Project Proposal

Basic and Clinical Aspects of Vertigo and Dizziness
22-25 June 2008
Kloster Seeon, Germany

Editors
Michael Strupp, Bernie Cohen and Ulrich Büttner

Background, aims and scope

Vertigo is not a unique disease entity. The term covers a number of multisensory and sensorimotor syndromes of various etiologies and pathogeneses, which can be elucidated only with an interdisciplinary approach. After headache, it is one of the most frequent presenting symptoms, not only in neurology.

Whether caused by a physiological stimulation (motion sickness, height vertigo) or a lesion (unilateral labyrinthine failure, central vestibular lesion), the resulting vertigo characteristically exhibits similar symptoms despite the different pathomechanisms - dizziness, nausea, nystagmus, and ataxia. Disorders of perception (dizziness), gaze stabilization (nystagmus), posture control (falling tendency, ataxia), and the vegetative system (nausea) are related to the main functions of the vestibular system which are located in different sites in the brain. The most important anatomical structure of the vestibular system is the vestibulo-ocular reflex (VOR). The VOR has three major planes of action: horizontal head rotation about the vertical, head extension and flexion about the horizontal and lateral head tilt about the sagittal axis. These three planes are the three-dimensional space in which the vestibular and ocular motor systems responsible for spatial orientation, perception of self-movement, stabilization of gaze, and postural control operate. The neuronal circuitry of the horizontal and vertical canals as well as the otoliths is based on a sensory convergence that takes place within the VOR. The VOR connects a set of extraocular muscles that are aligned by their primary direction of pull with the same particular spatial plane of the horizontal, the anterior, or the posterior canal. The canals of both labyrinths form functional pairs in the horizontal and vertical working planes. The otoliths function as a gauge of gravity and linear acceleration.

The most frequent forms of peripheral vestibular vertigo are benign peripheral paroxysmal positioning vertigo, vestibular neuritis, and Menière’s disease. The neurovascular compression syndrome of the VIIIth cerebral nerve (vestibular paroxysmia), bilateral vestibulopathy, and perilymph fistula occur more rarely. Peripheral vestibular attacks of vertigo are characterized by a strong rotatory vertigo and spontaneous nystagmus in one direction, a tendency to fall in the other direction, nausea, and vomiting.

Central vestibular forms of vertigo arise from lesions at the connections between the vestibular nuclei and the vestibulo-cerebellum as well as those between the vestibular nuclei, the ocular motor structures of the cerebellum, thalamus, and vestibular cortex. On the one hand, these are clearly defined major syndromes of various etiologies, for example, upbeat or downbeat nystagmus. The occurrence of these typical ocular motor findings in only the central brainstem or cerebellar functional disorders allows their definitive topical attribution. On the other hand, central vestibular vertigo can also be a part of a complex infratentorial clinical syndrome. Other symptoms such as supranuclear or nuclear ocular motor disorders and/or other neurological brainstem failures (e.g., Wallenberg’s syndrome) can also be observed.

During the last three decades new laboratory techniques have been developed to examine the vestibular cerebellar and ocular motor systems in health and disease. They include (1) the magnetic search-coil technique and video-oculography to record eye movements with high precision, (2) click-evoked myogenic potentials to test saccular function, (3) ocular counter roll and psychophysical determination of the subjective visual vertical to test utricular function, (4) posturography to evaluate balance and vestibulospinal reflexes, and (5) functional imaging of the brain to evaluate the central vestibular and ocular motor system.

Further, the various forms of vertigo can be treated with pharmacological therapy, physical therapy, surgery, and psychotherapeutic measures. During the last 10 years new therapeutic principles have been developed which significantly reduce the burden of disease of patients with vertigo and dizziness.

The whole field of vertigo and dizziness, imbalance, and eye movement disorders has been considered extremely difficult because of the variety of its manifestations and its resistance to compartmentalization. The study of the vestibular system in combination with eye movements is a source of valuable information to both basic scientists and clinicians. To the neurobiologist, the study of the vestibular systems gives an opportunity to understand the workings of the brain, including the development of mathematical models. For neurologists, ENT-doctors and ophthalmologists, abnormalities of the vestibular system and eye movements are often the clue to the anatomical localization of a disease process.

One aim of this meeting will be to make the different vestibular syndromes more understandable by developing clear, anatomical categories and clinical classifications.

This meeting should further stimulate the ongoing lively interaction between neuroanatomists, neurophysiologists, neurologists, ENT-doctors, ophthalmologists, biologists, neuroinformaticans, and engineers. Topics that will be of interest include the vestibular system and spatial orientation, the role of the cerebellum in postural control, genetics of vestibular disorders, control of gait, functional imaging of the vestibular system, ageing of the vestibular system and modeling of vestibular and ocular motor disorders.

Rationale

In the past five years, there have been over 2000 new peer-reviewed publications concerned with vertigo and dizziness. These papers deal with a broad range of issues, such as mechanisms underlying normal and abnormal function of the vestibular system or new ways to specifically treat certain vestibular syndromes. Thus, there is a great need to synthesize this work into a volume that will be accessible to a broad audience (see below).

            Over the years the N.Y. Acad. Sci has published several volumes on vestibular and ocular motor disorders, e.g., volume, 656 (1992) or 781 (1996). The most recent conference proceedings with similar goals were published in 2003 (volume 1004); this volume focused on the ocular motor and vestibular systems. Other proceedings were related to the ocular motor system only, such as volume 1039 in 2005. The planned conference has broad and, to some extent, more clinically oriented goals, and will contain much new information due to a number of advances in the field, for instance: (1) better understanding of the physiology of the peripheral and central vestibular system, (2) new mathematical models that also explain vestibular disorders, (3) new insights into the interaction between the vestibular and other sensory systems by functional imaging as well as parallel imaging by MRI, PET and MR-spectroscopy, (4) demonstration of the influence of the vestibular system on gait and postural control, (5) new clinical applications of methods to evaluate the vestibular system, such as vestibular evoked potentials and galvanic stimulation, (6) news from neurogenetics on vestibular migraine and other causes of vertigo and dizziness, and (7) application of animal models of channel disorders to develop drug treatments for disorders that cause ataxia. These are just a few illustrative examples of the strides that have been made in the past 2-3 years. With this flood of new information, reviews written by a group of experts will provide a valuable source.

Audience

1)       Neuroscientists (including neuroanatomists, electrophysiologists, computational neurobiologists, and information/artificial intelligence scientists). Target societies: Society for Neuroscience

2)      Neurologists. Target societies: American Academy of Neurology, Association of British Neurology, French Neurological Society, German Neurological Association, European neurological societies

3)      Otolaryngologists. Target society: Barany Society

4)      Also, psychologists, pharmacologists, and others

Organization

The organization of the volume would follow that of the conference program. Initial chapters deal with the basic anatomy and physiology of the peripheral and central vestibular system; this will also include topics such mathematical models of the vestibular system, spatial orientation, central control of gait, functional imaging. Then there will be descriptions of the most common vestibular disorders, including current methods of diagnosis and treatment with the application of new techniques; this will also include genetics of vestibular disorders and ageing of the vestibular system. Short contributions based on poster presentations would be integrated into the general structure of the volume, and not be relegated to a separate section. Illustrations should be capped at three or four per contribution. They should be gray-scale unless authors are prepared to shoulder the cost of color.