What is the next step in management for a patient with suspected stroke and a normal computed tomography (CT) scan?

Management of Suspected Stroke with Normal CT Scan

For patients with suspected stroke symptoms and a normal initial CT scan, the next step should be immediate vascular imaging with CT angiography (CTA) from arch to vertex to identify potential large vessel occlusions, followed by MRI if available, to confirm diagnosis and guide treatment decisions. 1

Diagnostic Pathway After Normal CT

1. Immediate Vascular Imaging

• Perform CTA from aortic arch to vertex to assess for large vessel occlusion 1
• This should be done without delay, especially for patients presenting within 6 hours of symptom onset who may be eligible for endovascular thrombectomy 1
• Primary stroke centers without CTA capability should arrange rapid transfer to a comprehensive stroke center 1

2. Advanced Imaging

• MRI with diffusion-weighted imaging (DWI) is significantly more sensitive than CT for detecting acute ischemic stroke 2
  • MRI detects acute ischemic stroke in 46% of suspected cases compared to only 10% with CT 2
  • In patients scanned within 3 hours of symptom onset, MRI detected ischemia in 46% versus only 7% with CT 2
• CT perfusion (CTP) can be considered if MRI is unavailable or contraindicated 1
  • Should not substantially delay treatment decisions 1

3. Laboratory Evaluation

• Complete blood count, coagulation studies (INR, aPTT), electrolytes, glucose, and renal function 1
• These should not delay imaging or treatment decisions 1

4. Cardiac Assessment

• 12-lead ECG to assess for atrial fibrillation or other cardiac abnormalities 1, 3
• Consider echocardiography to evaluate for cardiac sources of embolism 1
• For cryptogenic stroke, consider long-term cardiac monitoring 1

Treatment Considerations

Time-Sensitive Interventions

• If presenting within 4.5 hours and eligible, administer IV thrombolysis 1
• If large vessel occlusion is identified and presenting within appropriate time window, consider endovascular thrombectomy 1
• Do not delay emergency treatment to obtain additional multimodal imaging 1

Secondary Prevention

• Initiate appropriate secondary prevention based on stroke etiology 3
• For cryptogenic stroke, consider additional testing for hypercoagulable states or other etiologies 1

Special Considerations

Transient Ischemic Attack (TIA)

• Even with normal CT, patients with TIA symptoms should receive comprehensive evaluation 1
• Risk stratification should be based on symptom characteristics and timing 1
• Follow-up MRI is reasonable to predict risk of early stroke and support diagnosis 1

Pitfalls to Avoid

• Do not rule out stroke based on normal CT alone - CT has low sensitivity (26%) compared to MRI (83%) for acute stroke diagnosis 2
• Do not delay treatment while waiting for additional tests beyond necessary neuroimaging 3
• Do not overlook the need for complete vascular evaluation, even if initial CT is normal 3

Follow-up Imaging

• If initial CT or MRI does not demonstrate a symptomatic cerebral infarct, follow-up brain imaging (preferably MRI) is reasonable to confirm diagnosis 1
• This is particularly important for patients with suspected TIA to predict risk of early stroke 1

Remember that a normal CT scan does not exclude acute ischemic stroke, and further diagnostic workup is essential to guide appropriate management and prevent recurrent events.