Comprehensive Clinical Tests Of Vestibular Function To Track Vestibular Compensation And Meniere’s Disease
Funder
National Health and Medical Research Council
Funding Amount
$390,625.00
Summary
This Project will apply new, fast, safe, comprehensive, balance tests we have developed to measure the function of the balance receptors of the inner ear. We will track changes in balance function during disease and recovery in the many, and increasing, number of Australian patients with balance disorders. These tests will give us insight into changes in the inner ear associated with severe attacks of vertigo and why some patients recover so poorly after damage to inner ear balance receptors.
Combined linear and angular head movements are integral components of our natural head movements. The vestibular sensory apparatus in the labyrinth of the inner ear, which comprises three semicircular canals and two otoliths acts as an inertial guidance system during head motion. The vestibular sensors mediate the angular and linear vestibulo-ocular reflexive eye movements imperative to stabilise vision during the head motions. However, it is unclear how these responses to sudden linear and angu ....Combined linear and angular head movements are integral components of our natural head movements. The vestibular sensory apparatus in the labyrinth of the inner ear, which comprises three semicircular canals and two otoliths acts as an inertial guidance system during head motion. The vestibular sensors mediate the angular and linear vestibulo-ocular reflexive eye movements imperative to stabilise vision during the head motions. However, it is unclear how these responses to sudden linear and angular motion in three dimensions are combined and processed. Diseases of the inner ear can produce incapacitating visual and balance disturbances, yet the normal function of some of the inner ears receptors, in particular the otoliths, cannot be easily tested. Clinical evidence has shown that patients with incapacitating attacks of vertigo can have impairment of either or both the semicircular canals and the otoliths. The aim of this project is to measure quantitatively the semicircular canal-otolith response to transient, high-acceleration combined linear-angular head movements to find a reliable way to test the otolith function. Based on physiological principles and my preliminary experiment, we plan to use an off-axis head rotation procedure, a three-dimensional eye movement recordings and vector analysis technique to assess the linear and angular vestibulo-ocular reflex response from the otoliths and semicircular canals in the labyrinth. The practical significance of answers to these questions is that they will characterise the combined linear and angular vestibulo-ocular reflex responses that stabilise vision during transient head movements. It will provide us with a greater understanding of the visual disturbance that patients experienced during these kinds of head movements following vestibular disease or surgery. Measurement of the linear vestibulo-ocular reflex may also provide a diagnostic test of otolith function clinically in disease states.Read moreRead less
Vestibular Activation In Benign Paroxysmal Positional Vertigo And Superior Semicircular Canal Dehiscence
Funder
National Health and Medical Research Council
Funding Amount
$340,350.00
Summary
Vestibular Activation in Benign Paroxysmal Positional Vertigo and Superior Semicircular Canal Dehiscence The aim of this project is to study the pathological activation of the vestibular system in benign paroxysmal positional vertigo and superior canal dehiscence in order to achieve an improved diagnosis in both conditions and a more effective treatment for benign paroxysmal positional vertigo. These diseases provide unique opportunities to study unilateral activation of an otherwise normal huma ....Vestibular Activation in Benign Paroxysmal Positional Vertigo and Superior Semicircular Canal Dehiscence The aim of this project is to study the pathological activation of the vestibular system in benign paroxysmal positional vertigo and superior canal dehiscence in order to achieve an improved diagnosis in both conditions and a more effective treatment for benign paroxysmal positional vertigo. These diseases provide unique opportunities to study unilateral activation of an otherwise normal human vestibular system. Benign paroxysmal positional vertigo and its variants is prevalent, especially amongst the elderly, as a major cause of dizziness and imbalance. These conditions describe a variety of vestibular lithiasis where free-floating otoconia misplaced in a semicircular canal cause abnormal deflection of the cupula, resulting in activation of the semicircular canal in a vestibular system during changes in gravitational head position. This study endeavours to develop a scientific basis for accurate diagnosis of benign paroxysmal positional vertigo and its variants. Online real-time 3-D recording and vector analysis of the nystagmus could be adapted to a 3-D video-oculography system for a more systematic approach to diagnosis and treatment. Thus, we aim to develop and trial a suitable particle repositioning manoeuvre using a mechanical device as treatment for patients who did not respond to the clinical Epley or Semont manoeuvre. Superior semicircular canal dehiscence permits sound or pressure to abnormally activate the vestibular system. In the superior canal dehiscence study, we seek to develop a more sensitive diagnostic test. If the click-evoked 3-D VOR is due to direct activation of the otoliths, then it offers an avenue to examine otolithic function. Understanding the mechanism of unilateral activation of a normal human vestibular system is important for the development of implantable vestibular prosthesis.Read moreRead less
Behavioural And Physiological Tests Of Clinical Indicators Of Vestibular Function.
