Effect of acoustic features on discrimination ability in individuals with auditory neuropathy spectrum disorder: an electrophysiological and behavioral study.

PURPOSE: The present study aimed to investigate the discrimination ability for acoustic cues in individuals with auditory neuropathy spectrum disorder (ANSD) using both behavioral and neural measures and to compare the result with normal hearing individuals. METHODS: Four naturally produced syllables /ba/, /da/, /ma/ and /pa/ were used to study discrimination skills. They were combined in pairs such that the two syllables differ in acoustic features, that is place (/ba/-/da/), manner (/ba/-/ma/) and voicing (/ba/-/pa/) cues. Thirty individuals with ANSD and 30 individuals with normal hearing sensitivity were the participants. Syllable discrimination skill was assessed using behavioral (reaction time, sensitivity and D-prime) and neural (P300) measures. RESULTS: There was prolongation in latency and reduction in amplitude of P300 in individuals with ANSD compared to individuals with normal hearing sensitivity. Individuals with ANSD showed better discrimination skill for stimulus pairs differing in the manner followed by place and the least perceived was voicing information. CONCLUSION: Discrimination ability of individuals with ANSD is found to be affected as evident on behavioral and neural measures. The discrimination ability varies with acoustic features of speech.

Peripheral and central hearing impairment and their relationship with cognition: a review.

Objective: To consider the relationships between both peripheral and central hearing impairment and cognition. Design: Narrative review. Study sample: Numerous studies exploring the relationship between hearing impairment and cognitive function, particularly in an older population. Results: In addition to the well-documented relationship between peripheral hearing loss and cognition highlighted in previous comprehensive reviews, there is also some evidence to suggest that there is a relationship between central hearing impairment and cognition. Further research is required to better understand this relationship and its effects on hearing aid benefit in people with both peripheral hearing loss and central hearing impairment. Conclusions: To fully understand the relationship between hearing impairment and cognitive impairment, not only peripheral but central hearing needs to be considered. Such knowledge could be of benefit in the clinical management of people with both peripheral hearing loss and central hearing impairment.

Cortical processing of speech in individuals with auditory neuropathy spectrum disorder.

OBJECTIVE: Auditory neuropathy spectrum disorder (ANSD) is a condition where cochlear amplification function (involving outer hair cells) is normal but neural conduction in the auditory pathway is disordered. This study was done to investigate the cortical representation of speech in individuals with ANSD and to compare it with the individuals with normal hearing. DESIGN: Forty-five participants including 21 individuals with ANSD and 24 individuals with normal hearing were considered for the study. Individuals with ANSD had hearing thresholds ranging from normal hearing to moderate hearing loss. Auditory cortical evoked potentials-through odd ball paradigm-were recorded using 64 electrodes placed on the scalp for /ba/-/da/ stimulus. Onset cortical responses were also recorded in repetitive paradigm using /da/ stimuli. Sensitivity and reaction time required to identify the oddball stimuli were also obtained. RESULT: Behavioural results indicated that individuals in ANSD group had significantly lower sensitivity and longer reaction times compared to individuals with normal hearing sensitivity. Reliable P300 could be elicited in both the groups. However, a significant difference in scalp topographies was observed between the two groups in both repetitive and oddball paradigms. Source localization using local auto regressive analyses revealed that activations were more diffuses in individuals with ANSD when compared to individuals with normal hearing sensitivity. CONCLUSION: Results indicated that the brain networks and regions activated in individuals with ANSD during detection and discrimination of speech sounds are different from normal hearing individuals. In general, normal hearing individuals showed more focused activations while in individuals with ANSD activations were diffused.

Effectiveness of low-cut modified amplification strategy and channel-free hearing aid in individuals with auditory neuropathy spectrum disorder.

