In children, what is the most common cause of a stroke?

In children, the most common cause of a stroke is related to cardiac sources, such as congenital heart disease. This is primarily due to the fact that children with certain heart anomalies may have abnormal blood flow and clot formation. These clots can travel to the brain, leading to ischemic stroke. Conditions like atrial septal defects or patent ductus arteriosus can increase the risk of embolic strokes because they allow blood clots from the right side of the heart to enter the systemic circulation, eventually reaching the cerebral arteries.

Trauma, vascular malformations, and dehydration can contribute to strokes in children but are less common in comparison to cardiac sources. Trauma generally leads to hemorrhagic strokes, while vascular malformations can cause both ischemic and hemorrhagic strokes but occur with lower frequency overall. Dehydration, while it can potentially lead to changes in blood viscosity and subsequent stroke risk, is not a primary cause in pediatric populations. Thus, cardiac conditions remain the critical focus when discussing the etiology of strokes in children.