Hearing loss in an institutionalized mentally retarded population. Identification by auditory brainstem response

We report the results of auditory brainstem response testing of 122 profoundly retarded institutionalized children, a segment of the retarded population heretofore generally regarded as untestable by behavioral audiometry. Major findings include: 32% of the study population showed, by auditory brainstem response, hearing loss exceeding 20 decibels of hearing level in one or both ears (12% showed conductive loss and 20% sensorineural loss); of the 15.6% with evidence of bilateral sensorineural loss, 7.37% had losses in the 30- to 50-dB range, and 8.19% had losses of 60 dB or greater; and evidence of abnormal brain-stem function was found in 11%. Results of otologic examinations and audiologic habilitative follow-up in selected children are also reported.     

Auditory steady-state responses to multiple simultaneous stimuli in children with functional or sensorineural hearing loss

The goal of our study was to identify the role of auditory steady-state responses for hearing assessment in patients with functional hearing loss. The study design was to compare auditory steady-state response thresholds and standard pure-tone audiometry thresholds between patients with functional or sensorineural hearing loss. Subjects comprised 16 patients (24 ears) with functional hearing loss and 17 patients (24 ears) with sensorineural hearing loss. Differences and correlations between auditory steady-state response thresholds and standard pure-tone audiometry thresholds at 500, 1,000, 2,000 and 4,000 Hz were evaluated. In children with functional hearing loss, pure-tone audiometry thresholds and auditory steady-state response thresholds were significantly different at all frequencies and were not significantly correlated. In patients with sensorineural hearing loss, pure-tone audiometry thresholds and auditory steady-state response thresholds did not differ significantly at any frequencies and were significantly correlated. Auditory steady-state responses may have principal role in the assessment of auditory brainstem acuity, particularly at low frequencies in patients with functional hearing loss.     

Otologic manifestations of malignant osteopetrosis.

OBJECTIVE: To determine the incidence of hearing loss and describe the neurotologic manifestations over time in a large series of patients with malignant osteopetrosis. STUDY DESIGN: Longitudinal study. SETTING: Tertiary care referral center. PATIENTS: Thirty-two patients, including 19 infants (< 1 yr of age at initial visit) and 13 children (aged 1-7.6 yr at initial visit), with autosomal recessive osteopetrosis were followed-up during a 10-year period from 1991 to 2001. The average length of follow-up was 2.5 years (range, 0-9.1 yr). INTERVENTIONS: Patients underwent annual otologic evaluations including clinical examination, audiologic evaluation (auditory brainstem response, pure-tone thresholds, speech discrimination scores, and tympanograms), and high-resolution computed tomography of the temporal bone. MAIN OUTCOME MEASURES: Incidence of hearing loss, otitis media, and facial paralysis. Serial changes in temporal bone anatomy by computed tomographic scan. RESULTS: Twenty-six percent of infants' ears demonstrated hearing loss during the first year of life, and 78% of children's ears demonstrated hearing loss during the study period. Of the children's ears with hearing loss, 100% had a conductive component and 26% had an additional sensorineural component (mixed hearing loss); VIIIth nerve conduction was normal in 100% of infants and 78% of children. Five patients (16%) had unilateral facial nerve palsy. Common temporal bone findings included thickening and sclerosis of the calvarium; poor pneumatization of the mastoid bone; and narrowing of the external auditory canal, eustachian tube, and internal auditory canal. CONCLUSION: Otologic manifestations are common in malignant osteopetrosis secondary to the formation of dense, brittle bone. Frequent findings include external auditory canal stenosis, otitis media, conductive and sensorineural hearing loss, and facial nerve paralysis.     