OBJECTIVE: The present study attempted to compare the aided benefit using low-cut modified amplification and channel-free hearing aids in individuals with auditory neuropathy spectrum disorder (ANSD). It was also attempted to determine these effects in good and poor performers with ANSD. DESIGN: Cross-sectional within group pretest, post-test design. STUDY SAMPLE: Twenty-five individuals with acquired ANSD were selected for the study. The study sample included 11 males and 14 females between the age ranges of 17-40 years (mean age of 24.6 years). RESULTS: The results of the repeated measures analysis of variance (ANOVA) showed that aided benefit was significantly higher with the channel-free hearing aid. Mixed ANOVA results showed that the improvement was more in good performers than poor performers with ANSD. Multiple regression analyses showed that speech identification scores are a strong predictor of aided benefit. CONCLUSIONS: The results of the present study suggest that channel-free hearing aids and low-cut modified amplification can be used as an efficient alternative technique during hearing aid fitting for individuals with ANSD. However, further evidence-based studies on a larger group are essential to validate the results.

Deep band modulated phrase perception in quiet and noise in individuals with auditory neuropathy spectrum disorder and sensorineural hearing loss.

CONTEXT: Deep band modulation (DBM) improves speech perception in individuals with learning disability and older adults, who had temporal impairment in them. However, it is unclear on perception of DBM phrases at quiet and noise conditions in individuals with auditory neuropathy spectrum disorder (ANSD) and sensorineural hearing loss (SNHL), as these individuals suffer from temporal impairment. AIM: The aim is to study the effect of DBM and noise on phrase perception in individuals with normal hearing, SNHL, and ANSD. SETTINGS AND DESIGN: A factorial design was used to study deep-band-modulated phrase perception in quiet and at noise. MATERIALS AND METHODS: Twenty participants in each group (normal, SNHL, and ANSD) were included to assess phrase perception on four lists of each unprocessed (UP) and DBM phrases at different signal-to-noise ratios (SNRs) (-1, -3, and -5 dB SNR), which were presented at most comfortable level. In addition, a temporal processing was determined by gap detection threshold test. STATISTICAL ANALYSIS: A mixed analysis of variance was used to investigate main and interaction effects of conditions, noise, and groups. Further, a Pearson product moment correlation was used to document relationship between phrase perception and temporal processing among study participants in each experimental condition. RESULTS: In each group, a significant improvement was observed in DBM phrase perception over UP phrase recognition in quiet and noise conditions. Although a significant improvement was observed, the benefit of recognition from DBM over UP is negligible at -5 dB SNR in both SNHL and ANSD groups. In addition, as expected, a significant improvement in phrase perception in each condition was found in normal hearing than SNHL followed by ANSD. Further, in both atypical groups, a strong negative correlation was found between phrase perception and gap detection threshold in each of the experimental condition. CONCLUSION: This is to conclude that temporal envelope cues from DBM were made available for phrase perception in those individuals who have temporal impairment.

Acquired auditory neuropathy spectrum disorder after an attack of chikungunya: case study.

Auditory neuropathy spectrum disorder (ANSD) is a retrocochlear disorder in which the cochlear functioning is normal but the transmission in the auditory neural pathway is affected. The present study reports of a 14-year-old teenager with acquired ANSD after an attack of chikungunya. He reported symptoms of difficulty in understanding speech, tinnitus and vertigo when exposed to loud sounds. The audiological characteristics suggested auditory neuropathy spectrum disorder with raising audiogram configuration. The results of tinnitus evaluation showed low-pitched tinnitus and it was persistent causing significant handicap to him based on self report tinnitus handicap questionnaire results. The results of depression, anxiety and stress scale also suggested symptoms of mild depression and anxiety. Chikungunya virus is suspected to be neurotropic in nature which can damage auditory nerve cells and may have caused ANSD. The result also shows presence of tullio's phenomenon and absence of cervical vestibular evoked myogenic potentials suggesting damage to the vestibular neuronal system. The possible pathophysiology of chikungunya virus causing ANSD and vestibular symptoms needs to be explored further in future studies.

Parents' perspectives on the dilemmas with intervention for infants with auditory neuropathy spectrum disorder: A qualitative study.

