The brain requires about 20% of the body's total circulation of blood. The blood enters the brain from two carotid arteries in the neck, which branch off into multiple arteries that supply each specific area of the brain.

If blood flow in any of these arteries is interrrupted for longer than a few seconds, brain cells can die, causing permanent damage. The resulting stroke-related symptoms depend on the area of the brain affected, the extent of the damage, and the cause of the stroke.

Common symptoms include changes in vision, speech, and comprehension; weakness; vertigo; loss of sensation in a part of the body; or changes in the level of consciousness.

Stroke accounts for 1 out of every 15 deaths in the United States. It is the 3rd leading cause of death in most developed countries, and the leading cause of disability in adults. The risk doubles with each decade after age 35. Stroke occurs in men more often than women.

The risk of stroke is increased by smoking, hypertension, diabetes, hyperlipidemia, and heart disease. Rarely, strokes may happen in women on birth control pills -- the risk is increased if a woman also smokes and is older than 35. Women have a higher risk of stroke during pregnancy and the weeks immediately after pregnancy. Other illnesses such as vasculitis, lupus, or high blood viscosity may contribute to stroke.

The most common cause of stroke is atherosclerosis. (See stroke secondary to atherosclerosis.) Atherosclerosis is a condition in which fatty deposits and blood platelets collect on the wall of the arteries, forming plaques. Over time, the plaques slowly begin to block the flow of blood. A plaque may block the artery enough to cause a stroke, or it may trigger a blood clot that causes a stroke.

The formation of a plaque does not always lead to a stroke. The arteries are large enough that 75% of the blood vessel can be blocked, and there will still be adequate blood flow to that area of the brain. Furthermore, there are many small connections between the arteries in the brain. If the blood flow is gradually blocked in one artery, these small connections will increase in size and "by-pass" the obstructed area. Even a totally blocked artery may not cause a stroke.

A stroke may be caused by a blood clot that forms in the brain (a thrombus) or a blood clot, piece of plaque, or other material that travels to the brain from another location (an embolism). Bleeding (hemorrhage) within the brain can, on rare occasions, cause symptoms that mimic stroke.

A stroke caused by a blood clot in the brain (a thrombus) is most common in older people, and often there is underlying atherosclerosis or diabetes. This type of stroke may occur at any time, including at rest. The person may or may not lose consciousness.

Strokes caused by embolism (a blood clot that travels to the brain) are most commonly caused by heart disorders. An embolism may also originate in the aortic arch, especially where there is atherosclerotic plaque. The blood clot travels through the bloodstream and becomes stuck in a small artery in the brain. This stroke occurs suddenly with immediate, maximum damage to the brain. Consciousness may or may not be lost.

Embolic strokes are NOT associated with activity levels and can occur at any time. Arrhythmias of the heart, such as atrial fibrillation, are often seen with with this type of stroke and may be the cause of the clot. Other causes of embolic stroke include endocarditis (an infection of the heart valves), or a mechanical heart valve that may have a clot attached to it. A heart attack puts people at greater risk for having an embolic stroke.

The probable outcome is worsened if blood vessels damaged by stroke rupture and bleed (hemorrhagic stroke).

See also:

• Stroke secondary to carotid dissection (bleeding from the carotid arteries)
• Stroke secondary to carotid stenosis (narrowing of the carotid arteries)
• Stroke secondary to cocaine
• Stroke secondary to FMD (fibromuscular dysplasia)
• Stroke secondary to syphilis

• Loss of movement (paralysis) of any body area
• Weakness
• Decreased sensation
• Numbness
• Tingling or other sensation changes
• Decreased vision
• Language difficulties (aphasia):
  • slurred, thick, difficult speech
  • inability to speak
  • inability to understand speech
  • may have difficulty with reading or writing
• Inability to recognize or identify sensory stimuli (agnosia) resulting in "neglect" of one side of the body
• Loss of memory
• Vertigo (abnormal sensation of movement)
• Loss of coordination
• Swallowing difficulties
• Personality changes
• Mood/emotion changes (such as depression or apathy)
• Consciousness changes:
  • sleepy
  • stuporous/somnolent/lethargic
  • comatose/unconscious
• Urinary incontinence (lack of control over bladder)
• Lack of control over the bowels
• Cognitive decline
  • dementia
  • easily distracted
  • impaired judgment
  • limited attention

