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
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