OBJECTIVE: This paper explores parental experiences of choices surrounding auditory management and language and communication development for infants and children with auditory neuropathy spectrum disorder (ANSD) in the light of the heterogeneity of condition, a poor evidence base for best outcomes in relation to management options, and the scarcity of data rooted in parent and family experience. DESIGN: Qualitative narrative study. STUDY SAMPLE: Twenty-five parents of 21 children (aged four months to six years) identified with ANSD through the newborn hearing screening programme. RESULTS: Families identify barriers to early management due to conflicting expert opinions and ANSD-specific challenges with diagnosis and prognosis in infants, and share their accounts on their own evaluations of intervention benefit in their children. CONCLUSIONS: The results are of relevance to the clinicians and other professionals involved in early intervention, management, and support of infants with ANSD.

The correlation between ECochG parameters and early auditory behavior after cochlear implantation in children.

OBJECTIVE: The individual outcome after cochlear implantation in children with auditory synaptopathy/neuropathy (AS/AN) is difficult to predict. A tool for preoperative assessment would be helpful for counseling parents. This study evaluates the outcome after CI in children with AS/AN and with sensorineural hearing loss (SNHL), and correlates it with the preoperative ECochG results in order to find specific parameters of prognostic value. DESIGN: The improvement of auditory behavior after CI was retrospectively assessed using the LittlEARS questionnaire and quantified in a score (LS). This score was correlated with the CAP/SP ratio in the preoperative ECochG. The score was further correlated with the patient's age six months following CI. STUDY SAMPLE: Nine children with AS/AN were compared to nine children with SNHL. RESULTS: Both groups showed a significant improvement in LS following CI. There was a significant positive correlation between the CAP/SP ratio and the improvement in LS in all children. The correlation between age and LS was significantly negative in the SNHL group and positive in the AS/AN group. CONCLUSION: All children with AS/AN and SNHL benefit to a similar extent from CI. The preoperatively assessed CAP/SP ratio has a prognostic value for the development of auditory behavior following CI.

The prevalence of peripheral and central hearing impairment and its relation to cognition in older adults.

Age-related hearing loss (ARHL) and dementia are two highly prevalent conditions in the adult population. Recent studies have suggested that hearing loss is independently associated with poorer cognitive functioning. The aim of this study was to evaluate the prevalence of ARHL and cognitive impairment in a large sample of subjects older than 65 years and to correlate hearing function with cognitive function. A total of 488 subjects older than 65 years (mean age 72.8 years) participating in the Great Age Study underwent a complete audiological, neurological and neuropsychological evaluation as part of a multidisciplinary assessment. The prevalence of a hearing loss greater than 25 dB HL was 64.1%, of Central Auditory Processing Disorder (CAPD) was 14.3 and 25.3% of the subjects reported a hearing handicap as reported on the Hearing Handicap Inventory for the Elderly Screening Version questionnaire. Multiple logistic regression analysis corrected for gender, age and education duration showed that mild cognitive impairment (MCI) was significantly associated with hearing impairment (CAPD and hearing threshold; odds ratio 1.6, p = 0.05) and that Alzheimer's disease (AD) was significantly associated with CAPD (odds ratio 4.2, p = 0.05). Given that up to 80% of patients affected by MCI convert to AD, adding auditory tests to a screening cognitive battery might have value in the early diagnosis of cognitive decline.

Vestibular involvement in peripheral neuropathy: a review.

OBJECTIVE: This paper reviews the current literature on involvement of the vestibular division of the eighth cranial nerve in peripheral neuropathies. The literature abounds with references to auditory neuropathy, which is frequently related to more generalized neuropathies, but there is a marked paucity of work regarding vestibular neuropathy. A brief overview of neuropathies and the anatomy of the vestibulocochlear nerve provide the background for a review of the literature of vestibular nerve involvement in a range of neuropathies. DESIGN: A literature search including textbooks, and peer-reviewed published journal articles in online bibliographic databases was conducted. STUDY SAMPLE: Two databases for medical research were included in this review. RESULTS: The review of the literature indicates that vestibular involvement is a common and consistent finding in many peripheral neuropathies of different aetiologies. Specifically, if patients present unsteadiness/ataxia out of proportion to objective signs of somatosensory loss or muscle weakness. CONCLUSION: This review concludes that vestibular neuropathy, is common in peripheral neuropathy and should be identified to optimize patient management and rehabilitation.

