One of the remarkable things about our balance system is the ease at which it adapts to a myriad of different situations. When the system breaks down however, or even stutters, the ramifications are immense.
A simple example of a very complex balance mechanism is as follows. Focus on the word, BALANCE, on the screen in front of you. Now turn your head quickly to the side but keep your eyes fixed on that word. If you are able to do that easily it means that you have an intact vestibulo-ocular reflex. This is a connection from the balance organs in the ears via the brain, to your eyes.
The balance organs do not recognize constant velocity – this is why when travelling in your car down the motorway as a passenger, you can close your eyes and feel perfectly still. The balance organs in the ears do, however, recognize acceleration. If you close your eyes in the same car as it accelerates you certainly feel the speed change.
Parts of the inner ear called the semicircular canals are designed to measure acceleration that we term ‘angular’. This means acceleration on head turns. Three semicircular canals exist in each ear so that all dimensions are catered for.
When you focused on the word, BALANCE, and turned your head quickly to the side whilst keeping your eyes focused on the word, you did a number of things. As your head turned, it accelerated, moved for an instant at a constant speed, slowed down and then stopped. In order to stay fixed on the word, your eyes had to do exactly the same but in the opposite direction.
So for a commonplace task that we perform thousands of times a day, the balance system has to do some remarkable things. When the vestibulo-ocular reflex, or VOR, as balance specialists call it, doesn’t work properly the world seems to give a sudden jolt at the end of sudden head turns. This usually needs an expert to diagnose it and when found can be remedied in most people by exercises designed to improve the VOR. Although exercises need to be repeated daily for weeks and often months, the benefits gained are substantial and often lead to normal balance function being restored.