What is the most common cause of subarachnoid hemorrhage (SAH) in children?

The most common cause of subarachnoid hemorrhage (SAH) in children is arteriovenous malformation (AVM) rupture. AVMs are abnormal connections between arteries and veins that can lead to increased blood flow and pressure in the vessels, making them prone to rupture. When an AVM ruptures, it can cause bleeding into the subarachnoid space, resulting in SAH.

In the pediatric population, the incidence of SAH is not as high as in adults, but when it does occur, AVMs are more frequently the underlying cause. Other potential causes of SAH, such as aneurysm rupture, are relatively rare in children compared to adults, as the incidence of cerebral aneurysms is lower in this age group. Similarly, while head trauma can lead to bleeding, it is generally associated with acute injuries rather than being the most frequent cause of SAH in children.

Coagulation disorders can lead to various types of bleeding, but they are not typically the primary reason for SAH. Therefore, recognizing the prevalence of AVMs in causing SAH in children is critical for understanding the etiology of this condition.