Tiny Tip: HINTS exam to determine INFARCT

I recently wrote a post about the utility of the HINTS exam for patients who present with persistent vertigo known as acute vestibular syndrome (AVS). The available evidence suggests that this bedside exam is highly effective to help differentiate peripheral from central causes. And in one study, it may even be better than an MRI in the first 48hrs [1]! Finally, the answer to all of your vertiginous problems in the emergency department…except one.

How will you remember how to interpret each component of the HINTS exam?

Have no fear because there is a sweet mnemonic that has been developed. And the beauty of this one is that it actually relates to what you’re trying to remember! Nothing worse than not being able to remember the word that comprises the mnemonic!

Since the most common cause of central vertigo is infarct, it only makes sense that we use INFARCT to remember HINTS . So here goes…

INFARCT = Impulse Normal, Fast-phase Alternating or Refixation on Cover-Test [2].

What does this mean?

Let’s break it down. Recall we apply the HINTS exam to determine if a patient is suffering from a central cause of vertigo (refer to Boring Questions post for a more detailed overview). HINTS is comprised of 3 components:

Head impulse test
Nystagmus
Test of skew

So consider INFARCT (or another central cause) if any of the following:

head Impulse is Normal (no eye saccade with passive head turning)
Fast-phase Alternating (or bidirectional) nystagmus
The eye moves to Refixate during the Cover-Test

That’s it. Use HINTS to evaluate your next patient with persistent vertigo to determine if they have an INFARCT.

References

Kattah, J. C., Talkad, A. V., Wang, D. Z., Hsieh, Y. H., & Newman-Toker, D. E. (2009). HINTS to diagnose stroke in the acute vestibular syndrome three-step bedside oculomotor examination more sensitive than early MRI diffusion-weighted imaging. Stroke, 40(11), 3504-3510. DOI:10.1161/STROKEAHA.109.551234