Prashanth Prabhu

Audiological profiling of 198 individuals with auditory neuropathy spectrum disorder

Abstract Objective: The study aimed at exploring the audiological characteristics and the relationship between speech identification scores with cortical evoked potential measures and hearing aid benefit in individuals with auditory neuropathy spectrum disorder (ANSD). Study design: We initiated a retrospective study of patients who were diagnosed as having ANSD. In 198 patients with ANSD, patient history, risk factors, degree and configuration of hearing loss, speech identification scores in quiet and noise, otoacoustic emissions (OAE), immittance evaluation, auditory brainstem responses (ABR), long latency responses (LLR) and hearing aid benefit were assessed. Results: The results showed that the majority of the patients had bilateral ANSD with a female to male ratio of 1.25:1 with the majority having a rising configuration of hearing loss. OAEs were present in most with absent stapedial reflexes and ABR. The study also showed that individuals with ANSD do obtain benefit from hearing aids and it is related to the presence of LLR. Conclusions: The present study emphasizes the audiological characteristics of a large group with ANSD. Among the management options, hearing aids were found to be useful in only a few of the patients and other rehabilitation options, such as cochlear implants, need to be explored in future studies. Currently, the determining factors for benefit with hearing aid are speech identification scores and cortical auditory evoked potentials.

Predisposing Factors in Individuals with Late-Onset Auditory Dys-Synchrony

The aim of the study was to find possible predisposing factors that would result in the condition of late-onset auditory dys-synchrony. A detailed case history of the possible risk factors and the symptoms were recorded from two groups. The two groups consisted of 30 participants each diagnosed as late-onset auditory dys-synchrony and late onset cochlear hearing loss respectively. The results showed that factors such as low socioeconomic status, exposure to toxic chemicals, family history of the condition, and onset at the pubertal age could be the possible predisposing factors of late-onset auditory dys-synchrony. Most of the participants of the study with auditory dys-synchrony reported difficulty in understanding speech, and tinnitus was found to be one of the major complaints. The study shows that the predisposing factors for late-onset auditory dys-synchrony were not similar to those reported in the literature for congenital auditory dys-synchrony. Future studies should focus on understanding

Prevalence and characteristics of tinnitus in individuals with auditory neuropathy spectrum disorder

Abstract Objective: Tinnitus is one of the reported complaints in individuals with Auditory Neuropathy Spectrum Disorder (ANSD). The study highlights the prevalence of tinnitus and its characteristics in individuals with ANSD. Study design: The study consisted of 95 patients with tinnitus out of 149 individuals with ANSD. The overall prevalence, laterality and gender effect was studied in these 95 patients. The study also reports on the subjective nature of tinnitus in 23 subjects and its relationship with the configuration of the audiogram. Results: The prevalence of tinnitus was found to be around 67%, mostly bilateral (89.5%) and seen more often in females (70.52%). The subjective pitch was low-pitched in individuals with low frequency hearing loss and the perceived pitch was high with a flat configuration of loss. Conclusion: Our results show prevalence of tinnitus is more than 50% in individuals with ANSD and the tinnitus matched with the individuals frequency of maximal hearing loss.

Time–frequency analysis of transient evoked-otoacoustic emissions in individuals with auditory neuropathy spectrum disorder

The aim of the study was to describe and quantify the cochlear active mechanisms in individuals with Auditory Neuropathy Spectrum Disorders (ANSD). Transient Evoked Otoacoustic Emissions (TEOAEs) were recorded in 15 individuals with ANSD and 22 individuals with normal hearing. TEOAEs were analyzed by Wavelet transform method to describe and quantify the characteristics of TEOAEs in narrow-band frequency regions. It was noted that the amplitude of TEOAEs was higher and latency slightly shorter in individuals with ANSD compared to normal hearing individuals at low and mid frequencies. The increased amplitude and reduced latencies of TEOAEs in ANSD group could be attributed to the efferent system damage, especially at low and mid frequencies seen in individuals with ANSD. Thus, wavelet analysis of TEOAEs proves to be another important tool to understand the patho-physiology in individuals with ANSD.

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

Abstract 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 21 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 (15). 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. Sumario Objetivo. El objetivo de este estudio fue determinar las habilidades de percepción del lenguaje con señales de lenguaje espectralmente modificadas en sujetos con disincronía auditiva. Muestra de Estudio. Se estudiaron las puntuaciones de identificación de lenguaje de 30 normo-oyentes y de 12 individuos con diagnóstico de disincronía auditiva. Diseño. Se presentaron palabras fonéticamente balanceadas en Kannada, desarrolladas por 21 sin filtro y con filtro pasa/bajo de 1700 Hz y filtro pasa/alto de corte de frecuencias de 1700 Hz, y se evaluó el rendimiento en la identificación del lenguaje. Resultados. Los resultados revelan que existe una diferencia significativa muy alta en las puntuaciones de identificación de lenguaje para palabras no filtradas y con filtro pasa bajo. Esta diferencia puede ser atribuida al déficit fisiológico de codificación de la información e bajas frecuencias, que usualmente se codifican como respuestas con bloqueo de fase en las fibras del nervio auditivo (15). Conclusiones. Por lo tanto, las palabras filtradas pasa bajo pueden usarse como una herramienta útil para identificar personas con disincronía auditiva, especialmente aquellas que tienen buenas puntuaciones para la identificación de lenguaje en silencio.

