Head Impulse Test

Original Editor - User: Lenny Vasanthan T Top Contributors - Lenny Vasanthan T

Micheal Halmagyi and Ian Curthoys described this simple and reliable bedside test that could be used for detecting persons with unilateral peripheral vestibular deficits in 1988[1]. It is also known as the Head Thrust Test.

Purpose

This test works by testing the Vestibulo Ocular Reflex (VOR). This reflex is helpful to maintain corrective eye position during any change in head position and to correct the eye movement rapidly so that vision remains on the target[2].

Advantages of the test
- Relatively quick
- Can be used even on patients with acute Vertigo
- Can be repeated within a short time

Technique

Position of the Tester: Sitting
Position of the Subject: Sitting in front of the tester with eyes fixed on the examiner's nose or a distant target
Alternatively testing position: the tester can stand or sit behind the subject, but there needs to be a way to record the eye movement.
Precautions: The tester must ensure that the subject doesnot have any neck issues like Vertebro basilar insufficiency and neck range of motion is adequate
Expectation of the subject: The subject needs to keep their eyes focussed on the target during the testing procedure and avoid premature eye closure
Examiner action: The examiner moves the head quickly and unpredictably to 10 to 15 degrees of neck rotation[3], care needs to be ensured to avoid Cervical spine manipulation during the testing.
Normal response: Eyes remain on the target after the examiners movement
Abnormal response:

Eyes are dragged off the target by the turning of the head, followed by a corrective saccade back to the target after the turning of head.

Evidence


The corrective saccade indicates a deficient VOR on the same side of the head turn, indicating a peripheral vestibular lesion on the same side[4]. Use of Videonystagmography can help in the interpretation and accuracy of this test[5].
This test is reported to have a higher specificity (82 to 100 %) than sensitivity (34 to 39 %) [6][7][8]. In one report, flexing the head forward 30º during the test increased sensitivity to as high as 71 to 84 %[9].

The HIT works well for the person with complete vestibular loss, wheres it is less sensitive to a person with mild to moderate loss of function[10]. About 50% of the canal paresis is needed for the test to be positive[11].

References

  1. Halmagyi GM, Curthoys IS. A clinical sign of canal paresis. Arch Neurol (1988) 45:737–9
  2. Kuo CH, Pang L, Chang R. Vertigo - part 1 - assessment in general practice. Aust Fam Physician. 2008;37(5):341-7
  3. I.S. Curthoys & L. Manzari (2017) Clinical application of the head impulse test of semicircular canal function, Hearing, Balance and Communication.15:3, 113-26 DOI: 10.1080/21695717.2017.1353774
  4. Halmagyi GM, Cremer PD. Assessment and treatment of dizziness. J Neurol Neurosurg Psychiatry 2000; 68:129.
  5. MacDougall HG, Weber KP, McGarvie LA, et al. The video head impulse test: diagnostic accuracy in peripheral vestibulopathy. Neurology 2009; 73:1134
  6. Harvey SA, Wood DJ, Feroah TR. Relationship of the head impulse test and head-shake nystagmus in reference to caloric testing. Am J Otol 1997; 18:207.
  7. Harvey SA, Wood DJ. The oculocephalic response in the evaluation of the dizzy patient. Laryngoscope 1996; 106:6.
  8. Beynon GJ, Jani P, Baguley DM. A clinical evaluation of head impulse testing. Clin Otolaryngol Allied Sci 1998; 23:117.
  9. Schubert MC, Tusa RJ, Grine LE, Herdman SJ. Optimizing the sensitivity of the head thrust test for identifying vestibular hypofunction. Phys Ther 2004; 84:151.
  10. Beynon, G. J., P. Jani, et al. "A clinical evaluation of head impulse testing." Clin Otolaryngol Allied Sci 1998; 23(2): 117-22.
  11. Hamid, M. "More than a 50% canal paresis is needed for the head impulse test to be positive." Otol Neurotol 2005; 26(2): 318-9.