What are the diagnostic tests for a 12-year-old female patient with acute ischemic stroke?

Diagnostic Testing for Acute Ischemic Stroke in a 12-Year-Old Female

All pediatric patients with suspected acute ischemic stroke require immediate non-contrast CT or MRI of the brain, along with a core panel of laboratory tests including complete blood count with platelets, coagulation studies (PT/INR, aPTT), blood glucose, electrolytes, renal function tests, troponin, and a 12-lead ECG. 1, 2

Immediate Brain Imaging

Primary Imaging Modality

• Non-contrast CT should be the first imaging choice in the emergency setting when stroke is suspected in children, as it rapidly excludes hemorrhage (such as bleeding from arteriovenous malformation) and identifies stroke mimics like brain tumors 3, 1
• CT is often normal within the first hours of arterial ischemic stroke in children, but it remains the standard initial test due to speed and availability 3, 4
• MRI with diffusion-weighted imaging is the most sensitive technique for identifying ischemic lesions and should be obtained to confirm the diagnosis, though it requires sedation in children and may not be as readily available as CT 3, 5

Advanced Imaging Considerations

• MRI detects acute ischemic stroke in 46% of patients versus only 10% for CT, with sensitivity of 83% versus 26% for any acute stroke 5
• CT or MR angiography should be performed to detect arterial disease, stenosis, or occlusion of extra- and intracranial arteries 6, 3
• MR angiography is sensitive enough to visualize lesions in the proximal anterior cerebral artery, middle cerebral artery, and distal internal carotid artery 3

Essential Laboratory Tests

Core Panel (All Patients)

• Complete blood count with platelet count to detect thrombocytopenia, anemia, or polycythemia that could influence treatment decisions 1, 2
• Blood glucose must be checked immediately as hypoglycemia can mimic stroke symptoms and must be excluded before proceeding with interventions 1, 2
• Serum electrolytes and renal function tests to identify metabolic derangements and guide medication dosing 1, 2
• Coagulation studies (PT/INR, aPTT) are critical to identify coagulopathies, especially before considering thrombolytic therapy 1, 2
• Troponin and cardiac markers to identify concurrent cardiac conditions, as acute MI can cause stroke and stroke can precipitate myocardial ischemia 1, 2

Cardiac Evaluation

• 12-lead ECG is mandatory to assess cardiac rhythm and identify atrial fibrillation, atrial flutter, or evidence of structural heart disease 1, 2
• Echocardiography should be considered when stroke mechanism has not been identified 2

Oxygen and Vital Signs

• Oxygen saturation must be measured as part of initial assessment 1

Selective Additional Testing

When Clinically Indicated

• Hepatic function tests if liver dysfunction is suspected 1
• Toxicology screen and blood alcohol level in appropriate clinical contexts 1
• Arterial blood gas if hypoxia is suspected 1
• Chest radiography only if acute heart disease or pulmonary disease is evident 1
• Lumbar puncture if subarachnoid hemorrhage is suspected and CT scan is negative for blood 1
• Electroencephalogram if seizures are suspected as the cause of neurological deficits 1

Critical Timing Considerations

Do Not Delay Treatment

• Thrombolytic therapy should not be delayed while awaiting laboratory results unless there is clinical suspicion of bleeding abnormality, thrombocytopenia, the patient has received heparin or warfarin, or anticoagulant use is uncertain 1, 2
• CT should ideally be completed within 25 minutes of ED arrival and interpreted within 45 minutes 1
• Advanced neuroimaging (multimodal MRI, CT perfusion, CT angiography) should not delay initiation of IV rtPA in eligible patients 1

Swallowing Assessment

• Patient swallowing screen should be completed as early as possible using a validated tool, ideally within 24 hours, but should not delay acute stroke treatment decisions 1
• Patients must remain NPO until swallowing screen is completed 1

Important Caveats

Key differences in pediatric stroke imaging: While adult guidelines emphasize CT as the primary modality, MRI with diffusion-weighted imaging is ultimately more sensitive for pediatric ischemic stroke detection, though logistical challenges (sedation requirements, availability) often necessitate starting with CT 3, 5. The diagnostic evaluation should be completed within 48 hours of symptom onset, but acute interventions must not be delayed 2.