Manual rotational testing of the vestibulo-ocular reflex.

Abstract

Manual whole-body and head-on-body rotational testing of the vestibuloocular reflex (VOR) is comparable to conventional rotary chair methods with and without visual fixation from 0.025 to 1 Hz. Summary of four previously published trials from our laboratory and a fifth prospective blinded study comparing whole-body and head-on-body rotation with rotational chair results from 0.025 to 1 Hz in 10 patients with bilateral vestibular dysfunction. Subjects were fitted with standard electro-oculogram (EOG) electrodes and placed in the rotary chair for testing at 0.025, 0.05, 0.1, 0.25, 0.5, and 1 Hz in the dark (VOR) and in the light with a stationary target (VVOR). They were then placed in an otolaryngology examination, chair where an adjustable headband containing the velocity sensor and an opaque visor were placed on the forehead. Whole-body rotational trials from 0.025 to 1 Hz and both passive and active head-on-body trials from 0.25 to 1 Hz were performed with and without visual fixation. Data from each frequency were analyzed cycle-by-cycle and averaged for gain, phase, and asymmetry. These values were then compared to the results obtained during rotational chair testing. Throughout the five studies, no systematic differences were noted between the manual rotational methods and the rotary chair results. Specifically, no consistent effect of volition or cervico-ocular reflex (COR) enhancement was demonstrated. Manual rotational testing is a reliable technique for measuring the VOR up to 1 Hz as compared with standard rotary chair methods. Advantages to this technique include portability, lower equipment costs, and potential application up to 6 Hz using head-on-body rotation.