Patients are asked to watch a target on the wall while moving their heads back and forth with varying frequencies. The headband records head motion and acceleration and eye movement, and then the software calculates whether the vestibular ocular reflex system is working.
Explore This IssueApril 2006
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Posturography, which involves placing the patient on a platform in various positions with eyes open and closed, can enhance ENG and VNG by narrowing down the causes of dizziness. For example, the test could identify whether the nystagmus is sound-evoked, which would involve a disorder in the semicircular canal.
One new test, the vestibular evoked myogenic potential (VEMP), consists of electrically transmitting a sound into the ear. If the receptors of balance are damaged, the patient will then report the sensation of the room spinning. This test would be the closest version of an evoked potential, Dr. Goebel said.
One test in development is the subjective visual vertical test (SVVT). With the SVVT, the patient is asked take a light bar and place it in a vertical plane in complete darkness. Patients with vestibular problems tend to shift the bar to one side, Dr. Goebel said. It’s not ready for routine clinical testing, but it’s emerging as an easy way to examine the vestibular system, he said.
The experts interviewed agreed that testing should not only be for diagnosis, but also to help clinicians identify treatment. Testing can help us identify unusual problems that may be the cause, such as acoustic neuroma, Dr. Goebel said.
If a patient has BPPV and if the affected canal has been identified, the proper treatment is the Epley maneuver, Dr. Soileau said. The maneuver involves moving the head in a way that encourages the misplaced otoliths to move out of the affected canal and back into the chamber that is their proper residence.
The Epley maneuver is an easy, gentle, and highly effective way to resolve BPPV, Dr. Soileau said. The more vigorous Semont maneuver involves turning the patient’s head and rapidly moving the patient from a sitting to a reclining position on one side and then on the other side.
A Conjunction of Exam and History
Otolaryngologists need to understand the limitations of vestibular tests and communicate those limitations to patients in order to use the tests effectively, Dr. Barin said.
If physicians are sending patients for vestibular testing and patients are expecting the test to tell exactly what disease is causing the dizziness, the patients will be very disappointed, he said. This is where otolaryngologists need to help patients see that the glass is half full. These tests provide such information for half of patients.