Manual rotational testing of the vestibulo-ocular reflex

Abstract

Objectives/hypothesis: 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.

Study design: 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.

Methods: 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.

Results: 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.

Conclusions: 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.