SubarachnoidHemorrhageSeminar1-TheTorontoBrain.ppt

Subarachnoid HemorrhageSeminar 1 Incidence Genetic Factors Diagnosis Natural History William S. Tucker and Mubarak Al-Gahtany Incidence of Aneurysmal SAH Studies suggest that the incidence in the USA and Europe is 10 to 11 cases per 100,000 population per year Autopsy Series Total # Percentage Author #of Series of Cases with aneurysms Rupt’d Unrupt’d Jellinger 12 87,772 1.6 (0.2 to 9) 1 0.6 Bannerman 8 51,360 1.43 1.09 0.34 Overall, it is a reasonable approximation that less than 2% of the entire population will have an aneurysm; an intracranial aneurysm will rupture in less than 1% of the population and will be the cause of death in 0.5% Age and the Incidence of Aneurysmal SAH Aneurysmal rupture is extremely rare in the first decade of life Incidence gradually increases each decade and peaks in the sixth decade Gender and the Incidence of Aneurysmal SAH There is a clear female preponderance overall; the ratio of females to males in the Cooperative Study on Timing of Surgery was 1.6: 1 Before age 40 males and females were equally affected; after age 40 there is an increasingly strong predominance of females Natural HistoryPrognosis for Surgically Untreated SaccularIntracranial Aneurysms OVERVIEW Highest mortality occurs immediately after the hemorrhage and then decreases rapidly Rebleeding is estimated to occur in 50% of ruptured aneurysms within 6 months of the first hemorrhage, and afterwards at 3% per year 50-60% of patients die after rebleeding and 25% are left disabled Probably the best natural history data come from S Pakarinen: (Incidence, aetiology, and prognosis of primary subarachnoid hemorrhage: a study based on 589 cases diagnosed in a defined urban population during a defined period. Neurol Scand (Suppl) 1967; 29:1-128) Unselected series, involving the entire city of Helsinki, from 1954 to 1961; minimal surgical withdrawals; all sudden deaths were autopsied Mortality at 1 day was 32% Mortality at