Balance disorders can be caused by a variety of different problems. A patient with a balance problem may report vertigo (a sensation of spinning), lightheadedness, disequilibrium, as well as other complaints such as: a floating sensation, a fuzzy sensation, leaning to one side, blurred vision, nausea, etc.. These symptoms can be constant or can occur in episodes. Episodes can be transitory lasting only a few seconds or can last for minutes, hours, or even days. Symptoms may occur with other non-vestibular complaints such as hearing loss, tinnitus, cognitive problems, memory problems, poor tolerance for bright lights, fatigue, etc.. Fortunately, most balance disorders are peripheral vestibular disorders that usually respond well to treatment once they are diagnosed. Balance disorders that are not due to peripheral vestibular deficits can be caused by central nervous system disorders, vascular disorders, motor disorders, muscular/joint disorders, and vision disorders. Balance disorders require a very thorough history that details the onset and characteristics of the patient's symptoms. The ENG test is probably the most commonly ordered test for patients complaining of balance disorders or dizziness. ENG, well not perfect, is the best test that we have for diagnosing balance disorders. We find that it is much more sensitive than any imaging study currently available -- including high resolution CAT scans and high-resolution MRIs. When ENG is combined with rotary chair studies, the diagnostic sensitivity is improved even further. The history can usually be completed in 10 to 30 minutes while the ENG/rotary chair tests can usually be completed in one hour. In general, the tests are well-tolerated by patients. These tests will trigger some controlled dizziness and, approximately 5% of the time, the patient will experience some short-lasting nausea. Approximately 1% of the time the patient will require someone else to drive him home. We ask all patients to have someone available that they can call to drive them home. The peripheral vestibular organ is connected to the inner ear and shares some of the same fluids. It is a complex sensory organ that basically is responsible for detecting head movement and for coordinating eye reflexes to stabilize vision with movement. The eye reflexes that are triggered by the vestibular organ are called vestibular ocular reflexes. These vestibular ocular reflexes enable us to test the vestibular system by recording eye movements. The best way to measure eye movements is with binocular infrared videography. In other words, the patient's eye movements are recorded with infrared cameras and these eye responses are then graphically analyzed by the computer. The standard ENG is comprised of three test areas: Tests of Ocular Motility; Positional tests and BPPV tests; and Caloric testing. Test of ocular motility require the patient to follow a lighted dot or stare at moving dots. This testing is quite simple and is well-tolerated by patients. Positional tests and BPPV tests require the patient to be placed in different positions on an exam table. During the caloric test, the patient's ear canal is irrigated with warm or cool water. The water temperature is our precisely controlled the 7 degrees above or below body temperature. The complete caloric testing includes four irrigations: One cool irrigation and one warm irrigation in each ear. Rotary chair tests are usually well-tolerated by patients. We perform a sinusoidal harmonic acceleration test that has the patient sway back-and-forth in a swivel chair while eye movement is being recorded with and without visual fixation under infrared goggles. The rotary chair step test requires five complete rotations. The patient's eye movements are recorded during rotation and following rotation. This test triggers some relatively short-lasting dizziness as would be expected. It is our policy to perform only the tests that are necessary to reach a diagnosis. It is also our policy to discontinue testing at the patient's request. Patient should remember that these tests are well-tolerated 95% at the time. 5% of the time patients do experience some short lasting nausea. 1% of the time patients do experience unpleasant nausea that lasts for 20 to 30 minutes. BPPV (benign paroxysmal positional vertigo) is the most common vestibular disorder. Fortunately, it is also the most treatable vestibular disorder. We have been treating BPPV since 1993 and have extensive experience with this disorder. We have successfully treated a number of very complex BPPV cases. In order to understand this disorder, it is necessary to understand some basic anatomy and physiology. The peripheral vestibular organ is comprised of a linear motion detection system and a rotary motion detection system. The linear motion detection organ contains calcium carbonate "crystals" called otoconia. If these crystals escape from the linear motion detection system and get into the angular motion detection system, they can cause short lasting episodes of severe vertigo that are usually triggered by a positional change (for example rolling over in bed or bending over and then looking up). BPPV is a self-limiting disorder; this means that it usually clears up on its own. Unfortunately it doesn't always clear up on its own but treatment is 99% effective. Approximately 50% of the time, one treatment is required. 30% at the time, two treatments are required, and 20% of the time more than two treatments are required. The best time to treat BPPV is immediately after it is identified. Treatment typically takes 10 to 15 minutes to complete. The ENG/rotary chair test is terminated at that point. Post-treatment instructions are given and the patient is instructed to call if she experiences any severe vertigo or if her symptoms are not well-resolved in two weeks. Occasionally the patient will be scheduled to return to complete the ENG/rotary chair studies. Other peripheral vestibular disorders also respond well to therapy. For patients who have well identified peripheral vestibular disorders and no risk of falling, a home protocol of vestibular therapy exercises will be recommended. Most peripheral vestibular disorders will improve with time but the research has clearly shown that improvement comes faster and is more complete with intelligently designed therapy regimens. For patients with pervasive balance disorders or patients at risk of falling, vestibular rehabilitation with a physical therapist can be scheduled. Patients who want more information should consult with the Vestibular Disorders Association at http:// www.vestibular.org. VEDA is a nonprofit organization that serves people with vestibular disorders by "providing access to information, offering a support network, and elevating awareness of the challenges associated with these disorders". PRE INSTRUCTIONS FOR AN ENG |
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