Kaushlendra Kumar

Vestibular evoked myogenic potential in noise-induced hearing loss

Noise affects ones hearing as well as balance mechanism. The hearing mechanism of the noise-exposed individuals has been extensively studied. However, in view of the poor research focus on the sacculo-collic reflexes, especially in this study area, the present study was undertaken to examine the vestibular evoked myogenic potentials (VEMP) in subjects with noise-induced hearing loss (NIHL). A total of 30 subjects (55 ears) with NIHL participated in the present study within the age range of 30-40 years. VEMP recordings were done at 99 dBnHL using IHS instrument. The results indicated that as the average pure tone hearing threshold increased, the VEMP latencies were prolonged and peak to peak amplitude was reduced in NIHL subjects. Out of the 55 ears, VEMP was absent in 16 (29.0%) ears. The latency was prolonged and the peak to peak amplitude was reduced in 19 (34.6%) ears. VEMP results were normal in 20 (36.4%) ears. Therefore, VEMP was abnormal or absent in 67% of NIHL subjects in the present study. Hence it can be concluded that the possibility of vestibular dysfunction, specially the saccular pathway, is high in individuals with NIHL. VEMP, a non-invasive and user friendly procedure, can be employed in these individuals to assess sacculo-collic reflex.

Vestibular Evoked Myogenic Potential as a Tool to Identify Vestibular Involvement in Auditory Neuropathy

Abstract Auditory neuropathy is characterized by a unique pattern of hearing loss, absent or severely distorted ABR, preserved OAE, and measurable cochlear microphonics. As the vestibular and cochlear branches are parts of the same fiber bundle system called the vestibulocochlear nerve, it is likely that neuropathy in one (cochlear branch) might also form a feature in the other (vestibular branch). But none of these tests are able to explain the involvement of the vestibular system in these cases. Thus, the present study was undertaken to explore this aspect to determine: (1) the involvement of the vestibular pathway in cases with auditory neuropathy; (2) if there is any relationship between vestibular abnormalities and the symptoms they mimic; and (3) the incidence of vestibular abnormality in patients with auditory neuropathy. Ten subjects (7 male and 3 female) in the age range of 15 to 35 years participated in this study. The test battery administered included pure-tone audiometry, ABR, OAE, Immittance, and VEMP. The results showed: (1) nine out of the 10 subjects showed abnormal or absent VEMP; (2) there is no one-to-one correlation between the abnormal or absent VEMP and the vestibular symptoms that these subjects present; and (3) 80% of the ears with auditory neuropathy showed abnormal VEMP results giving an indication of high incidence of vestibular involvement in the auditory neuropathy population. The present study provides evidence for involvement of the vestibular branch of the VIIIth cranial nerve in a high percentage of the auditory neuropathy population; hence, it is suggested that there is need for vestibular assessment in cases of auditory neuropathy that would help to better understand the disorder. It is also suggested that the term “acoustic neuropathy” be used to indicate those patients in whom only the acoustic nerve is affected and “vestibuloacoustic neuropathy” to label those patients who also show involvement of the vestibular system.

Auditory Neuropathy/Dys-synchrony In School-aged Hearing-impaired Children: A South Indian Perspective

Abstract Recently, use of otoacoustic emission technology has led to identification of auditory neuropathy as a distinct hearing disorder in children as well as adults. Children with auditory neuropathy require audiologic and educational management that may differ from that required by other hearing impaired. The purpose of this study was to estimate the prevalence and audiologic characteristics of auditory dys-synchrony in school-aged hearing- impaired children in an integrated school; 220 students from grade one to grade eight were recruited for the study. Initially all the subjects were screened using DPOAE and the subjects who had otoacoustic emissions present were subjected for a detailed diagnostic evaluation. Results showed that the prevalence of auditory dys-synchrony was around 2.27% in hearing-impaired individuals. These results indicate that auditory dyssynchrony is not an extremely rare disorder and although only a small portion of the population of children with hearing loss is affected, it is undoubtedly important to detect this disorder so that individualized treatment plans can be devised.

