Our study demonstrates the use of a combination of DPOAE and AABR testing ensures high sensitivity and acceptable specificity, and predict the AN profile in NICU babies. Our efforts identified 22 NICU babies with auditory neuropathy who hopefully will benefit from early remediation of their hearing deficit.
Human communication depends mostly on the conversion of ideas into language, involving the interaction among all its components – phonological, semantic, syntactic and pragmatic. Pragmatics studies the relationship between the social meaning of language and its semantic content, expressed by the communicative act itself. Auditory neuropathy spectrum disorder generates a dyssynchrony in nerve conduction, contributing to an impairment in speech perception. In hearing impaired children the language acquisition and development process can be stimulated with intervention. The aim of this study was to present a longitudinal follow-up of the use of pragmatic communication abilities by a child with auditory neuropathy spectrum disorder. The child received speech-language pathology therapy during three years in the Educational Audiology area. Video recordings of spontaneous conversation were made in the beginning of each year. These recordings were transcribed and analyzed according to the verbal communicative abilities protocol. In the initial recording, the most frequent ability presented by the child was the direct response; however these were extended to more complex responses during the intervention. In the last recording the child proposes new topics of discourse, produce narratives and arguments. The emergence of more sophisticated communication skills is justified by the language development, which benefits from language therapy with hearing impaired children. This suggests that, for the case study described, speech-language pathology therapy contributed to the improvement of pragmatic communication abilities.
These results suggest that innovative speech processing strategies which enhance temporal cues may benefit individuals with auditory dys-synchrony.
from the Journal of Laryngology and Otology
This paper has provided an overview of mutation with some of the genes and/or loci discovered to be the cause for auditory neuropathy spectrum disorders (ANSDs). It has been noted that different gene mutations may trigger different pathological changes in patients with this disorder. These discoveries have provided us with vital information as to the sites of pathology in auditory neuropathy spectrum disorders (ANSDs), and the results highlight the heterogeneity of the disorder.
Conclusions: A rehabilitation program for AN should consider temporal modification of speech, training for auditory temporal processing and the use of devices with innovative signal processing schemes. Verbal modifications as well as visual imaging appear to be promising compensatory strategies for remediating the affected phonological processing skills.
from the International Journal of Audiology
OPA1 mutations are known to cause autosomal dominant optic atrophy (ADOA), and some types of OPA1 mutations also cause auditory neuropathy. In the present study, we evaluated the vestibular dysfunction that accompanied auditory neuropathy in a patient with an OPA1 mutation. A caloric test failed to elicit nystagmus or dizziness in either ear. Vestibular evoked myogenic potentials (VEMPs) in the right ear were characterized by a normal biphasic waveform. In contrast, no VEMPs were evoked in the left ear. Model building suggested that the OPA1 mutation, p.R445H, indirectly distorts the catalytic structure of the GTPase reaction center and decreases GTPase activity. The patient complained of instability while walking or moving but thought these symptoms were caused by visual dysfunction. This is the first report of a detailed evaluation of vestibular dysfunction in a patient with an OPA1 mutation. This case suggests that vestibular dysfunction may be involved in motor instability in patients with an OPA1 mutation, even when patients do not complain of vestibular symptoms. Based on this case, we suggest that vestibular evaluation should be performed in auditory neuropathy patients carrying an OPA1 mutation, even if the patients are free of symptoms of vestibular dysfunction.
from the Journal of the Neurological Sciences
In the infants treated in NICU, an incidence of ABR threshold of 50 dBnHL or more was 9.0%, and 6.9% of the infants with the ABR threshold abnormality showed a significant elevation of ABR threshold in their childhood. Factors significantly related to an elevation of ABR threshold were a history of congenital diaphragmatic hernia, severe respiratory disease, and elevation of CRP. In infants with such factors, periodical examination of hearing is required.
Genetic analysis identified five new mutations (a nonsense, a small and a large deletion and two splicing site mutations), and one missense mutation (F1795C) previously described. These results further confirm the role of OTOF gene in auditory neuropathy. In the absence of a context of neurological syndrome, the combination of absent ABR and positive OAE responses should lead to an auditory neuropathy diagnosis and to a mutational screening in OTOF.
