A Balancing Act: A Three-pronged Approach To Vestibular Assessment
Funder
National Health and Medical Research Council
Funding Amount
$419,180.00
Summary
Vertigo and imbalance are common and disabling symptoms of vestibular (balance) dysfunction. This project will investigate three aspects of vestibular function: by searching for new balance reflexes, revealing the pattern of vestibular deficits in patients with a common form of vertigo caused by migraine, and exploring the impact of vestibular disease on thinking and memory. This research will improve our understanding of the vestibular system and facilitate the diagnosis of episodic vertigo.
New Methods And Applications Of Vestibular Electrophysiology In Humans.
Funder
National Health and Medical Research Council
Funding Amount
$165,509.00
Summary
This project consists of a series of experiments and investigations using new methods to test the vestibular apparatus (balance organs). These receptors lie deep within the skull in the inner ear and disease of them can cause dizziness (vertigo) and unsteadiness. Due to their location, investigation of the function of these receptors has been difficult. With NH and MRC support, I have developed two new methods of vestibular assessment. These are now being applied both here and overseas. Perhaps ....This project consists of a series of experiments and investigations using new methods to test the vestibular apparatus (balance organs). These receptors lie deep within the skull in the inner ear and disease of them can cause dizziness (vertigo) and unsteadiness. Due to their location, investigation of the function of these receptors has been difficult. With NH and MRC support, I have developed two new methods of vestibular assessment. These are now being applied both here and overseas. Perhaps the clearest example of how these new techniques have improved current diagnostic methods is the Tullio phenomenon, in which patients feel dizzy in response to loud sounds. My colleagues and I have shown that these patients always have a characteristic abnormality to click activation of the inner ear, one of the tests that I developed. It is likely to have a very important role in distiguishing between patients with Xray abnormalities predisposing to this condition and those who actually have the full-blown syndrome, so that the correct treatment is offered. This proposal seeks to build on the previous successful one. In it, I propose further new methods of investigating the vestibular apparatus, which avoid some of the preconditions necessary for the present tests and would allow more widespread application of them. Furthermore, additional specific disease states which are characterised by unsteadiness (ataxia) will be assessed with these new methods to determine whether abnormal vestibular reflexes are partly responsible for the loss of balance. In one of the conditions to be investigated, gentamicin-induced vestibular impairment, there is the possibility in the future of applying these techniques to detect changes early, at a time when they are potentially reversible.Read moreRead less
Vestibular Reflexes Evoked By Brief Lateral Head Acclerations: A New Measure Of Utricular Function
Funder
National Health and Medical Research Council
Funding Amount
$225,357.00
Summary
The vestibular (balance) organs are difficult to investigate as they lie deep within bone. Disease of these organs may cause severe vertigo, imbalance and difficulty with vision. This project attempts to build on earlier developments in my laboratory and thereby improve understanding and diagnosis of these disorders. This grant relates to a new form of stimulation which may allow simple assessment of an important part of the vestibular apapratus, the utricle.
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