By Shane Huntington
Neurologist Dr David Szmulewicz describes the human balance system, and whats going on in our brains and ears when we experience vertigo.
SHANE HUNTINGTON I'm Dr Shane Huntington. Thanks for joining us. Most of us at some stage in our lives attempted to achieve the difficult task of taking a doll or action figure and standing it upright. At first glance, it would seem that these simple miniatures of the human form should stand as easily as we do but sadly they too easily topple over. Of course the reason for this poor performance is because these replicas lack something that we possess, namely a sophisticated balance system. The human body and that of many other animals has evolved a system of balance that is more sophisticated than anything we are yet able to model or reconstruct in the lab. Our balance system enables us to manage extraordinary acrobatic acts and, on a simpler scale, safely perform the necessary movements of day to day life. But what happens when this system fails? How do we react to a lack of balance and what can we do to resolve problems of this type? To discuss the balance system of the human body, the problems that can arise and the treatments that have been developed we are joined today on Up Close by Dr David Szmulewicz, a neurologist at the Royal Victorian Eye and Ear Hospital here in Melbourne, Australia. Welcome to Up Close, David.
DAVID SZMULEWICZ: Thank you, Shane.
SHANE HUNTINGTON Before we discuss the way in which the human body actually generates this perception of balance, I want to start with a description of dizziness and vertigo. These terms are often used interchangeably. Do they mean the same thing?
DAVID SZMULEWICZ: Not to us. So in the area of balance medicine, dizziness is a much more general term, far more inclusive whereas to us vertigo is quite specific. The broad definition of vertigo is an illusion of movement, however most commonly it's an illusion of rotatory movement such that a patient might describe spinning as if on a merry-go-round.
SHANE HUNTINGTON: In terms of our bodies, what systems are involved in us having this perception of balance?
DAVID SZMULEWICZ: It's a joint effort really. As you mentioned in your introduction, it's a combination of systems. The first one is the inner ear balance mechanism or vestibular system, the brain in general but particularly the cerebellum or coordination centre of the brain as well as our vision so we're constantly receiving visual cues from our environment.
SHANE HUNTINGTON: Let's go through these one by one and start with perhaps our vision. How does our vision give us the balance perception that we all feel?
DAVID SZMULEWICZ: We're constantly looking at our environment, we're getting horizontal and vertical cues from our environment such that if our brain perceives that we're moving, for example, to one side relative to a vertical line, for example the outline of a window, then there are mechanisms that will right us straight away without us knowing.
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