II. Indications
- Acute Vestibular Syndrome (AVS) exam to evaluate for posterior circulation Cerebrovascular Accident
- Requires ongoing Vertigo and Nystagmus at the time of the exam for accurate test (esp. head impulse)
- Not indicated in episodic or triggered Vertigo
III. Contraindications
- Severe Cervical Spine disease or injury
- Significant Carotid Stenosis
IV. Exam (Mnemonic: HiNTs)
- Head Impulse
- See Horizontal Head Impulse Test (Head Thrust Test, h-HIT)
- Head is rapidly rotated 20-40 degrees to one side or the other
- Intersperse this with gentle, slow rotations to either side (prevents patient from anticipating movement)
- Observe for one eye that lags in response to maintain forward gaze (other eye will lack corrective saccades)
- Makes quick saccade movement to catch-up or correct (HiNTs-Peripheral)
- "Normal" test or HiNTs-Central (no saccade/correction on head provocation) strongly suggests posterior CVA
- Test Specificity approaches 100%, but Test Sensitivity is only 85%
- Although saccade/correction on testing suggests peripheral cause, it does not exclude posterior CVA
- False Positive (absent saccades) may also be present if Vertigo has resolved
-
Direction Changing Nystagmus (or Nystagmus that is vertical or torsional)
- See Nystagmus
- Patient follows examiner's finger as they move it slowly in all directions
- Patient should look up, down, left or right, as well as to eccentric positions (off-center)
- Nystagmus should be present in all cases of acute vestibular system whether of peripheral or central cause
- Findings suggestive of peripheral Vertigo
- Horizontal Nystagmus suggests a peripheral cause (although it does not exclude a central cause)
- Findings suggestive of central Vertigo (e.g. posterior CVA)
- Vertical Nystagmus
- Torsional Nystagmus
- Nystagmus that changes direction
-
Test of Skew
- See Skew Deviation (Vertical Ocular Misalignment, Vertical Heterotropia, Vertical Strabismus)
- Perform as with Alternate Eye Cover Test (also used to evaluate for horizontal Strabismus in children)
- Alternately cover one eye and then the other
- Observe for quick vertical gaze corrections (abnormal)
- Uncovered eye shifts to center from its abnormal, vertically displaced position
- Abnormal skew test with quick vertical gaze corrections suggests a central cause (e.g. Brainstem CVA)
- Examiner may also see a Head Tilt at rest that often accompanies Skew Deviation
V. Interpretation
- Positive HiNTs Criteria (at least 1 of 3 positive) suggestive of Cerebellar CVA or Brainstem CVA
- Normal Horizontal Head Impulse Test (no saccade/correction on head rotation) OR
- Nystagmus that changes direction (or Vertical Nystagmus or torsional Nystagmus) OR
- Skew Deviation on Alternate Eye Cover Test
- Uncovered eye demonstrates quick vertical gaze corrections
VI. Efficacy
- Positive criteria (1 of 3 present as above) suggests posterior Cerebrovascular Accident (Cerebellar CVA or Brainstem CVA)
- Test Sensitivity: Approaches 100% when performed by specialists
- Test Specificity: 96%
VII. Resources
- EMCrit Blog - Video demonstrating the HiNTs Exam
VIII. References
- Warrington (2021) Crit Dec Emerg Med 35(9): 29
- Kattah (2009) Stroke 40:3504-10 [PubMed]
