Reliability of utricular function testing sinusoidal translation profile during unilateral centrifugation

The unilateral centrifugation test is one of the few vestibular tests that evaluate the utricles side by side. During this test, a subject is rotated about an earth vertical axis at high rotation speeds (e.g. 400 degrees/s) and translated sideways along the interaural axis to align the axis of rotation consecutively with the right and the left utricle. The combined rotation and translation induces ocular counter rolling (OCR), which is measured using three-dimensional video-oculography. Recently, a new model has been proposed to analyse the OCR. The model is based on contributions from both the semicircular canals and the utricles. Concomitant with the new model a new stimulation profile using a sinusoidal translation profile during the unilateral centrifugation has been introduced [1]. The current study presents the test-retest reliability as well as the robustness of the new stimulation method, based on data of 67 healthy subjects. Test-retest reliability was based on repeated measurements of a group of subjects. To test the robustness of the new sinusoidal translation paradigm, we investigated the effect of a different amplitude of the sinusoidal translation (6 cm instead of 4 cm) and of an offset in translation (from -3 to +5 cm, instead of from -4 to +4 cm) on the parameters. Several statistical measures were used to reflect the reliability: intraclass correlation coefficient (ICC), the "coefficient of variation of the method error" and the "minimal difference" (MD). All relevant variables from the physiological model for the OCR induced by unilateral centrifugation show a good to excellent reliability during the test-retest study and the relevant parameters remain unaffected by the changes applied to the translation profile (p > 0.05) as predicted by the model. Additionally, all observed differences are smaller than the MD values calculated in the test-retest part of the study.