Overview of Strokes
Welcome to this video tutorial on strokes.
Approximately 700,000 strokes occur in the United States every year. A stroke is a medical emergency that occurs when the blood flow to the brain is interrupted. A stroke is often called a CVA, or cerebrovascular accident; however, a stroke is usually caused by an underlying disorder and is therefore no accident. More recently, the term ‘brain attack’ is used due to the similarities between a stroke and a heart attack. As with a heart attack, the most common form of brain attack occurs when a blood vessel in the brain becomes clogged, cutting off the oxygen to the brain, resulting in death of brain cells.
Types of Stroke
There are two types of stroke: ischemic and hemorrhagic. Ischemic strokes are by far the most common, and occur when a blood vessel carrying blood to the brain is blocked. Hemorrhagic strokes occur when a blood vessel breaks and bleeds into the brain.
First, we’ll talk about the most common type, the ischemic stroke, which accounts for 87% of all strokes. They occur when an artery in the brain or an artery carrying blood to the brain becomes blocked, either by a blood clot or by a narrowing of the artery due to plaque buildup (atherosclerosis).
When blood flow is blocked to part of the brain, within minutes brain cells and tissues begin to die from lack of oxygen and nutrients. The area of tissue death is called an infarct. Ischemic strokes can be further divided into 2 groups to include thrombotic strokes and embolic strokes.
Thrombotic strokes are caused by a thrombus (blood clot) that develops in an artery in the brain. A blood clot that triggers a thrombotic stroke usually develops inside an artery that has already been narrowed by atherosclerosis.
Embolic strokes are caused by a blood clot or plaque debris that forms somewhere else in the body, such as the heart, traveling through the bloodstream to a blood vessel in the brain, where it is too small to pass. They are often a result of heart disease or heart surgery and occur quickly without any warning signs.
It is often difficult to determine whether a stroke is thrombotic or embolic because the signs and symptoms can be identical. Signs of stroke vary depending on which area of the brain is affected. The most widely recognized signs involve motor deficits, such as weakness or paralysis on one side of the body and trouble speaking. Other symptoms include sudden confusion; visual disturbance, including sudden loss of vision; sudden, severe numbness anywhere on the body; sudden dizziness; difficulty walking; coordination problems with arms and hands; and difficulty swallowing. Symptoms may go away, stay the same, or gradually get worse over hours or days.
Knowing the signs and symptoms of a stroke can be lifesaving. You can remember the classic stroke symptoms with the acronym BE FAST, in which each letter stands for a sign you should watch for in a stroke victim.
Eyes – Blurred vision, the eyes are not receiving enough oxygen for optimal functioning
Face – The face is uneven, there is sudden weakness or droopiness of the face
Arms – Sudden weakness or numbness in one or both arms or legs
Speech – The individual has difficulty speaking or their speech is slurred or garbled.
Time – It’s time to call 911. Time is very important in stroke treatment—the sooner treatment begins, the better the chances are for recovery.
Brief episodes of stroke-like symptoms often occur before a stroke, and are referred to as a transient ischemic attack (TIA). Most TIAs last less than 30 minutes, in which symptoms appear suddenly and then get better over the next few minutes to hours. However, TIAs generally reflect advanced atherosclerotic disease and are a warning sign of an impending stroke. TIAs are sometimes referred to as mini-strokes. A person who has had a TIA is more than nine times as likely to have a stroke as a person without a TIA, and therefore should be treated aggressively before a stroke occurs.
Hemorrhagic strokes, or bleeds, account for about 13% of stroke cases. They occur when there is a weakened blood vessel in the brain that ruptures. When an artery bleeds into the brain, brain tissues and cells do not receive oxygen and nutrients. At the same time, pressure builds up in surrounding tissues, causing irritation and swelling, which leads to further brain damage.
Hemorrhagic strokes are divided into 2 main categories. These include intracerebral hemorrhage and subarachnoid hemorrhage.
Intracerebral hemorrhage involves bleeding from the blood vessels within the brain and is usually caused by hypertension. Bleeding occurs suddenly and quickly, and there are usually no warning signs. It may be severe enough to cause death.
