Definition Aneurysmal subarachnoid hemorrhage occurs in approximately 1 per 10,000 persons in the United States every year, accounting for 5–15% of all strokes.  The overall case fatality of all‐cause SAH is as high as 50%.  Aneurysmal SAH carries a 30-day mortality rate of 45%.  Of those who survive, nearly 1/3 suffers significant and permanent neurological […]