Aneurysmal subarachnoid hemorrhage (aSAH)

The overall prevalence of cerebral aneurysms has been reported variably from 3.6% to 6% of the worldwide population, translating to approximately 1 in 50 people having an unruptured aneurysm in the United States. They are most prevalent at 35-60 years of age with newly diagnosed aneurysms mostly developing in patient’s older than 40. Paediatric cases are also diagnosed, mainly in the context of underlying syndromic conditions. There is a slight female predilection for aneurysms with a female to male ratio of approximately 3-2. The majority of the aneurysms measure between 3 and 2.5 cm in diameter (65-85%) and carry a low-rupture risk (less than or equal to 1% per year). Aneurysms larger than 2.5 cm are referred to as “Giant”. Ten to 15% of patients diagnosed with a cerebral aneurysm have another aneurysm.