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Simultaneous Nonmastoidectomy Infrapromontorial Tumor Removal and Cochlear Implantation in Vestibular Schwannoma Patient

Misron K, Mfuko G, Hur YK, Moon IS

Otol Neurotol, 2021 06 01;42(5):e631-e634.
PMID: 33741816 DOI: 10.1097/MAO.0000000000003132

INTRODUCTION: Restoration of hearing in patients with vestibular schwannoma (VS) and poor hearing poses a great challenge. Simultaneous cochlear implantation during surgery for VS removal offers favorable hearing outcome if the cochlear nerve remains intact. Recent refinement of surgical techniques using the endoscope has made it possible to simultaneously restore the hearing and remove the tumor.
CASE DESCRIPTION: A 62-year-old male had left severe sensorineural hearing loss and a 4 mm intracanalicular VS. We performed simultaneous nonmastoidectomy infrapromontorial VS removal and cochlear implantation in this patient to achieve minimal invasiveness and to provide maximal hearing restoration. The tumor was removed via this corridor while maintaining the integrity of cochlear as well as facial nerves with full insertion of a medium length cochlear implant electrode. After surgery, the patient showed good hearing rehabilitation.
CONCLUSION: Simultaneous infrapromontorial VS removal and nonmastoidectomy cochlear implantation serves as an option for hearing restoration with minimal invasiveness in small VS removal.

Matched MeSH terms: Cochlear Nerve/surgery
Fulltext A Robust Speaker Identification System Using the Responses from a Model of the Auditory Periphery

Islam MA, Jassim WA, Cheok NS, Zilany MS

PLoS One, 2016;11(7):e0158520.
PMID: 27392046 DOI: 10.1371/journal.pone.0158520

Speaker identification under noisy conditions is one of the challenging topics in the field of speech processing applications. Motivated by the fact that the neural responses are robust against noise, this paper proposes a new speaker identification system using 2-D neurograms constructed from the responses of a physiologically-based computational model of the auditory periphery. The responses of auditory-nerve fibers for a wide range of characteristic frequency were simulated to speech signals to construct neurograms. The neurogram coefficients were trained using the well-known Gaussian mixture model-universal background model classification technique to generate an identity model for each speaker. In this study, three text-independent and one text-dependent speaker databases were employed to test the identification performance of the proposed method. Also, the robustness of the proposed method was investigated using speech signals distorted by three types of noise such as the white Gaussian, pink, and street noises with different signal-to-noise ratios. The identification results of the proposed neural-response-based method were compared to the performances of the traditional speaker identification methods using features such as the Mel-frequency cepstral coefficients, Gamma-tone frequency cepstral coefficients and frequency domain linear prediction. Although the classification accuracy achieved by the proposed method was comparable to the performance of those traditional techniques in quiet, the new feature was found to provide lower error rates of classification under noisy environments.

Matched MeSH terms: Cochlear Nerve/physiology
Fulltext Reference-Free Assessment of Speech Intelligibility Using Bispectrum of an Auditory Neurogram

Hossain ME, Jassim WA, Zilany MS

PLoS One, 2016;11(3):e0150415.
PMID: 26967160 DOI: 10.1371/journal.pone.0150415

Sensorineural hearing loss occurs due to damage to the inner and outer hair cells of the peripheral auditory system. Hearing loss can cause decreases in audibility, dynamic range, frequency and temporal resolution of the auditory system, and all of these effects are known to affect speech intelligibility. In this study, a new reference-free speech intelligibility metric is proposed using 2-D neurograms constructed from the output of a computational model of the auditory periphery. The responses of the auditory-nerve fibers with a wide range of characteristic frequencies were simulated to construct neurograms. The features of the neurograms were extracted using third-order statistics referred to as bispectrum. The phase coupling of neurogram bispectrum provides a unique insight for the presence (or deficit) of supra-threshold nonlinearities beyond audibility for listeners with normal hearing (or hearing loss). The speech intelligibility scores predicted by the proposed method were compared to the behavioral scores for listeners with normal hearing and hearing loss both in quiet and under noisy background conditions. The results were also compared to the performance of some existing methods. The predicted results showed a good fit with a small error suggesting that the subjective scores can be estimated reliably using the proposed neural-response-based metric. The proposed metric also had a wide dynamic range, and the predicted scores were well-separated as a function of hearing loss. The proposed metric successfully captures the effects of hearing loss and supra-threshold nonlinearities on speech intelligibility. This metric could be applied to evaluate the performance of various speech-processing algorithms designed for hearing aids and cochlear implants.

