STROKE

BACKGROUND

Stroke is the medical term for when a part of the brain dies because of a problem with the blood. Strokes can happen when:

• An artery going to the brain gets clogged or closes off, and part of the brain goes without blood for too long.
• An artery breaks open and starts bleeding into or around the brain.

When the blood supply to the brain is interrupted or blocked for any reason, the consequences are usually dramatic. Control over movement, perception, speech, or other mental or bodily functions is impaired, and consciousness itself may be lost. Disruptions of blood circulation to the brain may result in a stroke.

DISEASE OCCURRENCE IN POPULATION:

According to World Health Organization estimates, 5.5 million people died of stroke in 2002, and roughly 20% of these deaths occurred in South Asia.

In Pakistan, stroke and transient ischemic attacks (TIA) are highly prevalent. A recent community-based survey suggested an estimated 21.8% prevalence of stroke and / or TIA in an urban slum of Karachi. Upto 63% of all stroke patients develop complications and upto 89% are dependent for activities of daily living. The estimated annual incidence of stroke in Pakistan is 250 / 100,000, which is projected to an estimate of 350,000 new cases every year.

RISK FACTORS:

A risk factor is anything that makes you more likely to have a particular health problem. Risk factors for stroke that you can treat or change include:

• High blood pressure (hypertension).
• Atrial fibrillation.
• High cholesterol.
• Heavy use of alcohol.
• Being overweight.
• Physical inactivity.
• Illegal drug use

Risk factors you cannot change include:

• Age: The risk of stroke increases with age.
• Race: African Americans, Native Americans, and Alaskan Natives have a higher risk than those of other races.
• Gender: Women have a higher risk of having a stroke compared to men.
• Family history: The risk for stroke is greater if a parent, brother, or sister has had a stroke or transient ischemic attack (TIA).
• History of stroke or TIA.
• Current or past history of blood clots.

SIGN AND SYMPTOMS:

Signs and symptoms of stroke often develop suddenly and then may temporarily improve or slowly worsen, depending upon the type of stroke and area of the brain affected.

CLASSIC SYMPTOMS: Knowing the signs and symptoms of a stroke can be lifesaving. Classic stroke symptoms can be recalled with the acronym Fast. Each letter in the word stands for one of the things you should watch for:

• Face – Sudden weakness or droopiness of the face, or problems with vision
• Arm – Sudden weakness or numbness of one or both arms
• Speech – Difficulty speaking, slurred speech, or garbled speech
• Time – Time is very important in stroke treatment. The sooner treatment begins, the better the chances are for recovery.

WHEN TO CALL FOR EMERGENCY MEDICAL ASSISTANCE: A stroke is a medical emergency. If you think you or someone around you may be having a stroke, call emergency help line immediately. Do not try to drive yourself to the hospital.

DIAGNOSTIC TEST:

Anyone who has signs or symptoms of a stroke needs immediate medical attention in an emergency department or hospital. Most clinics and medical offices do not have the ability to perform the tests needed to diagnose stroke, or the ability to provide the specialized treatment(s) needed to limit damage to the brain.

BLOOD TESTS AND BRAIN IMAGING: After doing a physical exam and reviewing the patient's history, the doctor or nurse usually orders blood tests and an imaging test (e.g. CT scan or MRI scan) of the brain and the surrounding blood vessels in the neck and head that supply the brain with blood. The imaging allows the doctor or nurse to see the area of the brain affected by the stroke, as well as to confirm the type of stroke (ischemic or hemorrhagic). Blood test includes:

• Complete blood count (CBC).
• Blood sugar.
• Liverand kidney
• Prothrombin time and INR(a test that measures how long it takes your blood to clot).

Occasionally, a catheter must be inserted through a blood vessel in the groin and threaded up to the blood vessels of the neck, where dye is injected to highlight any areas of blockage.

HEART TESTING: An electrocardiogram (ECG) is performed in most people who are thought to be having a stroke. Because many people with ischemic strokes also have coronary artery disease, there may be a lack of blood flow (called "ischemia") in the heart during the stroke. In some cases, the person may not be able to tell the clinician that he or she feels chest pain. The ECG will help the clinician to diagnose and treat any heart problems as quickly as possible.

Other heart testing may also be recommended, such as an echocardiogram. This test uses sound waves to examine the heart and the aorta (the main artery that supplies the whole body). In some people with embolic strokes, the heart or the aorta is the source of the blood clot that led to the stroke. As an example, a heart rhythm problem called atrial fibrillation is a high-risk condition for blood clot formation and ischemic stroke. Some people have occasional episodes of atrial fibrillation but are not aware of it, and it may not show up on routine heart tests such as the ECG. Therefore, doctors often use continuous cardiac monitoring to look for atrial fibrillation and other heart rhythm problems for the first day or two when patients are in the hospital for a stroke. In some cases, patients will need to wear a small portable cardiac monitor for a period of time after the stroke to see if they have episodes of atrial fibrillation.
If it seems that you may have a narrowing of a carotid artery, your doctor may want you to have a:

• Carotid ultrasound / Doppler scan to evaluate blood flow through the artery.
• Magnetic resonance angiogram (MRA).
• CT angiogram.
• Carotid angiogram.