Vestibular Function in Auditory Neuropathy

Auditory neuropathy is characterized by mild-to-moderate pure-tone hearing loss, poor speech discrimination out of proportion with this loss, absent or abnormal auditory brainstem responses and normal outer hair cell function as measured by otoacoustic emissions and cochlear microphonics. We followed three patients in our clinic whom we classified as auditory neuropathy patients. These patients also complained of balance disorders and we report our auditory and vestibular system analyses of these patients. The data presented herein include results of audiometric tests (serial pure-tone audiometry and speech discrimination tests), otoacoustic emissions, auditory-evoked brainstem responses and vestibular function tests (clinical tests of balance, electronystagmography, damped rotation tests and vestibular-evoked myogenic potentials). In all patients, pure-tone audiometry revealed mild-to-moderate sensorineural hearing loss, markedly poor speech discrimination scores and absent auditory-evoked brainstem responses, all in the presence of normal otoacoustic emissions. Balance tests (caloric tests and damped rotation test) were abnormal. Saccades, smooth pursuit eye movements and optokinetic nystagmus were normal in all patients. Neurological and motor system evaluations were normal in all patients. These three auditory neuropathy patients manifest a disorder of cochlear nerve function in the presence of normal outer hair cell activity. They additionally manifest a disorder of the vestibular nerve and its end organs. We conclude that, in patients with isolated auditory neuropathy, the vestibular branch of the VIIIth cranial nerve and its innervated structures may also be affected. We suggest the use of the term "cochlear neuropathy" to characterize those patients with involvement of only the auditory branch of the VIIIth cranial nerve and its innervation.     

Vestibular function in auditory neuropathy

Auditory neuropathy is characterized by mild-to-moderate pure-tone hearing loss, poor speech discrimination out of proportion with this loss, absent or abnormal auditory brainstem responses and normal outer hair cell function as measured by otoacoustic emissions and cochlear microphonics. We followed three patients in our clinic whom we classified as auditory neuropathy patients. These patients also complained of balance disorders and we report our auditory and vestibular system analyses of these patients. The data presented herein include results of audiometric tests (serial pure-tone audiometry and speech discrimination tests), otoacoustic emissions, auditory-evoked brainstem responses and vestibular function tests (clinical tests of balance, electronystagmography, damped rotation tests and vestibular-evoked myogenic potentials). In all patients, pure-tone audiometry revealed mild-to-moderate sensorineural hearing loss, markedly poor speech discrimination scores and absent auditory-evoked brainstem responses, all in the presence of normal otoacoustic emissions. Balance tests (caloric tests and damped rotation test) were abnormal. Saccades, smooth pursuit eye movements and optokinetic nystagmus were normal in all patients. Neurological and motor system evaluations were normal in all patients. These three auditory neuropathy patients manifest a disorder of cochlear nerve function in the presence of normal outer hair cell activity. They additionally manifest a disorder of the vestibular nerve and its end organs. We conclude that, in patients with isolated auditory neuropathy, the vestibular branch of the VIIIth cranial nerve and its innervated structures may also be affected. We suggest the use of the term "cochlear neuropathy" to characterize those patients with involvement of only the auditory branch of the VIIIth cranial nerve and its innervation.     

Audiologic results in patients with Moebiüs sequence

OBJECTIVE: Moebiüs sequence is a pathology not very well understood regarding to the hearing status. The main goal of this study was to describe the audiologic findings in children and adolescent who carry Moebiüs sequence. METHOD: Participated in this study 17 children and adolescent, with age ranging from 3 to 13 years old. Prior to the testing, the family answered an interview. It was realized external auditory canal inspection, and the hearing testing (auditory instrumentation, pure tone audiometry, speech audiometry, immittanciometric measures, and otoacoustic emissions) on the participants. RESULTS: The auditory instrumentation evaluation (n=6) was present in all participants. The pure tone audiometry presented normal hearing levels in 75.0% of the tested ears, one ear with conductive hearing loss, two ears with sensory neural hearing loss, and one ear with mixed hearing loss. The tympanometric measures showed Type A tympanograms in 63.0% of the ears, Type B in 11.1%, Type C in 18.5%, and Type As in 7.4%. T the acoustic reflexes measure showed contralateral acoustic reflexes present in 50.0% of the ears, and ipsilateral acoustic reflexes present in 34.6% ears. The OAE results showed presence in 73.0%, for the TOAE, and 76.9% for the DPOAE. CONCLUSION: These results support the idea that there is no audiologic pattern for conductive hearing loss. The majority of the participants presented hearing in the normal range. Care should be taken in drawing conclusions regarding to auditory status of the individual with Moebiüs sequence, but what can be said is that not always those individuals present hearing loss.     