Hearing impairment can be caused by a primary lesion to the spiral ganglion neurons (SGNs) with the hair cells kept intact, for example via tumours, trauma or auditory neuropathy. To mimic these conditions in animal models various methods of inflicting damage to the inner ear have been used. However, only a few methods have a selective effect on the SGNs, which is of importance since it might be clinically more relevant to study hearing impairment with the hair cells undamaged. β-Bungarotoxin is a venom of the Taiwan banded krait, which in vitro has been shown to induce apoptosis in neurons, leaving remaining cochlear cells intact. We wanted to create an in vivo rat model of selective damage to primary auditory neurons. Under deep anaesthesia, 41 rats received β-Bungarotoxin or saline to the round window niche. At postoperative intervals between days 3 and 21 auditory brainstem response (ABR) measurement, immunohistochemistry, SGN quantification and cochlear surface preparation were performed. The results in the β-Bungarotoxin-treated ears, as compared with sham-operated ears, show significantly increased ABR thresholds at all postoperative intervals, illustrating a severe to profound hearing loss at all tested frequencies (3.5, 7, 16 and 28 kHz). Quantification of the SGNs showed no obvious reduction in neuronal numbers until 14 days postoperatively. Between days 14 and 21 a significant reduction in SGN numbers was observed. Cochlear surface preparation and immunohistocemhistry showed that the hair cells were intact. Our results illustrate that in vivo application of β-Bungarotoxin to the round window niche is a feasible way of deafening rats by SGN reduction while the hair cells are kept intact.
from Hearing Research
Autosomal dominant optic atrophy (DOA) is a retinal neuronal degenerative disease characterized by a progressive bilateral visual loss. We report on two affected members of a family with dominantly inherited neuropathy of both optic and auditory nerves expressed by impaired visual acuity, moderate pure tone hearing loss, and marked loss of speech perception. We investigated cochlear abnormalities accompanying the hearing loss and the effects of cochlear implantation. We sequenced OPA1 gene and recorded cochlear receptor and neural potentials before cochlear implantation. Genetic analysis identified R445H mutation in OPA1 gene. Audiological studies showed preserved cochlear receptor outer hair cell activities (otoacoustic emissions), and absent or abnormally delayed auditory brainstem responses (ABRs). Trans-tympanic electrocochleography (ECochG) showed prolonged low amplitude negative potentials without auditory nerve compound action potentials. The latency of onset of the cochlear potentials was within the normal range found for inner hair cell summating receptor potentials. The duration of the negative potential was reduced to normal during rapid stimulation consistent with adaptation of neural sources generating prolonged cochlear potentials. Both subjects had cochlear implants placed with restoration of hearing thresholds, speech perception, and synchronous activity in auditory brainstem pathways. The results suggest that deafness accompanying this OPA1 mutation is due to altered function of terminal unmyelinated portions of auditory nerve. Electrical stimulation of the cochlea activated proximal myelinated portions of auditory nerve to restore hearing.
from Brain Research
Permanent Bilateral Sensory and Neural Hearing Loss of Children After Neonatal Intensive Care Because of Extreme Prematurity: A Thirty-Year Study
CONCLUSIONS. Permanent hearing loss remains an adverse outcome of extreme prematurity, complicated by significant delayed-onset and progressive loss. Prolonged supplemental oxygen use is a marker for predicting permanent hearing loss; this requires detailed analysis of the pathophysiologic features, to reduce the prevalence of permanent hearing loss.
Auditory neuropathy/auditory dyssynchrony (AN/AD) has become a well-accepted clinical entity. The combined use of oto-acoustic emissions (OAEs) and auditory brainstem response (ABR) testing in the universal newborn hearing screening (UNHS) has led to the easy recognition of this disorder. Although, we are now able to diagnose AN/AD reliably, little is known about its epidemiology, etiology, and especially the frequency of its occurrence. The primary goal of this study was to determine the frequency of AN/AD in the Western Anatolian region of Turkey. The secondary goal was to compare the detection rate of AN/AD before and after the implementation of the UNHS in the audiology department of Dokuz Eylul University Hospital.
Between 2005 and 2007, among the 23,786 newborns who were screened by automated click evoked oto-acoustic emissions (a-CEOAE) and automated auditory brainstem responses (a-ABRs), 2236 were referred to our department. All necessary audiological tests were performed for all the referred newborns. Among them, babies with deficient or abnormal ABR in combination with normal OAEs were considered as having AN/AD. These babies were evaluated with additional diagnostic audiological tests. Furthermore, comparison of the incidence of children diagnosed with AN/AD before and after the implementation of UNHS in our audiology department was also performed.
Among the referred newborns, 65 had abnormal or deficient ABR test results. Ten of these 65 newborn babies (mean diagnostic age: 5.7 months) with hearing impairment showed electrophysiological test results that were consistent with AN/AD. The frequency of AN/AD in these 65 children with hearing loss was 15.38%. Moreover, the frequency of AN/AD within UNHS was found to be 0.044%. Seven of the 10 babies with AN/AD had hyperbilirubinemia as a risk factor, which is a high rate to be emphasized. On the other hand, the retrospective investigation of children diagnosed with AN/AD in the same audiology department between 1999 and 2005 (i.e. before the implementation of UNHS) revealed only 7 children, with an average diagnostic age of 34 months.
