A stroke is the rapidly developing loss of brain function(s) due to disturbance in the blood supply to the brain. This can be due to ischemia (lack of blood supply) caused by thrombosis or embolism or due to a hemorrhage. As a result, the affected area of the brain is unable to function, leading to inability to move one or more limbs on one side of the body, inability to understand or formulate speech, or inability to see one side of the visual field. In the past, stroke was referred to as cerebrovascular accident or CVA.
A stroke is a medical emergency and can cause permanent neurological damage, complications, and death. It is the leading cause of adult disability in the United States and Europe. In the UK, it is the second most common cause of death, the first being heart attacks and third being cancer. Risk factors for stroke include advanced age, hypertension (high blood pressure), previous stroke or transient ischemic attack (TIA), diabetes, high cholesterol, cigarette smoking and atrial fibrillation. High blood pressure is the most important modifiable risk factor of stroke.
A stroke is occasionally treated with thrombolysis ("clot buster"), but usually with supportive care (speech and language therapy, physiotherapy and occupational therapy) in a "stroke unit" and secondary prevention with antiplatelet drugs (aspirin and often dipyridamole), blood pressure control, statins, and in selected patients with carotid endarterectomy and anticoagulation.
CLASSIFICATION
Strokes can be classified into two major categories: ischemic and hemorrhagic. Ischemia is due to interruption of the blood supply, while hemorrhage is due to rupture of a blood vessel or an abnormal vascular structure.
Ischemic stroke
In an ischemic stroke, blood supply to part of the brain is decreased, leading to dysfunction of the brain tissue in that area. There are four reasons why this might happen:
· Thrombosis (obstruction of a blood vessel by a blood clot forming locally)
· Embolism (due to an embolus from elsewhere in the body, see below)
· Systemic hypoperfusion (general decrease in blood supply, e.g. in shock)
· venous thrombosis. Stroke without an obvious explanation is termed "cryptogenic" (of unknown origin).
Hemorrhagic stroke
Intracranial hemorrhage is the accumulation of blood anywhere within the skull vault. A distinction is made between intra-axial hemorrhage (blood inside the brain) and extra-axial hemorrhage (blood inside the skull but outside the brain). Intra-axial hemorrhage is due to intraparenchymal hemorrhage or intraventricular hemorrhage (blood in the ventricular system). The main types of extra-axial hemorrhage are epidural hematoma (bleeding between the dura mater and the skull), subdural hematoma (in the subdural space) and subarachnoid hemorrhage (between the arachnoid mater and pia mater).
CAUSES
A stroke can happen when the following occurs:
A blood vessel that supplies blood to the brain is blocked by a blood clot. This is called an ischemic stroke.
A blood vessel breaks open, causing blood to leak into the brain. This is called a hemorrhagic stroke.
If blood flow is stopped for longer than a few seconds, the brain cannot get blood and oxygen. Brain cells can die, causing permanent damage.
Ischemic stroke usually results from clogged arteries, a condition called atherosclerosis. Fat, cholesterol, and other substances collect on the wall of the arteries, forming a sticky substance called plaque. Over time, the plaque builds up. This often makes it hard for blood to flow properly, which can cause the blood to clot.
Other causes of ischemic stroke include:
· Abnormal heart valve
· Inflammation of the inside lining of the heart chambers and heart valves
· Mechanical heart valve
Hemorrhagic stroke
Hemorrhagic stroke can occur when small blood vessels in the brain become weak and burst. The flow of blood that occurs after the blood vessel ruptures damages brain cells.
SYMPTOMS
Stroke symptoms typically start suddenly, over seconds to minutes, and in most cases do not progress further. The symptoms depend on the area of the brain affected. The more extensive the area of brain affected, the more functions that are likely to be lost. Some forms of stroke can cause additional symptoms: in intracranial hemorrhage, the affected area may compress other structures. Most forms of stroke are not associated with headache, apart from subarachnoid hemorrhage and cerebral venous thrombosis and occasionally intracerebral hemorrhage.
Symptoms usually develop suddenly and without warning. They may be episodic (occurring and then stopping) or they may slowly get worse over time.
