Head Impulse Test

Head Impulse Test

The head impulse test, also known as the head thrust test, assesses the vestibulo-ocular reflex. It consists of a rapid turning of the head to one side by about 15 degrees, sufficiently rapid to ensure that smooth pursuit eye movements do not compensate for head turning. The examiner observes the ability of the subject to maintain fixation on a distant target; if the vestibulo-ocular reflex is intact fixation is maintained. If the vestibulo-ocular reflex is impaired, then an easily visible saccade back to the target occurs at the end of the movement. Tilting the head down by 20 degrees and moving the head unpredictably may optimize testing. This test is recommended in patients suffering a first attack of acute spontaneous vertigo. Sensitivity and specificity of around 80% for detecting a peripheral vestibular lesion, such as acute unilateral vestibular neuritis has been reported.

References

Halmagyi GM, Curthoys IS. A clinical sign of canal paresis. Archivesof Neurology 1988; 45: 737-739
Schubert MC, Das VE, Tusa RJ, Herdman SJ. Optimizing the sensitivity of the head thrust test for diagnosing vestibular hypofunction. Neurology 2002; 58 (suppl3): A439 (abstract P06.031)

Cross References

Vertigo; Vestibulo-ocular reflexes