Stroke Causes, Symptoms, Diagnosis, Treatment, Prevention

Stroke Causes, Symptoms, Diagnosis, Treatment, Prevention


What is Stroke?

A stroke occurs when the blood supply to part of your brain is interrupted or severely reduced, depriving brain tissue of oxygen and food. Within minutes, brain cells begin to die.

Stroke Causes, Symptoms, Diagnosis, Treatment, Prevention

A stroke occurs when the blood supply to the part of the brain is suddenly interrupted (ischemic) or when a blood vessel in the brain bursts, spilling blood into the spaces surrounding the brain cells (hemorrhagic). The symptoms of stroke are easy to spot: sudden numbness or weakness, especially on one side of the body; sudden confusion or trouble speaking or understanding speech; sudden trouble seeing in one or both eyes; sudden trouble walking; dizziness; or loss of balance or coordination. Brain cells die when they no longer receive oxygen and nutrients from the blood or when they are damaged by sudden bleeding into or around the brain. These damaged cells can linger in a compromised state for several hours. With timely treatment, these cells can be saved. Stroke is diagnosed through several techniques: a short neurological examination, blood tests, CT scans, MRI scans, Doppler ultrasound, and arteriography. Stroke seems to run in some families. Family members may have a genetic tendency for stroke or share a lifestyle that contributes to stroke. The most important risk factors for stroke are hypertension, heart disease, diabetes, and cigarette smoking. Other risks include heavy alcohol consumption, high blood cholesterol levels, illicit drug use, and genetic or congenital conditions. Some risk factors for stroke apply only to women. Primary among these are pregnancy, childbirth, and menopause.

A stroke is a medical emergency. Prompt treatment is crucial. Early action can minimize brain damage and potential complications.

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Causes of  Stroke

A stroke occurs when the blood supply to your brain is interrupted or reduced. This deprives your brain of oxygen and nutrients, which can cause your brain cells to die. A stroke may be caused by a blocked artery (ischemic stroke) or a leaking or burst blood vessel (hemorrhagic stroke). Some people may experience a temporary disruption of blood flow through their brain (transient ischemic attack).

Ischemic stroke


About 85 percent of strokes are ischemic strokes. Ischemic strokes occur when the arteries to your brain become narrowed or blocked, causing severely reduced blood flow (ischemia). The most common ischemic strokes include:


  • Thrombotic stroke. A thrombotic stroke occurs when a blood clot (thrombus) forms in one of the arteries that supply blood to your brain. A clot often may be caused by fatty deposits (plaque) that build up in arteries and cause reduced blood flow (atherosclerosis) or other artery conditions.
  • Embolic stroke. An embolic stroke occurs when a blood clot or other debris forms away from your brain — commonly in your heart — and is swept through your bloodstream to lodge in narrower brain arteries. This type of blood clot is called an embolus.


Hemorrhagic stroke


Hemorrhagic stroke occurs when a blood vessel in your brain leaks or ruptures. Brain hemorrhages can result from many conditions that affect your blood vessels, including uncontrolled high blood pressure (hypertension) and weak spots in your blood vessel walls (aneurysms). A less common cause of hemorrhage is the rupture of an arteriovenous malformation (AVM) — an abnormal tangle of thin-walled blood vessels, present at birth. The types of hemorrhagic stroke include:


  • Intracerebral hemorrhage. In an intracerebral hemorrhage, a blood vessel in the brain bursts and spills into the surrounding brain tissue, damaging brain cells. Brain cells beyond the leak are deprived of blood and damaged. High blood pressure, trauma, vascular malformations, use of blood-thinning medications and other conditions may cause intracerebral hemorrhage.
  • Subarachnoid hemorrhage. In a subarachnoid hemorrhage, an artery on or near the surface of your brain bursts and spills into the space between the surface of your brain and your skull. This bleeding is often signaled by a sudden, severe headache. A subarachnoid hemorrhage is commonly caused by the rupture of an aneurysm, a small sack-shaped or berry-shaped outpouching on an artery in the brain. After the hemorrhage, the blood vessels in your brain may widen and narrow erratically (vasospasm), causing brain cell damage by further limiting blood flow to parts of your brain.


