HINTS
(2009)Objective
To assess the diagnostic accuracy of a three-step bedside oculomotor exam (H.I.N.T.S.: Head-Impulse-Nystagmus-Test-of-Skew) for differentiating stroke from vestibular neuritis in acute vestibular syndrome
Study Summary
• A benign HINTS result at the bedside rules out stroke better than a negative MRI with DWI in the first 24-48 hours after symptom onset.
• This simple 1-minute exam should be incorporated into the evaluation of all patients presenting with acute vertigo and stroke risk factors.
Intervention
Three-step bedside oculomotor exam: horizontal head impulse test (h-HIT), nystagmus assessment in multiple gaze positions, and alternate cover test for skew deviation
Inclusion Criteria
Acute vestibular syndrome: rapid onset of vertigo, nausea/vomiting, gait unsteadiness with head-motion intolerance and nystagmus lasting >24 hours
Study Design
Arms: Array
Patients per Arm: Peripheral: 25, Central: 76
Outcome
Bottom Line
The HINTS exam (Head-Impulse-Nystagmus-Test-of-Skew) was 100% sensitive and 96% specific for identifying stroke in acute vestibular syndrome, outperforming initial MRI DWI which was only 88% sensitive. A benign HINTS result at the bedside rules out stroke better than a negative MRI with DWI in the first 24-48 hours after symptom onset. This simple 1-minute exam should be incorporated into the evaluation of all patients presenting with acute vertigo and stroke risk factors.
Major Points
- 101 consecutive high-risk AVS patients enrolled: 25 peripheral (vestibular neuritis) and 76 central (69 ischemic strokes, 4 hemorrhages, 3 pontine/other CNS lesions). Study population was 65% male, mean age 62 years.
- The HINTS exam defines 'dangerous' signs as: normal h-HIT (Impulse Normal), direction-changing horizontal nystagmus (Fast-phase Alternating), or skew deviation (Refixation on Cover Test) — mnemonic: I.N.F.A.R.C.T.
- A dangerous HINTS result was 100% sensitive and 96% specific for stroke — positive LR 25 (95% CI 3.66-170.59), negative LR 0.00 (95% CI 0.00-0.11). No strokes were missed by HINTS.
- Initial MRI DWI was falsely negative in 8 of 69 ischemic stroke patients (12%): 5 lateral medullary, 1 lateral ponto-medullary, and 2 middle cerebellar peduncle infarctions. All false negatives occurred within the first 8-48 hours.
- For lateral medullary and lateral pontine strokes specifically, HINTS sensitivity was 100% vs MRI DWI sensitivity of only 72% (P=0.004), with comparable specificity (96% vs 100%, P=1.0).
- Skew deviation was present in 17% of central lesions overall and 30% of those with brainstem involvement (χ² P=0.003). It was particularly useful in identifying lateral pontine strokes where abnormal h-HIT falsely suggested peripheral disease (correctly reclassified 2 of 3 cases).
- Lateral brainstem and inferior cerebellar strokes (n=24) most closely mimicked peripheral vestibulopathy — 45% had no obvious neurologic or oculomotor signs, compared to only 5% of medial brainstem strokes (P=0.001).
- HINTS was more sensitive than traditional neurologic signs: general neurologic signs 19%, obvious oculomotor signs 28%, severe truncal ataxia 33%, any obvious signs combined 64% — all significantly inferior to HINTS 100% (all P<0.001).
- The entire HINTS exam can be performed in approximately 1 minute at the bedside, compared to 5-10 minutes for traditional neurologic exam and hours for MRI with DWI.
- 15 of 69 stroke patients (22%) were under age 50, and 6 were under age 40. Four had vertebral artery dissection — vertebral dissection is the leading cause of posterior circulation stroke in young adults.
Study Design
- Study Type
- Prospective, cross-sectional diagnostic accuracy study
- Randomization
- No
- Blinding
- Examiner masked to neuroimaging results at time of clinical assessment
- Sample Size
- 101
- Follow-up
- Until discharge with serial daily examinations
- Centers
- 1
- Countries
- United States
Primary Outcome
Definition: HINTS sensitivity for central lesions
| Control | Intervention | HR/OR | P-value |
|---|---|---|---|
| N/A (diagnostic study) | 100% sensitivity (76/76), 96% specificity (24/25) | - (Positive LR 25.0 (3.66-170.59), Negative LR 0.00 (0.00-0.11)) |
Limitations & Criticisms
- Single-center study with a single expert neuro-ophthalmologist (JCK) performing all examinations — generalizability to non-specialists is uncertain.
- Examiner was not fully masked: although blinded to imaging, he was aware of clinical history and general neurologic exam findings, which could introduce observer bias.
- Highly enriched cohort (76% central, 73% cerebrovascular, 69% ischemic stroke) due to enrollment requiring ≥1 stroke risk factor — may not reflect typical ED vertigo population.
- Selective MRI follow-up: only 8 patients with initial negative MRI underwent repeat imaging, potentially missing some misclassified strokes in the APV group.
- Small sample of peripheral cases (n=25) limits precision of specificity estimate.
- The 96% specificity means 1 in 25 peripheral patients had a false-positive dangerous HINTS — in a lower-prevalence setting, false positives could be more problematic.
- Does not address reproducibility of subtle oculomotor findings by non-specialists, though subsequent studies have shown reasonable inter-rater reliability.
Citation
Newman-Toker DE, et al. Stroke. 2009;40(11):3504-3510.