After implementing the UNHS, the incidence of AN/AD in the audiology department increased from 1.16 to 4.13. Furthermore, the age of diagnosis of AN/AD decreased from 34 months to 5.7 months. This study shows that AN/AD, when screened, is a comparatively common disorder in the population of hearing-impaired infants. While newborn hearing screening provides early detection of babies with hearing loss, it also helps to differentiate AN/AD cases when the screening is performed with both a-ABR and automated oto-acoustic emission (a-OAE) tests. Thus, the routine combined use of a-ABR and a-OAE tests in UNHS programs, especially for the high-risk infants, can provide better detection of newborns with AN/AD. Furthermore, hyperbilirubinemia is merely an association and maybe etiologically linked.
Conclusions. This study suggests that the asynchronization of the cochlear afferent pathway may be one mechanism of the etiopathogenesis of auditory neuropathy. Objective. To investigate the characteristics of the SP-AP compound wave and its generating mechanism in patients with auditory neuropathy. Subjects and methods. The electrocochleogram (ECochG) was recorded with external ear canal electrode in patients with auditory neuropathy and normal subjects. The peak-latency, amplitude, and time course of the SP-AP compound wave were measured by using an ‘assessor-blind’ study. The discrepancy between the two groups was evaluated by statistical analysis. Results. The SP-AP compound waveform in the auditory neuropathy patient group was unrepresentative. The transient character of the SP-AP compound wave was more atypical than that for the normal cases. SP dominance (-SP/AP>0.4) appeared. The amplitude of both AP and SP was lower than that of the control group. The width of the SP-AP compound wave at one-third of its peak was greater than that of the control group.
the diagnostic dilemma surrounding the presence of cochlear microphonics (cm) coupled with significantly elevated auditory brainstem response (abr) thresholds in babies failing the newborn hearing screening is highlighted. a case report is presented where initial electo-diagnostic assessment could not help in differentiating between auditory neuropathy/auditory dys-synchrony (an/ad) and sensorineural hearing loss (snhl). in line with the protocol and guidelines provided by the national newborn hearing screening programme in the uk (nhsp) an/ad was suspected in a baby due to the presence of cm at 85 dbnhl along with click evoked abr thresholds of 95 dbnhl in one ear and 100 dbnhl in the other ear. significantly elevated thresholds for 0.5 and 1 khz tone pip abr fulfilled the audiological diagnostic criteria for an/ad. however, the possibility of a snhl could not be ruled out as the 85 dbnhl stimuli presented through inserts for the cm would have been significantly enhanced in the ear canals of the young baby to exceed the threshold level of the abr that was carried out using headphones. snhl was eventually diagnosed through clinical and family history, physical examination and imaging that showed enlarged vestibular aqueducts. presence of cm in the presence of very high click abr thresholds only suggests a pattern of test results and in such cases measuring thresholds for 0.5 and 1 khz tone pip abr may not be adequate to differentiate between snhl and other conditions associated with an/ad. there is a need for reviewing the existing an/ad protocol from nhsp in the uk and new research to establish parameters for cm to assist in the differential diagnosis. a holistic audiological and medical approach is essential to manage babies who fail the newborn hearing screening.
Abstract Neonatal hyperbilirubinemia (NHB) above 20 mg/dl (NHB20) has been shown to increase the risk of hearing impairments. Up to now, audiological findings based on behavioural audiometry (BA), otoacoustic emissions (TEOAE) and auditory brainstem responses (ABR) from children after being diagnosed with NHB20 have not been thoroughly compared to those with lower NHB-levels. We, therefore, aimed to assess the presence and characteristics of auditory dysfunction in children with NHB20. The audiological data of 15 children aged 11 months to 9 years with a NHB level between 22.6 and 45.6 mg/dl and/or MRI-confirmed bilirubin encephalopathy (NHBG) were compared retrospectively to 15 children with NHB levels between 12.5 and 19.4 mg/dl (CG). After matching by weeks of gestation at birth, BA, TEOAE and ABR were performed in all the children. Subsequently the groups were compared. Only two children of the NHBG had consistently normal audiologic findings. Hearing function disorders were detected in 87% (13/15) of the NHBG-children, ranging from total deafness to normal BA, including unilateral and bilateral deafness as well as cochlear hearing loss. Auditory neuropathy/dys-synchrony (AN) was found in a total of eight children (53%) of the NHBG. In addition, it was found that after the occurrence of NHB20, initially detected TEOAE can disappear in some cases. In the comparison group (CG) only two children demonstrated a hearing dysfunction, both of which were cochlear hearing impairments, whereas no child had AN. A bias towards hearing impairments has to be taken into account for both groups. Detailed pedaudiologic testing should be mandatory for all children after the occurrence of NHB20 including follow-up during the first 12 months. Audiological diagnostic work-up in the affected children requires objective investigations of hearing functions, while BA is recommended to evaluate the adequate therapeutic procedure.