Transient ischemic attack (TIA)


A transient ischemic attack (TIA) - also called a ministroke - is a brief episode of symptoms similar to those you'd have in a stroke. A transient ischemic attack is caused by a temporary decrease in blood supply to part of your brain. TIAs often last less than five minutes.

Like an ischemic stroke, a TIA occurs when a clot or debris blocks blood flow to part of your brain. A TIA doesn't leave lasting symptoms because the blockage is temporary.

Seek emergency care even if your symptoms seem to clear up. If you've had a TIA, it means there's likely a partially blocked or narrowed artery leading to your brain, putting you at a greater risk of a full-blown stroke that could cause permanent damage later. It's not possible to tell if you're having a stroke or a TIA based only on your symptoms. Up to half of people whose symptoms appear to go away actually have had a stroke causing brain damage.

Symptoms of Stroke


The symptoms of stroke depend on what part of the brain is damaged. In some cases, a person may not know that a stroke has occurred. Most of the time, symptoms develop suddenly and without warning. However, symptoms may occur on and off for the first day or two. Symptoms are usually most severe when the stroke first happens, but they may slowly get worse.

A headache may occur if the stroke is caused by bleeding in the brain. The headache:



  • Starts suddenly and may be severe
  • Occurs when you are lying flat
  • Wakes you up from sleep
  • Gets worse when you change positions or when you bend, strain, or cough

Other symptoms depend on how severe the stroke is and what part of the brain is affected. Symptoms may include:



  • Change in alertness (including sleepiness, unconsciousness, and coma)
  • Changes in hearing
  • Changes in taste
  • Changes that affect touch and the ability to feel pain, pressure, or different temperatures
  • Clumsiness
  • Confusion or loss of memory
  • Difficulty swallowing
  • Difficulty writing or reading
  • Dizziness or abnormal feeling of movement (vertigo)
  • Lack of control over the bladder or bowels
  • Loss of balance
  • Loss of coordination
  • Muscle weakness in the face, arm, or leg (usually just on one side)
  • Numbness or tingling on one side of the body
  • Personality, mood, or emotional changes
  • Problems with eyesight, including decreased vision, double vision, or total loss of vision
  • Trouble speaking or understanding others who are speaking
  • Trouble walking

When To Call a Doctor



Call  emergency services immediately if you have signs of a stroke:

  • Sudden numbness, tingling, weakness, or loss of movement in your face, arm, or leg, especially on only one side of your body.
  • Sudden vision changes.
  • Sudden trouble speaking.
  • Sudden confusion or trouble understanding simple statements.
  • Sudden problems with walking or balance.
  • A sudden, severe headache that is different from past headaches.
Call your doctor immediately if you have:

  • Had recent symptoms of a TIA or stroke, even if the symptoms have disappeared.
  • Had a TIA or stroke and are taking aspirin or other medicines that prevent blood clotting and you notice any signs of bleeding.
  • Had a stroke and have a choking episode from food going down your windpipe.
  • Had a stroke and have signs of a blood clot in a deep blood vessel, which include redness, warmth, and pain in a specific area of your arm or leg.

Diagnosing stroke 


Strokes are usually diagnosed by studying images of the brain (brain imaging) and carrying out physical tests.
Your doctor may check for the causes of your stroke by taking blood tests to determine your cholesterol and blood sugar levels, checking your pulse for an irregular heartbeat and taking a blood pressure measurement.

Even if the physical symptoms of a stroke are obvious, brain imaging should also be carried out to determine:
  • if the stroke has been caused by a blocked artery or burst blood vessel
  • which part of the brain has been affected
  • how severe the stroke is
  • the risk of a transient ischaemic attack (TIA)
Different treatment is required for each type of stroke so a rapid diagnosis will make treatment more straightforward.

CT and MRI scans


Two common methods used for brain imaging are a computer tomography (CT) scan and a magnetic resonance imaging (MRI) scan.