Effect of companding on speech recognition in quiet and noise for listeners with ANSD.

OBJECTIVE: The present study assesses the effect of companding on speech perception in quiet and noise for listeners with auditory neuropathy spectrum disorder (ANSD). DESIGN: Speech perception was assessed using speech reception threshold in noise (SRTn) for sentences and consonant identification in quiet and at different signal-to-noise ratios (15, 10, 5, and 0 dB SNR). STUDY SAMPLE: Ten ANSD listeners and normal-hearing listeners participated in the study. RESULTS: ANSD listeners required significantly higher SRTn when compared to the normal-hearing listeners. Companding reduced SRTn more significantly in listeners with ANSD, but for normal-hearing listeners there was only a marginal reduction. In the consonant identification task, ANSD listeners performed poorer than normal-hearing listeners in quiet and noise. Companding improved consonant identification in quiet and at 15 dB SNR for listeners with ANSD, whereas no improvement was observed in normal-hearing listeners. CONCLUSION: Results of the present study demonstrate that companding improved speech perception in quiet and noise for ANSD listeners. The amount of improvement is higher at higher SNRs. In normal-hearing listeners, companding showed marginal improvement in both quiet and noise. The findings are discussed for rehabilitation of ANSD listeners by hearing aids which incorporate the companding strategy.

Impact of the presence of auditory neuropathy spectrum disorder (ANSD) on outcomes of children at three years of age.

OBJECTIVE: To determine the influence of the presence of auditory neuropathy spectrum disorder (ANSD) on speech, language, and psycho-social development of children at three years of age. DESIGN: A population-based, longitudinal study was performed on outcomes of children with hearing impairment (LOCHI) in Australia. The demographic characteristics of the children were described, and their developmental outcomes were evaluated at three years of age. Performance of children with ANSD was compared with that of children without ANSD in the LOCHI study. STUDY SAMPLE: There were 47 children with ANSD in the study sample. RESULTS: Sixty-four percent of children with ANSD have hearing sensitivity loss ranging from mild to severe degree, and the remaining have profound hearing loss. At three years, 27 children used hearing aids, 19 used cochlear implants, and one child did not use any hearing device. Thirty percent of children have disabilities in addition to hearing loss. On average, there were no significant differences in performance level between children with and without ANSD. Also, the variability of scores was not significantly different between the two groups. CONCLUSIONS: There was no significant difference in performance levels or variability between children with and without ANSD, both for children who use hearing aids, and children who use cochlear implants.

Spatial hearing in a child with auditory neuropathy spectrum disorder and bilateral cochlear implants.

OBJECTIVE: The neural dys-synchrony associated with auditory neuropathy spectrum disorder (ANSD) causes a temporal impairment that could degrade spatial hearing, particularly sound localization accuracy (SLA) and spatial release from masking (SRM). Unilateral cochlear implantation has become an accepted treatment for ANSD but treatment options for the contralateral ear remain controversial. We report spatial hearing measures in a child with ANSD before and after receiving a second cochlear implant (CI). STUDY SAMPLE: An 11-year-7-month old boy with ANSD and expressive and receptive language delay received a second CI eight years after his first implant. DESIGN: The SLA and SRM were measured four months before sequential bilateral CIs (with the contralateral ear plugged and unplugged), and after nine months using both CIs. RESULTS: Testing done before the second CI, with the first CI alone, suggested that residual hearing in the contralateral ear contributed to sound localization accuracy, but not word recognition in quiet or noise. Nine-months after receiving a second CI, SLA improved by 12.76° and SRM increased to 3.8-4.2 dB relative to pre-operative performance. Results were compared to published outcomes for children with bilateral CIs. CONCLUSIONS: The addition of a second CI in this child with ANSD improved spatial hearing.

Does cochlear implantation improve speech recognition in children with auditory neuropathy spectrum disorder? A systematic review.

