Head Impulse Test

In 1988, Michael Halmagyi and Ian Curthuoys described a simple yet reliable indicator of unilateral peripheral vestibular deficits at the bedside. This 'head impulse test' (HIT) as is has been known since, has stood the test of being a reliable indicator of vestibular deficit, especially for the horizontal semicircular canal. The test has been described using various techniques, such as the scleral search coil, the video HIT, etc. but even a simple bedside clinical evaluation with a little amount of experience usually sufficed to detect overt vestibular deficits. Numerous studies have compared the efficacy of the HIT as compared with other tests of vestibular deficit, the caloric test (CT) being the most commonly compared one. A look at the physiology behind the two tests reveals the differing pathways tested by the two tests in mention, and hence it would be wise to say that the two are complimentary, rather than exclusive of the other. The HIT today forms a vital part of the armamentarium of the otologist to arrive at rapid understanding of the nature of the vestibular deficit, the laterality of the lesion, and the probable prognostic significance.