A CT scan is like an X-ray, but uses multiple images to build up a more detailed, three-dimensional (3D) picture of your brain. An MRI scan uses a strong magnetic field and radio waves to produce a detailed picture of the inside of your body.

The type of scan you may have in hospital depends on your symptoms. If it is suspected you had a major stroke, a CT scan is sufficient to identify whether the stroke is due to bleeding or clotting. It's quicker than an MRI scan and improves the chances of rapidly delivering treatments such as clot-busting drugs (thrombolysis) that might be used in appropriate cases, but are time-limited and require the results of the scan before the treatment can be given safely.

For people with more complex symptoms, where the extent or location of the damage is unknown, and in patients who have recovered from a transient ischaemic attack, an MRI scan is more appropriate. This will provide greater detail of brain tissue, allowing smaller, or more unusually located strokes to be identified.
All patients with suspected stroke should receive a brain scan within 24 hours. Some patients should be scanned within the hour, especially those who:
  • might benefit from clot-busting drugs (thrombolysis) such as alteplase or early anticoagulant treatment
  • are already on anticoagulant treatments
  • have a lower level of consciousness
After the injection of a dye into an arm vein, both CT and MRI can be used to take pictures of the blood vessels in the brain, as well as the blood vessels in the neck that take blood to the brain from the heart. This is known as CT or MR angiography and is often done immediately after taking pictures of the brain itself.

Swallow tests


A swallow test is essential for anybody who has had a stroke.

Swallowing problems affect over a third of people after a stroke. When a person cannot swallow properly, there is a risk that food and drink may get into the windpipe and then into the lungs (called aspiration), which can lead to chest infections and pneumonia.

The test is simple. The person is given a few teaspoons of water to drink. If they can swallow this without choking and coughing they will be asked to swallow half a glass of water.

If they have any difficulty swallowing, they will be referred to the speech and language therapist for a more detailed assessment. They will usually be kept ‘nil by mouth’ until they have seen the therapist and may therefore need to have fluids or food given directly into an arm vein (intravenous drip) or through the nose using a nasogastric tube.

Heart and blood vessel tests 


Further tests on the heart and blood vessels might be carried out later to confirm what caused the stroke. These may include:

1. Ultrasound (carotid ultrasonography)

An ultrasound scan uses high frequency sound waves to produce an image of the inside of your body. Your doctor may use a wand-like probe (transducer) to send high-frequency sound waves into your neck. These pass through the tissue creating images on a screen that will show if there is any narrowing or clotting in the arteries leading to your brain.

This type of ultrasound scan is sometimes known as a doppler scan or a duplex scan. Where carotid ultrasonography is needed, it should happen within 48 hours.

2. Catheter angiography (arteriography)

Dye is injected into your carotid or vertebral artery via a tube called a catheter. This gives a more detailed view of your arteries than can be obtained using ultrasound, CT angiography or MR angiography.

3. Echocardiogram

In some cases an echocardiogram may be used to produce images of your heart using an ultrasound probe placed on your chest (transthoracic echocardiogram). In addition, transoesophageal echocardiography (TOE) may also be used. This involves an ultrasonic probe which is passed down the foodpipe (oesophagus), usually under sedation. Because it's directly behind the heart, it produces a clear image of blood clots and other abnormalities that may not get picked up by the transthoracic echocardiogram.

Treatments and drugs for Stroke


Emergency treatment for stroke depends on whether you're having an ischemic stroke blocking an artery — the most common kind - or a hemorrhagic stroke involving bleeding into the brain.

Ischemic stroke


To treat an ischemic stroke, doctors must quickly restore blood flow to your brain.

Emergency treatment with medications. Therapy with clot-busting drugs (thrombolytics) must start within 4.5 hours if they are given into the vein — and the sooner, the better. Quick treatment not only improves your chances of survival but also may reduce the complications from your stroke. You may be given:

  • Aspirin. Aspirin, an anti-thrombotic drug, is an immediate treatment after an ischemic stroke to reduce the likelihood of having another stroke. Aspirin prevents blood clots from forming. In the emergency room, you may be given a dose of aspirin. The dose may vary, but if you already take a daily aspirin for its blood-thinning effect, you may want to make a note of that on an emergency medical card so doctors will know if you've already taken some aspirin.

