What does a negative protective value on a Head Impulse, Nystagmus, and Test of Skew (HINTS) exam indicate in an adult patient presenting with dizziness or vertigo?

Negative Predictive Value of HINTS Exam in Acute Vestibular Syndrome

A "negative" HINTS exam (meaning HINTS suggests a peripheral cause) has excellent negative predictive value for ruling out stroke when performed by properly trained specialists, but should NOT be relied upon when performed by emergency physicians without specialized training—these patients still require MRI if they have vascular risk factors or are over age 50. 1, 2

Understanding HINTS Terminology and Interpretation

• A "HINTS peripheral" result (abnormal head impulse test, unidirectional horizontal nystagmus, no skew deviation) indicates a peripheral vestibular cause and effectively rules out stroke when performed by trained specialists. 2, 3

• The sensitivity of HINTS for detecting stroke is 95.3% when performed by subspecialists (neurologists, neuro-otologists), meaning it misses stroke in fewer than 5% of cases. 4

• However, when performed by emergency physicians without specialized training, HINTS sensitivity drops to 83% and specificity plummets to 44%, making it inadequate as a standalone test to exclude stroke. 5

Critical Limitations Based on Examiner Training

• The American College of Emergency Physicians and Society for Academic Emergency Medicine explicitly state that most emergency physicians have not received adequate training to perform HINTS with sufficient accuracy as a first-line test before MRI. 1, 2

• A meta-analysis demonstrated that subspecialists achieve 97.6% specificity compared to only 89.1% for non-subspecialists, a statistically significant difference that translates to substantially more false reassurance in non-expert hands. 4

• If HINTS is performed by non-expert examiners in the emergency department, do not rely on it alone to exclude stroke—proceed with MRI for high-risk patients. 2

When HINTS "Negative" Still Requires Imaging

Proceed directly to MRI with diffusion-weighted imaging regardless of HINTS results if any of the following are present: 2, 3

• Age over 50 years with vascular risk factors (hypertension, diabetes, smoking, atrial fibrillation) 2
• Focal neurologic deficits (diplopia, dysarthria, dysphagia, limb weakness) 2
• New severe headache or neck pain 2
• Severe imbalance disproportionate to vertigo, suggesting cerebellar involvement 6, 3

Stroke Location Affects HINTS Accuracy

• HINTS sensitivity is significantly lower for anterior inferior cerebellar artery (AICA) strokes (84%) compared to posterior inferior cerebellar artery (PICA) strokes (97.7%). 4

• Adding bedside hearing testing to create "HINTS Plus" increases sensitivity to 99.2% for AICA strokes, which often present with auditory symptoms. 2, 4

• This is critical because AICA strokes can present with isolated vertigo plus hearing loss, mimicking labyrinthitis. 4

HINTS Outperforms Early MRI—But Only When Done Right

• HINTS performed by trained specialists has higher sensitivity (95.3%) than MRI-DWI obtained within 24-48 hours of symptom onset (85.1%) for detecting posterior circulation stroke. 2, 4

• Early MRI has a false-negative rate of approximately 15% within the first 48 hours, particularly for small posterior fossa strokes. 1, 4

• However, this advantage only applies when HINTS is performed by properly trained clinicians—the comparison is meaningless if the examiner lacks expertise. 5, 7

Common Pitfalls to Avoid

• Do not use ambiguous terminology like "HINTS negative"—this creates confusion. Use "HINTS peripheral" (suggests benign cause) or "HINTS central" (suggests stroke). 8

• HINTS is ONLY valid for Acute Vestibular Syndrome (AVS)—acute, persistent vertigo with nausea/vomiting, head motion intolerance, nystagmus, and gait unsteadiness lasting hours to days. 2, 3

• Do not use HINTS for brief positional vertigo (likely BPPV) or chronic recurrent symptoms (likely Ménière's disease)—it will mislead you. 3

• A normal neurologic examination does NOT exclude stroke—up to 75-80% of posterior circulation stroke patients lack focal deficits on standard examination. 1, 6, 3

Practical Algorithm for Emergency Department Use

For patients presenting with acute, persistent vertigo:

1. If the examiner is NOT a trained subspecialist (neuro-otologist, vascular neurologist, neuro-ophthalmologist), proceed directly to MRI for patients over 50 with any vascular risk factors. 1, 2

2. If HINTS is performed and suggests a central cause (normal head impulse, direction-changing or vertical nystagmus, or skew deviation), obtain urgent MRI immediately. 2, 3

3. If HINTS suggests a peripheral cause but the patient has high-risk features (age >50 with vascular risk factors, focal deficits, severe headache/neck pain, or severe imbalance), obtain MRI regardless. 2, 3

4. Consider delayed MRI at 3-7 days if initial imaging is negative but clinical suspicion remains high, as some small strokes become visible only after this interval. 1