Subarachnoid hemorrhage results from bleeding between the brain and the meninges in the subarachnoid space. This type of hemorrhage is usually due to an aneurysm or an arteriovenous malformation (AV malformation).
An aneurysm is the ballooning of a weak area on an artery wall, which if left untreated, will continue to weaken until it ruptures and bleeds into the brain. Aneurysms may be congenital, or may develop later in life due to hypertension or atherosclerosis.
An AV malformation is a congenital disorder that consists of a cluster of abnormally formed blood vessels, which can rupture and also cause bleeding into the brain.
The classic symptom of a hemorrhagic stroke is a sudden violent headache. Immediate loss of consciousness may occur from the sudden rise in intracranial pressure. Some patients also experience seizures.
A stroke is initially diagnosed by means of a careful history and physical. It is necessary to differentiate between ischemic and hemorrhagic strokes, by a CT scan or MRI. The CT scan is used to rule out bleeding and the MRI can determine the ischemic zone within the first few hours after stroke; however, its high cost and limited accessibility usually make MRI the second option. A variety of other tests, such as MR-angiograms, CT-angiograms, and cerebral angiography, can be used to provide important information regarding the location of the occlusion and the degree of brain tissue affected.
When a stroke is diagnosed, early and aggressive intervention is necessary to attempt reperfusion of the ischemic portions of the brain. If reperfusion can be provided within 1 to 3 hours, blood flow and metabolism in the stunned cells may be normalized. Once infarction (cell death) occurs, damage is irreversible.
Treatment for a stroke depends on the type of stroke.
Ischemic stroke requires clot-busting or clot-removal. Commonly known as ‘clot-busters,’ thrombolytics or fibrinolytics can help reduce the damage to brain cells caused by the stroke. Dissolving the clot allows blood flow to the brain to be restored, and can decrease the severity of symptoms. The gold standard clot-busting medication is IV tissue plasminogen activator (tPA). tPA works by dissolving the clot and improving blood flow to the part of the brain being deprived of blood flow. When given within the first 3 hours of symptom onset, tPA can reduce the long-term effects of stroke. After the 3-hour window, the tPA is not as effective and the risks may outweigh the benefits.
Another treatment option for ischemic stroke is to physically remove the blood clot, known as a thrombectomy. By threading a catheter through an artery in the groin, a stent retriever is then used to grab and remove the clot from the blocked artery in the brain, or a suction tube may also be used to remove the clot. The procedure should be done only after the patient has received tPA and within six hours of acute stroke symptoms.
Treatment for a hemorrhagic stroke involves controlling the bleeding in the brain and reducing the pressure caused by the bleeding. Surgical treatment can then be considered, which usually involves an endovascular procedure to surgically repair the bleed. A catheter is inserted through a major artery in an arm or leg, guided by a camera to the source of bleeding in the brain, and then a mechanical agent, such as a coil, is deposited to prevent further rupture. Depending on the location and size of an aneurysm, it may be repaired with surgical clipping. If the stroke is caused by an AV malformation, surgery may be used to remove it, if it is in an accessible location.
Once a patient has had a stroke, the risks are much higher for having another one. Preventing a second stroke can be the most important treatment of all. Prevention measures include adopting healthy lifestyle habits and reducing key risk factors. These risk factors include high blood pressure, atrial fibrillation, and cigarette smoking. Medications for hypertension, elevated cholesterol, and atrial fibrillation are given, as well as antiplatelet agents or anticoagulants to prevent a blood clot from forming again. Lifestyle changes such as losing weight, exercising regularly, and quitting smoking are also necessary to reduce the risk of another stroke.
Every stroke is unique, but the effects seen in patients are very similar. When a stroke occurs, blood flow cannot reach all areas of the brain, therefore, the effects of the stroke are dependent on the location of the obstruction and the extent of brain tissue affected.
Since one side of the brain controls the opposite side of the body, a stroke occurring in the right side of the brain will result in neurological complications on the left side of the body. These may include any or all of the following: paralysis on the left side of the body; vision problems; quick, inquisitive behavioral style; and/or memory loss.