Other blood-thinning drugs, such as heparin, also may be given, but this drug isn't proven to be beneficial in the emergency setting so it's used infrequently. Clopidogrel (Plavix), warfarin (Coumadin), or aspirin in combination with extended release dipyridamole (Aggrenox) may also be used, but these aren't usually used in the emergency room setting.

  • Intravenous injection of tissue plasminogen activator (TPA). Some people who are having an ischemic stroke can benefit from an injection of a recombinant tissue plasminogen activator (TPA), also called alteplase, usually given through a vein in the arm. This potent clot-busting drug needs to be given within 4.5 hours after stroke symptoms begin if it's given into the vein. This drug restores blood flow by dissolving the blood clot causing your stroke, and it may help people who have had strokes recover more fully. Your doctor will consider certain risks, such as potential bleeding in the brain, to determine if TPA is the most appropriate treatment for you.

Emergency procedures. Doctors sometimes treat ischemic strokes with procedures that must be performed as soon as possible.

  • Medications delivered directly to the brain. Doctors may insert a long, thin tube (catheter) through an artery in your groin and thread it to your brain, and then release TPA directly into the area where the stroke is occurring. The time window for this treatment is somewhat longer than for intravenous TPA but still limited.
  • Mechanical clot removal. Doctors may use a catheter to maneuver a tiny device into your brain to physically grab and remove the clot.

Other procedures. To decrease your risk of having another stroke or TIA, your doctor may recommend a procedure to open up an artery that's moderately to severely narrowed by plaque. Doctors sometimes recommend these procedures to prevent a stroke. Options may include:

  • Carotid endarterectomy. In a carotid endarterectomy, a surgeon removes fatty deposits (plaques) from your carotid arteries that run along each side of your neck to your brain. In this procedure, your surgeon makes an incision along the front of your neck, opens your carotid artery, and removes fatty deposits (plaques) that block the carotid artery. Your surgeon then repairs the artery with stitches or a patch made with a vein or artificial material (graft). The procedure may reduce your risk of ischemic stroke. However, a carotid endarterectomy also involves risks, especially for people with heart disease or other medical conditions.
  • Angioplasty and stents. In an angioplasty, a surgeon inserts a catheter with a mesh tube (stent) and balloon on the tip into an artery in your groin and guides it to the blocked carotid artery in your neck. Your surgeon inflates the balloon in the narrowed artery and inserts a mesh tube (stent) into the opening to keep your artery from becoming narrowed after the procedure.

Hemorrhagic stroke


Emergency treatment of hemorrhagic stroke focuses on controlling your bleeding and reducing pressure in your brain. Surgery also may be used to help reduce future risk.

Emergency measures. If you take warfarin (Coumadin) or anti-platelet drugs such as clopidogrel (Plavix) to prevent blood clots, you may be given drugs or transfusions of blood products to counteract their effects. You may also be given drugs to lower pressure in your brain (intracranial pressure), lower your blood pressure or prevent seizures. People having a hemorrhagic stroke can't be given clot-busters such as aspirin and TPA, because these drugs may worsen bleeding.

Once the bleeding in your brain stops, treatment usually involves bed rest and supportive medical care while your body absorbs the blood. Healing is similar to what happens while a bad bruise goes away. If the area of bleeding is large, surgery may be used in certain cases to remove the blood and relieve pressure on the brain.