Guidelines recommend that risk factors for heart disease also be assessed after a stroke to prevent disability or death from a future heart problem. This is because many people who have had a stroke also have coronary artery disease.

TREATMENT OPTIONS:

VERY EARLY TREATMENTS: For people who have an ischemic stroke, the goal of treatment is to restore blood flow to the affected area of the brain as quickly as possible, which means within the first hours after the stroke begins. The main very early treatments for ischemic stroke are:

• Intravenous thrombolytic ("clot buster") therapy withalteplase
• Intra-arterial mechanical thrombectomy (opening of the blocked artery) with stent retriever devices

ALTEPLASE (THROMBOLYTIC THERAPY): Intravenous thrombolytic therapy uses a medication called tissue plasminogen activator (tPA, alteplase) that is injected into a vein. Alteplase works to dissolve clots that are blocking blood flow within arteries of the brain. The benefit of thrombolytic treatment slowly decreases over several hours. Thus, the earlier the treatment is given after the stroke begins, the more likely the artery can be opened.

Overall, it is estimated that alteplase treatment is 10 times more likely to help than to harm. However, approximately 1 in 15 patients who receive thrombolytic therapy develops excessive bleeding (hemorrhage) in the brain; this type of bleeding can be fatal.

MECHANICAL THROMBECTOMY: Intra-arterial mechanical thrombectomy is a treatment that uses a catheter containing a device called a stent retriever. The catheter is placed within an artery to the brain and guided to the clot that is causing the stroke symptoms. This stent retriever device can restore blood flow to the brain by capturing and removing the clot blocking the large artery. Mechanical thrombectomy can be beneficial if it is given within six hours from the start of the stroke symptoms. It is used only for patients who have a blockage in one of the large arteries within the brain, so not all patients with ischemic stroke will need this type of treatment. For those who do need it, the sooner mechanical thrombectomy is started, the more likely that it will help.

Mechanical thrombectomy for stroke is a highly specialized treatment and should only be performed at hospitals with experience in the use of stent retrievers.

OTHER EARLY TREATMENTS: The medicines used for the early treatment of ischemic stroke are aspirin and anticoagulants.

ASPIRIN: Antiplatelet therapy helps prevent new clots from developing. Unlike thrombolytic drugs, these agents do not dissolve clots that are already present. They are often used acutely if thrombolytic drugs cannot be given or after thrombolytics have been given.

Aspirin is the only antiplatelet agent that has been established as effective for the early treatment of acute ischemic stroke. Thus, doctors may use early aspirin therapy (within 48 hours of the start of stroke symptoms) for patients with ischemic stroke who are not receiving alteplase or anticoagulants.

Platelets are tiny cell fragments circulating in the blood that normally clump together to stop bleeding. This clumping leads to the formation of a blood clot. In strokes, platelets clump together and form clots inside of narrowed arteries. The platelet "plug" itself and / or the clot that forms around the plug can block blood flow in the brain.

ANTICOAGULANTS: Anticoagulants are often, but incorrectly, referred to as blood thinners. They work by decreasing the formation of additional blood clots. Heparin and low molecular weight heparin are anticoagulants.

Because of the risk of excessive bleeding, anticoagulation is seldom recommended for the treatment of patients with acute ischemic stroke. However, anticoagulant therapy with heparin or low molecular weight heparin is used by some practitioners for certain types of stroke. For example, some doctors use anticoagulants for the early treatment of stroke caused by blood clots that travel from the heart (cardioembolism) in patients who have heart valve disease or severe heart failure, and for patients who have stroke caused by dissection (a tear of the inner blood vessel wall) of a large artery that supplies blood to the brain.

LONG TERM PREVENTION OF ISCHEMIC STROKE: For people who have already had an ischemic stroke, doctors often prescribe medicines that can prevent another stroke from happening. This is called secondary prevention. The treatments for secondary prevention of ischemic stroke include antiplatelet medications, anticoagulants, and surgical procedures to reopen blockages in blood vessels (revascularization).

ANTIPLATELET THERAPY: The antiplatelet medicines aspirin, clopidogrel, and the combination of aspirin plus extended-release dipyridamole are all acceptable options for preventing recurrent ischemic stroke for patients other than those who have a stroke caused by embolism from the heart.

DIPYRIDAMOLE: Dipyridamole is a medication that may be given after a stroke to reduce the risk of another stroke. It is often given in an extended-release form, which combines dipyridamole with aspirin.

Side effects of dipyridamole include headache, stomach upset, and / or diarrhea. Headaches usually improve over the first week.

CLOPIDOGREL: Clopidogrel is an antiplatelet medication that is also used in patients after stroke to reduce the risk of having another stroke. In one trial, the combined risk of stroke, myocardial infarction (MI), or vascular death, was modestly reduced with clopidogrel treatment compared with aspirin treatment, and the result was statistically significant.

For this reason, some experts recommend use of clopidogrel for patients who are not treated with the combination of aspirin and extended release dipyridamole, rather than use of aspirin alone. Compared with aspirin, clopidogrel causes a slightly higher frequency of rash and diarrhea, and a slightly lower frequency of stomach upset and gastrointestinal bleeding.