OBJECTIVE: Cochlear implantation (CI) is a standard treatment for severe-profound sensorineural hearing loss (SNHL). However, consensus has yet to be reached on its effectiveness for hearing loss caused by auditory neuropathy spectrum disorder (ANSD). This review aims to summarize and synthesize current evidence of the effectiveness of CI in improving speech recognition in children with ANSD. DESIGN: Systematic review. STUDY SAMPLE: A total of 27 studies from an initial selection of 237. RESULTS: All selected studies were observational in design, including case studies, cohort studies, and comparisons between children with ANSD and SNHL. Most children with ANSD achieved open-set speech recognition with their CI. Speech recognition ability was found to be equivalent in CI users (who previously performed poorly with hearing aids) and hearing-aid users. Outcomes following CI generally appeared similar in children with ANSD and SNHL. Assessment of study quality, however, suggested substantial methodological concerns, particularly in relation to issues of bias and confounding, limiting the robustness of any conclusions around effectiveness. CONCLUSIONS: Currently available evidence is compatible with favourable outcomes from CI in children with ANSD. However, this evidence is weak. Stronger evidence is needed to support cost-effective clinical policy and practice in this area.

Central auditory maturation and behavioral outcome in children with auditory neuropathy spectrum disorder who use cochlear implants.

OBJECTIVE: We examined cortical auditory development and behavioral outcomes in children with ANSD fitted with cochlear implants (CI). DESIGN: Cortical maturation, measured by P1 cortical auditory evoked potential (CAEP) latency, was regressed against scores on the infant toddler meaningful auditory integration scale (IT-MAIS). Implantation age was also considered in relation to CAEP findings. STUDY SAMPLE: Cross-sectional and longitudinal samples of 24 and 11 children, respectively, with ANSD fitted with CIs. RESULTS: P1 CAEP responses were present in all children after implantation, though previous findings suggest that only 50-75% of ANSD children with hearing aids show CAEP responses. P1 CAEP latency was significantly correlated with participants' IT-MAIS scores. Furthermore, more children implanted before age two years showed normal P1 latencies, while those implanted later mainly showed delayed latencies. Longitudinal analysis revealed that most children showed normal or improved cortical maturation after implantation. CONCLUSION: Cochlear implantation resulted in measureable cortical auditory development for all children with ANSD. Children fitted with CIs under age two years were more likely to show age-appropriate CAEP responses within six months after implantation, suggesting a possible sensitive period for cortical auditory development in ANSD. That CAEP responses were correlated with behavioral outcome highlights their clinical decision-making utility.

Auditory neuropathy spectrum disorder in the wider health context: experiences of parents whose infants have been identified through newborn hearing screening programme.

OBJECTIVE: This paper presents an insight into the parental experiences of how parents made sense of having their child identified with auditory neuropathy spectrum disorder (ANSD), given the broader context of their child's other health issues. DESIGN: Qualitative narrative study. STUDY SAMPLE: Twenty-one families participated whose children had been identified with ANSD through the newborn hearing screening programme. RESULTS: The majority of parents in the sample were overwhelmed with perinatal health issues and initially gave the diagnosis of ANSD very low priority. CONCLUSIONS: An understanding of parents' perspective is particularly relevant to everyone involved in early support and management of infants with ANSD.

Speech perception abilities for spectrally modified signals in individuals with auditory dys-synchrony.

OBJECTIVE: The objective of the study was to determine the speech perception abilities for spectrally modified speech signals in individuals with auditory dys-synchrony. STUDY SAMPLE: The speech identification scores of 30 normal hearing and 12 individuals diagnosed as having auditory dys-synchrony were studied. DESIGN: Phonemically balanced words in Kannada developed by Yathiraj and Vijayalakshmi (2005) were presented unfiltered and filtered at 1700 Hz low-pass and 1700 Hz high-pass cut-off frequencies, and speech identification performance was assessed. RESULTS: Results revealed that there is a highly significant difference in speech identification scores for unfiltered and low-pass filtered words. This difference could be attributed to the physiological coding deficits of low frequency information which are usually coded by phase locked responses in auditory nerve fibers ( Sek & Moore, 1995 ). CONCLUSIONS: Thus, low-pass filtered words can be used as an effective tool to identify individuals with auditory dys-synchrony, especially those who have good speech identification scores in quiet.

Cortical maturation and behavioral outcomes in children with auditory neuropathy spectrum disorder.

