A 6-year-old child with sickle cell disease develops sudden onset of severe headache, focal neurological deficit, and altered consciousness. What is the most common type of stroke in pediatric sickle cell disease?

Explanation

## Most Common Type of Stroke in Pediatric SCD **Key Point:** Ischemic stroke from large artery occlusion (particularly affecting the middle cerebral artery and internal carotid artery) is the most common type of stroke in children with sickle cell disease, often associated with a moyamoya-like pattern of collateral vessel development. ### Stroke in SCD: Epidemiology and Pathophysiology **Incidence:** - Occurs in ~11% of children with SCD by age 20 years (untreated) - Second leading cause of death in SCD (after acute chest syndrome in adults) - Peak incidence: 2–5 years of age **Mechanism of Ischemic Stroke in SCD:** 1. Vaso-occlusion of large cerebral vessels 2. Endothelial injury and inflammation 3. Hypercoagulability (elevated tissue factor, platelets, fibrinogen) 4. Chronic stenosis → moyamoya-like collateral development 5. Hemodynamic compromise during pain crisis or infection ### Stroke Types in SCD: Frequency Comparison | Type | Frequency | Mechanism | Clinical Feature | |------|-----------|-----------|------------------| | **Ischemic (large artery)** | 70–80% | Vaso-occlusion, thrombosis | Acute focal deficit, MCA/ICA territory | | **Hemorrhagic** | 10–20% | Rupture of collateral vessels, hypertension | Sudden severe headache, ICH | | **Venous thrombosis** | Rare | Hypercoagulability, dehydration | Seizures, focal deficit | | **Subarachnoid** | Rare | Ruptured aneurysm or collateral | Sentinel headache, meningismus | **High-Yield:** Transcranial Doppler (TCD) ultrasound is the gold standard for stroke risk stratification in children with SCD. Elevated blood flow velocity (>200 cm/s) predicts high stroke risk and is an indication for chronic transfusion therapy. **Clinical Pearl:** The **moyamoya-like syndrome** in SCD develops due to chronic stenosis of large intracranial vessels with compensatory proliferation of fine collateral vessels, creating a characteristic "puff of smoke" appearance on angiography. This is distinct from primary moyamoya disease but functionally similar. **Mnemonic — Stroke Prevention in SCD: "TRANSFUSE"** - **T**ranscranial Doppler screening (TCD) - **R**isk stratification (elevated velocity) - **A**cute management (thrombolytics contraindicated in SCD) - **N**euroimaging (MRI/MRA) - **S**troke prevention (chronic transfusion) - **F**ollow-up imaging - **U**se of hydroxyurea (reduces stroke risk) - **S**upport and rehabilitation - **E**ducation on warning signs **Warning:** Thrombolytic therapy (tPA) is generally contraindicated in acute ischemic stroke in SCD due to risk of hemorrhagic transformation and sickling complications. Management focuses on exchange transfusion to lower HbS levels and supportive care.