Frontonasal dysplasia: clinical evaluation on audiological and brainstem electrophysiological profiles

Frontonasal dysplasia (FND) is a rare malformative complex affecting the frontal portion of the face, the eyes and the nose; it may occur singly or associated with other clinical signs. No systematic studies describing hearing in this condition were found.AimTo evaluate hearing sensitivity and sound stimulus conduction from cochlea to brainstem in patients with clinical signs of FND.Methods21 patients with isolated or syndromic FND were submitted to a clinical (otological/ vestibular antecedents and otoscopy) and instrumental (pure tone and speech audiometry, tympanometry and brainstem auditory evoked response) hearing evaluation.DesignA clinical, cross-sectional observational prospective study.ResultsHearing thresholds were normal in 15 (70%) patients, abnormal in 5 (25%), mostly with conductive hearing loss; one patient did not cooperate with testing. The tympanometric curve was type A in 30 (72%) ears, type C in 5 (12%), type As in 4 (9%) and type B in 3 (7%). The auditory brainstem response (ABR) showed no abnormalities.ConclusionPatients with FND showed no abnormalities in the auditory system from cochlea to brainstem in this study. Mild conductive hearing loss found in some is probably related to cleft palate. Further evaluation of hearing pathways at higher levels is recommended.     

Functional hearing loss in children

This report reviewed 39 school-age children diagnosed as having a functional hearing loss utilizing auditory brainstem response (ABR) audiometry during the past 5 years at the Department of Otolaryngology, Kyushu University Hospital in Japan. Twenty-seven cases were females and 12 were males. Seven cases had a hearing loss unilaterally and 32 bilaterally. Although pure-tone audiometry revealed a variety of audiogram shapes, two-thirds of the cases had a flat or saucer-shaped audiogram with a mild to moderately severe hearing loss. ABR audiometry for the frequencies of 1, 2 and 4 kHz indicated a normal hearing threshold in 65 ears of 35 patients, and mild threshold elevations of at least one frequency in the remaining 6 ears of 4 patients. Three illustrative cases were demonstrated, and a discussion was held regarding the features in audiometric tests, and environmental factors surrounding the children with this condition. We emphasized that the physiological hearing measurement such as ABR audiometry should be performed when any discrepancy was noted between the patient's history and results of pure-tone audiometry, because of not infrequent occurrence of functional hearing loss.     

Auditory neuropathy in childhood

Objectives: Auditory neuropathy is a recently described disorder in which patients demonstrate hearing loss for pure tones, impaired word discrimination out of proportion to pure tone loss, absent or abnormal auditory brainstem responses, and normal outer hair cell function as measured by otoacoustic emissions and cochlear microphonics. We have identified eight pediatric patients having hearing deficits that are most likely due to a neuropathy of the eighth nerve. In this study, the results of audiologic testing performed with these eight children are described. Study Design: Retrospective review of audiologic findings in eight children with auditory neuropathy. Methods. Each subject was tested with pure tone and speech audiologic testing, auditory brainstem response, and click-evoked otoacoustic emissions. Results of these tests were tabulated and summarized. Results: Pure tone audiologic testing revealed five children with upsloping sensorineural hearing loss, two with high frequency loss, and one with a mild, flat configuration. Six children demonstrated poor word discrimination scores, and the other two had fair to good word discrimination. All eight subjects had normal distortion product and transient otoacoustic emissions. All eight children demonstrated absent or marked abnormalities of brainstem auditory evoked potentials. These findings suggest that while cochlear outer hair cell function is normal, the lesion is located at the eighth nerve. Conclusions: Recent advances in otoacoustic emissions testing permit differentiation of neural deafness from sensory deafness. This paper describes the clinical presentation and audiologic findings in pediatric auditory neuropathy, as well as the recommended management of these patients. Otolaryngologists should be aware of this disorder and implications for its management, which differs from treatment of sensorineural hearing loss. Key Words: Auditory neuropathy, childhood, hearing loss, auditory brainstem response, evoked otoacoustic emissions.     

An initial overestimation of sensorineural hearing loss in NICU infants after failure on neonatal hearing screening

Objective

Infants admitted to neonatal intensive care units have a higher incidence of significant congenital hearing loss. We classified audiologic diagnoses and follow-up in infants who had been admitted to our neonatal intensive care unit.

Methods

We included all infants admitted to the neonatal intensive care unit at Sophia Children's Hospital between 2004 and 2009 who had been referred for auditory brainstem response measurement after failing neonatal hearing screening with automated auditory brainstem response. We retrospectively analyzed the results of auditory brainstem response measurement.

