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Although cerebral vascular disease is the third leading cause of death in the United States after heart disease and cancer, it remains the single most important cause of disability. One of several pathologic processes that either lead to occlusion or rupture of an extra- or intracranial artery or vein produces the clinical manifestation of cerebral vascular disease in terms of primary ischemic stroke, transient ischemic attacks (TIAs), and/or primary hemorrhagic stroke. With either TIA or primary ischemic or hemorrhagic stroke, the prelude to acute, chronic, or preventive therapy is precise diagnosis. The diagnostic formulation must not only establish that the clinical entity is an ischemic stroke or TIA, or a hemorrhagic stroke, but also must localize and characterize the precise arterial or venous pathologic process causing the stroke, as well as elucidate the nature of the spared collateral circulation (Figures 64-1 and 64-2). This chapter focuses on identifying this pathological process as the pivot on which hinge rational medical and/or surgical treatments or preventive strategies. For both primary ischemic and/or primary hemorrhagic stroke, as for TIAs, the precise pathophysiologic process divides logically into specific stroke or TIA subtypes.

Figure 64-1.

(A) Arrangement of the major arteries of the right side carrying blood from the heart to the brain. Also shown are vessels of collateral circulation that may modify the effects of cerebral ischemia (a, b, and c). Not shown is the circle of Willis, which also provides a source for collateral circulation. a. The anastomotic channels between the distal branches of the anterior and middle cerebral artery, termed borderzone or watershed anastomotic channels. Note that they also occur between the posterior and middle cerebral arteries and the anterior and posterior cerebral arteries. b. Anastomotic channels occurring through the orbit between branches of the external carotid artery and ophthalmic branch of the internal carotid artery. c. Wholly extracranial anastomotic channels between the muscular branches of the ascending cervical arteries and muscular branches of the occipital artery that anastomose with the distal vertebral artery. Note that the occipital artery arises from the external carotid artery, thereby allowing reconstitution of flow in the vertebral from the carotid circulation.(Part A courtesy of C. M. Fisher, MD.) (B) Diagram of the brainstem, cerebellum, inferior right frontal lobe, and temporal lobe transected. Principal branches of the vertebral basilar arterial system are pictured. Small branches of the vertebral and basilar artery that penetrate the medulla and pons are not pictured. The stem of the middle cerebral artery with its small, deep-penetrating lenticulostriate arteries and the circle of Willis with its small, deep-penetrating branches, are shown. (C). Roman numerals I, II, III, and IV represent some of the possible variations of the circle of Willis caused by atresia of one or more of its ...

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