Clinical and imaging features of intracranial arterial aneurysms in the pediatric population.

Intracranial arterial aneurysms (IAAs) are rare in children. Nevertheless, IAAs account for at least 10%-15% of hemorrhagic strokes during the first 2 decades of life. Traditional vascular risk factors, which are common in the adult population, are generally absent in the pediatric population, engendering distinct modes of IAA pathogenesis. Classification of pediatric IAAs according to the pathogenetic mechanism shows eight distinct categories: idiopathic, traumatic, those due to excessive hemodynamic stress, vasculopathic, infectious, noninfectious inflammatory, oncotic, and familial. Pathogenetic mechanism is the best predictor of the clinical course of the disease, response to treatment, and long-term prognosis. The pathogenetic subtypes of pediatric IAA show characteristic and variably overlapping features. In most cases, IAAs manifesting during the first 2 decades of life are idiopathic. IAAs that are idiopathic, traumatic (second most common type), or due to excessive hemodynamic stresses (third most common type) account for more than 80% of IAAs in the pediatric age group. Most of the remaining pediatric IAAs are the result of congenital cerebral aneurysmal arteriopathies or infection. Multiple IAAs are unusual in young children except in those with acquired (secondary to immune deficiency states) or congenital cerebral aneurysmal arteriopathies or infectious IAAs. RSNA, 2012