Physiological bases and a technique for testing the full range of vestibular function

Abstract

The vestibulo-ocular reflex (VOR) is most active at higher frequencies (> 2 Hz) during locomotion, in order to stabilize vision. Use of active head movements, monitored by a sensor on a head strap, is a new method of testing the horizontal and vertical VORs which utilizes this natural frequency range, and doesn't require a rotating chair. Specialized computer processing based on Fourier analysis is necessary to analyze head and eye signals, which can be erratic. Higher harmonics of these erratic movements are particularly useful for VOR testing, in the analogous sense that complex sound processing is necessary for speech processing in audition. Use of portable computers with VOR active head analysis can be done at the bedside, as a portable vestibular test. Sophisticated software can effectively substitute for rotating chair hardware, provided that physiological corrections are applied to actively-generated movements at higher frequencies. In summary, the resulting test is brief, comfortable to the patient, portable, and useful for diagnostic screening over the frequency range that is most active during common daily movements.