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Utricular and visual aspects of inner ear disorders

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Agarwal-K-2016-MD(Res)-Thesis.pdfThesis1.82 MBAdobe PDFView/Open
Title: Utricular and visual aspects of inner ear disorders
Authors: Agarwal, Kiran
Item Type: Thesis or dissertation
Abstract: The research described in this thesis is about investigation of the two less well understood mechanisms of balance system, namely utricular function and interactions of visual and vestibular system. Utricules are part of otolith apparatus and sense linear acceleration including gravity and lateral head tilts. Recent advances in rotational technology allow robust methods of assessment of unilateral utricular function using centrifugation techniques. Unilateral centrifugation generates substantial linear acceleration and the utricular response can be measured via tilt perception using subjective visual vertical (chapter 2). Utricular function was studied in common vestibular disorders seen in clinics, like chronic vestibular neuritis, benign positional paroxysmal vertigo, unilateral Ménière’s disease, migraine and bilateral vestibular hypofunction. Bilateral vestibular hypofunction produced significantly low utricular gain (chapter 3). A detailed study of the utricular function of larger group of unilateral Ménière’s disease showed significantly greater utricular asymmetry and lower utricular gain than normal controls. Interestingly, hearing loss was a predictor of utricular asymmetry (chapter 4). There was poor correlation between subjective measures and audiovestibular function. The chronic course of Ménière’s disease is well known with slow decline over years and absence of correlation between symptoms and function may point to ‘burn out’ as long term phenomenon (chapter 5). An investigation into visual dependence and vertigo was performed to understand the effect of visual dependence on tilt perception in chronic vertigo. Individuals with vestibular symptoms can have increased visual dependency and migraineurs can have a non-adaptable increase in visual dependency (chapter 6). In summary, we found that the unilateral centrifugation is a safe and well tolerated technique and provides additional, potentially useful information about utricular function. In future, the study of utricular function during acute phases of vertigo will further help overall understanding of otolith pathophysiology and mechanisms used for compensation.
Content Version: Open Access
Issue Date: Apr-2015
Date Awarded: Mar-2016
URI: http://hdl.handle.net/10044/1/32022
DOI: https://doi.org/10.25560/32022
Supervisor: Bronstein, Adolfo
Sponsor/Funder: Meniere's Society
Department: Department of Medicine
Publisher: Imperial College London
Qualification Level: Doctoral
Qualification Name: Doctor of Medicine (Research) MD (Res)
Appears in Collections:Medicine PhD theses



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