What is the HINTS (Head Impulse, Nystagmus, and Test of Skew) test for vertigo?

HINTS Test for Vertigo

The HINTS (Head Impulse, Nystagmus, Test of Skew) examination is a three-part bedside neurological assessment that differentiates central from peripheral causes of acute vestibular syndrome, with greater sensitivity than early MRI for detecting stroke when performed by properly trained clinicians. 1

What HINTS Stands For and Its Purpose

The HINTS examination is specifically designed for patients presenting with Acute Vestibular Syndrome (AVS), characterized by acute, persistent vertigo with nausea/vomiting, head motion intolerance, nystagmus, and gait unsteadiness. 1 This is critical—the test should not be used for intermittent dizziness or patients without nystagmus. 2

The Three Components

1. Head Impulse Test (HI)

• Assesses the vestibulo-ocular reflex by rapidly turning the patient's head while they fixate on a target. 1
• An abnormal response (corrective saccade) suggests peripheral vestibular dysfunction, which is reassuring. 1
• A normal head impulse test in a dizzy patient raises concern for a central (stroke) cause. 1

2. Nystagmus Assessment (N)

• Evaluates the direction and characteristics of involuntary eye movements. 1
• Direction-changing nystagmus (changes direction with gaze) suggests a central cause. 1, 3
• Unidirectional horizontal nystagmus suggests a peripheral cause. 1
• Pure vertical nystagmus strongly indicates a central lesion. 4

3. Test of Skew (TS)

• Detects vertical misalignment of the eyes, suggesting a central lesion. 1
• Performed by covering and uncovering each eye while the patient fixates on a target, looking for vertical correction movements. 1
• Presence of skew deviation indicates a central cause. 1

Interpretation: Central vs. Peripheral

A "central" HINTS examination (concerning for stroke) includes ANY of the following:

• Normal head impulse test (no corrective saccade) 1, 3
• Direction-changing nystagmus 1, 3
• Skew deviation present 1

A "peripheral" HINTS examination (reassuring) includes ALL of the following:

• Abnormal head impulse test (corrective saccade present) 1
• Unidirectional horizontal nystagmus 1
• No skew deviation 1

Diagnostic Accuracy

When performed by trained clinicians, the clinical HINTS examination demonstrates 94.0% sensitivity and 86.9% specificity for identifying central causes of AVS. 5 This makes it more sensitive than early MRI for detecting posterior circulation stroke. 1

The HINTS Plus examination adds assessment of auditory function (hearing loss suggests peripheral labyrinthitis) and shows 95.3% sensitivity and 72.9% specificity. 5

Critical Caveats and Common Pitfalls

Examiner Experience Matters

• Accuracy depends heavily on examiner expertise, with subspecialists achieving higher accuracy than non-subspecialists. 1
• The American College of Emergency Physicians and Society for Academic Emergency Medicine state that most emergency physicians have not received adequate training to perform HINTS with sufficient accuracy as a first-line test before MRI. 6
• Studies show emergency physicians frequently misapply the test to patients without continuous vertigo or nystagmus, limiting diagnostic value. 2

Patient Selection is Essential

• Only use HINTS for patients with Acute Vestibular Syndrome: acute, persistent (not intermittent) vertigo, nystagmus present, nausea/vomiting, and gait unsteadiness. 1, 2
• Do not use HINTS for benign paroxysmal positional vertigo (BPPV), which requires Dix-Hallpike testing instead. 2
• Up to 25% of AVS cases are caused by stroke, and approximately 75-80% of posterior circulation stroke patients lack focal neurologic deficits on standard examination. 6, 4

When HINTS is Negative but Concern Remains

• A meta-analysis suggests that when HINTS is performed by emergency physicians (not neurologists) in isolation, it is not adequately sensitive to exclude stroke. 6
• Consider MRI with diffusion-weighted imaging for patients over 50 years with vascular risk factors, or when severe imbalance is disproportionate to vertigo. 4
• If HINTS suggests a central cause, urgent MRI is indicated, as it is superior to CT for detecting posterior circulation stroke. 7

Terminology Pitfall

Avoid ambiguous documentation like "HINTS negative"—instead use "HINTS central" (concerning for stroke) or "HINTS peripheral" (reassuring for benign cause). 8