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Vestibular testing involves various tools used to evaluate whether or not an inner ear disorder is causing a patient’s dizziness. Several assessment techniques determine if a reflex in the ear that regulates vision during motion works properly. Some of the exams measure nystagmus, an involuntary eye movement that occurs when a problem exists in the vestibular region of the ear. Balance may also be evaluated during vestibular testing.
The inner ear contains five sensors that keep vision in balance when the head or body is moving. If any one of the five areas fails to function properly, vertigo and dizziness might occur. Vestibular testing can analyze how three of these five sensors are operating.
One form of vestibular testing is the rotational chair test, used to measure function in both ears at the same time. A motorized chair turns the patient while he or she tracks and observes lights or stripes. Involuntary eye movements are studied to determine if an inner ear disorder or brain dysfunction might be present. A patient may become less dizzy during this test if his or her vertigo is related to the inner ear, pointing to a potential brain condition.
In an electronystagmography test, electrodes are placed near each eye to record eye movement during the parts of the test. The test checks one ear at a time and tests a patient’s balance system in four ways. It also evaluates nystagmus while the patient tries to track a moving object with his or her eyes. The exam can also reveal if the position of a person’s head causes dizziness. The third part of this type of vestibular testing, called a caloric test, uses warm or cold water injected into the ear canal to measure visual responses. A fistula test, which measures eye movement after pressure is applied to the inner ear, is more sensitive.
Balance also is sometimes assessed through a posturography exam. The patient is placed on a moving platform to evaluate whether dizziness symptoms have improved with treatment. This type of vestibular testing is not considered foolproof, however, and may register normal when vestibular disease exists.
Dizziness and involuntary eye movement can stem from vestibular disease in the inner ear, a head injury or a reaction to medication. Vestibular testing might be helpful as a first step to diagnosis because it is less expensive than the types of tests that analyze brain function. If vestibular testing fails to pinpoint an inner ear problem, the patient can continue with more expensive procedures, such as magnetic resonance imaging, to investigate disorders of the brain.