Intracranial atherosclerotic disease (ICAD) is a major cause of ischemic stroke worldwide and represents a significant health problem. The pathogenesis and natural history of ICAD are poorly understood, and rigorous treatment paradigms do not exist as they do for extracranial atherosclerosis. Currently, the best treatment for ICAD remains aspirin therapy, but many patients who are placed on aspirin continue to experience recurrent strokes. As microsurgical and endovascular techniques continue to evolve, the role of extracranial to intracranial bypass operations and stenting are increasingly being reconsidered. We performed a PubMed review of the English literature with a particular focus on treatment options for ICAD and present evidence-based data for the role of surgery and stenting in ICAD against medical therapy alone. 1. Introduction Intracranial atherosclerotic disease (ICAD) is the process by which atherosclerotic plaques affect large intracranial arteries. Intracranial stenosis represents the most advanced stage of ICAD and is a precursor to ischemic stroke. ICAD is the leading cause of stroke among patients of Asian ancestry [1], and Hispanics and Africans also appear to be more prone to [2] intracranial as opposed to extracranial atherosclerosis. Whites, on the other hand, are less affected, but ICAD is still thought to account for almost 10% of ischemic strokes in this subpopulation [3]. Thus, worldwide, ICAD may be the leading the cause of ischemic stroke. Atherosclerotic lesions, as elsewhere in the body, develop silently and insidiously over years prior to becoming suddenly symptomatic in the form of a stroke. Symptomatic ICAD is burdened with an unacceptably high recurrence rate, such that among patients with symptomatic ICAD and >70% stenosis, approximately 23% will have a recurrent stroke over the ensuing 12 months [4], and nearly half of these recurrent strokes tend to be disabling. The prevalence and natural history of asymptomatic ICAD are much less understood, particularly in people of European descent. Due to this lack of insight, rigorous treatment paradigms do not exist for ICAD as they do for extracranial atherosclerotic disease. The treatment strategies for ICAD include optimal medical management, surgical, and endovascular options. In this paper, we aim to define the optimal treatment strategies for this devastating disease. 2. Methods MEDLINE and PubMed searches of the English literature were performed with the following keywords: intracranial atherosclerosis, extracranial-intracranial bypass, intracranial stenting, Wingspan,
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