HINTS exam: how the three bedside steps are combined

HINTS stands for Head-Impulse, Nystagmus, Test-of-Skew, a three-step bedside eye exam for people already in acute vestibular syndrome. Magent's calculator marks the result dangerous if any of three findings is present (a normal head impulse, direction-changing nystagmus, or skew deviation) and benign if none is.

Not a medical device. Not a diagnosis or dosing recommendation.

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Kattah JC et al. · 2009
Worked examples
Frequently asked questions

What is the HINTS exam?

HINTS comes from Jorge C. Kattah and colleagues, published in Stroke in 2009. Their abstract describes a prospective study at an academic hospital of consecutive patients with acute vestibular syndrome (vertigo, nystagmus, nausea or vomiting, head-motion intolerance and unsteady gait) who had at least one stroke risk factor. Each had a structured exam: a horizontal head impulse test, a look at nystagmus in different directions of gaze, and a prism cross-cover test of eye alignment.

The three findings are often remembered as INFARCT: Impulse Normal, Fast-phase Alternating, Refixation on Cover Test. Magent's calculator is the three-step HINTS. It isn't HINTS-plus, which adds a hearing check.

This page explains how the calculator combines the three findings into dangerous or benign, as written in the exact expression below. It doesn't say what a result means for a particular person.

The HINTS rule

dangerous = head impulse normal
         OR direction-changing nystagmus
         OR skew deviation
benign    = none of the three

Exact expression the calculator uses:

dangerous iff head_impulse_normal or direction_changing_nystagmus or skew_deviation; benign iff not dangerous (Kattah 2009 three-step HINTS for acute vestibular syndrome; INFARCT: Impulse Normal, Fast-phase Alternating, Refixation on Cover Test)

What each finding means

Input	True when	INFARCT letter
`head_impulse_normal`	The horizontal head-impulse test is normal	Impulse Normal
`direction_changing_nystagmus`	Nystagmus changes direction in eccentric gaze	Fast-phase Alternating
`skew_deviation`	Skew deviation, a vertical misalignment of the eyes on the cover test	Refixation on Cover Test

How the rule works

Record each finding true or false from the bedside exam.
Check for any true. If one or more is true, dangerous is true and benign is false.
Otherwise dangerous is false and benign is true.

There are no points and no total. One finding is enough to set dangerous.

Why a normal head impulse counts

The first input is easy to get backwards. In HINTS it's a normal head-impulse test that counts as a dangerous sign, which is why the input is named head_impulse_normal and the mnemonic says Impulse Normal. An abnormal head impulse is entered as false.

Inputs come from the user

All three inputs are true or false, and anything else is rejected with an error. Magent doesn't examine the patient. The calculator returns dangerous, benign and a line for each finding.

Worked examples

These use Magent's own expected values for the calculator.

Example 1: none of the three findings

Head impulse not normal; no direction-changing nystagmus; no skew.
Result: dangerous false, benign true.

Example 2: normal head impulse alone

head_impulse_normal true; the other two false.
Result: dangerous true, benign false.

Example 3: direction-changing nystagmus alone

direction_changing_nystagmus true; the other two false.
Result: dangerous true, benign false.

Example 4: skew deviation alone

skew_deviation true; the other two false.
Result: dangerous true, benign false.

Example 5: all three findings

All three true.
Result: dangerous true, benign false. More findings don't change the result.

History of HINTS

The calculator cites Kattah JC, Talkad AV, Wang DZ, Hsieh YH and Newman-Toker DE, Stroke, 2009 (volume 40, issue 11, pages 3504–3510). The abstract's conclusion names the three-step bedside eye exam HINTS: Head-Impulse-Nystagmus-Test-of-Skew.

When it's used

The 2009 study enrolled people who were already in acute vestibular syndrome and had at least one stroke risk factor. The calculator is meant for patients already in acute vestibular syndrome, as in that paper.

Where it's used

The 2009 study was done at an academic hospital: a structured bedside eye exam came first, and every patient then had neuroimaging.

Who uses it

The person examining the patient records the three findings. The calculator applies the any-of-three rule.

Limits of the calculation

It combines three findings. It doesn't confirm or rule out a stroke.
It isn't a substitute for brain imaging.
It's meant for people already in acute vestibular syndrome, not for every kind of dizziness.
It's three-step HINTS. It doesn't include hearing (HINTS-plus).
This page doesn't say what to do with a result.

Clinical decisions belong to a qualified clinician who knows the patient.

HINTS-plus adds a hearing check. Magent's calculator doesn't take hearing.
ROSIER scale is a separate stroke recognition scale with seven caller-assigned items, two of which subtract a point.
Glasgow Coma Scale scores eye, verbal and motor responses; HINTS doesn't use it.

Glossary

Acute vestibular syndrome: sudden, continuous vertigo with nystagmus, nausea and unsteady walking.
Nystagmus: involuntary, rhythmic movement of the eyes.
Eccentric gaze: looking to the side rather than straight ahead.
Head-impulse test: a quick turn of the head while the person keeps looking at a target.
Skew deviation: one eye sitting higher than the other.

Common mistakes

Entering an abnormal head impulse as true. The input is head_impulse_normal; it's true when the test is normal.
Expecting a score. The result is dangerous or benign, not a number.
Using it outside acute vestibular syndrome. The calculator is limited to that setting.
Adding a hearing finding. That's HINTS-plus, which this calculator doesn't cover.

Source

Kattah JC, Talkad AV, Wang DZ, Hsieh YH, Newman-Toker DE. Stroke. 2009;40(11):3504-3510. DOI: 10.1161/STROKEAHA.109.551234. PMID: 19762709

Frequently asked questions

What does HINTS stand for?

Head-Impulse, Nystagmus, Test-of-Skew.

What is the INFARCT mnemonic?

Impulse Normal, Fast-phase Alternating, Refixation on Cover Test: the three findings that set dangerous in the calculator.

Is a normal head impulse test reassuring in HINTS?

In HINTS a normal head impulse is one of the three dangerous findings, so the calculator returns dangerous true when it's present. This page doesn't say what that means for a particular person.

How many findings does it take to be dangerous?

One. Any single finding sets dangerous to true.