Evaluation of the rotatory vestibular test: exploration of stimulus parameters

The aim of this study was to construct a rotational test protocol after exploring the stimulus parameters of the rotatory vestibular test.

Twenty-four normal subjects were submitted to three different rotational paradigms: the sinusoidal harmonic acceleration test (SHAT), the pseudorandom rotation test (PRRT), and the velocity step test (VST). We investigated the influence of frequency and velocity on gain, phase and asymmetry values for the SHAT and the PRRT. In the case of the VST, we examined the influence of velocity and deceleration on gain, slow component velocity at deceleration, time constant, nystagmus preponderance, and time constant asymmetry.

Frequency affected the SHAT response parameters, with significant phase differences between the frequencies 0.01, 0.02, 0.05, 0.1, and 0.2 Hz, while velocity, if kept below 150 degrees/s, had no influence on the results. In the case of the VST, responses were influenced by stimulus velocity and not by stimulus deceleration, with significantly higher gain values for the velocities 50 and 250 degrees/s.

A velocity of 50 degrees/s tested at the frequencies 0.01, 0.02, 0.05, 0.1, and 0.2 Hz was suggested for the SHAT and PRRT protocol, whereas a velocity of 100 degrees/s with a deceleration of 200 degrees/s2 was preferred for the VST. The relevance of this rotational protocol has yet to be established from patient data.