Clinical Application of the Head Impulse Test in Vestibular Disorders / 대한평형의학회지

ABSTRACT

The head impulse test (HIT) is an established way to test the angular vestibulo-ocular reflex (aVOR) at the bedside. When the aVOR is normal, the eyes rotate opposite to the head movement through the angle required to keep images stable on the fovea. If the aVOR is impaired, the eyes move less than required and, at the end of the head rotation, the eyes are not directed at the intended target and the visual image is displaced from the fovea. A promptly-generated corrective saccade brings the image of the target back on the fovea. The identification of this corrective saccade is the signature feature of vestibular hypofunction and has greatly increased the utility of the bedside examination for identifying an aVOR deficit. However, sometimes it is not easy to detect corrective saccades without quantitative HIT devices. Exact execution and interpretation of the HIT are warranted to reduce the diagnostic errors, because the HIT has become an important part of the differential diagnosis of both acute and chronic vestibular disturbances.