Head Impulse Test: Sensitivity and Specificity
from UpToDate: "The head thrust test is performed by instructing the patient to keep his or her eyes on a distant target while wearing his usual prescription eyeglasses. The head is then turned quickly and unpredictably by the examiner, about 15º; the starting position should be about 10º from the primary position in the orbit. This is sometimes called the head impulse test.
The normal response is that the eyes remain on the target. The abnormal response is that the eyes are dragged off of the target by the head turn (in one direction), followed by a saccade back to the target after the head turn; this response indicates a deficient VOR on the side of the head turn, implying a peripheral vestibular lesion (inner ear or vestibular nerve) on that side."
35% sensitive, 95% specific