Abstract:
Introduction: The computerized rotational head impulse test (crHIT) was recently developed to overcome limitations of the video head impulse test (vHIT) and assess the functioning of the lateral semicircular canals (SCC) in a more objective manner. Instead of an examiner applying rapid, brief, and unpredictable head rotations, as during the vHIT, the crHIT utilizes computer-controlled whole-body rotations. Since the crHIT is newly developed, its test-retest reliability for clinical use needed to be determined.
Methods: Thirty-one healthy adult participants, between the ages of 18 and 40, with normal lateral SCC functioning and no symptoms or history of vestibular dysfunction were assessed with the crHIT using both earth-bound, stationary and head-fixed targets. These participants were assessed on three separate occasions: the second evaluation took place one to six hours after the initial evaluation and the third evaluation 24 hours to two weeks after the second evaluation.
Results: For the stationary target, the mean angular vestibulo-ocular reflex (aVOR) gain ranged from 0.98 to 1.02 at a 95% confidence interval. A one-way repeated measures ANOVA test was performed to provide information about the reliability and repeatability of the aVOR gain across the different time intervals. It was demonstrated that the mean aVOR gain values were statistically equal across all three time intervals, and between both protocols that utilized stationary targets. Additionally, Bland-Altman plots demonstrated high Limits of Agreement (LoA). For the head-fixed target, a one-way repeated measures ANOVA demonstrated significant differences in the aVOR gain values both across and within the three testing sessions. These significant differences were demonstrated as a decrease in aVOR gains both across and within the three testing sessions.
Conclusion: The crHIT is a reliable measure of determining lateral SCC function. Further investigation is required to determine the physiological mechanisms underlying the decreased aVOR gain values across multiple testing sessions. However, it is suspected that vestibular habituation as well as aVOR and saccadic adaptation mechanisms have potentially contributed to the decrease in aVOR gain values across the multiple testing sessions.
