The primary risk factor for ischemic stroke is age (over age 65). High blood pressure (hypertension) and heart disease are also major risk factors. Maintaining healthy blood pressure through diet, exercise, and medication, if necessary, can decrease the risk for stroke.
Atrial fibrillation occurs when muscles in the atria contract too quickly, resulting in an irregular heartbeat (arrhythmia). Arrhythmia alters blood flow and may cause blood clots to form in the heart. These clots can travel through blood vessels to the brain, causing stroke. Atrial fibrillation causes an almost five-fold increase in the risk for stroke.
Other risk factors include the following:
- Alcohol abuse
- Brain tumor
- Cardiac conditions (e.g., myocardial infarction [heart attack],mitral regurgitation)
- Coagulopathy (blood clotting disorder)
- Drug abuse (may cause decreased blood flow)
- Fibromuscular dysplasia (causes stenosis and hypertension)
- Family or personal history of stroke
- High blood pressure (hypertension)
- High cholesterol (hypercholesterolemia)
- Infection (e.g., meningitis, endocarditis)
- Narrowing of arteries (arterial stenosis)
- Plaque build-up in arteries (atherosclerosis)
- Secondary hemorrhage following an ischemic stroke
- Sickle cell disease
- Sudden rise in blood pressure
- Surgical incision of an artery (treatment for atherosclerosis)
ecent studies have shown that patients who experience a transient ischemic attack (TIA) or stroke are at increased risk for suffering an additional brain attack.
Risk factors for hemorrhagic stroke include untreated aneurysm, congenital (present at birth) arteriovenous malformations (AVMs), and traumatic brain injury (TBI).
Stroke occurs when blood flow to a region of the brain is obstructed, causing brain tissue death. Ischemic stroke is usually caused by a blood clot in an artery that supplies blood to the brain. Introduction of a foreign substance into the bloodstream may also cause ischemic stroke. For example, an air embolism may occur in deep-sea divers who surface too quickly or may be introduced during intravenous injection.
Hemorrhagic stroke is caused by ruptured blood vessel (aneurysm), arteriovenous malformation (AVM, blood vessel defect), tumor, or traumatic brain injury.