Cerebrovascular Disease

The causes of ischemic cerebrovascular disorders, including TIA and cerebral infarction, can be classified on the basis of the site of the source for the arterial blockage (embolus from a proximal site or thrombosis in situ from distal causes) within the vascular system, starting from most proximal to distal. First, a cardiac source as the most proximal site includes both arrhythmias and structural disorders such as valve disease, dilated cardiomyopathy, recent myocardial infarction, and other cardiac structural disorders. Also, paradoxical emboli with a right-to-left shunt through a patent foramen ovale must be considered, although most patent foramen ovales are asymptomatic.rnAnother potential proximal site of emboli is the aorta. The second site includes large-vessel disorders, with the most common cause being atherosclerosis or dissection in the carotid or vertebrobasilar system. rnThe third site involves small-vessel occlusive disease caused by either inflammatory or noninflammatory arteriopathies (hypertension-induced disease, isolated CNS angiitis, and systemic lupus erythematosus). The fourth source is hematologic disorders, including polycythemia, sickle cell anemia, thrombocytosis, severe leukocytosis (i.e., acute leukemia), antithrombin III deficiency, protein C deficiency, protein S deficiency, hereditary resistance to activated protein C, factor V Leiden mutation, anticardiolipin antibody syndrome, lupus anticoagulant positivity, and hypercoagulable states caused by carcinoma. You can buy plavix, the drug is used a common cause of stroke in young persons and results in arrhythmia, inflammatory arteriopathies, and a relative hypercoagulable state.rnPathophysiologic mechanisms of ischemic cerebrovascular disease include artery-to-artery emboli (e.g., extracranial carotid bifurcation to a branch of the middle cerebral artery), cardiac embolic stroke, and lacunar infarction (small-vessel disease). Other causes are hematologicrndisorders and states of altered coagulability (as mentioned above). Still other causes are nonarteriosclerotic vasculopathies (fibromuscular dysplasia, granulomatous angiitis, congophilic angiopathy, and systemic lupus erythematosus), dissection of the carotid or vertebral arteries, hemodynamic crisis with impaired distal flow, mechanical compression of arteries, steal syndromes, and AIDS.rnRecreational drugs are a major risk factor for stroke in young adults.rnRisk factors for atherosclerotic occlusive disease are similar to those predisposing to coronary artery disease: hypertension, male sex, advanced age, cigarette smoking, diabetes mellitus, and hypercholesterolemia. Emboli from intracardiac mural thrombi are also an important cause of TIA and cerebral infarction. Major cardiac risk Modified from Karkal SS. Rapid accurate appraisal of acute muscular weakness. Updates Neurology. 1991, pp 31-39. Used with permission. factors include left-sided chamber enlargement or aneurysm, congestive heart failure, atrial fibrillation, transmural myocardial infarction, mitral valve disease, septic emboli, paradoxical emboli, and atrial myxoma.rnHypertension is the most powerful modifiable risk factor for stroke, but other modifiable risk factors include cigarette smoking, alcohol consumption, sedentary lifestyle, obesity, elevated cholesterol level, and, possibly, elevated homocysteine levels. Although low levels of alcohol consumption appear to have a protective effect for ischemic stroke, heavy alcohol consumption increases the risk of all types of stroke, particularly intracerebral and subarachnoid hemorrhage.