If the stroke occurs on the left side of the brain, the right side of the body will be affected, producing paralysis on the right side of the body; speech or language problems; slow, cautious behavioral style; and/or memory loss.
If a stroke occurs in the brain stem, it may affect both sides of the body or leave the patient in a “locked-in” state, where the patient is generally unable to speak or achieve any movement below the neck.
Disabilities Caused by Strokes
Strokes generally cause five types of disabilities.
The first and most common is paralysis or problems with motor control. This usually involves hemiplegia (one-sided paralysis) or hemiparesis (one-sided weakness), dysphagia (problems with swallowing), and ataxia (loss of control of the body’s ability to coordinate movement), which causes problems with body posture, walking, and balance.
Stroke patients may also have sensory disturbances in which they lose the ability to feel touch, pain, temperature, or position. Some patients may experience paresthesias, in which they feel pain, numbness, tingling, or prickling in paralyzed or weakened limbs. Urinary incontinence often results from a combination of sensory and motor deficits and is fairly common immediately after a stroke.
At least one-fourth of all stroke survivors experience problems understanding or using language, called aphasia. The type of problem is dependent on the area of the brain’s language-control center that was damaged. Patients may have expressive aphasia, in which it is difficult to convey thoughts through words or writing. They lose the ability to speak the words they are thinking and put words together in coherent sentences. Patients with receptive aphasia have difficulty understanding spoken or written language and usually have incoherent speech. Global aphasia is the most severe form, in which the patient loses nearly all language capabilities; they cannot understand language or use it to convey thought.
Stroke can also cause problems with memory and thinking. Learning may be affected, as well as the ability to make plans, comprehend meaning, or engage in complex mental activities. There may be deficits in short-term memory and the ability to follow a set of instructions.
Finally, many stroke survivors deal with emotional disturbances. They may feel fear, anxiety, sadness, frustration, anger, and a sense of grief for their physical and mental losses. Some emotional disturbances and personality changes are caused by the physical effects of brain damage. However, clinical depression is the most common emotional disorder experienced by stroke survivors.
For the stroke patient, one of the most important phases of recovery involves rehabilitation. Depending on the severity of the stroke and the amount of tissue damage that occurred, different types of therapy may be involved, including physical therapy, occupational therapy, or speech therapy. Though rehab doesn’t “cure” the effects of a stroke or reverse brain damage, it does significantly help people achieve the best possible long-term outcome. The primary goal of therapy for the stroke patient is to restore as much function as possible and attain the best possible quality of life.
Rehabilitation will depend on what the patient needs to become independent. This may include:
- Mobility skills such as walking, transferring, or moving a wheelchair
- Self-care skills such as dressing, bathing, grooming, feeding, and toileting
- Communication skills in language and speech
- Social skills for interacting with other people
- Cognitive skills such as memory or problem-solving
Rehabilitative therapy begins in the hospital once the patient has been medically stabilized, often within 24 to 48 hours after the stroke. For some stroke survivors, rehab will be an ongoing process, working with specialists for months or years after the stroke.
Nursing education for the stroke survivor and family includes several important points:
- Teach the patient to resume as much self-care as possible, providing assistive devices as needed.
- Help the family coordinate care of the various health care professionals and therapists needed.
- Instruct the family that the patient may tire easily, show less interest in daily activities, and become irritable and upset by small events.
- Discuss the patient’s depression with the family and physician for possible antidepressant therapy.
- Encourage the patient to continue with hobbies and leisure interests, and contact friends to prevent social isolation.
- Encourage the family to support the patient and give positive reinforcement.
Teach the patient to prevent another stroke by implementing the following:
- Keep blood pressure low
- Lower cholesterol
- Eat healthy food
- Exercise regularly
- Maintain a healthy weight
- Treat sleep apnea
- Manage diabetes
- Drink in moderation
- Quit smoking
- Avoid stress
These prevention measures apply to all individuals who may be at increased risk for a stroke.