The balance study, also called videonystagmography (VNG), takes an important place in research into the functionality of the organ of balance. Here the functioning of the organ of balance and the equilibrium nerve that leads these signals to the brains are studied in particular. In this balance study the contribution that the eyes and the pressure receptors in the feet make to your balance remains neglected.
A part of the balance study is done in a completely dark room. In connection with the study the researcher thoroughly cleans the skin around the eyes and sticks electrodes beside the eyes. The VNG takes a lot of time (about 60-90 min.). You have to wear video glasses registering the eye movements.
You are tested in several ways. For instance, you have to follow lamps with your eyes and you take place in a swivel chair. Position tests are taken and sometimes the ears are rinsed with lukewarm to warm water to stimulate the organ of balance.
The test is painless. Although some dizziness may occur during some parts of the test, this will usually soon disappear after every test.
If you suffer from Usher Syndrome, it may be very difficult to function in a darkened room and to communicate with the person carrying out the tests. Please indicate this before taking the test and ask if he/she can turn on the light and explain everything before starting any test.
A part of the tests is done by following lamps with the eyes. This can be really difficult for people suffering from Usher Syndrome as well. Tell the person doing the test that you have trouble seeing in the dark, that it will take longer for your eyes to get used to the dark and that the lamps are difficult to see for you. The person doing the test will then take this into account by taking more time and by making the lamps brighter and moving them more slowly.
The rotation test is done with a chair that rotates at a continuous speed after an acceleration. The eye movements will be measured during the rotation and when the rotation has stopped.
The Video Head Impulse Test (VHIT) is a newly developed test. The functioning of the organ of balance can be quickly tested by filming the eyes, during which the person doing the test makes fast movements with the patient’s head.
The caloric tests consist of successively introducing warm and cold water in each ear. This test measures the reaction of the organ of balance on both sides by registering the number of eye shocks.
The posturograph, used for testing the balance system, measures disturbances of position and balance by means of a platform with sensitive pressure sensors. This shows how you keep your balance during various tests.
The posturograph records fall-out and compensation of all subsystem of the balance system (organs of balance, eyes and pressure receptors in the feet). Additionally, the posturograph can be useful when training the balance (vestibular revalidation).