Symptoms may include:
· Change in alertness (consciousness), including
· Coma
· Lethargy
· Sleepiness
· Stupor
· Unconsciousness
· Withdrawn
· Difficulty speaking or understanding others
· Difficulty swallowing
· Difficulty writing or reading
· Headache
· Occurs when lying flat
· Wakes you up from sleep
· Gets worse when you change positions or when you bend, strain, or cough
· Starts suddenly
· Loss of coordination
· Loss of balance
· Movement changes, usually on only one side of the body
· Difficulty moving any body part
· Loss of fine motor skills
· Nausea or vomiting
· Seizure
· Sensation changes, usually on only one side of the body
· Decreased sensation
· Numbness or tingling
· Suddent confusion
· Weakness of any body part
· Vision changes
· Decreased vision
· Loss of all or part of vision
TREATMENT
A stroke is a medical emergency. Immediate treatment can save lives and reduce disability.
It is important to get the person to the emergency room immediately to determine if the stroke is due to bleeding or a blood clot so appropriate treatment can be started within 3 hours of when the stroke began .
Treatment depends on the severity and cause of the stroke. A hospital stay is required for most strokes.
TREATMENT IN THE HOSPITAL
Thrombolytics, such as tPA, may be given if the stroke is caused by a blood clot. Such medicine breaks up blood clots and helps restore blood flow to the damaged area. Persons who receive thrombolytics are less likely to have long-term stroke-related problems. However, not everyone can receive this type of medicine. The most important rule is that the person be examined and treated by a specialized stroke team within 3 hours of when the symptoms start. If the stroke is caused by bleeding rather than clotting, thrombolytics can make the damage worse -- so care is needed to diagnose the cause before giving treatment.
In other circumstances, blood thinners such as heparin and Coumadin are used to treat strokes due to blood clots. Aspirin may also be used.
Other medications may be needed to control other symptoms, including high blood pressure. Painkillers may be given to control severe headache.
Nutrients and fluids may be necessary, especially if the person has swallowing difficulties. These may be given through a vein (intravenously) or a feeding tube in the stomach (gastrostomy tube). Swallowing difficulties may be temporary or permanent.
For hemorrhagic stroke, surgery is often required to remove pooled blood from the brain and to repair damaged blood vessels.
LONG-TERM TREATMENT
The goal of long-term treatment is to help the patient recover as much function as possible and prevent future strokes. The recovery time and need for long-term treatment differs from person to person. Depending on the symptoms, rehabilitation may include occupational therapy, physical therapy, and speech therapy.
Therapies such as repositioning and range-of-motion exercises can help prevent complications related to stroke, such as infection and bed sores. Those who have had a stroke should try to remain as active as physically possible.
Alternative forms of communication such as pictures, verbal cues, and other techniques may be needed in some cases.
Sometimes, urinary catheterization or bladder and bowel control programs may be needed to control incontinence.
A safe environment must be considered. Some people with stroke appear to have no awareness of their surroundings on the affected side. Others show indifference or lack of judgment, which increases the need for safety precautions.
Caregivers may need to show the person pictures, repeatedly demonstrate how to perform tasks, or use other communication strategies, depending on the type and extent of the language problems.
PREVENTION
To help prevent a stroke:
· Avoid fatty foods. Follow a healthy, low-fat diet.
· Do not drink more than 1 to 2 alcoholic drinks a day.
· Exercise regularly: 30 minutes a day if you are not overweight; 60 - 90 minutes a day if you are overweight.
· Get your blood pressure checked every 1 - 2 years, especially if high blood pressure runs in your family.
· Have your cholesterol checked. If you are at high risk for stroke, your LDL "bad" cholesterol should be lower than 100 mg/dL. Your doctor may recommend that you try to reduce your LDL cholesterol to 70 mg/dL.
· Follow your doctor's treatment recommendations if you have high blood pressure, diabetes, high cholesterol, and heart disease.
· Quit smoking.
Aspirin therapy (81mg a day or 100mg every other day) is recommended for stroke prevention in women under 65 as long as the benefits outweigh the risks. It should be considered for women over age 65 only if their blood pressure is controlled and the benefit is greater than the risk of gastrointestinal bleeding and brain hemorrhage. Ask your doctor if aspirin is right for you.
Your doctor may also recommend aspiring therapy or another blood thinner if you have had a transient ischemic attach (TIA) or stroke in the past or if you currently have:
· Congestive heart failure
· Irregular heart beat (such as atrial fibrillation)
· Mechanical heart valve
· Other risk factors for stroke
A type of surgery called carotid endarterectomy may help prevent new strokes from occurring in persons with large blockages in their neck arteries.
