Subarachnoid hemorrhage (SAH) is a common and frequently devastating condition, accounting for
5% of all strokes and affecting as many as 30 000 Americans each year.The American Heart Association (AHA) previously published “Guidelines for the Management of Aneurysmal Subarachnoid Hemorrhage.”Since then, considerable advances have been made in endovascular techniques, diagnostic methods, and surgical and perioperative management paradigms. Nevertheless, outcome for patients with SAH remains poor, with population-based mortality rates as high as 45% and significant morbidity among survivors.4–9 Several multicenter, prospective, randomized trials and prospective cohort analyses have influenced treatment protocols for SAH. However, rapid evolution of newer treatment modalities, as well as other practical and ethical considerations, has meant that rigorous clinical scientific assessment of the treatment protocols has not been feasible in several important areas.