Results

Between 2004 and 2009 3316 infants admitted to our neonatal intensive care unit had neonatal hearing screening. 103 infants failed neonatal hearing screening: 46 girls and 57 boys. After first auditory brainstem response measurement we found 18% had normal hearing or a minimal hearing loss. The remainder had a type of hearing loss, distributed as follows: 15% conductive, 32% symmetric sensorineural, 14% asymmetric sensorineural, and 21% absent auditory brainstem responses. Repeated auditory brainstem response measurement showed a shift in hearing outcome. The main difference was an improvement from symmetric sensorineural hearing loss to normal hearing. However, in a small percentage of children, the hearing deteriorated.

Conclusions

As many as 58% of infants in this high-risk population who failed the neonatal hearing screening were diagnosed with sensorineural hearing loss or absent auditory brainstem responses. An initial overestimation of sensorineural hearing loss of about 10% was seen at first auditory brainstem response measurement. This may be partially explained by a conductive component that has resolved. Finally, in a small percentage of children the hearing deteriorated.     

Neonatal conductive hearing loss does not compromise brainstem auditory function and structure in rhesus monkeys

The effect of conductive hearing loss on the maturation of the auditory pathway was evaluated using the auditory brainstem response (ABR) in rhesus monkeys. Ten newborn rhesus monkeys were assigned to control (N = 4), unilateral hearing loss (N = 3), or bilateral hearing loss (N = 3) groups. Hearing loss was created by surgically excising a 3 mm section of the external auditory canal and suturing the canal. Auditory brainstem responses to click stimuli were recorded prior to and after the surgical procedure and bi-monthly or monthly for a 14 month follow-up period. Results showed that after surgery all ears developed an estimated 30-50 dB conductive hearing loss which was retained throughout the follow-up period. Contrary to expectations, the latencies of the ABR component waves decreased with age in all ears. When adjusted for hearing level, there were no differences between ears in maturation of the component waves of the ABR. These data suggest that, in primates, a conductive hearing loss does not affect the maturation of those aspects of the auditory pathway reflected in the ABR. Furthermore, the conductive losses were not accompanied by any discernible change in the neuronal sizes of brainstem auditory neurons or the volume of the cochlear nuclei.     

强直性脊柱炎患者的听力学及抗膜迷路蛋白抗体的检测

目的　对强直性脊柱炎 (ankylosingspondylitis ,AS)患者进行听力学检测并分析听力减退的特点。方法　采用问卷调查、临床耳鼻咽喉科检查、听力学测试、抗膜迷路抗体检查、血清免疫学检测方法 ,对确诊为AS的 34例 (6 8耳 )患者的临床资料加以分析。结果　 34例中主诉听力减退 11例 ,纯音测听发现听力减退 2 4例 (41耳 ) ,占 6 0 3% (41/ 6 8) ,2耳见鼓膜穿孔为混合性聋 ,39耳为感音神经性聋 ,其中高频听力减退 2 6耳 (2 6 / 39,6 6 7% )。听性脑干反应 (auditorybrainstemresponse ,ABR)除 1例 (2耳 )因重度聋无反应外 ,余 2 6例均正常。抗原抗体反应检测法检查 32例抗膜迷路抗体 ,9例阳性 (2 8 1% )。实验室检查 34例 ,HLA B2 7全部阳性 ,抗核抗体 (antinclearantibody,ANA)、类风湿因子(rheumatoidfactor,RF)均阴性 ,C 反应蛋白 (C reactiveprotein ,CRP)增高占 81 8% (2 7/ 33)。其余免疫学指标也有不同改变。结论　半数以上的AS伴有感音神经性听力减退 ,以高频听力减退居多 ,为耳蜗性聋伴免疫学异常 ,是全身性自身免疫病的内耳表现。对AS患者应定期进行听力学监测。     

