You make me dizzy, Miss Lizzy: HINTS for assessing acute dizziness

The evaluation of the dizzy patient in the Emergency Department can be very complicated. The differential diagnosis is broad and misdiagnosis carries with it the potential for a high degree of morbidity and mortality. This summary will focus on patients with acute vestibular syndrome—patients with acute onset, continuous dizziness—and differentiating peripheral and central causes. We are not going to discuss vertigo or other causes of dizziness (see Table 1).

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Table 1: Timing and Trigger Approach to dizziness (from TiTrATE Approach to Dizziness, David E. Newman-Toker, MD, PhD)

One of the simplest ways to approach the dizzy patient is to categorize them based on the timing (episodic vs acute/continuous) and trigger (positional vs spontaneous; post-exposure vs spontaneous). Dizziness is difficult for patients to describe, so thinking of it in this way will minimize problems posed by vague and alternating histories to help narrow your differential and inform a targeted exam (Table 1).

A minority but significant percent of patients with acute vestibular syndrome have a stroke (population estimates range from 10-40%).1 Peripheral and benign causes includes cerumen impaction and benign positional vertigo. Symptoms are localized to the inner ear or CN8, are acute, benign, self-limited and often viral or post-viral. Vertigo with stroke is often abrupt, with maximum intensity at time of onset. Severe ataxia is common, but not always seen. Larger cerebellar strokes will produce symptoms localizing to the brainstem, like diplopia, dysarthria, limb ataxia, dysphagia, weakness or numbness, but 10% will have isolated vertigo without other symptoms.2

So, how can you tell the difference between central and peripheral causes?

Great reviews of vertigo can be found here, here, and here. While there are a number of articles in the Emergency Medicine literature, the most notable exam tool that is currently most broadly discussed is the HINTS exam.

The HINTS exam is an acronym for the three exam tools that help differentiate a non-hemorrhagic posterior cerebrovascular accident from other peripheral causes of acute vestibular syndrome. It stands for Head Impulse, Nystagmus, and Test of Skew. A number of derivation and validation studies, many of which were led by Dr. David Newman-Toker, have been published in recent years.

Kattah, et al6 found the HINTS. exam to be 100% sensitive and 96% specific for stroke in their 2009 publication in Stroke. In 2013, Newman-Toker, et al4 compared HINTS to the ABCD2 score in predicting ischemia in a prospective study among ED patients with one hour of dizziness at least one risk factor for stroke. They found HINTS to be superior to ABCD2 (ABCD2, SE61%, SP 62% vs HINTS SE 96.5% SP 84.4%), but both of these studies are limited by the fact that exams involved evaluations by specialists, primarily neuroophthalmologists, however Newman-Toker’s study included a vascular stroke trained emergency physician.

Finally, fresh off the presses is a new study just published in Neurology5 which used a combination of the ABCD2 score and HINTS exam to risk stratify patients into low, moderate, and high risk groups. The study was limited in that they used the HINTS exam in all patients, some who did not have nystagmus.   In the end, few patients with nystagmus who had a negative HINTS exam had a stroke.

Can EM physicians do it?

Obviously more studies remain to be done, but initial research is promising. Studies in EDs in Italy and Australia, for example, have shown high inter-evaluator reliability between emergency physicians and specialists7, 8 when assessing for stroke using exam findings of nystagmus, head impulse testing, and ability to ambulate.

What is the HINTS exam?

HINTS is a three part exam:

  1. Head Impulse
  2. Nystagmus
  3. Test of Skew
  • Head Impulse. This test relies on the vestibular-ocular reflex, which is a peripheral reflex that allows your eyes to focus while moving your head. When this is interrupted, your eyes lag. A POSITIVE test is consistent with peripheral vertigo. To

    Vestibulo-ocular Reflex

    say it another way, a positive head impulse test is reassuring.

    1. How to do it:
      1. Have patient fix eyes on your nose. And rapidly turn their head 20 degrees to one direction and back to center, then to other side.
        1. Eyes will stay fixed on your nose (if central)
        2. Eyes will first move to direction you moved their head, and then re-fixate on your nose. It is called “catch up” saccades. Eyes have to re-orient to your nose. = peripheral lesion

F4.large

  • Nystagmus
    1. Peripheral vertigo should have fast beating nystagmus in only one direction.
    2. If it is direction changing = central
    3. Vertical nystagmus = central

  • Test of Skew
    1. You are looking for vertically disconjungate gaze (aka one eye is higher than other).
    2. This can be overcome by fixation, but can be ‘uncovered’ by the alternating cover test. Have them look at nose, cover one eye, will prevent covered eye from fixating. Then rapidly remove hand and see if eye misaligned will come back into alignment. Seeing realignment as eye is fixating on your nose. You are looking for that re-alignment.

