Use it only in acute vestibular syndrome

HINTS is validated only in the acute vestibular syndrome (AVS): rapid-onset, continuous vertigo lasting >24 hours (or clearly ongoing) with nausea/vomiting, head-motion intolerance, unsteady gait — and spontaneous or gaze-evoked nystagmus present at the time of examination.
The patient must be currently symptomatic with nystagmus. HINTS is meaningless if there is no nystagmus to characterise.

Do not apply HINTS to episodic or positional vertigo, or to a patient who is asymptomatic at rest — in those cases it gives falsely reassuring results. Episodic positional vertigo is assessed with the Dix–Hallpike manoeuvre instead.

Why it matters

In AVS, HINTS performed by a trained examiner is more sensitive than early MRI-DWI for posterior circulation stroke — small infarcts can be missed on MRI in the first 24–48 hours.
A reassuring (peripheral) HINTS requires all three components to be peripheral. A central finding in any one component means the pattern is central.
It is operator-dependent — if you are not confident performing and interpreting it, treat as potentially central and involve stroke/neurology / image.

The three components

HI — Head Impulse test
Ask the patient to fix on your nose. Hold the head, turn it rapidly ~10–20° to one side, and watch for a corrective (re-fixation) saccade. An abnormal test — a catch-up saccade — is the reassuring, peripheral finding (impaired vestibulo-ocular reflex on the affected side). A normal head impulse in a patient with AVS is worrying for a central cause.
N — Nystagmus
Observe in primary gaze and on lateral gaze to each side. Peripheral: unidirectional, horizontal (fast phase always the same way), worse on gaze toward the fast phase (Alexander's law), suppressed by fixation. Central: direction-changing gaze-evoked nystagmus, or vertical/torsional nystagmus.
TS — Test of Skew
Alternate-cover test: cover and uncover each eye in turn while the patient fixes ahead. A vertical corrective movement of the uncovered eye (skew deviation) is a central sign. Absence of skew is reassuring.

Peripheral vs central pattern

Component	Peripheral (reassuring)	Central (concerning)
Head Impulse	Abnormal — catch-up saccade present	Normal — no saccade
Nystagmus	Unidirectional, horizontal, fixation-suppressed	Direction-changing, or vertical / torsional
Test of Skew	No skew (absent)	Vertical skew deviation present

INFARCT — the central pattern is Impulse Normal, Fast-phase Alternating, Refixation on Cover Test. Any one of these three = treat as central.

HINTS-plus (add hearing)

Add a bedside hearing check (finger rub / whispered voice) — HINTS-plus.
New unilateral hearing loss in AVS should be treated as central until proven otherwise: it can indicate an AICA territory infarct (the labyrinthine artery arises from AICA), even when the rest of HINTS looks peripheral.
HINTS-plus improves sensitivity for stroke over HINTS alone.

Acting on the result

Central pattern (any component), new hearing loss, or any focal neurology → treat as posterior circulation stroke until proven otherwise: MRI with DWI, and stroke/neurology involvement.
Fully peripheral pattern (all three peripheral, no hearing loss, no other neurology) supports a peripheral vestibular cause such as vestibular neuritis — but only reliable when performed correctly in true AVS.
Remember additional stroke risk factors and the wider differential; HINTS complements, and does not replace, overall clinical judgement.

Supervision pointers

Generic ED skills entrustment levels — not a named curriculum DOPS:

1	Observed only — defines acute vestibular syndrome and when HINTS applies.
2a	Performs the head impulse, characterises nystagmus and does the cover test with supervision.
2b	Correctly interprets the pattern and recognises HINTS-plus hearing loss.
3	Indirect supervision; safely selects patients and escalates central patterns.
4	Independent; teaches the examination and its pitfalls.

References

Kattah JC, et al. HINTS to Diagnose Stroke in the Acute Vestibular Syndrome: Three-Step Bedside Oculomotor Examination More Sensitive Than Early MRI DWI. Stroke 2009;40(11):3504–3510.
Newman-Toker DE, et al. HINTS outperforms ABCD2 to screen for stroke in acute continuous vertigo and dizziness. Acad Emerg Med 2013;20(10):986–996.
Tarnutzer AA, et al. Does my dizzy patient have a stroke? A systematic review of bedside diagnosis in AVS. CMAJ 2011;183(9):E571–E592.

HINTS Examination