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Special Senses
Published in Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard, Toxicologic Pathology, 2018
Kenneth A. Schafer, Oliver C. Turner, Richard A. Altschuler
The sensorineural epithelium of the sacculus and utricle maculae is flat and located in a region of each called the maculae. The stereocilia of type I and type II hair cells of the utricle and sacculus are embedded in a gelatinous mass (otolith). The otolith contains calcium carbonate and calcite crystals (otoconia). These add weight to the otolith and allow sensitivity to gravity. The hair cells in the macula have several rows of stereocilia arranged in a specific orientation. Movement of the endolymph fluid in the sacculus is induced by linear acceleration or deceleration, head tilt and also influenced by gravity, even when the head is at rest.
Evaluation of Balance
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
Another way of obtaining controlled stimulation of the otolith is to rotate the subject about an axis which is tilted (off-vertical axis rotation (OVAR)) or orthogonal (‘barbeque-spit rotation’) with respect to the gravitational vector; in these tests the stimulus is provided by the continuous reorientation of the head with respect to gravity.140,141 It is important to note that, whenever the linear acceleration is generated by rotation, the otolith response is assessed either by subtracting the component due to angular motion (e.g. subtracting head-eccentric response from head-centred response, in the head-eccentric test) or by waiting until the angular VOR has ceased (e.g. in OVAR or BBQ rotation). Finally, a simple way of stimulating the otoliths is head tilt with respect to gravity. This can be refined with precision gimbals systems (Figures 62.27a and b).142 A summary of the stimulation techniques for otolith assessment is presented in Figures 62.27, 62.28 and 62.29.
Genetic and Developmental Implications for Trace Metal metabolism from Mutant and Inbred Strains of Animals
Published in Owen M. Rennert, Wai-Yee Chan, Metabolism of Trace Metals in Man, 2017
Given the evidence for such a severe Zn deficiency, at least during lactation, I began to question whether or not there might also be a vestibular defect. Purichia and Erway71 showed that Zn deficiency, as well as an inhibitor of carbonic anhydrase, caused otolith defects observed in the newborn mice. However, we subsequently discovered that such defects disappeared, and the otoliths became normal again within 3 days after birth.72 This suggested that otoconia were very sensitive to such effects, even after they were already formed, and that they could recover from damage evident at birth.
Application of supervised machine learning algorithms for the evaluation of utricular function on patients with Meniere’s disease: utilizing subjective visual vertical and ocular-vestibular-evoked myogenic potentials
Published in Acta Oto-Laryngologica, 2023
Phillip G. Bragg, Benjamin M. Norton, Michelle R. Petrak, Allyson D. Weiss, Lindsay M. Kandl, Megan L. Corrigan, Cammy L. Bahner, Akihiro J. Matsuoka
The anatomical and physiological differences between the transient and sustained systems suggest these two systems could react differently to diagnostic tests that evaluate utricular function. Previously published data supports this claim. Immediately after the surgical unilateral vestibular loss, such as acoustic neuroma removal or labyrinthectomy, the results of a Subjective Visual Vertical (SVV) test initially appear asymmetrical. However, over time the effect of unilateral loss on SVV is not consistent such that the sustained function of the otolithic organ does not clearly detect a chronic unilateral vestibular loss [4]. It has been speculated that processes of vestibular compensation might contribute to reducing any asymmetry. The data from studies of SVV on patients after vestibular neuritis also show significant variability. Nevertheless, it is not known conclusively whether otolith function may have returned after the neuritis [7]. By contrast, the asymmetrical VEMPs are preserved for many years and probably permanently after the vestibular loss [8].
Patterns of vestibular function in patients with dizziness after COVID-19 vaccination; dual tertiary referral center study
Published in Acta Oto-Laryngologica, 2022
Joonsik Yoon, Min Seok Song, Sang-Yeon Lee, Moo Kyun Park, Jun Ho Lee, Seung Ha Oh, Min Young Lee, Myung-Whan Suh
Four patients had a history of dizziness events 3–30 years ago (BPPV in two patients and vestibulopathy in two patients). However, the subjective feeling of dizziness was different from past dizziness events in all cases. Nystagmus, whether it was spontaneous or positional, was detected in all patients. Most of them were horizontal nystagmus. But two patients showed torsional and a patient showed vertical nystagmus (Table 2). Semicircular dysfunction was observed in all patients. The results of gains and the presence of catch-up saccade of three semicircular canals are shown in Table 3. Four patients showed unilateral gain decreases with horizontal nystagmus towards the contralesional side. Among them, two patients showed multicanal weakness (anterior and lateral), and canal paresis was observed in these patients. Meanwhile, otolith dysfunction was only observed in two patients. Concurrent acute sensory neural hearing loss was documented in one patient.
The effect of sport training on otolith function in adults with profound sensorineural hearing loss
Published in Hearing, Balance and Communication, 2021
Homa Zarrinkoob, Arash Bayat, Nasim Kaka
The absence and impairment of vestibular evoked potentials indicated otolithic dysfunction. However, in the analysis of the medical records of “non-athletes deaf” patients, neither the physicians nor the patients noticed balance dysfunctions or otolith involvements. It has been suggested that vestibular dysfunction in hearing-impaired individuals can be a debilitating condition that leads to oscillopsia, imbalance, and increased risk of falls [21]. Patients with vestibular deficit have difficulty conducting activities of daily living such as driving, climbing stairs, and walking, and these patients also report increased dependence on others, reduced life satisfaction, and decreased productivity [22–24]. Ernst et al. [25] also showed that younger patients with otolith dysfunction are at risk in their everyday life, especially when they are moving fast (e.g. in a car) without full visual control of the surrounding (e.g. in the dark).