Speakers' Abstracts
Investigating peripheral and central vestibular dysfunction in multiple sclerosis
Vertigo and balance (Part One)
Luxon L, Chair of Audiovestibular Medicine, University of London
Balance in man is a complex system which relies on input from the labyrinth, vision and the proprioceptive system. These sensory inputs are integrated and modulated by central nervous system activity to provide a perception of orientation in space, one means of controlling eye movements, via the vestibulo-ocular reflexes, and control of posture and motion, via the vestibulo-spinal reflexes.
The labyrinthine vestibular receptors include both the semicircular canals, which sense angular acceleration, and the otolith organs, which sense linear acceleration. The most accurate and well established clinical method of investigating central and peripheral vestibular function is the application of a quantified stimulus to the horizontal semicircular canal and recording the resultant vestibulo-ocular response, which relies on both vestibular and brainstem activity. However, recently it has become possible to record a muscle response to stimulation of the saccule, one of the two otolith organs, and thus obtain greater information about labyrinthine function, the connections in the cranial nerve taking information from the labyrinth to the brain and the pathways in the brainstem.
Eye movement control depends not only on vestibular input, but also on visual inputs and the interaction of visual and vestibular signals takes place in the brainstem and is modulated by cerebellar activity. Thus, tests of visuo-vestibular interaction are invaluable in identifying pathology in the brainstem and cerebellum – sites commonly affected by MS and giving rise to disequilibrium and imbalance.
This talk will outline the clinical and investigative techniques for evaluating peripheral and vestibular dysfunction and highlight the common abnormalities found in multiple sclerosis.