EBQ:HINTS Exam
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Clinical Question
Is the HINTS exam (Head-Impulse—Nystagmus—Test-of-Skew) more sensitive for diagnosing stroke than early MRI diffusion-weighted imaging in Acute Vestibular Syndrome?
Conclusion
A negative HINTS examination can rule out a stroke better than a negative MRI with DWI in the first 24 to 48 hours after symptom onset with a specificity of 96%.
Major Points
Inclusion Criteria
- HINTS exam should only be used in patient with acute persistent vertigo, nystagmus, and a normal neurological exam.
- HINTS exam, when done correctly, has high sensitivity and specificity in distinguishing peripheral vs central etiologies of vertigo
- Note that the original study was done by neuro-ophthalmologists in a differentiated patient base. This exam has not been studied in a large ED population yet
The 3 components of the HINTS exam include:
| HINTS Test | Reassuring Finding |
| Head Impulse Test | Abnormal (corrective saccade) |
| Nystagmus | Unidirectional, horizontal |
| Test of Skew | No skew deviation |
- Always use correct terminology; "HINTS negative" does not convey a clear interpretation. State "HINTS central" or "HINTS peripheral" as suggested in literature
- If able, specify the exact exam finding as shown by chart above
Head Impulse Test
Test of vestibulo-ocular reflex function
- Have patient fix their eyes on your nose
- Move their head rapidly in the horizontal plane to the left and right
- When the head is turned towards the normal side, the vestibular ocular reflex remains intact and eyes continue to fixate on the visual target
- When the head is turned towards the affected side, the vestibular ocular reflex fails and the eyes make a visible corrective saccade to re-fixate on the visual target [1][2]
- Normally, a functional vestibular system will identify any movement of the head position and instantaneously correct eye movement accordingly so that the center of the vision remains on a target.
- This reflex fails in peripheral causes of vertigo affecting the vestibulocochlear nerve unilaterally; thus, failure of the reflex unilaterally is reassuring (since the cause is peripheral)
- Note that in central causes of vertigo, test may show normal reflex response OR failure of the reflex BILATERALLY
Nystagmus
- Observation for nystagmus in primary, right, and left gaze
- No nystagmus (normal) or only horizontal unilateral nystagmus (fast direction only in one direction) is reassuring
- Any other type of nystagmus is abnormal, including vertical or bidirectional nystagmus
Test of Skew
- Have patient look at your nose with their eyes and then cover one eye
- Then rapidly uncover the eye and quickly look to see if the eye moves to re-align.
- Repeat with on each eye
- Skew deviation is a fairly specific predictor of brainstem involvement in patients with acute vestibular syndrome. The presence of skew may help identify stroke when a positive head impulse test falsely suggests a peripheral lesion.
- Skew is also known vertical dysconjugate gaze and is a sign of a central lesion
Inclusion Criteria
At least one stroke risk factor:
- atrial fibrillation
- diabetes
- eclampsia
- hypercoagulable state
- hyperlipidemia
- hypertension
- prior stroke or myocardial infarction.
- recent cervical trauma
- smoking
Exclusion Criteria
A history of recurrent vertigo with or without auditory symptoms
Interventions
Patients presenting with symptoms of acute vestibular syndrome underwent neurological and vestibular examination according to a standard protocol:
- head impulse test
- prism cross-cover test for ocular alignment
- observation of nystagmus in different gaze positions
All patients underwent neuroimaging, generally after bedside evaluation, otherwise the examiner was masked to these results at the time of clinical assessment.
All patients were admitted for observation and underwent serial daily examinations for evolution of clinical findings.
Outcome
Primary Outcomes
- A positive HINTS exam: 100% sensitive and 96% specific for the presence of a central lesion.
- The HINTS exam was more sensitive than general neurological signs: 100% versus 51%.
- The sensitivity of early MRI with DWI for lateral medullary or pontine stroke was lower than that of the HINTS examination (72% versus 100%, P=0.004) with comparable specificity (100% versus 96%, P=1.0).
Secondary Outcomes
Subgroup analysis
Further Discussion
This was performed in an outpatient setting by neuro ophthalmologists not emergency physicians and may not be generalizable to an ED population
Further Reading
- Newman-Toker et al. HINTS Outperforms ABCD2 to Screen for Stroke in Acute Continuous Vertigo and Dizziness. Academic Emergency Medicine. Volume 20, Issue 10, pages 986–996, October 2013
- Babak et al. Application of the ABCD2 Score to Identify Cerebrovascular Causes of Dizziness in the Emergency Department. Stroke. 2012; 43: 1484-1489
- Perry et al. Prospective validation of the ABCD2 score for patients in the emergency department with transient ischemic attack. CMAJ July 12, 2011 vol. 183 no. 10.
Funding
The National Institutes of Health and the Agency for Healthcare Research and Quality