Standardizing vHIT protocols: The influence of human factors on VOR gain outcomes

This study, conducted from the examiner's perspective, thoroughly investigates various examiner-related influencing factors, aiming to optimize operational procedures, reduce the effects of interfering elements, and ultimately ensure the accuracy and reliability of video head impulse test (vHIT) results.

The effects of four key variables - head impulse velocity, examiner experience, target distance, and manipulation techniques - on vHIT outcome measurements were analyzed in this study.

The following key findings were observed: (1) an inverse correlation existed between head impulse velocity and the vestibulo-ocular reflex (VOR) gain; (2) novice examiners generated abnormal vHIT results more frequently than experienced examiners, with the latter obtaining VOR gain values closer to the ideal vestibulo-ocular reflex (VOR) reference; (3) the difference in VOR gain values measured at target distances of 1.5 m and 1.2 m was not statistically significant; (4) VOR gain values of the horizontal semicircular canals measured using the head hand position were significantly higher than those obtained with the jaw hand position.

To ensure reliable vHIT results and minimize examiner-related interference, we recommend that vHIT examinations meet the following requirements: utilization of a fixed target distance (1.2 m or 1.5 m), adoption of the jaw hand positioning technique (for horizontal semicircular canal testing), and execution by properly trained and experienced examiners.