II. Indications
-
Acute Vestibular Syndrome (AVS) evaluation
- Component of the HiNTs Exam
- Distinguishes Acute Peripheral Vestibulopathy (APV) from posterior CVA
- Catch-up saccades are present in APV but absent in Cerebellar Stroke
III. Contraindications
- See HiNTs Exam
IV. Mechanism
- Vestibulo-ocular reflex function test
- Peripheral Vertigo disrupts the Medial Longitudinal Fasciculus
- Medial Longitudinal Fasciculus is the communication between the vestibular system and Oculomotor Nucleus
- Catch-up saccade is present due to a delay in the eyes needing to correct for the head position change
- In a posterior CVA, the defect is at a higher level and the eye correction is immediate (no saccade is seen)
V. Technique
- Examiner asks the patient to focus on the examiners nose throughout the procedure
- Examiner rapidly rotates a patients head 20-40 degrees to the right or left
- Patients eyes are observed for Nystagmus
- Observe for one eye that lags in response to maintain forward gaze
- Makes quick saccade movement to catch-up or correct
- Procedure is repeated several times on each side
- Avoiding habituation
- In between rapid movements, examiner gently and slowly rotates the patient's head from side to side
- Procedure is repeated multiple times, randomly selecting one side or the other
- Prevents the patient from anticipating which side will be tested next
- Consider recording the exam on smartphone to improve efficacy
- Have an assistant record the exam with smartphone camera (flash on, landscape mode)
- Image should include half of patient's forehead and the bottom of the patient's nose
- Johns (2023) communication, 10/20/2023
VI. Interpretation
-
Vertigo with a "normal" test (no saccade correction)
- Strongly suggests central Vertigo (e.g. Cerebellar infarction)
-
Vertigo with an "abnormal" test (saccade corrections are present)
- Weakly suggests Acute Peripheral Vestibulopathy (APV)
VII. Efficacy
- High Test Specificity for central Vertigo (low False Positive Rate)
- Strongly suggests central Vertigo (e.g. posterior CVA)
- Test is most valuable when "normal" (no saccade/correction) suggesting an Acute Vestibular Syndrome (AVS)
-
Test Sensitivity for central Vertigo: 85%
- Saccade present despite central Vertigo in 15% of cases (False Negative Rate)
- Presence of a saccade does not exclude central Vertigo
VIII. Resources
- HiNTs Exam Review (Dr. Peter Johns)
- Video of a Head Impulse Test with saccades present