Matched MeSH terms: Cochlear Nerve/physiopathology
Modeling the effects of medial olivocochlear efferent stimulation at the level of the inferior colliculus

Kwan TJM, Zilany MSA, Davies-Venn E, Abdul Wahab AK

Exp Brain Res, 2019 Jun;237(6):1479-1491.
PMID: 30903206 DOI: 10.1007/s00221-019-05511-4

Various studies on medial olivocochlear (MOC) efferents have implicated it in multiple roles in the auditory system (e.g., dynamic range adaptation, masking reduction, and selective attention). This study presents a systematic simulation of inferior colliculus (IC) responses with and without electrical stimulation of the MOC. Phenomenological models of the responses of auditory nerve (AN) fibers and IC neurons were used to this end. The simulated responses were highly consistent with physiological data (replicated 3 of the 4 known rate-level responses all MOC effects-shifts, high stimulus level reduction and enhancement). Complex MOC efferent effects which were previously thought to require integration from different characteristic frequency (CF) neurons were simulated using the same frequency inhibition excitation circuitry. MOC-induced enhancing effects were found only in neurons with a CF range from 750 Hz to 2 kHz. This limited effect is indicative of the role of MOC activation on the AN responses at the stimulus offset.

Matched MeSH terms: Cochlear Nerve/physiology*
Fulltext Auditory Performance in Early Implanted Children with Cochleovestibular Malformation and Cochlear Nerve Deficiency

Othman IA, Abdullah A, See GB, Umat C, Tyler RS

J Int Adv Otol, 2020 Dec;16(3):297-302.
PMID: 33136006 DOI: 10.5152/iao.2020.8563

OBJECTIVES: This study aimed to report the auditory performance in children with cochleovestibular malformation (CVM)/cochlear nerve deficiency (CND) who were implanted early at the Universiti Kebangsaan Malaysia Medical Centre, using Categorical Auditory Performance (CAP)-II score and Speech Intelligibility Rating (SIR) scales, and to compare the outcome of their matched counterparts.
MATERIALS AND METHODS: A total of 14 children with CVM/CND with unilateral cochlear implant (CI) implanted before the age of 4 years old were matched and compared with 14 children with normal inner ear structures. Their improvement in auditory performance was evaluated twice using CAP-II score and SIR scales at 6-month intervals, with the baseline evaluation done at least 6 months after implantation.
RESULTS: The average age of implantation was 31±8 and 33±7 months for the control group and the case (CVM/CND) group, respectively. Overall, there were no significant differences in outcome when comparing the entire cohort of case subjects and their matched control subjects in this study. However, the improvement in CAP-II scores and SIR scales among the case subjects in between the first and second evaluations was statistically significant (p=0.040 and p=0.034, respectively). With longer duration of CI usage, children with CVM/CND showed significant speech perception outcome evident by their SIR scales (p=0.011).
CONCLUSION: Children with radiographically malformed inner ear structures who were implanted before the age of 4 years have comparable performance to their matched counterparts, evident by their similar improvement of CAP-II scores and SIR scales over time. Hence, this group of children benefited from cochlear implantation.

Matched MeSH terms: Cochlear Nerve
A new experience of auditory brainstem implantation in Malaysia

Tang IP, Kevin Ng BH, Prepageran N, Donald Ngian SL, Albert Sii HW

Med J Malaysia, 2018 10;73(5):347-348.
PMID: 30350824 MyJurnal

Auditory brainstem implantation (ABI) is the only solution to restore hearing when cochlear nerves are disrupted together with the pathologies where bilateral cochleae do not provide a suitable location for cochlear implantation. We reported first two successful auditory brainstem implantation cases in patients with neurofibromatosis Type II (NF2) with bilateral acoustic neuroma causing bilateral profound sensorineural hearing loss in Malaysia. A good candidate selection, dedicated surgeons and rehabilitation team as well as strong family support are the crucial factors in achieving the best possible surgical, audiological and speech outcomes.

Matched MeSH terms: Cochlear Nerve
Cochlear nerve canal stenosis and associated semicircular canal abnormalities in paediatric sensorineural hearing loss: a single centre study

Zainol Abidin Z, Mohd Zaki F, Kew TY, Goh BS, Abdullah A

J Laryngol Otol, 2020 Jul;134(7):603-609.
PMID: 32713375 DOI: 10.1017/S0022215120001334

OBJECTIVE: This study aimed to evaluate the association between cochlear nerve canal dimensions and semicircular canal abnormalities and to determine the distribution of bony labyrinth anomalies in patients with cochlear nerve canal stenosis.
METHOD: This was a retrospective study in which high-resolution computed tomography images of paediatric patients with severe-to-profound sensorineural hearing loss were reviewed. A cochlear nerve canal diameter of 1.5 mm or less in the axial plane was classified as stenotic. Semicircular canals and other bony labyrinth morphology and abnormality were evaluated.
RESULTS: Cochlear nerve canal stenosis was detected in 65 out of 265 ears (24 per cent). Of the 65 ears, 17 ears had abnormal semicircular canals (26 per cent). Significant correlation was demonstrated between cochlear nerve canal stenosis and semicircular canal abnormalities (p < 0.01). Incomplete partition type II was the most common accompanying abnormality of cochlear nerve canal stenosis (15 out of 65, 23 per cent).
CONCLUSION: Cochlear nerve canal stenosis is statistically associated with semicircular canal abnormalities. Whenever a cochlear nerve canal stenosis is present in a patient with sensorineural hearing loss, the semicircular canal should be scrutinised for presence of abnormalities.

