Stroke

Topic Highlights

●    Stroke is the result of permanent damage to part of the brain which occurs due to inadequate blood flow to that part of the brain.

●    This visual presentation is a graphic description of the types of stroke, risk factors, warning signs, diagnosis, treatment, recovery and rehabilitation.

Transcript

Stroke is a serious and life-threatening condition in which blood vessel disorders in the brain cause the sudden onset of symptoms. It is one of the leading causes of disability and death in adults. Stroke is the result of permanent damage to a part of the brain due to inadequate blood flow and loss of oxygen supply. This may be caused by blockage or rupture of a blood vessel inside the brain. The part of the brain which is damaged dies and can no longer function.

Risk factors for stroke include smoking, high blood pressure, diabetes, heart disease, obesity and heavy alcohol use. Age and a family history of stroke also increase a person's risk of stroke.

There are two types of stroke, ischemic and hemorrhagic. Ischemic stroke is caused when a blood clot blocks an artery in or leading to the brain. It is the most common type of stroke and accounts for nearly 80% of all strokes. Blockage is triggered by the build-up of plaque in an artery due to atherosclerosis. Other causes include abnormal heart valves and a history of heart attack, or rarely, blood clotting disorders or traumatic injury.

Atherosclerosis is the hardening of the walls of the arteries and the narrowing of the space inside them, due to the slow build-up of plaque inside the arteries. Plaque is made up of deposits of fat, cholesterol, calcium, and other substances circulating in the blood.

Plaques are of two types, hard and soft. Hard or stable plaques have a relatively thick covering and cause artery walls to thicken and harden. Soft or unstable plaques are more likely to rupture without warning. When a soft plaque bursts, it triggers the formation of a clot in the artery at the site and restricts the flow of blood drastically, and may cause a larger blockage in the artery.

When a blood clot that has formed in the brain blocks an artery, this type of stroke is called thrombotic. A clot formed elsewhere in the body can also dislodge, travel to the brain and block an artery there. This type of stroke is called embolic.

Hemorrhagic stroke is caused by bleeding from a ruptured blood vessel in or near the brain. Bleeding inside the brain is called intracerebral hemorrhage. The bleeding results in a sudden increase in pressure, causing tissue damage. Other parts of the brain may not get enough oxygen and can also be damaged. This type of stroke is most often caused by high blood pressure. It may also be caused by head injury, malformed blood vessels or an aneurysm.

In the other main type of hemorrhagic stroke, subarachnoid hemorrhage, a blood vessel ruptures between the brain and its lining. The part of the lining surrounding the brain fills with blood, leading to tissue damage. This is usually caused by an aneurysm, a weak spot in an artery where the wall has become thin and bulges out.

Because different parts of the brain control different parts of the body, symptoms vary from person to person and depend on how severe the stroke is. Symptoms usually come on suddenly. The person may feel weak or numb on one side of the body, often in the face, arm or leg. They may have trouble speaking and understanding others. They may have problems seeing or hearing, or lose their balance and coordination. They may feel dizzy or have a severe headache.

Stroke is a medical emergency and emergency services should be called if a person seems to be having a stroke, to get them to hospital as fast as possible. Rapid diagnosis can prevent further stroke.

Blood tests and scans help doctors tell what type of stroke has occurred, and eliminate other conditions that may produce similar symptoms. Scans include computed tomography or CT, ultrasound, magnetic resonance imaging or MRI, and angiography, where the head and neck are X-rayed while a substance visible under X-rays is injected into an artery.

Treatment depends on the type of stroke. Early treatment can help limit damage to the brain. Long-term medication and lifestyle changes may be required to prevent further strokes. Rehabilitation therapy aims to help the patient regain as much independence as possible.

Initial medication for ischemic stroke aims to break up the clot and restore blood flow in the blocked artery. In some cases, tissue plasminogen activator or tPA within 3 hours of the stroke can limit further brain damage. Longer-term medication to reduce the risk of further stroke includes drugs to reduce blood pressure, cholesterol-lowering drugs, and anti-clotting medication such as aspirin. Anti-clotting medication is not used in hemorrhagic stroke.

If the stroke is caused by an aneurysm or weak place in the artery wall, it may be surgically clipped. The aneurysm is clamped off with a tiny metal clip to stop future bleeding, without blocking the artery. In arterial occlusion and bypass, which is less common, the artery leading to the aneurysm is blocked off and bypassed using an artery grafted from another part of the body.

Endovascular treatment is used after some subarachnoid hemorrhage, and sometimes other kinds of stroke. A long, thin, flexible tube is inserted into a large artery in the thigh, and guided to the brain. It may be used to insert a tiny metal coil or stent to occlude an aneurysm, deliver a clot-dissolving drug, or to mechanically remove a clot.

Rehabilitation is an important part of stroke treatment. The exact treatment will depend on the type of stroke. Weakness in an arm or leg is common, and exercise and physiotherapy are essential to stop the muscles from losing their strength. Speech therapy, occupational therapy and psychological help are other treatments that allow stroke patients to regain independence.

People can reduce their chances of having a stroke. It is important to give up smoking and control high blood pressure. People with diabetes should make sure they are receiving the correct treatment. For people who are overweight, losing weight can reduce high blood pressure. Regular exercise, a healthy diet and drinking no more than the recommended levels of alcohol also help to prevent stroke.