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 disequi librium. 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 a n interval of 7 days (group A), and on a single occasion on another 17 volu nteers of similar age and health (group B). The parameters studied were ver tical 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, ch osen at random. Variances for the sets of numbers in each parameter as a wh ole and for each frequency of stimulation were calculated and statistical v alidity was determined. Results. No significant differences were found between the inter-session an d inter-individual results. Variances of gain (horizontal and vertical) wer e small, but variances of phase and symmetry were large. An analysis of fre quencies of stimulation revealed that variances increased with the elevatio n of frequency. Conclusions, For clinical research and evaluation, the VAT affords sufficie ntly consistent figures for vertical and horizontal gain in the entire spec trum 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 st ated purpose. (C) 2000 IMSS, Published by Elsevier Science Inc.