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Stroke & Neurovascular Disorders
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Objectives
After studying this chapter, the student should be able to:
Build upon existing knowledge of neuroanatomy to provide anatomic and vascular localization for patients presenting with cerebrovascular disease.
Understand the pathophysiology of cerebral ischemia and autoregulation and how these lead to the signs and symptoms of ischemic stroke and influence therapeutic options for patients.
Understand the classification and etiology of various forms of intracerebral hemorrhage.
Understand how cerebral venous sinus thrombosis (CVST) can lead to both ischemic and hemorrhagic events and the treatment options for this condition.
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Cerebrovascular diseases represent a heterogeneous class of disorders affecting the central nervous system including ischemic and hemorrhagic strokes, cerebral venous thrombosis, aneurysms, and vascular malformations. These disorders are frequently associated with high morbidity and mortality. Fortunately, advances in diagnostic and therapeutic options for cerebrovascular diseases have led to improved clinical outcomes for many of these conditions.
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Cerebrovascular diseases now represent the fifth leading cause of death in the United States. Approximately 3% of adults have experienced a clinical stroke; however, the incidence of subclinical or “silent” strokes is likely much higher. Nearly 795,000 strokes occur annually in the United States, of which approximately 610,000 are first-time strokes and 185,000 are recurrent attacks. It is estimated that someone has a stroke every 40 seconds. The highest incidence and mortality rates are seen in the southeastern states (termed the “Stroke Belt”) and among racial and ethnic minorities. As the population ages, it is expected that the number of incident strokes will more than double in the coming decades, especially among patients age ≥75 years. Despite the declining incidence and mortality of stroke, the global burden of stroke is increasing, particularly in low- and middle-income countries.
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CEREBROVASCULAR LOCALIZATION
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Clinical localization is perhaps no better demonstrated than in cerebrovascular diseases. Medical students frequently encounter their first opportunity to “localize a lesion” when evaluating a stroke patient. In addition to determining what level of the neuroaxis or which lobes of the brain are affected, symptoms of cerebrovascular disease can frequently be localized by vascular territories. For example, in a patient with right hemiparesis and hemianesthesia affecting the face and arm, coupled with aphasia, one can say that the frontal, parietal, and temporal lobes are affected in the left hemisphere. Knowledge of the homunculus will further localize the motor and sensory deficits to the lateral aspect of the hemisphere. Taken together, it becomes apparent that all of the affected areas fall within the left middle cerebral artery (MCA) territory. When a cerebrovascular disorder appears on the differential diagnosis for a patient, it is important to consider not only the anatomic localization but also the vascular localization for the symptoms.
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Among all strokes, approximately 80% to 85% are categorized as ...