Tone-evoked brainstem responses and auditory steady state responses to 40hz and 80hz amplitude modulated stimuli with different frequencies - a comparative study

AbstractTone burst evoked auditory brainstem responses and auditory steady state responses with 40 or > 80 Hz modulation can be used to determine frequency specific threshold.AimThe present study was taken up to check for the efficacy of estimating hearing thresholds by tone burst ABR and ASSR. The frequency effect (low, mid and high) on estimating the threshold was also focused upon.Methods20 normal hearing adults (40 ears) in the age range of 16 to 30 years participated in the study. The pure tone audiometry and immittance was initially done. Subsequently, tone-burst ABR, 80Hz ASSR and 40Hz ASSR to estimate the threshold with three frequencies 500Hz (low), 2000Hz (mid) and 4000Hz (high) was done. The data was analyzed statistically using pair sample t-test.ResultsASSR threshold for 80Hz and 40Hz was almost comparable. ASSR was superior to estimate the threshold than tone-burst ABR. For the low frequency the discrepancy between the behavioral threshold and frequency-specific evoked audiometry was more when compared to mid and high frequency.ConclusionPresent study showed that steady-state responses were efficient means of threshold detection than visual detection of ABR wave-V. In awake adult subjects, 40Hz and 80Hz amplitude modulated produced similar results. For the threshold estimation ASSR was better than tone-burst ABR.

Effect of short-duration noise exposure on behavioral threshold and transient evoked otoacoustic emission

Background: It is well known that the short- or long-duration exposure to loud noise can either cause temporary or permanent threshold shift. Pure tone audiometry is most widely used to predict the individual who is susceptible to such noise-induced hearing loss (NIHL). Transient evoked otoacoustic emission (TEOAE) is a noninvasive, objective technique and required less time to administer to find out such effect. However, one must know the sensitivity of TEOAEs to predict susceptibility of NIHL. Objectives: Thus, the present study was taken up to find out the susceptibility of TEOAE to identify the individual who is more susceptible by comparing behavioral temporary threshold shift (TTS). Materials and Methods: There were 28 ears in the age range of 18 to 30 years participated in the study. All participants were evaluated for pure tone thresholds and TEOAEs amplitude before and after exposure to the short-duration noise. Results: Results indicated that there were statistically significant differences observed for both behavioral thresholds shift and TEOAEs amplitude reduction after exposure to short-duration noise at 0.05 levels at different frequencies. Conclusion: Further, it was observed that though there was agreement between the two, TEOAE amplitude shift was not as much as pure tone TTS. Reason and the importance of the TEOAE to use as a tool to find out susceptibility are being discussed in the article.

Effect of click stimuli and speech bursts on cortical processing

Late latency responses (LLR) are components of auditory evoked potential (AEP) responses that are found between 50 and 250 milliseconds from the time of stimulation and reflect the responses of the auditory cortex. LLR may be used for threshold estimation as well as to diagnose certain auditory deviations. In view of hardly any studies done on the comparison of LLR with different speech burst stimuli and click stimuli, this study was designed. A total of 12 (24 ears) normal hearing sensitivity subjects were included with no otologic or neurologic symptoms. LLR was recorded with speech burst stimuli /pa/, /ta/, /ka/ and click. All the components of LLR were elicited in all the participants with the click stimuli. Among speech burst stimuli, /ta/ stimulus was better than /pa/ and /ka/ stimuli in eliciting all the components of LLR. This difference could be attributed to the spectral energy present in the click stimuli. The difference in latencies when burst stimuli were used can be attributed to spectral differences, duration of stimulus and bandwidth. It can be concluded that the speech burst stimuli can be used to elicit cortical LLR, but responses will be more accurate with click stimuli. The result of this demonstrates the effect of stimulus variation on the LLR response pattern. LLR may be used to objectively measure differences in neural encoding and perception of spectrally different speech sounds.

