Vestibulo-ocular Reflex Physiology, Pathology And Rehabilitation
Funder
National Health and Medical Research Council
Summary
A sensation of movement from the inner ear is used to stabilise vision during head movements. Without it, every time you walk, run, or drive on a bumpy road, the world would appear to bounce. It can be debilitating when this sense doesn't work due to various diseases. This research examines how this sense works normally and the factors important for self-repair after injury. This work will also develop training exercises using a device for take-home balance rehabilitation.
A New Mouse Model That Determines The Effects Of A Unilateral Vestibular Prosthesis On Vestibular Plasticity.
Funder
National Health and Medical Research Council
Funding Amount
$455,678.00
Summary
Much like a cochlear implant restores auditory function, a vestibular prosthesis restores balance function. It is not clear whether the limited results from vestibular prostheses is due the device not stimulating one component (the otoliths) of the vestibular system essential for self-repair. We will test mutant mice that lack otoliths to determine the importance of stimulating the otoliths in restoring function. This work will shape the future direction of prosthesis development.
Optimising Balance Function In Vestibular Schwannoma
Funder
National Health and Medical Research Council
Funding Amount
$271,817.00
Summary
This project examines human balance function in subjects with vestibular Schwannoma, a slow growing tumor that presents with hearing loss and imbalance. We will measure inner ear balance function using 2 new non invasive tests called the video head impulse and the vestibular evoked myogenic potential. We will seek test parameters that predict tumor growth, explore reasons for post surgical imbalance, develop and validate home-based rehabilitation methods to optimise balance after surgery.
The Role Of Vestibular Efferents In The Mammalian Vestibulo-ocular Reflex.
Funder
National Health and Medical Research Council
Funding Amount
$323,341.00
Summary
The aim of this study is to determine how a group of nerve fibres that travel from the brain to the balance organ alter balance function in mammals. Balance function in mice will be tested under conditions that modify the balance system response. Results will be compared between normal mice and mutant mice in which these nerves do not function. This work will determine how these nerves alter balance function and whether they are a viable target for future patient treatments.
Dizziness, vertigo, and imbalance affect nearly half the population by the age of 60 and balance-related falls, especially in the elderly, are a serious health concern. Surveys of primary care doctors have shown that dizziness and vertigo are as prevalent as hypertension and angina, and approximately 40% of the population experience dizziness severe enough to seek medical attention. Unfortunately, most symptoms are not relieved by currently available medical treatment. There is, however, a remar ....Dizziness, vertigo, and imbalance affect nearly half the population by the age of 60 and balance-related falls, especially in the elderly, are a serious health concern. Surveys of primary care doctors have shown that dizziness and vertigo are as prevalent as hypertension and angina, and approximately 40% of the population experience dizziness severe enough to seek medical attention. Unfortunately, most symptoms are not relieved by currently available medical treatment. There is, however, a remarkable hidden reserve of 'self-repair' in the balance system that can be triggered under certain conditions. We call this process 'vestibular compensation' and if we can understand those conditions and discover the means by which this reserve affects the nervous system, we may be able harness its power to alleviate the all distressing symptoms of imbalance. Perhaps we may even be able to apply these principles to other critical systems that may need repair. We propose to look at a key region in the central nervous system that is responsible for processing balance signals and may be very important in 'vestibular compensation'. We will try to activate this recovery process under controlled conditions so that we can understand the changes that occur. Specifically we will examine the role of vestibular (balance) neurons in the central nervous system that appear to be modified following trauma of the inner ear balance organs. We will use our new recording techniques to examine these vestibular neurons to see how their intrinsic properties may change and what external or internal factors influences this change. Our aim is to understand what factors promote and what factors inhibit full recovery.Read moreRead less
Our vestibular system provides us with the important sense of balance. When it fails we suffer debiltating bouts of vertigo and dizziness. A great deal is known about how balance signals are sent from the inner ear to our brains, but virtually nothing is known about the important signals the brain sends to the inner ear. In this study we will use a new perparation develped in our laboratory to examine how these essential brain signals control the function of our balance organs.
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
Vestibulo-ocular Responses To Bone Conducted Vibration
Funder
National Health and Medical Research Council
Funding Amount
$282,772.00
Summary
This project is about an entirely new way of clinically evaluating balance function of the inner ear by using bone conducted vibration (BCV). We will make measures of the BCV stimulus in order to specify the stimulus at the receptors, and relate this stimulus to the eye-movement responses it causes. Measuring the exact stimulus and the response will give us a much better understanding of why this stimulus works, allowing us to optimize the clinical tests of balance function.
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
Oculomotor Tests Of Otolith Function Using Human Centrifugation
Funder
National Health and Medical Research Council
Funding Amount
$284,450.00
Summary
The effects of dysfunction of the balance system of the inner ear (the vestibular system) can range from mild brief episodes of dizziness to almost complete incapacitation: where the patient feels unstable, their posture is unstable, their vision is unstable. In order to guide appropriate treatment and rehabilitation, diagnostic tests are needed to identify whether the dysfunction is due to a brain problem or a problem in the inner ear, and if an ear problem - which part of the inner ear system ....The effects of dysfunction of the balance system of the inner ear (the vestibular system) can range from mild brief episodes of dizziness to almost complete incapacitation: where the patient feels unstable, their posture is unstable, their vision is unstable. In order to guide appropriate treatment and rehabilitation, diagnostic tests are needed to identify whether the dysfunction is due to a brain problem or a problem in the inner ear, and if an ear problem - which part of the inner ear system is affected. By combining basic research with clinically feasible methods my colleagues and I have, with NH and MRC support, developed some of the most widely used clinical tests of balance function available today (see Halmagyi, Cremer and Curthoys 2003 for a review). In this Project I seek to continue the development of a test of part of the balance system (the utricular macula) for which there are few acceptable tests. I will do that by using the unique facilities available at Sydney University and RPA Hospital, presenting controlled stimuli (linear accelerations) to healthy human subjects and patients with known vestibular losses, and measuring precisely their eye movement responses to these stimuli using computerized image processing techniques. The experiments will test an hypothesis about how part of the vestibular system, the utricular macula, works and controls eye movements. One eye movement response, rolling of the eye around the line of sight (called ocular torsion) during maintained roll head-tilts (to the patients left or right) may be due to the joint activation of two regions of the balance receptors: the utricular and saccular maculae. As a result of a recent direct test we have managed to conduct on two normal subjects, we think that hypothesis should be thoroughly re-tested on subjects and patients with known vestibular losses and in doing so provide new understanding of otolith function which may lead to new clinical tests.Read moreRead less