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Cochlear nerve

Nathaniel T Greene, Jameson K Mattingly, Renee M Banakis Hartl, Daniel J Tollin, Stephen P Cass
HYPOTHESIS: Cochlear implant (CI) electrode insertion into the round window induces pressure transients in the cochlear fluid comparable to high-intensity sound transients. BACKGROUND: Many patients receiving a CI have some remaining functional hearing at low frequencies; thus, devices and surgical techniques have been developed to use this residual hearing. To maintain functional acoustic hearing, it is important to retain function of any hair cells and auditory nerve fibers innervating the basilar membrane; however, in a subset of patients, residual low-frequency hearing is lost after CI insertion...
October 5, 2016: Otology & Neurotology
Jia Ke, Shao-Xing Zhang, Lei Hu, Chang-Sheng Li, Yun-Feng Zhu, Shi-Long Sun, Li-Feng Wang, Fu-Rong Ma
BACKGROUND: A single drilled tunnel from the lateral mastoid cortex to the cochlea via the facial recess is essential for minimally invasive cochlear implant surgery. This study aimed to explore the safety profile of this kind of new image-guided and bi-planar device-assisted surgery procedure in vitro. METHODS: Image-guided minimally invasive cochlear implantations were performed on eight cadaveric temporal bone specimens. The main procedures were: (1) temporal bone specimens were prepared for surgery and fiducial markers were registered...
2016: Chinese Medical Journal
Constantin von Kirschbaum, Robert Gürkov
Introduction. Vestibular schwannomas (VS) are benign tumours of the vestibular nerve and can lead to hearing loss, tinnitus, vertigo, facial palsy, and brainstem compression. Audiovestibular diagnostic tests are essential for detection and treatment planning. Methods. Medline was used to perform a systematic literature review with regard to how audiovestibular test parameters correlate with symptoms, tumour size, and tumour location. Results. The auditory brainstem response can be used to diagnose retrocochlear lesions caused by VS...
2016: BioMed Research International
Lijuan Shi, Ying Chang, Xiaowei Li, Steve Aiken, Lijie Liu, Jian Wang
Recent studies on animal models have shown that noise exposure that does not lead to permanent threshold shift (PTS) can cause considerable damage around the synapses between inner hair cells (IHCs) and type-I afferent auditory nerve fibers (ANFs). Disruption of these synapses not only disables the innervated ANFs but also results in the slow degeneration of spiral ganglion neurons if the synapses are not reestablished. Such a loss of ANFs should result in signal coding deficits, which are exacerbated by the bias of the damage toward synapses connecting low-spontaneous-rate (SR) ANFs, which are known to be vital for signal coding in noisy background...
2016: Neural Plasticity
I Diogo, U Walliczeck, J Taube, N Franke, A Teymoortash, J Werner, C Güldner
Due to an increasing number of cochlear implantations, quality control has become more important. In addition to intraoperative biophysical measurements, radiological imaging is another possibility. An upcoming technique regarding this is Cone Beam CT (CBCT). Sixty-five data sets (35 Nucleus Contour Advance-Cochlear; 30 Flex Soft-MedEl) of postoperative imaging by CBCT (Accu-I-tomo F17, Morita, Kyoto, Japan) underwent further evaluation. Insertion angle, height of the cochlea, distance of the electrode to the medial or lateral wall, angle between chorda tympani and facial nerve and the precise position of the electrode cable in the facial-chordal angle were determined...
August 2016: Acta Otorhinolaryngologica Italica
Jingjing Sherry Wu, Eric D Young, Elisabeth Glowatzki
: Auditory nerve fibers (ANFs) exhibit a range of spontaneous firing rates (SRs) that are inversely correlated with threshold for sounds. To probe the underlying mechanisms and time course of SR differentiation during cochlear maturation, loose-patch extracellular recordings were made from ANF dendrites using acutely excised rat cochlear preparations of different ages after hearing onset. Diversification of SRs occurred mostly between the second and the third postnatal week. Statistical properties of ANF spike trains showed developmental changes that approach adult-like features in older preparations...
October 12, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Marc S Schwartz, Eric P Wilkinson
OBJECTIVE: Auditory brainstem implants (ABIs), which have previously been used to restore auditory perception to deaf patients with neurofibromatosis type 2 (NF2), are now being utilized in other situations, including treatment of congenitally deaf children with cochlear malformations or cochlear nerve deficiencies. Concurrent with this expansion of indications, the number of centers placing and expressing interest in placing ABIs has proliferated. Because ABI placement involves posterior fossa craniotomy in order to access the site of implantation on the cochlear nucleus complex of the brainstem and is not without significant risk, we aim to highlight issues important in developing and maintaining successful ABI programs that would be in the best interests of patients...
