) in age range of 14-30 years with auditory neu¬ropathy/ dys-synchrony and 16 individuals in age range of 16-30 years from both sexes. The results of transient otoacoustic emissions, cochlear microphonics and auditory brainstem response measures were compared in both groups and the effects of age, sex, ear and degree of hearing loss were studied. The pure-tone average was 48.1 dB HL in auditory neuropathy/dys-synchrony group and the fre¬quency of low tone loss and flat audiograms were higher among other audiogram's shapes. Transient oto¬acoustic emissions were shown in all auditory neuropathy/dys-synchrony people except two cases and its average was near in both studied groups. The latency and amplitude of the biggest reversed co-chlear microphonics response were higher in auditory neuropathy/dys-synchrony patients than control peo¬ple significantly. The correlation between cochlear microphonics amplitude and degree of hearing loss was not significant, and age had significant effect in some cochlear microphonics measures. Audi-tory brainstem response had no response in auditory neuropathy/dys-synchrony patients even with low stim¬uli rates. In adults with speech understanding worsen than predicted from the degree of hearing loss that suspect to auditory neuropathy/ dys-synchrony, the frequency of low tone loss and flat audiograms are higher. Usually auditory brainstem response is absent in this patients and use of both otoacoustic emis¬sions and cochlear microphonics responses to measure cochlear hair cells function are suggested in them.

Sensorineural hearing loss is one of the most important complications of meningitis, however, it can be neglected during the acute course of the disease. By early detection and medical intervention, the retardation of lingual development can be avoided.

The hearing function of 40 children with meningitis was evaluated at 24-72 hours after diagnosis (acute period) and 24 hours before discharging from hospital (recovery period) with auditory brainstem responses (ABR).

During the acute period, ABR test revealed normal hearing in 35 patients (87.5%) and severe to profound sensorineural hearing loss in 5 patients (12.5%). The same results were obtained in re-evaluation in the recovery period. There were significant differences between the female gender, positive culture of cerebrospinal fluid, the age below 2 years of old and hearing loss. (P value = 0.03, 0.02, 0.02, respectively).

ABR can be used for early detection of hearing loss during the acute and recovery period of meningitis