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Cochlear nerve

Daniel Q Sun, C Blake Sullivan, Raymund W Kung, Megan Asklof, Marlan R Hansen, Bruce J Gantz
OBJECTIVE: To evaluate the association between signal changes during intraoperative audiologic monitoring and postoperative audiometric outcome in patients undergoing vestibular schwannoma (VS) resection via middle cranial fossa (MCF) approach. STUDY DESIGN: Retrospective chart review. SETTING: Academic tertiary referral center. PATIENTS: One hundred twenty-six consecutive patients (mean age 48.6 yrs, range 16-67; mean tumor size 9...
June 15, 2018: Otology & Neurotology
Aran Yoo, Jonathan Jou, Jeffrey D Klopfenstein, Jorge C Kattah
Background: Infratentorial siderosis (iSS) is a progressive degenerative disorder targeting primarily the cerebellum and cranial nerve eighth; therefore, progressive ataxia and its neuro-otological findings are common. Toxicity from hemosiderin involves selectively vulnerable neurons and glia in these posterior fossa structures. Other neurologic findings may be present, though our focus relates to the cochlea-vestibular cerebellar involvement. Radiographic evidence of siderosis may be the result of recurrent, albeit covert bleeding in the subarachnoid space, or the consequence of an overt post-traumatic or aneurysmal subarachnoid hemorrhage (SAH)...
2018: Frontiers in Neurology
Jeroen P M Peters, Anne W Wendrich, Ruben H M van Eijl, Koenraad S Rhebergen, Huib Versnel, Wilko Grolman
HYPOTHESIS: A cochlear implant (CI) restores hearing in patients with profound sensorineural hearing loss by electrical stimulation of the auditory nerve. It is unknown how this electrical stimulation sounds. BACKGROUND: Patients with single-sided deafness (SSD) and a CI form a unique population, since they can compare the sound of their CI with simulations of the CI sound played to their nonimplanted ear. METHODS: We tested six stimuli (speech and music) in 10 SSD patients implanted with a CI (Cochlear Ltd)...
July 2018: Otology & Neurotology
Robert P Carlyon, Stefano Cosentino, John M Deeks, Wendy Parkinson, Julie A Arenberg
Previous psychophysical and modeling studies suggest that cathodic stimulation by a cochlear implant (CI) may preferentially activate the peripheral processes of the auditory nerve, whereas anodic stimulation may preferentially activate the central axons. Because neural degeneration typically starts with loss of the peripheral processes, lower thresholds for cathodic than for anodic stimulation may indicate good local neural survival. We measured thresholds for 99-pulse-per-second trains of triphasic (TP) pulses where the central high-amplitude phase was either anodic (TP-A) or cathodic (TP-C)...
June 7, 2018: Journal of the Association for Research in Otolaryngology: JARO
Nadine Schart-Morén, Karin Hallin, Sumit K Agrawal, Hanif M Ladak, Per-Olof Eriksson, Hao Li, Helge Rask-Andersen
OBJECTIVES: Dehiscence between the cochlear otic capsule and the facial nerve canal is a rare and relatively newly described pathology. In cochlear implantation (CI), this dehiscence may lead to adverse electric facial nerve stimulation (FNS) already at low levels, rendering its use impossible. Here, we describe an assessment technique to foresee this complication. METHODS: Pre- and postoperative computed tomography (CT) scans and intraoperative electrically evoked auditory brainstem response (e-ABR) measurements were analyzed in two patients with cochlear-facial dehiscence (CFD)...
June 7, 2018: Cochlear Implants International
Y Gong, X M Wei, Y X Li
Cochlear nerve deficiency (CND) refers to a small or absent cochlear branch of the vestibulocochlear nerve (VCN) or cochlear nerve (CN). Congenitally deaf children with CND who received cochlear implants (CIs) generally exhibit poorer auditory performance than CI children without CND. It is important to confirm the integrity of the auditory pathway before surgery. High-resolution computed tomography (HRCT) and three-dimensional magnetic resonance imaging (3D MRI) are major techniques used to diagnosis CND. In this paper, we reviewed the methods of preoperative evaluation, cochlear nerve embryonic development, techniques for diagnosis and outcomes of cochlear implantation...
May 2018: Journal of Clinical Otorhinolaryngology, Head, and Neck Surgery
Thomas van den Boogert, Marc van Hoof, Stephan Handschuh, Rudolf Glueckert, Nils Guinand, Jean-Philippe Guyot, Herman Kingma, Angelica Perez-Fornos, Bart Seppen, Lejo Johnson Chacko, Anneliese Schrott-Fischer, Raymond van de Berg
Introduction: Knowledge of the neuro-anatomical architecture of the inner ear contributes to the improvement and development of cochlear and vestibular implants. The present knowledge is mainly based on two-dimensional images (histology) or derived models that simplify the complexity of this architecture. This study investigated the feasibility of visualizing relevant neuro-anatomical structures of the inner ear in a dynamic three-dimensional reproduction, using a combination of staining, micro-CT imaging and an image processing algorithm...