Funder
National Health and Medical Research Council
Funding Amount
$205,500.00
Summary
Part of the inner ear is responsible for our sense of balance and for maintaining clear vision and stable posture. Recurring vertigo attacks and persistent imbalance can disrupt the most productive years of patients' lives and balance-related falls account for more the half of accidental deaths in the elderly. Despite this most doctors find dizziness difficult to diagnose and impossible to treat, so specialist Balance Disorders Clinics see many patients a year but still have very long waiting ti ....Part of the inner ear is responsible for our sense of balance and for maintaining clear vision and stable posture. Recurring vertigo attacks and persistent imbalance can disrupt the most productive years of patients' lives and balance-related falls account for more the half of accidental deaths in the elderly. Despite this most doctors find dizziness difficult to diagnose and impossible to treat, so specialist Balance Disorders Clinics see many patients a year but still have very long waiting times. There is then clearly a major need to improve the understanding and the treatment of dizzy patients and improvement will come about through scientific understanding of vestibular dysfunction, and technological realization of improvements in the assessment and treatment of patients. This project seeks to identify whether 3 simple new indicators of balance function are valid, using tests on guinea pigs to understand the way in which they work.Read moreRead less
The Neural Basis Of Clinical Vestibular Testing By Bone Conducted Sound
Funder
National Health and Medical Research Council
Funding Amount
$260,986.00
Summary
Dysfunction of the balance system of the inner ear (the vestibular system) causes recurring dizzy attacks and persistent unsteadiness which can disrupt the most productive years of some people's lives. Balance-related falls account for more than half of accidental deaths in the elderly (Marchetti and Whitney 2005). Despite this, most doctors find dizziness difficult to diagnose and almost impossible to treat in part because of the subjective nature of the patients' reports. Fast, simple, safe, o ....Dysfunction of the balance system of the inner ear (the vestibular system) causes recurring dizzy attacks and persistent unsteadiness which can disrupt the most productive years of some people's lives. Balance-related falls account for more than half of accidental deaths in the elderly (Marchetti and Whitney 2005). Despite this, most doctors find dizziness difficult to diagnose and almost impossible to treat in part because of the subjective nature of the patients' reports. Fast, simple, safe, objective clinical tests are needed to diagnose these patients' problems and to identify which of the 10 vestibular sensory regions is affected. A new way of testing balance function is to use sound because sound can activate the vestibular system as well as the auditory system. We are using that fact to develop a whole new way of clinical testing of vestibular function and this largely Australian development has been very rapidly accepted by the international vestibular community. In a recent NHMRC project (253620) we discovered 1) that bone conducted vibration specifically activates some sensory nerves from one of the gravity sensing regions of the balance system (the otoliths) and 2) that air-conducted (AC) sound and bone-conducted vibration (BCV) appear to probe the function of different vestibular sensory regions 3) most importantly that BCV causes an eye movement response in alert guinea pigs (as it does in alert human subjects). This seems to be the objective response for testing otolith function which we are seeking. In this project we plan to extend these results by recording single vestibular nerve cells in guinea pigs, testing hypotheses about their responses to various types of sound and then injecting the neurons with stains which will allow us to confirm definitely the location of the receptors activated by the sound stimuli. The outcome will be the physiological basis of a new clinical test of balance using bone conducted vibration.Read moreRead less