Frequency of hearing disorders in children with langerhans' cell histiocytosis

BACKGROUND: The aims of the study were to find out the frequency of hearing disorders in children with Langerhans' cell histiocytosis (LCH) and to find out possible risk factors for hearing disorders due to the disease itself and the therapy. PATIENTS AND METHODS: 30 patients with LCH were examined audiologically by using standard audiometric procedures. In cases of central nervous system (CNS) lesions, brainstem evoked response audiometry (BERA) was done additionally. A significant hearing disorder was defined as a hearing impairment affecting speech, thus being characterized by the following features: Both ears should present either conductive and/or sensorineural hearing loss of at least moderate degree. The frequencies important for speech development (1 - 4 kHz) had to be affected. Also, prolongation of BERA interpeak latencies was regarded as a significant hearing impairment, because those children had an increased risk for a central auditory and speech processing disorder. RESULTS: In our study 3 patients had a significant hearing disorder according to our definition. The prevalence of a significant hearing disorder is increased in patients with LCH compared to the prevalence of permanent hearing disorders in German children. We found the following risk factors for the development of a significant hearing disorder: LCH of the temporal bone, CNS lesions. CONCLUSIONS: We recommend periodical audiological follow up examinations for LCH patients with lesions of the temporal bone and/or the brain. BERA is indicated in cases with CNS lesions, because central auditory and speech processing disorders are possible in those patients.     

Vestibular and audiologic functions in gentamicin-treated Menière's disease

Fifteen patients with disabling Meniere's disease were treated with local intratympanic administration of gentamicin once daily. They had suffered from frequent attacks of vertigo and vomiting, the hearing in the affected ears was decreased permanently, and spontaneous nystagmus was observed. The number of treatment days ranged between 3 and 11. Follow-up time was 1 to 6 years. For evaluation of the treatment, audiologic and vestibular examinations were used, including the broad frequency-band rotatory test (0.4-4.5 Hz). Fourteen patients were free from vertigo after treatment. In 5 patients, there was an increased hearing loss, and in 10 it remained unchanged. Tinnitus and fullness sensations were diminished. After treatment, all ears were unresponsive to caloric stimulation. The clinical examination and rotatory testing in light with sinusoidal stimulation revealed good central compensation of the vestibular loss. However, with pseudorandomized oscillations in darkness, the broad frequency-band rotatory test quantified the loss of peripheral vestibular function and was able to detect the side of the lesion in eight of nine patients.     

Conductive hearing loss assessment in children with otitis media with effusion. A comparison of pure tone and BERA results

A comparison between pure-tone audiometry and brainstem electric response audiometry was made in 25 children with a conductive hearing loss due to otitis media with effusion. Pure-tone audiometry, including bone and air-conduction thresholds, was recorded using standard procedures. BERA was used to construct a latency-intensity function and from this the conductive hearing loss could be estimated. For all frequencies except for 2000 Hz a good correlation was found between the conductive loss in the pure-tone audiogram and the conductive loss as estimated by BERA. The moderate correlation for 2000 Hz is due to a 'Carhart'-notch-like phenomenon in the pure-tone audiogram.     

Prevention and management of hearing loss in syndromic craniosynostosis: A case series

ObjectiveTo assess the audiological profile in a cohort of children affected by syndromic craniosynostosis.MethodsEleven children with Apert syndrome (n = 4), Saethre-Chotzen syndrome (n = 3), Muenke syndrome (n = 2), Crouzon syndrome (n = 1) and Pfeiffer syndrome type 1 (n = 1) were submitted to a complete audiologic evaluation including otoscopy, pure-tone audiometry, tympanometry and acoustic reflex testing, ABR, otoacustic emissions, temporal bone High Resolution CT (HRCT) scan. The main outcome measures were prevalence, type and severity of hearing loss, prevalence of chronic otitis media, correlation with the time of first surgical correction.ResultsSeven of 11 patients (64%) presented hearing loss (HL), conductive in 3/7 patients (43%) and mixed in 4/7 (57%). No patients showed a purely sensorineural HL. All hearing impaired patients displayed middle ear disorders: the patients with conductive HL had otitis media with effusion (OME) and 3/4 patients with mixed HL showed tympanic alterations or cholesteatoma. A bilateral vestibular aqueduct enlargement was detected by HRCT scan in one normal hearing patient. The ABRs resulted normal in all cases.ConclusionOur study confirms the high prevalence of otologic diseases in such patients. In contrast with previous studies, middle ear disorders were responsible for the hearing impairment also in patients with mixed HL due to secondary inner ear damage. These findings restate the necessity of a close audiologic follow-up. We did not detect the specific ABR abnormalities previously reported, possibly because of an early correction of the cranial vault malformations.     

