Evolution of Cerebral Revascularization Techniques
As a leading cause of death and disability in patients across the world, stroke is a problem that plagues both neurosurgeons and neurologists alike. Whether a result of atherosclerosis, moyamoya disease, or a complication in the treatment of a complex intracranial aneurysm, cerebrovascular occlusion can have devastating effects on patients. For nearly half a century neurosurgeons have searched for safer, more effective ways to increase the amount of blood flow to ischemic brain tissue. From the first extracranial-intracranial bypasses to the recent technological advancements seen with endovascular therapy, cerebral revascularization techniques have been constantly evolving. Over the years cerebral ischemia has gone from a condition that was previously considered surgically untreatable, to a condition with several viable options for prevention and treatment. In this paper the authors discuss the historical evolution of treatment for cerebrovascular occlusive disease.

Stroke remains a leading cause of disability and death in industrialized societies, affecting more than 750,000 persons in the United States each year. In 8-10% of cases these events are due to the presence of intracranial atherosclerosis, a disease that poses challenges for neurosurgeons and neurologists alike. Cerebrovascular atherosclerotic disease portends a particularly poor prognosis and is present with increased frequency in those of Asian, African American, and Hispanic ethnicities. In 2005, the results of the Warfarin, Aspirin, and Intracranial Disease Trial were published. This study compared warfarin and aspirin in the treatment of symptomatic intracranial atherosclerosis and demonstrated that in patients with > 50% stenosis of an intracranial vessel, the rates of recurrent stroke in the associated vascular territory were 11 and 14% at 1 and 2 years, respectively. Perhaps most importantly from a neurosurgical perspective, a second stroke occurred despite the implementation of maximal medical therapy. This finding has provided further impetus in the search for alternative therapies and improved outcomes for patients with cerebrovascular atherosclerotic disease. Although many of the advances in cerebral revascularization over the past 50 years were initially developed for the treatment of intracranial atherosclerotic disease, a number of techniques arose from attempts to revascularize nonatherosclerotic occlusive conditions such as moyamoya disease and acute vessel occlusion for the treatment of intracranial aneurysms ( Table 1 ). Regardless of the initial intended purpose of these revascularization techniques, the end result has been a wide array of options for the treatment of cerebroocclusive disease that continues to evolve.