These subcategories included incidence, risk factors, prevention, natural history and outcome, diagnosis, prevention of re- bleeding, surgical and endovascular repair of ruptured aneu- rysms, systems of care, anesthetic management during repair, management of vasospasm and DCI, management of hydro- cephalus, management of seizures, and management of med- ical complications. Together, these categories were thought to encompass all of the major areas of disease management, including prevention, diagnosis, and treatment. Each subcat- egory was led by 1 author, with 1 or 2 additional coauthors who made contributions. Full MEDLINE searches were conducted independently by each author and coauthor of all English-language papers on treatment of relevant human disease. Drafts of summaries and recommendations were circulated to the entire writing group for feedback. A confer- ence call was held to discuss controversial issues. Sections were revised and merged by the writing group chair. The resulting draft was sent to the entire writing group for comment. Comments were incorporated into the draft by the writing group chair and vice chair, and the entire writing group was asked to approve the final draft. The chair and vice chair revised the document in response to peer review, and the document was again sent to the entire writing group for additional suggestions and approval. The recommendations follow the AHA Stroke Council s methods of classifying the level of certainty of the treatment effect and the class of evidence (Tables 1 and 2). All Class I recommendations are listed in Table 3. All new or revised recommendations are listed in Table 4. Incidence and Prevalence of aSAH Considerable variation in the annual incidence of aSAH exists in different regions of the world. 