Subarachnoid hemorrhage is a devastating condition, often resulting in severe neurologic disability or death, in which blood extravasates into the subarachnoid space between the arachnoid membrane and the pia mater. The majority of subarachnoid hemorrhages are due to the rupture of an intracranial aneurysm. Intracranial aneurysms have been known to exist since ancient Egyptian times (de Moulin 1961). In 1813, John Blackhall of Oxford, England was the first to report a ruptured intracranial aneurysm as the cause of a subarachnoid hemorrhage (Blackhall 1813). However, it was not until the end of the 19th century, due in part to the more detailed description of the signs and symptoms of subarachnoid hemorrhage and the technique of lumbar puncture developed by Quincke (Quincke 1872), that the diagnosis of subarachnoid hemorrhage could be made prior to death. In 1927, Egaz Moniz was the first to successfully carry out cerebral angiography, which would enable surgeons to confirm the diagnosis of ruptured intracranial aneurysm in those patients presenting with signs and symptoms of subarachnoid hemorrhage (Moniz et al 1928). In 1973, Geoffrey Hounsfield introduced computed tomography, which revolutionized the diagnosis and treatment of subarachnoid hemorrhage of any etiology (Hounsfield 1973). Victor Horsley was the first physician to surgically treat a cerebral aneurysm in 1855. In 1937, Dr. Walter Dandy performed the first clipping of an internal carotid artery aneurysm. The advent of the operating microscope in the 1960s allowed for the development of cerebrovascular microsurgical techniques pioneered largely by Dr. Gazi Yasargil. Endovascular techniques for cerebral aneurysm treatment began in the 1970s with proximal balloon occlusion developed by Russian neurosurgeon, Fjodor Serbinenko. Endovascular coils, developed by Guido Guglielmi in the United States, were first used to coil cerebral aneurysms in 1991.