2017 Volume 76 Issue 3 Pages 212-218
The head impulse test (HIT) is a safe and quick way of assessing at the bedside semicircular canal function in patients with peripheral vestibular loss, first described in 1988. This test is practical even in sick patients and needs no equipment. The clinician identifies overt (=visible) catch-up saccades back to the target after passive head rotation as a clinical sign of canal paresis. However, it is known that some patients with absence of vestibular function do not make overt saccades, but instead make covert catch-up saccades during a passive unpredictable head turn, which are extremely difficult for the clinician to detect with the naked eye.
In 2009, a new lightweight, nonslip, high-speed video-oculography system (vHIT; video head impulse test) was developed, that measures eye velocity during head rotations. This system is easy to use in a clinical setting, provides an objective measure of the vestibulo-ocular-reflex (VOR), and detects both overt and covert catch-up saccades in patients with vestibular loss.
This article discusses the diagnostic values of vHIT which can evaluate both horizontal and vertical semicircular canal functions in patients with a variety of vestibular diseases.
