TESTING BALANCE DISORDERS
How you maintain your balance is a complex process that relies on information from your senses and coordinated movements from different parts of your body. How the balance control mechanism works is discussed on this web site under "How You Control Your Balance?". Because of the complexity of balance control, diagnosing a balance problem and its specific cause or causes can be difficult. The good news is that there are a number of medical tests that can be very beneficial in accurately determining why you have a balance problem.
To determine the cause of a balance problem, you will first be asked to describe your problems and symptoms and will be given a physical examination. Based on your descriptions and exam results, your doctor will develop a working diagnosis. Depending on what he or she determines, your doctor may then order tests designed to confirm the diagnosis. The test results also determine how key components of your balance systems are functioning.
There is a possibility that your problem does not have one specific cause. If no single cause is identified, your doctor may also use the test results to design an exercise-based treatment program that can maximize your functional abilities and minimize disruptive symptoms.
While most balance disorders are caused by inner ear abnormalities, many balance disorders are caused by central nervous system abnormalities, cardiovascular problems or both. There are specific observational tests that can help your doctor figure out what is causing your balance problems.
Assessment of Eye and Head Movement Functions: The ability to coordinate movements of your eyes and head is essential to seeing objects in your environment clearly while you are in motion during such tasks as walking, running, or driving a car. To test your eye movement control, you may be asked to shift your direction of gaze from one object to another as quickly as you can. You may also be asked to look as far as you can to the left, right, up, and down while facing directly forward. To test eye and head coordination, your physician may observe how accurately you can stay focused on an object while shaking your head.
Assessment of Cerebellar Function: This includes specific physical examinations to evaluate your cerebellum, the part of your brain that is essential to your ability to control balance and movements. When your cerebellum has been damaged you can still move, but your movements become jerky, making it harder to get your hands or legs to stop moving just where and when you want them to. Your doctor can test how well your cerebellum is working by asking you to reach out and touch points with your index fingertip, tap your hand rhythmically, and move your arms and legs accurately.
Assessment of Walking Function: Your doctor can learn about your balance and movement control by observing how well you walk. He or she may ask you to walk in a straight line without veering from side to side and then quickly and accurately turn and walk in the opposite direction without hesitating or stumbling. A more challenging walking task is called "heel to toe" walking, where each new step is placed directly in front the preceding step.
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The type of medical tests you need will vary depending on what your physician suspects is the problem. Because there are so many possible causes, not all patients will require all tests. For example, if you think you might be at risk for falling, but your symptoms and exam results do not point to a specific cause, your physician might order a balance screening test, which will determine whether your balance is functionally impaired. If balance problems are detected, further tests would be warranted to pin point your risk factors and accurately identify their causes. On the other hand, if your symptoms and exam results are suggestive of a specific cause, your doctor may order tests designed to confirm a diagnosis and suggest the best course of treatment.
Some common tests that may be ordered for someone with a balance disorder are described below.
Audiometric (Hearing) Tests: Your doctor may order hearing tests as the hearing and motion sensing parts of your inner ears are sometimes both affected by the same disease. Basic hearing tests are designed to determine how well you can sense very faint sound at different frequencies, as well as how well you can comprehend speech.
Nystagmography Tests: This is a series of tests designed to document your ability to follow visual objects with your eyes and how your eyes respond to some types of information from your vestibular system. To monitor the movements of your eyes, your doctor may place electrodes around your eyes (electronystagmography--ENG) or may use an infrared video camera (IR video nystagmography). Eye movement tests are useful, because some patients with balance system problems have problems seeing clearly when moving, or they get the erroneous sense that objects are moving.
- Occular Motility: You will be asked to follow with your eyes objects that jump from place to place or move smoothly. Your doctor will be looking for any slowness or inaccuracies in your ability to follow visual targets.
- Optokinetc Nystagmus: You will be asked to view a large, continuously moving visual image to see if your eyes can appropriately track these movements.
- Positional Nystagmus: Your doctor will move your head and body into various positions to make sure that there are no inappropriate movements of your eyes when your head is in different positions.
- Caloric Test: Your doctor will stimulate both of your inner ears (usually one at a time) with warm and then cold water. He or she will be monitoring the movements of your eyes to make sure that both your ears can sense this stimulation.
Computerized Dynamic Posturography: This is a series of tests that measure how well you are able to maintain your balance under different conditions. You will be asked to stand as steadily as possible on a platform inside a small booth. The platform will have sensors that measure how well you maintain your balance as the walls of the booth move around you and the surface you are standing on moves under your feet. The tests will be conducted with your eyes open and with your eyes closed. You will be supported by a safety harness in case you become unsteady. Some of the tests are designed to mimic different conditions you encounter in every day life. Other tests are designed to determine the source of your balance problem. The computerized tests are able to isolate the different sensory information you rely on to maintain your balance. The test results provide a better understanding of your balance problem and can point to possible causes. This allows your doctor to focus on the abnormal system.
Rotational Chair: You will be seated on a rotating chair placed in a darkened room with electrodes on your eyes to measure their movements. The chair will rotate back and forth at different speeds to see how your eyes move in response to rotations when you cannot see anything. You will also be asked to keep your eyes on a small light while the chair rotates. You will be given mental tasks during these tests to keep you alert, because your eyes will not move as accurately if you get drowsy. Some laboratories also test your responses to rotation with your eyes open and viewing visual patterns.
Imaging: Well known tests like CAT scans and MRI are now so sensitive that your doctor can actually see the tiny structures of the balance organs in your inner ear, as well as the nerves that connect these organs to the brain. If your doctor wants to make certain that there are no structural problems within the balance organs or with the nerves connecting them to the brain, he or she may order an imaging test.
If your physician would like more information about assessing balance and mobility disorders, we encourage him or her to visit our clinical information web site at www.onbalance.com
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