强直性脊柱炎患者的听力学及抗膜迷路蛋白抗体的检测

目的 对强直性脊柱炎（ａｎｋｙｌｏｓｉｎｇ ｓｐｏｎｄｙｌｉｔｉｓ,ＡＳ）患者进行听力学检测并分析听力减退的特点。方法 采用问卷调查、临床耳鼻咽喉科检查、听力学测试、抗膜迷路抗体检查、血清免疫学检查方法,对确诊为ＡＳ的３４例（６８耳）患者的临床资料加以分析。结果 ３４例中主诉听力减退１１例,纯音测听发现听力减退２４例（４１耳）,占６０．３％（４１／６８）,２耳见鼓膜穿孔为混合性聋,３９耳为感生聋,     

Audiologic and otologic phenotype in children with Duane's Retraction Syndrome: A rare ophthalmologic disorder

ObjectiveThe focus of this study was to evaluate the prevalence, type, and severity of hearing impairment in patients with Duane's Retraction Syndrome and to relate these measures to patient demographics and other otologic and audiologic factors.Study designRetrospective AudGen Database analysisSettingTertiary academic referral centerPatientsPediatric patients in AudGenDB with a diagnosis of Duane's Retraction Syndrome (DRS).InterventionsAppropriate audiologic, otologic, and demographic data were recorded.Main outcome measureSeventy-nine patients (n = 79) met inclusion criteria. The first encounter with available audiometric data or the first encounter with hearing loss were documented. Audiograms were stratified by type and severity of hearing loss, and common associated medical issues were documented.Results57 children had normal hearing; 22 had hearing loss. 9 ears had pure conductive hearing loss, 1 had pure sensorineural, 14 ears had components of both, and 79 had hearing loss that could not be specified. Multivariate regression revealed episodes of chronic otitis and craniofacial anomalies are associated with worse hearing loss.ConclusionThis study presents a detailed characterization of hearing loss in patients with Duane's retraction syndrome. Conductive and sensorineural hearing loss are both prevalent among these children. Careful and early audiologic evaluation of all patients with DRS is important.     

Perilymphatic fistulas in children: rationale for therapy

We report 26 consecutive patients (32 ears) who were identified in a 2 year period (July 1, 1985-June 30, 1987) with unexplained sudden, fluctuating, or progressive sensorineural hearing loss (SNHL). All patients underwent an exploratory tympanotomy and a perilymphatic fistula was identified in 13 patients (14 ears). The mean change of 14 +/- 27 dB in speech reception threshold before and after surgery was significant at p = 0.08 among children with fistula and ranged from -30 to 80 dB. In children with sudden, progressive or fluctuating SNHL and multiple sensory deficits, including blindness or contralateral SNHL, or prior head trauma, prompt surgical exploration is mandatory. Additionally, the aggressive management of otitis media with effusion is essential in such patients to minimize fluctuations in hearing caused by superimposed conductive hearing loss. Caution must be exercised to separate fluctuating hearing loss from fluctuations in audiologic testing.     

Speech evoked auditory brainstem response findings in children with epilepsy

Objectives

Children with epilepsy are at a considerable risk of cognitive impairment and school failure. Previous studies have typically documented abnormal responses in children with epilepsy at cortical level using speech stimuli. Recent studies reported that abnormal neural encoding of a speech syllable could be detected at the level of the brainstem using speech-evoked auditory brainstem response (ABR). The aim of this study is to investigate speech-evoked (ABR) results in children with epilepsy.

Methods

The study group consisted of 38 recently diagnosed epileptic children; none of them has received antiepileptic therapy. They were 22 males and 16 females with age 9.1 ± 3.1 years. The control group consisted of 38 healthy normal hearing children with matched age and gender distribution. All subjects underwent full history taking, basic audiologic evaluation including pure-tone, speech audiometry and immittance testing. Click ABR response was recorded monaurally from both ears at 90 dB nHL then speech ABR was recorded monaurally from each ear at 80 dB SPL.

Results

Though the study group disclosed normal click ABR compared to age matched normative values, speech-evoked ABR revealed a delayed waves V and A latencies in both ears. These findings reflect abnormal neural encoding of speech at the level of brainstem. The younger the age of epileptic child the more prolonged wave A latency and increased V/A inter-latency values.

Conclusions

Speech-evoked ABR results denote abnormal timing in the brainstem; such brainstem abnormality could be detected by speech evoked ABR rather than conventional click evoked ABR.