Test-Retest Reliability of Vestibular Evoked Myogenic Potential across Different Age Groups

Background: VEMPs are used to evaluate the function of otolith system. cVEMP evaluate the function of saccule and oVEMP evaluate the function of utricle. There are equivocal findings in the test-retest reliability of cVEMP and oVEMP response among the young adults groups. Therefore, the present study was taken up to see test-retest reliability the test-retest reliability of cVEMPs (with and without integrated visual feedback system) and oVEMP parameters across different age groups. Method: A total of 60 participants were included among the three groups (young adult, middle adult and old adult) with an equal number of in each group. cVEMP and oVEMP were performed thrice for all the participants to see the test-retest reliability. Results: Present study results showed test-retest reliability was fair to good and above for all the parameters for cVEMP as well as oVEMP response. cVEMP peak to peak amplitude retest reliability with integrated visual feedback showed more reliability than without integrated visual feedback system in middle and old adults. Conclusion: It can be concluded from the current study that cVEMP and oVEMP testing procedures are reliable in the young, middle and old adult groups during and between test recordings.

Psycho acoustical Measures in Individuals with Congenital Visual Impairment

INTRODUCTION In congenital visual impaired individuals one modality is impaired (visual modality) this impairment is compensated by other sensory modalities. There is evidence that visual impaired performed better in different auditory task like localization, auditory memory, verbal memory, auditory attention, and other behavioural tasks when compare to normal sighted individuals. OBJECTIVE The current study was aimed to compare the temporal resolution, frequency resolution and speech perception in noise ability in individuals with congenital visual impaired and normal sighted. METHODS Temporal resolution, frequency resolution, and speech perception in noise were measured using MDT, GDT, DDT, SRDT, and SNR50 respectively. Twelve congenital visual impaired participants with age range of 18 to 40 years were taken and equal in number with normal sighted participants. All the participants had normal hearing sensitivity with normal middle ear functioning. RESULTS Individual with visual impairment showed superior threshold in MDT, SRDT and SNR50 as compared to normal sighted individuals. This may be due to complexity of the tasks; MDT, SRDT and SNR50 are complex tasks than GDT and DDT. CONCLUSION Visual impairment showed superior performance in auditory processing and speech perception with complex auditory perceptual tasks.

Binaural Interaction Component in Speech Evoked Auditory Brainstem Responses

OBJECTIVE This article aims to describe the characteristics of the binaural interaction component (BIC) of speech-evoked auditory brainstem response (ABR). MATERIALS AND METHODS All 15 subjects had normal peripheral hearing sensitivity. ABRs were elicited by speech stimulus /da/. RESULTS The first BIC (BIC-SP1) in the speech-evoked ABR occurred at around 6 ms in the region of peak V. The second BIC (BIC-SP2) was present around 8 ms in the latency region of peak A. The third and fourth BICs of speech-evoked ABR (BIC-SP3 & BIC-SP4) were observed at around 36 ms and 46 ms, respectively, in the latency regions of peaks E and F, respectively. BIC-SP1 and BIC-SP2 were present in all subjects tested (100%), whereas BIC-SP3 and BIC-SP4 were present in 11 (73%). CONCLUSION Because ABRs are not affected by sleep and mature early, this tool can be evaluated in identifying binaural interaction in younger and difficult-to-test populations.

Ocular vestibular evoked myogenic potential using different test stimuli.

Aim. Ocular Evoked Myogenic Potential (oVEMP) are short latency potentials evoked by higher acoustic stimulation. In this study, we aimed at comparing the click, 500 Hz mixed modulated, and 500 Hz short duration tone burst stimuli using oVEMP. Material. Click, 500 Hz mixed modulated and 500 Hz short duration tone burst stimuli were used for the study. Method. Conventional sampling and conveneint study design were used. Sixty healthy subjects underwent contralateral oVEMP testing maintaining 30 degrees upward gaze. Single channel electrode montage was applied to record oVEMP response. Results. On statistical analysis the three stimuli evoked equal response rates (100%), and when latency of n1 and p1 and peak-peak amplitude were compared, the click evoked showed significantly early latency and lower peak-peak amplitude than the 500 Hz stimuli. Five hundred Hz stimuli did not show significant difference in latency and peak-peak amplitude of n1-p1. Discussion. Thus, 500 Hz stimuli can evoke better latency and peak-peak amplitude. oVEMP has good clinical significance in diagnosing subjects with vestibular dysfunction. To add to the sensitivity of the oVEMP test, 500 Hz stimuli may also be used as it can evoke better oVEMP responses in clinical population with good morphology.