What other stroke tests should I perform on a patient with suspected stroke?

Stroke Testing: Essential Diagnostic Workup

For a patient with suspected stroke, you must immediately perform brain imaging (CT or MRI), vascular imaging (CTA from aortic arch to vertex), 12-lead ECG, and a core panel of laboratory tests including complete blood count with platelets, electrolytes, renal function, coagulation studies (aPTT/INR), glucose, and troponin. 1, 2

Immediate Imaging Studies

Brain Imaging

• Non-contrast CT or MRI is mandatory as the first imaging test to differentiate ischemic from hemorrhagic stroke 1
• MRI with diffusion-weighted imaging is more sensitive than CT for detecting acute ischemic stroke (83% vs 26% sensitivity), particularly within the first 3 hours of symptom onset 3
• However, CT remains acceptable and should not delay treatment if more readily available 1

Vascular Imaging

• CTA from aortic arch to vertex should be performed immediately, ideally at the time of initial brain CT, to assess both extracranial and intracranial circulation 1
• This identifies significant carotid stenosis requiring revascularization and large vessel occlusions that may benefit from endovascular therapy 1
• Carotid ultrasound or MRA are acceptable alternatives based on availability, though CTA is preferred for comprehensive visualization 1

Advanced Imaging (When Appropriate)

• CT perfusion (CTP) and multiphase/dynamic CTA should be considered to assess cerebral blood flow and collateral vessels, but must not delay thrombolytic therapy 1

Laboratory Investigations

Core Panel (Immediate)

• Complete blood count with platelets: detects thrombocytopenia, anemia, or polycythemia affecting treatment decisions 2, 4
• Electrolytes and renal function (creatinine, eGFR): identifies metabolic derangements and guides medication dosing 1, 2
• Coagulation studies (aPTT, INR): critical before thrombolytic therapy to identify coagulopathies 1, 2
• Random glucose or HbA1c: hypoglycemia can mimic stroke and must be excluded immediately; hyperglycemia worsens outcomes 2, 5
• Troponin: identifies concurrent myocardial infarction or ischemia 1, 2

Subsequent Laboratory Tests

• Lipid profile (fasting or non-fasting) for cardiovascular risk assessment 1, 2
• Diabetes screening with HbA1c or 75g oral glucose tolerance test if not already obtained 1, 2

Cardiac Investigations

Electrocardiogram

• 12-lead ECG is mandatory to assess cardiac rhythm, detect atrial fibrillation, and identify structural heart disease (prior MI, left ventricular hypertrophy) 1
• Should not delay thrombolytic assessment in hemodynamically stable patients 1

Prolonged Cardiac Monitoring

• Extended ECG monitoring up to 30 days is recommended when initial ECG shows no atrial fibrillation but cardioembolic mechanism is suspected 1, 2
• This significantly improves detection of paroxysmal atrial fibrillation 2

Echocardiography

• Echocardiogram should be performed when cardiac source is suspected, particularly in young adults, when infectious endocarditis is suspected, or when stroke mechanism remains unidentified 1, 2

Critical Timing Considerations

The entire diagnostic evaluation should be completed or underway within 48 hours of symptom onset, with brain imaging and vascular imaging completed according to risk stratification: 1

• Highest risk patients (presenting within 48 hours with motor weakness or speech disturbance): comprehensive evaluation within 24 hours 1
• Moderate risk patients (presenting within 48 hours without motor/speech symptoms): evaluation within 2 weeks 1
• Lower risk patients (presenting after 2 weeks): evaluation within 1 month 1

Common Pitfalls to Avoid

• Never delay acute treatment while awaiting laboratory results unless there is clinical suspicion of bleeding abnormality, thrombocytopenia, or known anticoagulant use 2
• Do not skip vascular imaging: CTA identifies large vessel occlusions that may benefit from endovascular therapy up to 24 hours from symptom onset 1, 5
• Do not rely on CT alone for diagnosis: MRI detects acute ischemic stroke in 46% of patients versus only 10% with CT, particularly in early presentations 3
• Do not forget glucose testing: this is the only stroke mimic that requires immediate exclusion before proceeding with other interventions 2, 5