2018: Frontiers in Neuroanatomy
Y R Kim, M H Yoo, J Y Lee, C J Yang, J W Park, B C Kang, W S Kang, J H Ahn, J W Chung, H J Park
Incidence of facial nerve stimulation (FNS) was 2.8% (32 out of 1151) and higher in ears with cochlear anomaly (6.4%, 25 out of 391) than without cochlear anomaly (0.9%, 7 out of 760). FNS occurred at various current levels and locations of electrodes by different mechanisms related to incomplete insertion of electrodes, cochleo-facial dehiscence, and types of cochlear anomalies. FNS at apical electrodes related to cochleo-facial dehiscence with low current levels, and FNS at basal electrodes with high current levels and partial insertion of electrodes...
May 29, 2018: Clinical Otolaryngology
Hongsun Guo, Mark Hamilton, Sarah J Offutt, Cory D Gloeckner, Tianqi Li, Yohan Kim, Wynn Legon, Jamu K Alford, Hubert H Lim
Ultrasound (US) can noninvasively activate intact brain circuits, making it a promising neuromodulation technique. However, little is known about the underlying mechanism. Here, we apply transcranial US and perform brain mapping studies in guinea pigs using extracellular electrophysiology. We find that US elicits extensive activation across cortical and subcortical brain regions. However, transection of the auditory nerves or removal of cochlear fluids eliminates the US-induced activity, revealing an indirect auditory mechanism for US neural activation...
May 19, 2018: Neuron
Hannah J D North, Simon K W Lloyd
Bilateral vestibular schwannomas are almost pathognomonic of neurofibromatosis type 2 (NF2). As a result of these tumors, hearing loss is the presenting symptom in 60% of adults and 30% of children with NF2. It is often bilateral. The best means of preserving hearing in patients with NF2 is conservative management. Even so at least 28% of patients have progression of hearing loss following diagnosis. The likelihood of progression of hearing loss is, at least in part, determined by the type of mutation. Treatment of vestibular schwannomas often has a detrimental effect on hearing...
2018: Advances in Oto-rhino-laryngology
Simon R Freeman, Levent Sennaroglu
Approximately 2% of congenital profound deafness cases are due to cochlear nerve (CN) deficiency. MRI is essential to confirm if the nerve is deficient, but because of limitations with resolution, especially when the internal auditory canal is narrowed, it is often unable to distinguish between hypoplasia and aplasia. A full audiometric test battery should always be performed, even if the MRI suggests CN aplasia, as there will sometimes be evidence of audition. Electrically evoked auditory brainstem response testing can be carried out transtympanically via the round window or using an intracochlear test electrode to help determine the status of the CN...
2018: Advances in Oto-rhino-laryngology
Hidemi Miyazaki, Per Caye-Thomasen
A new electrophysiological system for intraoperative, continuous, near-real time monitoring of cochlear nerve function through acoustic stimulation in the ear canal and recording of the evoked dorsal cochlear nucleus potentials (DNAPs) by a specially designed DNAP electrode placed directly on the brainstem is described. The system is denominated "(cerebellopontine angle) CPA Master" and is designed for hearing preservation surgery in the cerebello-pontine angle, through the retro-sigmoid or the retro-labyrinthine approach...
2018: Advances in Oto-rhino-laryngology
M Sindou, P Mercier
Primary hemifacial spasm with few exceptions is due to the vascular compression of the facial nerve that can be evidenced with high resolution MRI. Microvascular decompression is the only curative treatment for this pathology. According to literature review detailed in chapter "conflicting vessels", the compression is located at the facial Root Exit Zone (REZ) in 95% of the cases, and in 5% distally at the cisternal or the intrameatal portion of the root as the sole conflict or in addition to one at brainstem/REZ...
May 18, 2018: Neuro-Chirurgie
Pavel Mistrík, Claude Jolly, Daniel Sieber, Ingeborg Hochmair
Objective: A design comparison of current perimodiolar and lateral wall electrode arrays of the cochlear implant (CI) is provided. The focus is on functional features such as acoustic frequency coverage and tonotopic mapping, battery consumption and dynamic range. A traumacity of their insertion is also evaluated. Methods: Review of up-to-date literature. Results: Perimodiolar electrode arrays are positioned in the basal turn of the cochlea near the modiolus...