UNLABELLED: OBJECTIVE. Auditory neuropathy spectrum disorder (ANSD) affects approximately 10% of patients with sensorineural hearing loss. While many studies report abnormalities at the level of the cochlea, auditory nerve, and brainstem in children with ANSD, much less is known about their cortical development. We examined central auditory maturation in 21 children with ANSD. DESIGN. Morphology, latency and amplitude of the P1 cortical auditory evoked potential (CAEP) were used to assess auditory cortical maturation. Children's scores on a measure of auditory skill development (IT-MAIS) were correlated with CAEPs. Study Sample. Participants were 21 children with ANSD. All were hearing aid users. RESULT: Children with ANSD exhibited differences in central auditory maturation. Overall, two-thirds of children revealed present P1 CAEP responses. Of these, just over one third (38%) showed normal P1 response morphology, latency and amplitude, while another third (33%) showed delayed P1 response latencies and significantly smaller amplitudes. The remaining children (29%) revealed abnormal or absent P1 responses. Overall, P1 responses were significantly correlated with auditory skill development. CONCLUSION: Our results suggest that P1 CAEP responses may be: (i) A useful indicator of the extent to which neural dys-synchrony disrupts cortical development, (ii) A good predictor of behavioral outcome in children with ANSD.

Perception of temporally modified speech in auditory neuropathy.

OBJECTIVE: Disrupted auditory nerve activity in auditory neuropathy (AN) significantly impairs the sequential processing of auditory information, resulting in poor speech perception. This study investigated the ability of AN subjects to perceive temporally modified consonant-vowel (CV) pairs and shed light on their phonological awareness skills. DESIGN: Four Arabic CV pairs were selected: /ki/-/gi/, /to/-/do/, /si/-/sti/ and /so/-/zo/. The formant transitions in consonants and the pauses between CV pairs were prolonged. Rhyming, segmentation and blending skills were tested using words at a natural rate of speech and with prolongation of the speech stream. STUDY SAMPLE: Fourteen adult AN subjects were compared to a matched group of cochlear-impaired patients in their perception of acoustically processed speech. RESULTS: The AN group distinguished the CV pairs at a low speech rate, in particular with modification of the consonant duration. Phonological awareness skills deteriorated in adult AN subjects but improved with prolongation of the speech inter-syllabic time interval. 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.

Music and psychoacoustic perception abilities in cochlear implant users with auditory neuropathy spectrum disorder.

OBJECTIVE: Auditory neuropathy spectrum disorder (ANSD) is a condition wherein the pre-neural or cochlear outer hair cell activity is intact, but the neural activity in the auditory nerve is disrupted. Cochlear implant (CI) can be beneficial for subjects with ANSD; however, little is known about the music perception and psychoacoustic abilities of CI users with ANSD. Music perception in CI users is a multidimensional and complex ability requiring the contribution of both auditory and nonauditory abilities. Even though auditory abilities lay the foundation, the contribution of patient-related variables such as ANSD may affect the music perception. This study aimed to evaluate the psychoacoustic and music perception abilities of CI recipients with ANSD. STUDY DESIGN: Twelve CI users with ANSD and twelve age- and gendermatched CI users with sensorineural hearing loss (SNHL) were evaluated. Music perception abilities were measured using the Turkish version of the Clinical Assessment of Music Perception (T-CAMP) test. Psychoacoustic abilities were measured using the spectral ripple discrimination (SRD) and temporal modulation transfer function (TMTF) tests. In addition, the age of diagnosis and implantation was recorded. RESULTS: Pitch direction discrimination (PDD), timbre recognition, SRD, and TMTF performance of CI users with ANSD were concordant with those reported in previous studies, and differences between ANSD and SNHL groups were not statistically significant. However, the ANSD group performed poorly compared with SNHL group in melody recognition subtest of T-CAMP, and the difference was statistically significant. CONCLUSION: CI can prove beneficial for patients with ANSD with respect to their music and psychoacoustic abilities, similar to patients with SNHL, except for melody recognition. Recognition of melodies requires both auditory and non-auditory abilities, and ANSD may have an extensive but subtle effect in the life of CI users.