Cerebrovascular Events Health Article

Definition/epidemiology

A stroke is an interruption of blood circulation to the brain causing a neurologic deficit reflecting the area of the brain affected. Stroke can be ischemic or hemorrhagic. ¹

Ischemic stroke is most prevalent. It is occlusive in nature, which is the result of atherosclerotic disease, and progresses slowly as the affected artery becomes more occluded with plaque. Clotting in the narrowed vessel can bring about full occlusion and symptoms. Another type of ischemic stroke is the result of embolism, or the rupture of atherosclerotic plaque that travels to the brain and blocks blood flow. Atrial fibrillation can result in clot formation in the heart, which then seeds small embolic particles that travel to the brain. Lacunar strokes are seen more in older adults and in people with diabetes. They affect smaller areas of the brain by closing off arterioles.

Hemorrhagic stroke has a lower incidence than ischemic stroke but is associated with greater mortality. Subarachnoid stroke can be the result of a congenital (berry) aneurysm rupture, arteriovenous malformation, or trauma. ² Subarachnoid stroke is a rupture of a large vessel within the protective lining of the brain. Intracerebral stroke is the rupture of a vessel within the brain itself.

Transient ischemic attacks (TIA) are small ischemic events. Neurologic deficits resolve completely within a few hours, but no more than 24 hours. A study by the University of California and Kaiser Permanente evaluated about 1700 patients presenting to the Emergency Department with TIA. Of those patients, 10% went on to have a stroke within 90 days after the event. ³ Other authors believe up to 25% of TIAs will signal impending stroke. The American Heart Association has calculated that people with TIAs have nine times the risk of a stroke. ⁴ These numbers reflect the growing practice of aggressive assessment and early treatment of persons presenting with TIA symptoms.

Stroke is the third leading cause of death in the United States after coronary heart disease and cancer. ⁵ There are approximately 600,000 cases of stroke each year, of which 100,000 are recurrences. Of all strokes, 83% were ischemic, 10% were intracerebral hemorrhage, and 7% were subarachnoid hemorrhage. More than 7.5% of ischemic strokes and nearly 38% of hemorrhagic strokes resulted in death within 30 days. Although from 1988 to 1998 the incidence of stroke fell by 15.5%, the death rate from stroke increased by 5.5%. ⁵

The rate of stroke death is 58.6 per 100,000 people when all ages, sexes, and races are considered; however, it is a disease of age, with the prevalence being 404.5 per 100,000 in the over-65-year-old population. Women experience stroke at a rate 1.75 times that of men. Hispanics are twice as likely as whites to suffer a stroke. African-Americans are four times more likely to have a stroke than whites. ⁶

Ischemic strokes tend to occur in older patients with other disease processes, whereas hemorrhagic strokes generally occur in healthy individuals between the ages of 40 and 60 years. Risk factors for ischemic stroke include hypertension, age, cigarette smoking, male gender, family history, race, previous stroke, carotid stenosis >80%, atrial fibrillation, congestive heart failure, mitral stenosis, prosthetic cardiac valves, myocardial infarction, and drug abuse (e.g., cocaine). ⁷ Other factors that may contribute to stroke are diabetes, obesity, a sedentary lifestyle, and an elevated serum cholesterol level.

Risk factors for hemorrhagic stroke include intracranial vascular anomalies, hypertension, family history, polycystic kidney disease, Ehlers-Danlos syndrome, systemic lupus erythematosus, neurofibromatosis, and tuberous sclerosis. Pregnancy, cigarette smoking, atherosclerosis, acute alcohol intoxication, and recreational drug use (e.g., cocaine) also increase the risk of hemorrhagic stroke. ⁸

Stroke represents a significant burden for long-term care. Although 50% to 70% of stroke survivors regain functional independence, 15% to 30% are permanently disabled. Institutional care is required by 20% at 3 months after onset. Approximately 25% of stroke victims die within 1 year of their first stroke. ⁵

Immediate emergency department referral/ physician consultation is indicated for all patients with a suspected cerebrovascular accident.