II. Indications

  1. Acute Vestibular Syndrome (AVS) exam to evaluate for posterior circulation Cerebrovascular Accident
  2. Requires continuous Vertigo and Nystagmus at the time of the exam for accurate test (esp. head impulse)
    1. Not indicated in episodic or triggered Vertigo (e.g. BPPV)

III. Contraindications

  1. Severe Cervical Spine disease or injury
  2. Significant Carotid Stenosis
  3. Absent Nystagmus or Vertigo at rest
  4. Associated Central Nervous System findings suggest Cerebrovascular Accident or other central cause
    1. New Headache or Neck Pain
    2. New Hearing Loss
    3. Focal weakness or Paresthesias
    4. Diplopia
    5. Dysmetria
    6. Dysarthria, Dysphonia or Dysphagia
    7. Vertical Nystagmus at rest
    8. New inability to ambulate without assistance
  5. References
    1. Johns (2023) HiNTs Exam Review, Youtube (see reference below)

IV. Exam (Mnemonic: HiNTs)

  1. Head Impulse
    1. See Horizontal Head Impulse Test (Head Thrust Test, h-HIT)
    2. Head is rapidly rotated 20-40 degrees to one side or the other
      1. Intersperse this with gentle, slow rotations to either side (prevents patient from anticipating movement)
    3. Observe for one eye that lags in response to maintain forward gaze (other eye will lack corrective saccades)
      1. Makes quick saccade movement to catch-up or correct (HiNTs-Peripheral)
    4. "Normal" test or HiNTs-Central (no saccade/correction on head provocation) strongly suggests posterior CVA
      1. Test Specificity approaches 100%, but Test Sensitivity is only 85%
      2. Although saccade/correction on testing suggests peripheral cause, it does not exclude posterior CVA
      3. False Positive (absent saccades) may also be present if Vertigo has resolved
  2. Direction Changing Nystagmus (or Nystagmus that is vertical or torsional)
    1. See Nystagmus
    2. Patient follows examiner's finger as they move it slowly in all directions
      1. Patient should look up, down, left or right, as well as to eccentric positions (off-center)
    3. Nystagmus should be present in all cases of acute vestibular system whether of peripheral or central cause
    4. Findings suggestive of peripheral Vertigo
      1. Horizontal Nystagmus suggests a peripheral cause (although it does not exclude a central cause)
    5. Findings suggestive of central Vertigo (e.g. posterior CVA)
      1. Vertical Nystagmus
      2. Torsional Nystagmus
      3. Nystagmus that changes direction
        1. Rightward Nystagmus with rightward gaze
        2. Leftward Nystagmus with leftward gaze
  3. Test of Skew
    1. See Skew Deviation (Vertical Ocular Misalignment, Vertical Heterotropia, Vertical Strabismus)
    2. Perform as with Alternate Eye Cover Test (also used to evaluate for horizontal Strabismus in children)
    3. Alternately cover one eye and then the other
    4. Observe for quick vertical gaze corrections (abnormal)
      1. Uncovered eye shifts to center from its abnormal, vertically displaced position
    5. Abnormal skew test with quick vertical gaze corrections suggests a central cause (e.g. Brainstem CVA)
    6. Examiner may also see a Head Tilt at rest that often accompanies Skew Deviation
  4. Consider recording the exam on smartphone to improve efficacy
    1. Have an assistant record the exam with smartphone camera (flash on, landscape mode)
    2. Image should include half of patient's forehead and the bottom of the patient's nose
    3. Johns (2023) communication, 10/20/2023

V. Interpretation

  1. Positive HiNTs Criteria (at least 1 of 3 positive) suggestive of Cerebellar CVA or Brainstem CVA
    1. Normal Horizontal Head Impulse Test (no saccade/correction on head rotation) OR
    2. Nystagmus that changes direction (or Vertical Nystagmus or torsional Nystagmus) OR
    3. Skew Deviation on Alternate Eye Cover Test
      1. Uncovered eye demonstrates quick vertical gaze corrections

VI. Efficacy

  1. Positive criteria (1 of 3 present as above) suggests posterior Cerebrovascular Accident (Cerebellar CVA or Brainstem CVA)
    1. Test Sensitivity: Approaches 100% when performed by specialists
    2. Test Specificity: 96%

VII. Resources

  1. HiNTs Exam Review (Dr. Peter Johns)
    1. https://www.youtube.com/watch?v=-VXwD2nskhQ

VIII. References

  1. Warrington (2021) Crit Dec Emerg Med 35(9): 29
  2. Kattah (2009) Stroke 40:3504-10 [PubMed]

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