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Central nervous system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
Vestibular schwannomas are relatively common benign tumours that arise from peri-neural Schwann cells of the vestibulocochlear nerve. Typically, they are intracanalicular but may arise outside the acoustic canal at the cerebro-pontine angle. They may be symptomatic when only a few millimetres but may develop into larger lesions; extracanalicular extension into the cerebello-pontine angle (path of least resistance) can lead to the ’ice-cream cone’ appearance shown in Figs 11.11d, e.
Micronutrients in Prevention and Improvement of the Standard Therapy in Hearing Disorders
Published in Kedar N. Prasad, Micronutrients in Health and Disease, 2019
Sensorineural hearing loss is due to insensitivity of the inner ear, the cochlea, or to impaired function of the auditory nervous system. This form of hearing loss could be moderate to severe and can lead to complete deafness. The sensorineural hearing loss is caused due to damage to hair cells of the cochlea. It also can be caused by the damage to the VIII cranial nerve and the vestibulocochlear nerve.
Physiology of Hearing
Published in John C Watkinson, Raymond W Clarke, Christopher P Aldren, Doris-Eva Bamiou, Raymond W Clarke, Richard M Irving, Haytham Kubba, Shakeel R Saeed, Paediatrics, The Ear, Skull Base, 2018
Soumit Dasgupta, Michael Maslin
The auditory or cochlear nerve, cranial nerve VIII, originates from the joining of the spiral ganglion cells in the cochlea where their cell bodies lie. There are two types of nerve fibres originating from the spiral ganglion cells: type 1, which have large diameters, innervate the IHCs constituting 95% of the nerve fibre population and are myelinated, and type 2 fibres, which are smaller diameter, innervate the OHCs and are unmyelinated. The nerve traverses the internal auditory canal and joins with the vestibular nerve forming the vestibulocochlear nerve. One type 1 fibre innervates one IHC but one IHC may synapse with several nerve fibres. The cochlear nerve fibres terminate at the cochlear nuclear complex located in the medulla of the brainstem.
Leveraging real-world data to improve cochlear implant outcomes: Is the data available?
Published in Cochlear Implants International, 2023
Callum Findlay, Mathew Edwards, Kate Hough, Mary Grasmeder, Tracey A. Newman
Hearing loss is the fourth leading cause of disability globally (Vos et al., 2016) and occurs throughout the life-course with peak incidence in both early and older age (Russ et al., 2017). One in three adults will experience significant hearing loss with the majority of those affected developing sensorineural hearing loss due to age-related hearing loss (presbycusis). Sensorineural hearing loss describes increased hearing thresholds due to damage within the inner ear, cochlea, or vestibulocochlear nerve (Lee and Bance, 2019). The recommended therapy for bilateral severe to profound sensorineural hearing loss is cochlear implantation (NICE, 2009). Cochlear implants are a safe and effective surgically inserted prosthesis which give the majority of users functional hearing (Wilson B, 2008). Unfortunately, a minority of users have less favourable outcomes and the percentage of people affected by poor outcomes is persistent despite improvements in the field. The reasons for poor outcomes are not well understood and likely multi-factorial with implant performance, linguistic ability, and cognition contributing to CI user experience (Battmer et al., 2007; Moberly et al., 2016).
Dysfunction along the continuum of vestibulocochlear anatomy, and the corresponding spectrum of clinical presentation: how little we know, and what else we need to learn
Published in Hearing, Balance and Communication, 2021
Marcello Cherchi, Darío Andrés Yacovino
Almost all textbooks, and much of the medical literature, depict vestibular neuritis, labyrinthitis and sudden sensorineural hearing loss as distinct clinical entities, which may be didactically useful, but is probably an oversimplification. The reality is likely more complex since damage can occur to varying proportions of the vestibulocochlear nerve, varying proportions of the labyrinth, and varying combinations thereof; in other words, the underlying pathobiology probably spans a continuum, with a corresponding range of clinical presentations – with different combinations/degrees of vestibular symptoms (dizziness/imbalance) and ear symptoms (hearing loss, tinnitus). In view of the anatomical proximity of these structures, their shared vascular supplies, and (in the case of the labyrinth) shared endolymph, this ‘continuum’ is not surprising.
Current perspectives on galvanic vestibular stimulation in the treatment of Parkinson’s disease
Published in Expert Review of Neurotherapeutics, 2021
Soojin Lee, Aiping Liu, Martin J. McKeown
Anatomically, the vestibular nerve combines with the cochlear nerve and becomes the vestibulocochlear nerve. Traveling by the cerebellopontine angle, this nerve enters the brainstem at the pontomedullary junction where the vestibular and cochlear nerves separate [49]. Some of the nerve fibers project to the flocculonodular lobe and nearby vermis of the cerebellum, while the majority of the fibers project to the ipsilateral vestibular complex in the pons [49]. The vestibular complex is where the vestibular inputs are primarily processed, and consists of four major nuclei including medial, lateral, superior, and inferior [50] as well as several adjacent cell groups. The vestibular pathways from the vestibular nuclei have different functional roles. Projections to the spinal cord are essential for postural reflexes to adjust head and body movements [51], and projections to the ocular motor nuclei are critical for compensatory eye movements during head motion (the vestibular-ocular reflex). Projections to the cerebellum are important for balance, postural control, and movement coordination [49], and pathways to the thalamus, hippocampus, and ultimately to the cortical areas are responsible for multisensory integration [50,52], contributing to movement planning and execution, spatial navigation and memory, attention, and emotional processing [52–54].