• A head CT or MRI of head may be used to rule out bleeding (hemorrhage) or other lesions and define the location and extent of the stroke
• An ECG (electrocardiogram) may be used to determine underlying heart disorders
• An echocardiogram may be used if the cause is suspected to be cardiac embolus
• A carotid duplex (ultrasound) may be used if the cause is suspected to be carotid artery stenosis
• A cerebral (head) arteriography may be used if a disorder involving the blood vessels is suspected

• Platelet aggregation test
• Osmolality
• LDH isoenzymes
• LDH
• Cytometric study
• CSF collection
• CPK isoenzymes
• BERA (brainstem evoked response audiometry)

A stroke is serious condition. Immediate treatment is required. The treatment varies depending on the severity of symptoms. For virtually all strokes, hospitalization is required, possibly including intensive care and life support.

There is no known cure for a stroke. The treatment involves rehabilitation (based on the symptoms) and prevention of future strokes. Recovery may occur as other areas of the brain take over functioning for the damaged areas. The goal of treatment is to prevent the spread of the stroke and to maximize the patient's ability to function.

IMMEDIATE TREATMENT
Life support and coma treatment are performed as needed.

A number of medications may be used. RTPA is a medicine that lyses the clot and potentially restores blood flow to the affected area to prevent cell death and permanent damage. However, there are strict criteria for who can receive RTPA -- most important is that the stroke victim be evaluated and treated by a specialized stroke team within 3 hours of onset of symptoms. It is a controversial medication because there is a risk of serious bleeding.

In appropriate circumstances, other anti-coagulants such as heparin and coumadin are used to prevent recurrent strokes. Aspirin and other anti-platelet agents are used to prevent strokes as well.

Analgesics may be needed to control severe headache. Anti-hypertensive medication may be needed to control high blood pressure.

Nutrients and fluids may be necessary, especially if the person has swallowing difficulties. The nutrients and fluids may given through an intravenous tube or a tube in the stomach (feeding tube or gastrostomy tube). Swallowing difficulties may be temporary or permanent.

Surgery may be appropriate in some cases, including surgical removal of blood clots from the brain.

Carotid endarterectomy, removal of plaque from the carotid arteries, may help prevent new strokes from occurring in some people.

LONG-TERM TREATMENT
The recovery time and need for long-term treatment vary. Depression and other symptoms should be treated.

Speech therapy, occupational therapy, physical therapy, positioning, range of motion exercises, and other therapies may prevent complications and promote maximum recovery of function. People should stay active within their physical limitations.

In some cases, urinary catheterization or bladder/bowel control programs may be necessary to control incontinence.

The individual's safety must be considered. Some people with stroke appear to have no awareness of their surroundings on the affected side. Others show a marked indifference or lack of judgment, which increases the need for safety precautions. For these people, friends and family members should repeatedly reinforce important cues, like name, age, date, time, and where they live, to help reduce disorientation.

Communication may require pictures, demonstration, verbal cues, or other strategies, depending on the type and extent of language deficit.

In-home care, boarding homes, adult day care, or convalescent homes may be required to provide a safe environment, control aggressive or agitated behavior, and meet physiological needs.

Behavior modification may be helpful for some people in controlling unacceptable or dangerous behaviors. This consists of rewarding appropriate or positive behaviors and ignoring inappropriate behaviors (within the bounds of safety).

Family counseling may help in coping with the changes required for home care. Visiting nurses or aides, volunteer services, homemakers, adult protective services, and other community resources may be helpful.

Legal advice may be appropriate. Advance directives, power of attorney, and other legal actions may make it easier to make ethical decisions regarding the care of the person with organic brain syndromes such as stroke.

Toll free phone line for stroke survivors and caregivers: 1-888-4STROKE

• Pressure sores
• Permanent loss of movement or sensation of a part of the body
• Bone fractures
• Joint contractures
• Muscle spasticity
• Permanent loss of cognitive or other brain functions
• Disruption of communication, decreased social interaction
• Decreased ability to function or care for self
• Decreased life span
• Multi-infarct dementia
• Side effects of medications
• Aspiration
• Malnutrition
• Pain syndromes (reflex sympathetic dystrophy)

Stroke prevention involves controlling the risk factors. Treat hypertension, diabetes, heart disease, and other associated disorders. Reduce or stop smoking. A low-cholesterol, low-salt diet may be appropriate if the risk factors include atherosclerosis or hypertension. Exercise more.

The treatment of TIA can prevent some strokes.