To help guide your evaluation of the patient with acute vestibular syndrome, check out this new, handy guideline put together by Dr. Napoli and Dr. Siket:

Posterior stroke visio. AN 12#2

Guideline for the Acute Dizzy Patient in the Emergency Department, 2015

Try out the exam on your next dizzy patient and see how it goes. The best way to get comfortable with this exam is to practice!

 

Looking for more info?

Another EM overview of acute vestibular syndrome can be found on EMCrit.

Thank you to my Faculty Editors: Anthony Napoli, MD and Matt Siket, MD, MS

References/Further Reading:

  1. Tarnutzer AA, Berkowitz AL, Robinson KA, Hsieh Y, Newman-Toker DE. Does my dizzy patient have a stroke? A systematic review of bedside diagnosis in acute vestibular syndrome. CMAJ, June 14, 2011, 183(9).
  2. Nelson JA, Viirre K. Review: The Clinical Differentiation of Cerebellar Infarction from Common Vertigo Syndromes. West J Emerg Med. 2009;10(4):273-277.
  3. Newman-Toker DE, Kerber KA, Hsieh YH, et al. HINTS outperforms ABCD2 to screen for stroke in acute continuous vertigo and dizziness. Acad Emerg Med 2013;20:986–996.
  4. Seemungal BM, Bronstein AM. Review: A practical approach to acute vertigo. Pract Neurol 2008; 8: 211–221.
  5. Kerber KA, Meurer WJ, Brown DL, Burke JF, Hofer TP, Tsodikov A, Hoeffner EG, Fendrick AM, Adelman EE, Morgenstern LB. Stroke risk stratification in acute dizziness presentations: A prospective imaging-based study. Neurology 2015;85:1869–1878.
  6. Kattah, JC, Talkad AV, Wang DZ, Hsieh Y, Newman-Toker DE. HINTS to Diagnose Stroke in the Acute Vestibular Syndrome: Three-Step Bedside Oculomotor Examination More Sensitive Than Early MRI Diffusion-Weighted Imaging. Stroke 2009;40;3504-3510.
  7. Vanni S, Pecci R, Casati C, Moroni F, Risso M, Ottaviani M, Nazerian P, Grifoni S, Vannucchi P. STANDING, a four-step bedside algorithm for differential diagnosis of acute vertigo in the Emergency Department. Acta Otorhinolaryngol Ital 2014;34:419-426.
  8. Vanni S, Nazerian P, Casati C, Moroni F, Risso M, Ottaviani M, Pecci R, Pepe G, Vannucchi P, Grifoni S. Can emergency physicians accurately and reliably assess acute vertigo in the emergency department? Emerg Med Australas. 2015 Apr;27(2):126-31.

4 thoughts on “You make me dizzy, Miss Lizzy: HINTS for assessing acute dizziness

  1. Such a great review! I’d encourage everyone to practice HINTS on all dizzy patients (episodic, positional included) to become more comfortable with the exam. Test of skew can be subtle, and head impulse requires a trusting patient.

  2. Question! I’ve had some difficulty reconciling interpretation of the HIT and the “doll’s eyes” reflex in the assessment of the comatose patient. A positive doll’s eyes test (the same as a positive HIT, where the patient’s eyes remain fixed straight ahead, and so the vestibule-ocular reflex is said to be *intact*) indicates an *intact* brainstem. A negative doll’s eyes test (where the eyes remain fixed mid-orbit) indicates a brainstem lesion. So with the HIT, is it true that a *negative* test could represent a brainstem infarct? I can see how a negative test virtually rules out a cerebellar lesion, but it seems like a brainstem lesion could still be a possibility?

  3. Ok I think I answered my own question. From the 2009 Stroke paper by Kattah et al:

    “Recent studies provide evidence that a normal VOR by h-HIT strongly indicates a central localization, but an abnormal VOR is a weaker predictor of a peripheral localization.5,6 The sign’s diagnostic usefulness is diluted principally by the fact that some patients with abnormal h-HIT (implying APV) actually harbor lateral pontine strokes.6”

    “Skew deviation is an insensitive marker of central pathology but fairly specific predictor of brainstem involvement among patients with AVS. The presence of skew may help identify stroke when a positive h-HIT falsely suggests a peripheral lesion.”

    Take home: beware of the falsely reassuring abnormal HIT; use in context with the other 2 tests!

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