Head impulse test (head thrust test)

Head Impulse Test

• also known as "head thrust test", is a sensitive and specific investigation method which detects unilateral hypofunction of the peripheral vestibular system caused mainly by acute vestibulopathy (1,2)
  • normally, a functional vestibular system will identify any movement of the head position and rapidly correct eye movement accordingly so that the centre of the vision remains on a target (2)
  • this investigation method will test this vestibular ocular reflex in a patient (1)

This investigation method should be used carefully in patients with neck pathology since it involves rapid repositioning of the head (2).

Usually the clinician performing the test sits face to face with the patient and holding the patient's head from the front. Patient is advised to fix their gaze on a target (e.g. - usually the examiner's nose) and the head is rapidly turned to one side and then to the other side while watching the eyes for presence or absence of any corrective movements (1)

• when the head is turned towards the normal side the vestibular ocular reflex remains intact and eyes continue to fixate on the visual target
• when the head is turned towards the affected side, the vestibular ocular reflex fails and the eyes make a corrective saccade to re-fixate on the visual target (1).

A corrective saccade indicates a positive test and the general practitioners can confidently make a diagnosis of vestibular as opposed to brainstem disease (1).

Reference:

• 1. Barraclough K, Bronstein A. Vertigo. BMJ. 2009;339:b3493
• 2. Kuo CH, Pang L, Chang R. Vertigo - part 1 - assessment in general practice. Aust Fam Physician. 2008;37(5):341-7