December 2017: World Journal of Otorhinolaryngology—Head and Neck Surgery
C Lane Anzalone, Sarah Nuhanovic, Amy P Olund, Matthew L Carlson
Introduction: Charcot-Marie-Tooth (CMT) disease is a peripheral hereditary neuropathy associated with motor and sensory impairment and can result in profound sensorineural hearing loss (SNHL). Currently, the role of cochlear implantation in the setting of CMT and other progressive peripheral neurodegenerative disorders is not well established. Methods: Case report and review of the English literature. Results: A 70-year-old male with CMT was referred for evaluation of progressive asymmetric SNHL and reported a 15-year duration of deafness involving the left ear...
2018: Case Reports in Medicine
P Mercier, F Bernard
Classically in the cerebello-pontine angle the facial (CN VII) and vestibular-cochlear (CN VIII) nerves should run parallel with the anterior inferior cerebellar artery, whereas the lower nerves (CN IX-XI) continue with the posterior-inferior-cerebellar artery (PICA). In fact, this is not always true, particularly when dealing with hemispasm surgery where the relationships between CN VII, CN VIII and PICA are often different and closer. Knowledge of anatomical bases in surgical situation will help neurosurgeons to appreciate anatomical nuances, that are important to increase effectiveness and safety of hemifacial spasm surgery...
May 17, 2018: Neuro-Chirurgie
Nobuyuki Watanabe, Takuya Ishii, Kazuhiko Fujitsu, Shogo Kaku, Teruo Ichikawa, Kosuke Miyahara, Tomu Okada, Shin Tanino, Yasuhiro Uriu, Yuichi Murayama
OBJECTIVE The authors describe the usefulness and limitations of the cochlear nerve compound action potential (CNAP) mobile tracer (MCT) that they developed to aid in cochlear nerve mapping during vestibular schwannoma surgery (VSS) for hearing preservation. METHODS This MCT device requires no more than 2 seconds for stable placement on the nerve to obtain the CNAP and thus is able to trace the cochlear nerve instantaneously. Simultaneous bipolar and monopolar recording is possible. The authors present the outcomes of 18 consecutive patients who underwent preoperative useful hearing (defined as class I or II of the Gardner-Robertson classification system) and underwent hearing-preservation VSS with the use of the MCT...
May 18, 2018: Journal of Neurosurgery
W T Sun, Y Chen, H H Lu, H Y Ruan, R M Liang, C Chen, J P Zhang
Objective: To investigate the values of electrocochleograph(ECochG)in patients with OSAHS. Method: ECochG was performed in 31 (62 ears) OSAHS patients (moderately 5 cases, severely 26 cases) and 28 healthy adults (56 ears). AP latency ,AP amplitude and SP/AP were measured and analyzed. Result: There was no difference between the two groups in SP/AP amplitude ratio( P >0.05) while both AP latency( P <0.05) and AP amplitude( P <0.05) were significantly different. Conclusion: ECochG can confirm the damage of cochlear and auditory nerve near the cochlear segment in patients with moderate to severe OSAHS...
May 2018: Journal of Clinical Otorhinolaryngology, Head, and Neck Surgery
Nils K Prenzler, Rolf Salcher, Max Timm, Lutz Gaertner, Thomas Lenarz, Athanasia Warnecke
Suppression of foreign body reaction, improvement of electrode-nerve interaction, and preservation of residual hearing are essential research topics in cochlear implantation. Intracochlear pharmaco- or cell-based therapies can open new horizons in this field. Local drug delivery strategies are desirable as higher local concentrations of agents can be realized and side effects can be minimized compared to systemic administrations. When administered locally at accessible, basal parts of the cochlea, drugs reach apical regions later and in much lower concentrations due to poor diffusion patterns in cochlear fluids...
May 14, 2018: Drug Delivery and Translational Research
Shraddha Jain, Sagar Gaurkar, Prasad T Deshmukh, Mohnish Khatri, Sanika Kalambe, Pooja Lakhotia, Deepshikha Chandravanshi, Ashish Disawal
INTRODUCTION: Various aspects of the round window anatomy and anatomy of posterior tympanum have relevant implications for designing cochlear implant electrodes and visualizing the round window through facial recess. Preoperative information about possible anatomical variations of the round window and its relationships to the adjacent neurovascular structures can help reduce complications in cochlear implant surgery. OBJECTIVE: The present study was undertaken to assess the common variations in round window anatomy and the relationships to structures of the tympanum that may be relevant for cochlear implant surgery...
April 19, 2018: Brazilian Journal of Otorhinolaryngology
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