Testing the gain and phase of low-frequency vestibulo-ocular reflex (VOR) has provided valuable clinical information for patients with balance disorders, but such testing has required an expensive investment in a servocontrolled rotating chair. Commercially available chairs are used to deliver controlled sinusoids to a patient's entire body. As an alternative, we propose to obtain low-frequency gain and phase information from active head movements of subjects wearing an instrumented head strap. Broadband, pseudorandom analysis methods will be employed. Special-purpose software analysis algorithms will be investigated to determine those which can produce gain and phase information with greatest accuracy. Normal subjects will be tested both in the light and the dark. Subjects will also undergo conventional rotational chair testing for comparison of results. The long-term objectives are to develop a low-frequency active head movement system for clinical use. Practical advantages of the proposed system, relative to currently available rotating chairs are: l) shorter test times, 2) improved patient comfort, 3) portability for bedside testing, 4) no dedicated space requirement, and 5) reduced projected total cost. The proposed system will make low-frequency testing feasible for small clinical practices, in an era of cost containment in modern medicine.Proposed commercial application:The research will provide a method of testing the low-frequency gain and phase of the VOR with active head movements, and use of signal processing instead of expensive rotating machinery. This will have wide commercial appeal for medical specialists interested in balance disorders, because of its significantly lower cost than present rotating chair systems.National Institute of Neurological Disorders and Stroke (NINCDS)