September 26, 2016: Laryngoscope
Adem Binnetoğlu, Tekin Bağlam, Murat Sarı, Yavuz Gündoğdu, Çağlar Batman
Duplication of the internal auditory canal is an uncommon, congenital malformation that can be associated with sensorineural hearing loss owing to aplasia/hypoplasia of the vestibulocochlear nerve. Only 14 such cases have been reported to date. We report the case of a 13-month-old girl with bilateral, congenital, sensorineural hearing loss caused by narrow, duplicated internal auditory canals and discuss the challenges encountered in the diagnosis and treatment of this condition.
August 2016: Journal of International Advanced Otology
Renato Torres, Guillaume Kazmitcheff, Daniele De Seta, Evelyne Ferrary, Olivier Sterkers, Yann Nguyen
It has previously reported that alignment of the insertion axis along the basal turn of the cochlea was depending on surgeon' experience. In this experimental study, we assessed technological assistances, such as navigation or a robot-based system, to improve the insertion axis during cochlear implantation. A preoperative cone beam CT and a mastoidectomy with a posterior tympanotomy were performed on four temporal bones. The optimal insertion axis was defined as the closest axis to the scala tympani centerline avoiding the facial nerve...
October 4, 2016: European Archives of Oto-rhino-laryngology
Nicolas -Xavier Bonne, Rabih Aboukais, Marc Baroncini, Audrey Hochart, Pierre Leblond, Franck Broly, Frédérique Dubrulle, Jean-Paul Lejeune, Christophe Vincent
OBJECTIVE: This study aims to describe the clinical and molecular presentation of pediatric neurofibromatosis type 2 (NF2) and the subsequent management of vestibular schwannomas (VS) and hearing rehabilitation. METHODS: This is a single-center retrospective study of neurofibromatosis type 2 diagnosed before the age of 18 years old from 1997. Natural history of vestibular schwannomas and surgical outcomes were evaluated using volumetric MRI, hearing, and facial nerve assessment...
October 4, 2016: Child's Nervous System: ChNS: Official Journal of the International Society for Pediatric Neurosurgery
Yiyuan Zhao, Benoit M Dawant, Jack H Noble
Cochlear implants (CIs) are neural prostheses that restore hearing by stimulating auditory nerve pathways within the cochlea using an implanted electrode array. Research has shown when multiple electrodes stimulate the same nerve pathways, competing stimulation occurs and hearing outcomes decline. Recent clinical studies have indicated that hearing outcomes can be significantly improved by using an image-guided active electrode set selection technique we have designed, in which electrodes that cause competing stimulation are identified and deactivated...
July 2016: Journal of Medical Imaging
Aaron K Remenschneider, Robert Gaudin, Elliott D Kozin, Reuven Ishai, Olivia Quatela, Tessa A Hadlock, Michael J McKenna
OBJECTIVES: Facial nerve schwannomas (FNSs) and vestibular nerve schwannomas (VNSs) may occupy similar locations in the internal auditory canal (IAC). Risk factors for hearing loss in patients with FNS are unknown. Similar to VNSs, we hypothesize that the size and location of FNSs do not correlate with hearing loss. STUDY DESIGN: Retrospective cohort study and otopathology case review. METHODS: A single institution retrospective review of all patients diagnosed with FNS was performed...
October 4, 2016: Laryngoscope
David Goyer, Stefanie Kurth, Charlène Gillet, Christian Keine, Rudolf Rübsamen, Thomas Kuenzel
Sensory processing in the lower auditory pathway is generally considered to be rigid and thus less subject to modulation than central processing. However, in addition to the powerful bottom-up excitation by auditory nerve fibers, the ventral cochlear nucleus also receives efferent cholinergic innervation from both auditory and nonauditory top-down sources. We thus tested the influence of cholinergic modulation on highly precise time-coding neurons in the cochlear nucleus of the Mongolian gerbil. By combining electrophysiological recordings with pharmacological application in vitro and in vivo, we found 55-72% of spherical bushy cells (SBCs) to be depolarized by carbachol on two time scales, ranging from hundreds of milliseconds to minutes...
