Evaluation of the vestibular autorotation test (VAT) for measuring vestibular oculomotor reflex in clinical research.

BACKGROUND

A method is needed to measure parameters of vertigo and disequilibrium. Our objective was to ascertain whether the vestibular autorotation test (VAT) gives numerical data on the vestibular oculomotor reflex (VOR) that are useful for clinical research.

METHODS

A VAT was carried out on 17 healthy young volunteers twice, with an interval of 7 days (group A), and on a single occasion on another 17 volunteers of similar age and health (group B). The parameters studied were vertical and horizontal gains and phases and horizontal eye velocity symmetry. The resulting values were paired inter-session in the same individuals of group A, and between the first test of group A with the test in group B, chosen at random. Variances for the sets of numbers in each parameter as a whole and for each frequency of stimulation were calculated and statistical validity was determined.

RESULTS

No significant differences were found between the inter-session and inter-individual results. Variances of gain (horizontal and vertical) were small, but variances of phase and symmetry were large. An analysis of frequencies of stimulation revealed that variances increased with the elevation of frequency.

CONCLUSIONS

For clinical research and evaluation, the VAT affords sufficiently consistent figures for vertical and horizontal gain in the entire spectrum of frequencies tested (2-5.9 Hz) and for horizontal phases between 2-3.9 Hz. Vertical phases and horizontal asymmetry vary too greatly for our stated purpose.