1.0 INTRODUCTION 1.1 Background Intracranial aneurysms (IAs) are common cerebrovascular abnormalities. The prevalence of IAs has been reported to be 0.8-2.0% of the population. [1-3] The most common presentation of IAs is subarachnoid hemorrhage (SAH), the annual incidence of which varies by geographic region from 10 to 20 per 100,000. [4 5] SAH is a devastating injury with a case-fatality rate of 51% [5]. Nearly half of its survivors are functionally incapacitated [6].