Otolaryngology Book

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Horizontal Head Impulse Test

Aka: Horizontal Head Impulse Test, Head Thrust Test, h-HIT
  1. See Also
    1. HiNTs Exam (Three-Step Bedside Oculomotor Examination)
    2. Nystagmus
    3. Skew Deviation (Vertical Ocular Misalignment, Vertical Heterotropia, Vertical Strabismus)
    4. Dix-Hallpike Maneuver
    5. Vertigo
    6. Vertigo Causes
    7. Peripheral Causes of Vertigo
    8. Central Causes of Vertigo
    9. Vertigo Diagnostic Testing
    10. Vertigo Management
    11. Meniere's Disease
    12. Motion Sickness
    13. Vestibular Neuronitis
    14. Benign Paroxysmal Positional Vertigo
    15. Perilymphatic Fistula (Hennebert's Sign)
    16. Acute Labyrinthitis
    17. Bacterial Labyrinthitis (Acute Suppurative Labyrinthitis)
    18. Dizziness
    19. Dysequilibrium
    20. Syncope
    21. Light Headedness
  2. Indications
    1. Acute Vestibular Syndrome (AVS) evaluation
    2. Distinguishes Acute Peripheral Vestibulopathy (APV) from posterior CVA
      1. Catch-up saccades are present in APV but absent in cerebellar stroke
  3. Mechanism
    1. Vestibulo-ocular reflex function test
    2. Peripheral Vertigo disrupts the Medial Longitudinal Fasciculus
      1. Medial Longitudinal Fasciculus is the communication between the vestibular system and Oculomotor Nucleus
      2. Catch-up saccade is present due to a delay in the eyes needing to correct for the head position change
      3. In a posterior CVA, the defect is at a higher level and the eye correction is immediate (no saccade is seen)
  4. Technique
    1. Examiner asks the patient to focus on the examiners nose throughout the procedure
      1. Examiner rapidly rotates a patients head 20-40 degrees to the right or left
      2. Patients eyes are observed for Nystagmus
      3. Observe for one eye that lags in response to maintain forward gaze
        1. Makes quick saccade movement to catch-up or correct
      4. Procedure is repeated several times on each side
    2. Avoiding habituation
      1. In between rapid movements, examiner gently and slowly rotates the patient's head from side to side
      2. Procedure is repeated multiple times, randomly selecting one side or the other
        1. Prevents the patient from anticipating which side will be tested next
  5. Interpretation
    1. Vertigo with a "normal" test (no saccade correction)
      1. Strongly suggests central Vertigo (e.g. cerebellar infarction)
    2. Vertigo with an "abnormal" test (saccade corrections are present)
      1. Weakly suggests Acute Peripheral Vestibulopathy (APV)
  6. Efficacy
    1. High Test Specificity for central Vertigo (low False Positive Rate)
      1. Strongly suggests central Vertigo (e.g. posterior CVA)
      2. Test is most valuable when "normal" (no saccade/correction) suggesting an Acute Vestibular Syndrome (AVS)
    2. Test Sensitivity for central Vertigo: 85%
      1. Saccade present despite central Vertigo in 15% of cases (False Negative Rate)
      2. Presence of a saccade does not exclude central Vertigo
  7. Resources
    1. Video of a Head Impulse Test with saccades present
      1. https://www.youtube.com/watch?v=4EBwtckFfTo
  8. References
    1. Halmagyi (1988) Arch Neurol 45(7):737-9 [PubMed]

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