Matched MeSH terms: Vestibulocochlear Nerve Diseases/complications*; Vestibulocochlear Nerve Diseases/etiology; Vestibulocochlear Nerve Diseases/pathology; Cochlear Nerve/pathology
Fulltext Updated parameters and expanded simulation options for a model of the auditory periphery

Zilany MS, Bruce IC, Carney LH

J Acoust Soc Am, 2014 Jan;135(1):283-6.
PMID: 24437768 DOI: 10.1121/1.4837815

A phenomenological model of the auditory periphery in cats was previously developed by Zilany and colleagues [J. Acoust. Soc. Am. 126, 2390-2412 (2009)] to examine the detailed transformation of acoustic signals into the auditory-nerve representation. In this paper, a few issues arising from the responses of the previous version have been addressed. The parameters of the synapse model have been readjusted to better simulate reported physiological discharge rates at saturation for higher characteristic frequencies [Liberman, J. Acoust. Soc. Am. 63, 442-455 (1978)]. This modification also corrects the responses of higher-characteristic frequency (CF) model fibers to low-frequency tones that were erroneously much higher than the responses of low-CF model fibers in the previous version. In addition, an analytical method has been implemented to compute the mean discharge rate and variance from the model's synapse output that takes into account the effects of absolute refractoriness.

Matched MeSH terms: Cochlear Nerve/physiology*
Fulltext The heterospecific calling song can improve conspecific signal detection in a bushcricket species

Abdelatti ZAS, Hartbauer M

Hear Res, 2017 11;355:70-80.
PMID: 28974384 DOI: 10.1016/j.heares.2017.09.011

In forest clearings of the Malaysian rainforest, chirping and trilling Mecopoda species often live in sympatry. We investigated whether a phenomenon known as stochastic resonance (SR) improved the ability of individuals to detect a low-frequent signal component typical of chirps when members of the heterospecific trilling species were simultaneously active. This phenomenon may explain the fact that the chirping species upholds entrainment to the conspecific song in the presence of the trill. Therefore, we evaluated the response probability of an ascending auditory neuron (TN-1) in individuals of the chirping Mecopoda species to triple-pulsed 2, 8 and 20 kHz signals that were broadcast 1 dB below the hearing threshold while increasing the intensity of either white noise or a typical triller song. Our results demonstrate the existence of SR over a rather broad range of signal-to-noise ratios (SNRs) of input signals when periodic 2 kHz and 20 kHz signals were presented at the same time as white noise. Using the chirp-specific 2 kHz signal as a stimulus, the maximum TN-1 response probability frequently exceeded the 50% threshold if the trill was broadcast simultaneously. Playback of an 8 kHz signal, a common frequency band component of the trill, yielded a similar result. Nevertheless, using the trill as a masker, the signal-related TN-1 spiking probability was rather variable. The variability on an individual level resulted from correlations between the phase relationship of the signal and syllables of the trill. For the first time, these results demonstrate the existence of SR in acoustically-communicating insects and suggest that the calling song of heterospecifics may facilitate the detection of a subthreshold signal component in certain situations. The results of the simulation of sound propagation in a computer model suggest a wide range of sender-receiver distances in which the triller can help to improve the detection of subthreshold signals in the chirping species.

Matched MeSH terms: Cochlear Nerve/physiology*
Fulltext Auditory neuropathy: three cases among a group with sensorineural hearing loss

Mohd Khairi MD, Normastura AR, Wan Zaharah AW

Singapore Med J, 2009 Sep;50(9):e324-5.
PMID: 19787161

The prevalence of auditory neuropathy is not known, although the majority of cases are felt to lie within the population of neonatal intensive care unit graduates. We report three cases of auditory neuropathy, out of 211 children with sensorineural hearing loss, seen at our audiology clinic from April 1, 1999 to December 31, 2003. Two patients did not have a risk factor for hearing impairment. Screening policies based solely on transient evoked otoacoustic emissions testing will not detect auditory neuropathy effectively, and may falsely reassure parents and professionals unaware of this condition.
Study site: Audiology clinic, Hospital Universiti Sains Malaysia, Kelantan, Malaysia

Matched MeSH terms: Cochlear Nerve/physiopathology