Subarachnoid hemorrhage in childhood and adolescence.

The authors have reviewed 167 cases of subarachnoid hemorrhage (SAH) occurring in patients aged 20 years and younger in a 23-year period. The modes of presentation and etiology of SAH are similar in childhood and adolescence and in the adult population, but there was a different incidence of the specific pathology producing the bleeding in this series. Twenty-six percent of cases were due to bleeding arteriovenous malformations, 52% were due to ruptured aneurysms, and in 19% no cause was found. Aneurysms in this young age group differed in several important respects from those in the adult population: there was a male predominance, a higher incidence of internal carotid bifurcation aneurysms was seen, and multiple aneurysms were encountered less commonly.