Aneurysms in children under 18 years of age are rare. In contrast to adults, brain aneurysms in children occur more often in males than in females (by a 1:8 to 1 ratio). This suggests that the formation of pediatric brain aneurysms is different than that of adults. 

Pediatric brain aneurysms are not as well understood as brain aneurysms in adults. However, it has been observed that approximately 20 percent of aneurysms in children are so-called giant aneurysms (larger than 2.5 cm in diameter), and that children are four times more likely to present with subarachnoid hemorrhage (SAH) than without SAH. Fortunately, with improvements in brain imaging techniques, increasing numbers of children with brain aneurysms are being diagnosed before their aneurysm ruptures. 

Although they can occur with no known cause, aneurysms in children are commonly associated with severe head trauma, connective tissue disorders, or infection. A tendency to develop aneurysms can sometimes run in families or can occur as part of a genetic disorder, such as Marfan syndrome, Ehlers-Danlos syndrome, or autosomal dominant polycystic kidney disease. 

As with adults, the treatment options for pediatric patients include open surgery (clipping), endovascular therapies (such as coiling), or careful observation. The decision about treatment, or even whether to treat, is based on a careful analysis of the risks and benefits. It is important that children who have been diagnosed with an aneurysm diligently maintain long-term follow-up with their medical team.