September 2016: ENeuro
Mahan Azadpour, Robert L Smith
Cochlear implants (CIs) bypass some of the mechanisms that underlie normal neural behavior as occurs in acoustic hearing. One such neural mechanism is short-term adaptation, which has been proposed to have a significant role in speech perception. Acoustically-evoked neural adaptation has been mainly attributed to the depletion of neurotransmitter in the hair-cell to auditory-nerve synapse and is therefore not fully present in CI stimulation. This study evaluated a signal processing method that integrated a physiological model of hair-cell adaptation into CI speech processing...
September 30, 2016: Hearing Research
Hannah J D North, Deborah Mawman, Martin O'Driscoll, Simon R Freeman, Scott A Rutherford, Andrew T King, Charlotte Hammerbeck-Ward, D Gareth Evans, Simon K W Lloyd
In neurofibromatosis type 2 (NF2) bilateral vestibular schwannomas (VS) or their treatment usually results in bilateral hearing loss. Cochlear implantation (CI) was traditionally not used in these patients due to concern that retrocochlear disease would render the implant ineffective. This paper describes the auditory outcomes of CI in 13 patients with NF2 and includes patients with untreated VS and patients undergoing VS removal with cochlear nerve preservation. The non-user rate was 7.7%. Of the active users, median CUNY score was 98%, median BKB score in quiet was 90% and median BKB score in noise was 68%...
July 2016: Cochlear Implants International
Rensa Chen, Martin Schwander, Mary F Barbe, Marion M Chan
Globally, a body of comparative case-control studies suggests that rheumatoid arthritis (RA) patients are more prone to developing hearing loss (HL). However, experimental evidence that supports this hypothesis is still lacking because the human auditory organ is not readily accessible. The aim of this study was to determine the association between bone damage to the ossicles of the middle ear and HL, using a widely accepted murine model of collagen-induced arthritis (RA mice). Diarthrodial joints in the middle ear were examined with microcomputer tomography (microCT), and hearing function was assessed by auditory brainstem response (ABR)...
2016: PloS One
Elham Zarei, Hamed Sadjedi
BACKGROUND: Speech synthesis models have been considered as viable tools for performance evaluation of cochlear stimulation algorithms, due to the difficulties of clinical tests. OBJECTIVE: The present study has developed a tool that can be used before any audio signal reconstruction algorithm, which shows more conformity with the electrophysiological parameters of the patient in evaluation of the cochlear implant stimulation algorithms. METHODS: In this method, excitable nerve fiber characteristics such as stimulation threshold and effective refractory period have been considered in the signal pre-reconstruction process...
September 23, 2016: Technology and Health Care: Official Journal of the European Society for Engineering and Medicine
Anu Sharma, Hannah Glick, Emily Deeves, Erin Duncan
We review evidence for a high degree of neuroplasticity of the central auditory pathways in early childhood, citing evidence of studies of the P1 and N1 cortical auditory evoked potentials in congenitally deaf children receiving cochlear implants at different ages during childhood, children with auditory neuropathy spectrum disorder and children with hearing loss and comorbid multiple disabilities. We discuss neuroplasticity, including cortico-cortical de-coupling and cross-modal re-organization that occurs in deafness...
December 2015: Otorinolaringologia
Cheryl Clarkson, Flora M Antunes, Maria E Rubio
UNLABELLED: Sound deprivation by conductive hearing loss increases hearing thresholds, but little is known about the response of the auditory brainstem during and after conductive hearing loss. Here, we show in young adult rats that 10 d of monaural conductive hearing loss (i.e., earplugging) leads to hearing deficits that persist after sound levels are restored. Hearing thresholds in response to clicks and frequencies higher than 8 kHz remain increased after a 10 d recovery period. Neural output from the cochlear nucleus measured at 10 dB above threshold is reduced and followed by an overcompensation at the level of the lateral lemniscus...
September 28, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Ruili Xie
Age-related hearing loss (ARHL) is largely attributed to structural changes and functional declines in the peripheral auditory system, which include synaptopathy at the inner hair cell/spiral ganglion cell (SGC) connection as well as the loss of SGCs. However, functional changes at the central terminals of SGCs, namely the auditory nerve synapses in the cochlear nucleus, are not yet fully understood during ARHL. Using young (1-3 months) and old (25-30 months) CBA/CaJ mice, this study evaluated the intrinsic properties of the bushy neurons postsynaptic to the endbulb of Held synapses, and the firing properties of these neurons to direct current injections as well as to synaptic inputs from the auditory nerve...
September 28, 2016: Journal of Neurophysiology
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