Clopidogrel is not usually recommended in combination with aspirin after a stroke because the combination is no more effective for preventing another stroke than either clopidogrel or aspirin alone, while using the two in combination increases the risk of bleeding in the brain. However, selected patients with a recent acute myocardial infarction, other acute coronary syndrome, or recent arterial stent placement are often treated with the combination of clopidogrel plus aspirin.

ASPIRIN: Aspirin is effective for preventing ischemic stroke. Most studies have found that 50 to 325 mg / day of aspirin is as effective as higher doses for preventing stroke. Furthermore, lower doses within this range appear to provide the same benefit as higher doses.

ANTICOAGULANT THERAPY: Anticoagulant therapy is used to prevent stroke for selected patients. As an example, for long-term stroke prevention, virtually all patients with atrial fibrillation who have a history of embolic stroke or transient ischemic attack should be treated with anticoagulation (warfarin or one of the newer oral anticoagulant drugs) in the absence of contraindications.

Warfarin is a pill that is taken by mouth. It is often recommended as a long-term treatment for people who have conditions that promote the formation of blood clots, such as atrial fibrillation of the heart. People who take warfarin must be closely monitored with blood tests to ensure that the correct dose is used and that the risk of excessive bleeding or developing blood clots is minimized.

Dabigatran, apixaban, rivaroxaban, and edoxaban are newer anticoagulants that work as well as warfarin, and are as safe, but do not require periodic blood tests.

REVASCULARIZATION: Revascularization is the medical term for reestablishing blood flow to an area. In people who have had a stroke, revascularization usually refers to a surgical procedure (carotid endarterectomy) that opens a blocked artery in the neck (the carotid artery), which improves blood flow to the brain and reduces the risk of stroke. The amount of blockage in the carotid artery can be measured with an ultrasound imaging test, CT angiogram, MR angiogram, or conventional arteriogram.

Carotid endarterectomy is most successful when it is performed by a vascular surgeon who has specialized training and experience with the procedure. However, even in experienced hands, the procedure has risks, including bleeding, brain injury, stroke, and even death. Some people are likely to benefit from carotid endarterectomy while for others; the risks of the procedure are greater than the potential benefits. Placement of a stent in the carotid artery is another alternative, although this therapy carries a greater risk of stroke and disability, especially in people over the age of 70 years.

PRECATIONS:

A number of behavioral and lifestyle modifications may be beneficial for reducing the risk of ischemic stroke and cardiovascular diseases. These include smoking cessation, limited alcohol consumption, weight control, regular aerobic physical activity, salt restriction, and a Mediterranean diet.

SMOKING CESSATION: All patients who are recent or current tobacco smokers should quit smoking.

ALCOHOL CONSUMPTION: All patients with ischemic stroke who are heavy drinkers should eliminate or reduce their alcohol consumption because of the increased risk of stroke and high morbidity associated with alcoholism.

PHYSICAL ACTIVITY AND EXERCISE: For patients with ischemic stroke who are capable of regular exercise, should do moderate to vigorous intensity physical exercise most days of the week for at least 40 minutes. Moderate intensity exercise is defined as activity sufficient to break a sweat or noticeably raise the heart rate (e.g. walking briskly, using an exercise bicycle)

DIET: Emerging evidence suggests that dietary interventions, and in particular a Mediterranean diet improves outcomes in patients with established cardiovascular disease. Mediterranean-type diet that emphasizes the intake of vegetables, fruits, whole grains, low-fat dairy products, poultry, fish, legumes, nontropical vegetable oils, and nuts. It limits the intake of sweets, sugar-sweetened beverages, and red meats. Calories from saturated fat should be limited to 5 to 6 percent and calories from trans-fat should be reduced. For patients who would benefit from blood pressure lowering, a reduction in sodium (no more than 2400 mg per day) is also suggested.

WEIGHT REDUCTION: Weight reduction for obese patients is potentially beneficial for improved control of other important parameters, including blood pressure, blood glucose, and serum lipid levels ultimately preventing stroke.

MANAGING UNDERLYING CONDITIONS:

If patient is suffering from any condition which is known to increase risk of stroke such as high cholesterol, high blood pressure, atrial fibrillation, diabetes or a transient ischaemic attack (TIA), ensuring the condition is well controlled is also important in helping prevent strokes.

REFERENCE:

• World Health Organization (WHO). The Atlas of Heart Disease and Stroke. http://www.who.int/cardiovascular_diseases/resources/atlas/en/
• Kamal AK, Itrat A, Murtaza M, Khan M, Rasheed A, Ali A, et al. The burden of stroke and transient ischemic attack in Pakistan: a community-based prevalence study. BMC Neurol 2009; 9:58.
• Farooq MU, Majid A, Reeves MJ, Birbeck GL. The epidemiology of stroke in Pakistan: past, present, and future. Int J Stroke 2009; 4:381-9.
• Khealani BA, Wasay M. The burden of stroke in Pakistan. Int J Stroke 2008; 3:293-6