Figure 2.

The HIT. (a). (Top picture) the clinician instructs the patient to fixate a target straight ahead and then turns the head rapidly either to the left or right. A right head turn as shown tests the right horizontal canal. The normal response results in a slow-phase compensatory eye movement to the left, which occurs almost instantaneously (modified from, Bronstein and Lampert²⁸ with permission). In (b) (middle picture), the clinician turns the patients head to the left by ∼30°, to align the right anterior and left posterior (RALP) semicircular canals along a vertical axis. The clinician then places one hand on the top of the patient's head and one hand below and rapidly thrusts the head either forwards (testing right anterior canal) or backwards (testing left posterior canal). In (c) (bottom picture), the clinician asks the patient to turn their head to the right by ∼30°, to align the left anterior and right posterior (LARP) semicircular canals along a vertical axis. The clinician then places one hand on top of the patient's head and one hand below and rapidly thrusts the head either forwards (testing left anterior canal) or backwards (testing right posterior canal).