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.
Assessment Of Vestibular Function And Balance In Humans
Funder
National Health and Medical Research Council
Funding Amount
$205,500.00
Summary
This proposal focuses upon the function of the vestibular apparatus and the related problem of impaired balance. The vestibular apparatus contains receptors which help us to maintain balance. Their clinical assessment is difficult because they are small and lie deep within the skull. With previous NH and MRC support, I have been able to develop a series of new tests to assess the function of the vestibular apparatus and these are having significant clincal impact. Amongst the findings has been a ....This proposal focuses upon the function of the vestibular apparatus and the related problem of impaired balance. The vestibular apparatus contains receptors which help us to maintain balance. Their clinical assessment is difficult because they are small and lie deep within the skull. With previous NH and MRC support, I have been able to develop a series of new tests to assess the function of the vestibular apparatus and these are having significant clincal impact. Amongst the findings has been a clear demonstration that vestibular function declines with age, starting relatively early. This proposal builds upon the findings of the previous application. Two main types of investigations are planned. In one a new technique of activating the vestibular apparatus (localised skull vibration) will be used to study the brain areas that receive its signals (evoked potentials). This will be the first time that it has been possible to study the connections between the balance organs and the cortex of the brain in intact humans. I will apply the technique to patients with disturbed vestibular function to improve our knowledge of how the brain adapts to disease of these organs. In the second part of this study, a series of recordings will be done measuring sway under a variety of conditions both in normal volunteers and in patients with some common disease states affecting balance. This should reveal new information about both the factors that affect normal balance function and why balance is disturbed in these diseases.Read moreRead less
Dynamic Postural Stability And Falls Prediction In Older People During Walking In Real-world Environments.
Funder
National Health and Medical Research Council
Funding Amount
$680,793.00
Summary
The increased occurrence of falls with advancing age (33-50% of people aged >65 years) is a significant cause of mortality (1014 deaths in 1998), morbidity, and disability, affecting not only the individuals concerned, but the health care system (45,069 fall related hospitalizations in 1998 in Australia) and the broader community (National falls Prevention Initiative, 2004). Although there are a number of falls risk tests, most rely on determination of body sway while standing when the body i ....The increased occurrence of falls with advancing age (33-50% of people aged >65 years) is a significant cause of mortality (1014 deaths in 1998), morbidity, and disability, affecting not only the individuals concerned, but the health care system (45,069 fall related hospitalizations in 1998 in Australia) and the broader community (National falls Prevention Initiative, 2004). Although there are a number of falls risk tests, most rely on determination of body sway while standing when the body is static rather than in motion. Given that up to 70% of falls occur during walking and performing transfers, there is a clear need to develop tests of falls risk prediction that incorporate indices of postural stability measured during more dynamic activities. Test development needs to be underpinned by clear evidence of how age-related sensory and motor deficits affect postural stability during walking. The studies outlined in this application will develop and utilise new accelerometer-based technologies to determine the fundamental mechanisms underlying balance control during walking in older people. Specifically, this project will aim to develop a clear understanding of how changes in factors as vision, neuromuscular function (strength, stiffness) and proprioception contribute to the overall decline in stability and balance during walking in older people. Combined with physiological assessment measures developed by the research team, the research will allow the development of a more definitive predictive test of stability and falls risk. This test will be able to be used by health professionals for assessment of older people to determine the most effective therapeutic and-or exercise interventions to target those individuals at risk. This technology will also be adaptable to a biofeedback device to allow individuals to monitor their own stability.Read moreRead less
We do not possess a clinical test to assess balance pathways to the trunk and lower limbs. This project will use vibration pulses and a gentle electrical pulses to activate inner ear balance organs and evoke a postural response. We will assess healthy volunteers across age groups and dizzy patients . We will develop and disseminate a simplified test for widespread clinical use. Our findings will be used to refine and validate a predictive model of postural responses to electrical stimulation.
Testing Of Vestibular Function By Active Head Movements.
Funder
National Health and Medical Research Council
Funding Amount
$180,509.00
Summary
The vestibular system of the inner ear is responsible for our sense of balance and for maintaining clear vision and stable posture during head movements. This complex interdependent sensory system is comprised of three paired semicircular canals for sensing head rotations and two paired otolith organs for sensing head position and linear movements of the head. A major goal of our research programs is to develop simple tests which can be used in the clinic or at the bedside to diagnose specific d ....The vestibular system of the inner ear is responsible for our sense of balance and for maintaining clear vision and stable posture during head movements. This complex interdependent sensory system is comprised of three paired semicircular canals for sensing head rotations and two paired otolith organs for sensing head position and linear movements of the head. A major goal of our research programs is to develop simple tests which can be used in the clinic or at the bedside to diagnose specific deficits of each vestibular sensory region. Most present clinical tests only test the part of the system concerned with horizontal head rotations but there are many other sensory regions in the inner ear whose functional status needs to be evaluated, especially those regions concerned with signalling linear head movements and head position - the otolith sensory regions. The usual principle in vestibular testing is to move the person's head and measure the eye movement which occurs in response to that passive movement. One of our recent observations suggest that it may be possible to measure vestibular functioning during active head movements. Active testing does not require expensive, invasive testing systems and could be carried out in the clinic. This project will compare the eye movement response to active and passive head movements in the same patients. We will test both the angular and linear sensing systems by asking patients to rotate their head or slide it laterally, recording the head movement stimulus and eye movement response. Two groups of patients will be studied; those who have recovered well and those who are poorly recovered after unilateral vestibular loss. The outcome will, we hope, be safe simple low cost tests which will evaluate the functional status of all the inner ear sensory regions and yet be clinically practical. They may provide the answer as to why some patients do not recover well after unilateral loss whereas others do.Read moreRead less
Experimental Validation Of A Clinical Indicator Of Utricular Function.
Funder
National Health and Medical Research Council
Funding Amount
$198,689.00
Summary
The vestibular system is responsible for our sense of balance, it is located in the inner ear and is responsible for maintaining posture and helping an organism to make appropriate eye movements when the head moves. Damage to the vestibular system by disease or accident is extremely debilitating for a patient. A chief goal of our research program is to develop simple tests of the vestibular system that can be used in the clinic to diagnose vestibular disorders. Most present clinical tests only t ....The vestibular system is responsible for our sense of balance, it is located in the inner ear and is responsible for maintaining posture and helping an organism to make appropriate eye movements when the head moves. Damage to the vestibular system by disease or accident is extremely debilitating for a patient. A chief goal of our research program is to develop simple tests of the vestibular system that can be used in the clinic to diagnose vestibular disorders. Most present clinical tests only test the part of the vestibular system that responds to angular rotations (the semicircular canals). There are few good tests that can reliably diagnose problems concerned with sensed position (the otoliths). Recent evidence from human studies has shown that by delivering small electrical currents (galvanic stimulation) via electrodes located on the surface of the skin behind the ears, a characteristic pattern of eye movement occurs. Our hypothesis is that the distinctive pattern of eye movement produced is a result of otolith stimulation. The aim of this project is to determine exactly how these small currents produce the eye movements and if these eye movements are in fact mediated by the otoliths. To determine the physiology that underlies these types of responses we are unable to conduct these experiments in humans. Our present program will therefore use both behavioural and physiological experiments on guinea pigs to test our hypotheses about galvanic stimulation and otolith function. The significance of this work lies in that it will lead to a new way of evaluating the function of the gravity sensing part of the human vestibular system which appear to be uniquely important for patients with balance problems.Read moreRead less