How to differentiate giddiness from stroke and other causes in a patient, particularly in those with a history of cardiovascular disease, hypertension, or other risk factors?

Differentiating Giddiness from Stroke and Other Causes

In patients presenting with dizziness or vertigo, particularly those with cardiovascular risk factors, use the HINTS examination (Head Impulse, Nystagmus, Test of Skew) to differentiate stroke from benign causes—but only if performed by a trained specialist, as it has 96.7% sensitivity and 94.8% specificity for detecting stroke when done correctly. 1

Immediate Risk Stratification

High-Risk Features Requiring Urgent MRI (Bypass HINTS)

Proceed directly to MRI with diffusion-weighted imaging if any of the following are present:

• Age >50 years with vascular risk factors (hypertension, diabetes, smoking, atrial fibrillation) 1
• Focal neurologic deficits: diplopia, dysarthria, dysphagia, limb weakness, or facial droop 1
• New severe headache or neck pain 1
• Abnormal standard neurological examination 2

Critical pitfall: Up to 75-80% of posterior circulation stroke patients lack focal neurologic deficits on standard examination, so a normal neurologic exam does NOT exclude stroke 1

Clinical Presentation Patterns

Stroke characteristics 2:

• Smooth symptomatic progression of focal deficit over minutes to hours (uncommon in other stroke types)
• Vomiting more common than in ischemic stroke or subarachnoid hemorrhage
• Elevated blood pressure and impaired consciousness common
• Headache present but less common than subarachnoid hemorrhage

Benign peripheral vertigo characteristics 2:

• Brief episodes triggered by head movements (suggests BPPV)
• Positive Dix-Hallpike test differentiates BPPV from central causes
• Unidirectional horizontal nystagmus (peripheral pattern)

HINTS Examination Protocol (For Trained Specialists Only)

Patient selection: Use ONLY in patients with Acute Vestibular Syndrome (AVS)—acute, persistent vertigo with nausea/vomiting, head motion intolerance, nystagmus, and gait unsteadiness 1

Three-Component Assessment

1. Head Impulse Test 1:

   • Assesses vestibulo-ocular reflex
   • Abnormal (corrective saccade) = peripheral cause
   • Normal in dizzy patient = concerning for central/stroke

2. Nystagmus Assessment 1:

   • Direction-changing or vertical nystagmus = central cause
   • Unidirectional horizontal nystagmus = peripheral cause

3. Test of Skew 1:

   • Cover/uncover each eye while patient fixates on target
   • Any vertical corrective movement = central/brainstem pathology

ANY ONE central finding (normal head impulse, direction-changing nystagmus, OR skew deviation) requires urgent MRI 1

Critical Limitations of HINTS

• Most emergency physicians lack adequate training to perform HINTS with sufficient accuracy as a first-line test before MRI 2, 1
• Meta-analysis shows HINTS performed by emergency physicians in isolation is NOT adequately sensitive to exclude stroke 2
• Subspecialists achieve 97.6% specificity vs. 89.1% for non-subspecialists 1
• If performed by non-expert examiners, do NOT rely on HINTS alone—proceed with MRI for high-risk patients 1

Imaging Strategy

When to Use MRI vs. CT

MRI with diffusion-weighted imaging is superior to CT for detecting posterior circulation stroke 2, 1:

• CT sensitivity for posterior fossa stroke is only ~10% 2
• MRI-DWI has 85.1% sensitivity within 24-48 hours 1
• HINTS by trained specialists (95.3% sensitivity) is MORE sensitive than early MRI 1

Important caveat: Early MRI has ~15% false-negative rate within first 48 hours, particularly for small posterior fossa strokes 1

CT head without contrast 2:

• Rapidly excludes hemorrhage for thrombolysis decisions
• Very low yield (2.2%) for acute dizziness in emergency department
• Use primarily to rule out hemorrhage, not to diagnose ischemic stroke

Additional Diagnostic Considerations

Cardiovascular Assessment

For all patients with dizziness and cardiovascular risk factors 3:

• 12-lead ECG immediately to detect atrial fibrillation (5-fold stroke risk increase)
• Cardiac enzymes (troponin) as acute MI can cause stroke
• Continuous ECG monitoring for ≥24 hours to detect paroxysmal atrial fibrillation
• Consider prolonged monitoring up to 30 days if cardioembolic mechanism suspected

Vascular Risk Factor Context

Hypertension is the most important modifiable stroke risk factor 4, 5:

• 10 mmHg systolic BP increase raises hemorrhagic stroke risk by 72% in Asians, 49% in Caucasians 2
• However, vertigo in hypertensive patients is typically NOT caused by elevated BP itself but by associated neurological or peripheral vestibular diseases, or paradoxically by hypotension after antihypertensive medication 6

Practical Algorithm

1. Assess for immediate high-risk features (age >50 with vascular risks, focal deficits, severe headache) → If present, proceed directly to MRI 1

2. If isolated AVS without high-risk features:

   • If HINTS available AND performed by trained specialist → Use HINTS to guide imaging decision 1
   • If HINTS unavailable OR performed by non-specialist → Proceed to MRI for patients with any vascular risk factors 1

3. If brief positional vertigo → Perform Dix-Hallpike test; positive suggests BPPV (imaging unnecessary) 2

4. Obtain cardiac evaluation in all cases with cardiovascular disease history 3

Common pitfall: Do not assume elevated blood pressure is causing the dizziness—treat the underlying cause, not just the pressure 6