How do you differentiate between ischemic stroke and hemorrhagic stroke in a patient?

Differentiating Ischemic from Hemorrhagic Stroke

Rapid neuroimaging with non-contrast CT or MRI is the only reliable method to differentiate ischemic from hemorrhagic stroke—clinical features alone have inadequate sensitivity and specificity to guide treatment decisions. 1, 2, 3

Why Imaging is Mandatory

Clinical examination cannot reliably distinguish stroke types. While clinical scoring systems exist, they are insufficient for treatment decisions, particularly regarding thrombolytic therapy or antiplatelet agents. 3, 4 Relying solely on clinical features without imaging can lead to catastrophic outcomes if antithrombotic therapy is given to a patient with hemorrhagic stroke. 3

Imaging Algorithm

First-Line Imaging: Non-Contrast CT

Non-contrast CT is the most widely used and recommended initial imaging modality because of: 1, 2

• Widespread availability and rapidity (seconds to acquire) 5
• High diagnostic accuracy for detecting acute hemorrhage 1, 5
• Ability to rule out hemorrhage before administering time-sensitive treatments 1, 2

CT should be performed within 30 minutes of hospital admission to guide hyperacute care and treatment decisions. 2

MRI as Alternative First-Line Imaging

MRI with gradient echo or susceptibility-weighted sequences can detect hyperacute hemorrhage with high accuracy (100% sensitivity in prospective studies). 1 However, MRI should only be used as first-line imaging if: 2, 5

• It does not delay treatment administration 5
• It is immediately available 5
• The patient has no contraindications to MRI 5

MRI with diffusion-weighted imaging (DWI) is more sensitive than CT for early ischemic changes but this advantage should not delay hemorrhage exclusion or treatment. 5

Additional Imaging for Treatment Planning

CT Angiography (CTA)

CTA of extracranial and intracranial arteries should be performed alongside non-contrast CT to identify large vessel occlusions and guide endovascular therapy decisions. 2 This is particularly critical because: 2

• Proximal large-vessel occlusions may respond better to mechanical thrombectomy than IV thrombolysis 2
• Focusing solely on non-contrast CT without vascular imaging may miss treatable large vessel occlusions 5

CTA within the first few hours may also identify patients at risk for hemorrhage expansion through detection of contrast extravasation (spot sign). 1

Advanced Imaging for Extended Time Windows

For patients beyond 6 hours from symptom onset, multimodal imaging with perfusion assessment is essential for treatment selection. 5 This includes: 5

• CT perfusion to differentiate infarcted core from salvageable penumbra 5
• Assessment of tissue at risk to guide mechanical thrombectomy decisions 5

Key Distinguishing Features on Imaging

Hemorrhagic Stroke on CT

• Acute blood appears hyperdense (bright white) on non-contrast CT 1
• May show intraventricular extension 1
• Serial imaging within 24 hours can detect hemorrhage expansion 1

Ischemic Stroke on CT

• Early signs include loss of gray-white differentiation and hypodensity 6
• CT is relatively insensitive for detecting acute and small infarctions, especially in posterior fossa 2
• Hypodensity becomes more apparent over hours 6

Critical Pitfalls to Avoid

Never administer aspirin, heparin, or any antithrombotic therapy until hemorrhage is excluded by imaging. 3 The risk of expanding an intracranial hemorrhage outweighs potential benefits of empiric treatment. 3

Do not delay imaging to obtain laboratory studies that won't change immediate management. 3 Brain imaging is the priority and should occur within 30 minutes of arrival. 2

Do not assume stroke type based on severity alone—there is substantial overlap in clinical presentation between hemorrhagic and ischemic strokes. 3

Do not delay thrombolytic therapy to obtain multimodal imaging studies beyond basic CT unless the patient is outside standard treatment windows and being considered for extended-window therapies. 2, 5

Special Circumstances: When Imaging is Unavailable

In rural or resource-limited settings where imaging is absolutely unavailable and transfer is impossible, this represents an extreme clinical dilemma. 3 The only evidence-based approach in this scenario showed that early aspirin use alone improved stroke outcomes in rural settings without imaging, but this carries significant risk and should only be considered when transfer is absolutely impossible. 3 The preferred approach is always immediate transfer to a facility with imaging capabilities. 3