Amplification strategy to enhance speech perception in individuals with auditory neuropathy spectrum disorder

Objective: The present study was conducted to determine if low-cut modified amplification improved aided speech perception compared to standard NAL-NL1 prescriptive amplification in individuals with ANSD. The study further aimed to check the influence of the number of channels in a hearing aid on speech perception with low-cut modification of amplification. Study design: A total of 22 individuals with ANSD in the age range 15–42 years were recruited for the study. The unaided and aided speech identification scores were obtained with standard amplification and low-cut amplification settings in both a four- and a 16-channel digital hearing aid. Results: The results showed that low-cut amplification was slightly better than standard amplification for aided speech perception. Such an improvement could be attributed to the elimination of upward spread of masking during low-cut modification of amplification. In addition, improvement was greater with a four-channel hearing aid compared to a 16-channel hearing aid. Conclusions: The use of low-cut amplification with a low number of channels in the hearing aid for individuals with ANSD is recommended. However, further studies are essential to determine whether the slight improvement in aided scores with a low-cut fitting strategy leads to actual improvement in quality of life.

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

Abstract 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.

Effectiveness of Low Cut Modified Amplification using Receiver in the Canal Hearing Aid in Individuals with Auditory Neuropathy Spectrum Disorder

Introduction  The studies on hearing aid benefit in individuals with auditory neuropathy spectrum disorder (ANSD) shows limited benefit. Low cut modified amplification is found to be effective in few individuals with ANSD. With advancement in technology, receiver in the canal (RIC) hearing aids have proven to be more effective than traditional behind the ear (BTE) hearing aids. Objective  Thus, the present study attempts to determine the effectiveness of low cut modified amplification using RIC and BTE. Method  Twenty participants with ANSD were fitted with BTE and RIC using traditional and low cut modified amplification. We divided them into good and poor performers based on unaided speech identification scores (SIS). We then compared aided SIS and aided benefit across conditions in good and poor performers with ANSD across both conditions using BTE and RIC. Results  The results of the study showed that the aided performance improved with low cut modified amplification in both BTE and RIC hearing aids. The improvement noticed with low-cut modified fitting with RIC was significant in more than BTE, especially in good performers with ANSD. Conclusion  The improved clarity and naturalness of sound with RIC may have led to better aided scores and better acceptance of the hearing aid. Thus, low-cut modified amplification, preferably with RIC, needs to be attempted in fitting individuals with ANSD, especially in those with good unaided SIS in quiet.

Audiological changes over time in adolescents and young adults with auditory neuropathy spectrum disorder

AbstractAuditory neuropathy spectrum disorder (ANSD) describes a condition in which a patient’s otoacoustic emissions (OAE) are (or were at one time) present and auditory brainstem responses (ABR) are abnormal or absent. ANSD is also diagnosed based on the presence of cochlear microphonics and abnormal or absent ABRs with or without abnormalities of OAE. We noted the changes in audiological characteristics over time with respect to pure tone thresholds, OAEs and Speech Identification Scores (SIS) in seven individuals with ANSD. The results indicated that all the individuals with ANSD had decreased SIS over time, whereas there was subsequent reduction in pure tone thresholds only in nine out of fourteen ears. There was absence of OAEs for two individuals in both ears during the follow-up evaluations. There was no regular pattern of changes in pure tone thresholds or SIS across all individuals. This indicates that there may be gradual worsening of hearing abilities in individuals with ANSD. Thus, regular follow-up and monitoring of audiological changes are necessary for individuals with ANSD. Also, longitudinal studies need to be done to further add evidence to the audiological changes over time in individuals with ANSD.

Influence of smoking on contralateral suppression of distortion product otoacoustic emissions

Abstract The present study attempted to determine the influence of smoking on contralateral suppression of distortion product otoacoustic emissions (DPOAE). It was attempted to determine the differences in the amount of contralateral suppression of DPOAE between smokers and non-smokers. In addition, correlation was also determined among duration of smoking, frequency of smoking and number of cigarettes per day on contralateral suppression of DPOAE. The study was carried out on 25 smokers and non-smokers. The results of the study showed that the amount of suppression was reduced in smokers at all the frequencies suggesting an efferent auditory system dysfunction. The increase in the duration of smoking, the frequency of smoking and the number of cigarattes smoked correlated negatively with the amount of suppression. This shows that chronic smoking habits increases the risk of efferent auditory damage. Thus, the present study highlights the ill-effects of smoking on efferent auditory system.