Surgical blood vessel repair. Surgery may be used to repair certain blood vessel abnormalities associated with hemorrhagic strokes. Your doctor may recommend one of these procedures after a stroke or if you're at high risk of a spontaneous aneurysm or arteriovenous malformation (AVM) rupture:

  • Surgical clipping. A surgeon places a tiny clamp at the base of the aneurysm, to stop blood flow to it. This can keep the aneurysm from bursting, or it can prevent re-bleeding of an aneurysm that has recently hemorrhaged.
  • Coiling (endovascular embolization). In this procedure, a surgeon inserts a catheter into an artery in your groin and guides it to your brain using X-ray imaging. Your surgeon then guides tiny detachable coils into the aneurysm (aneurysm coiling). The coils fill the aneurysm, which blocks blood flow into the aneurysm and causes the blood to clot.
  • Surgical AVM removal. Surgeons may remove a smaller AVM if it's located in an accessible area of your brain, to eliminate the risk of rupture and lower the risk of hemorrhagic stroke. However, it's not always possible to remove an AVM if it's too large or if it's located deep within your brain.

Stroke recovery and rehabilitation


Following emergency treatment, stroke care focuses on helping you regain your strength, recover as much function as possible and return to independent living. The impact of your stroke depends on the area of the brain involved and the amount of tissue damaged. If your stroke affected the right side of your brain, your movement and sensation on the left side of your body may be affected. If your stroke damaged the brain tissue on the left side of your brain, your movement and sensation on the right side of your body may be affected. Brain damage to the left side of your brain may cause speech and language disorders. In addition, if you've had a stroke, you may have problems with breathing, swallowing, balancing and vision.

Most stroke survivors receive treatment in a rehabilitation program. Your doctor will recommend the most rigorous therapy program you can handle based on your age, overall health and your degree of disability from your stroke. Your doctor will take into consideration your lifestyle, interests and priorities, and availability of family members or other caregivers.

Your rehabilitation program may begin before you leave the hospital. It may continue in a rehabilitation unit of the same hospital, another rehabilitation unit or skilled nursing facility, an outpatient unit, or your home.

Every person's stroke recovery is different. Depending on your condition, your treatment team may include:

  • Doctor trained in brain conditions (neurologist)
  • Rehabilitation doctor (physiatrist)
  • Nurse
  • Dietitian
  • Physical therapist
  • Occupational therapist
  • Recreational therapist
  • Speech therapist
  • Social worker
  • Case manager
  • Psychologist or psychiatrist

Preventing stroke


Knowing your stroke risk factors, following your doctor's recommendations and adopting a healthy lifestyle are the best steps you can take to prevent a stroke. If you've had a stroke or a TIA, these measures may help you avoid having another stroke.

Controlling high blood pressure (hypertension)


One of the most important things you can do to reduce your stroke risk is to keep your blood pressure under control. If you've had a stroke, lowering your blood pressure can help prevent a subsequent transient ischemic attack or stroke. Exercising, managing stress, maintaining a healthy weight, and limiting the amount of sodium and alcohol you eat and drink are all ways to keep high blood pressure in check. Adding more potassium to your diet also may help. In addition to recommending lifestyle changes, your doctor may prescribe medications to treat high blood pressure.

Exercise


Combining a healthy diet with regular exercise is the best way to maintain a healthy weight. Having a healthy weight reduces your chances of developing high blood pressure.

Regular exercise will make your heart and blood circulatory system more efficient. It will also lower your cholesterol level and keep your blood pressure at a healthy level.

The recommended level of cholesterol is 5mmol/litre (5 millimoles per litre of blood).

Blood pressure is measured using two figures. One figure represents the pressure of the heart as it contracts to pump blood around the body. This is known as the systolic pressure. The second figure represents the pressure of the heart as it rests, expands and fills with blood, while waiting for the next contraction. This is known as the diastolic pressure.

For most people, an ideal blood pressure is a systolic pressure of 90-120 millimeters of mercury (mmHg) and a diastolic pressure of 60-80mmHg. Or, as blood pressure is normally expressed, a level between 90/60mmHg or 120/80mmHg.

For most people, at least 150 minutes (2 hours and 30 minutes) of moderate-intensity aerobic activity, such as cycling or fast walking, every week is recommended.

If you are recovering from a stroke, you should discuss possible exercise plans with the members of your rehabilitation team. Regular exercise may be impossible in the first weeks or months following a stroke but you should be able to begin exercising once your rehabilitation has progressed.

Smoking


Smoking doubles your risk of having a stroke. This is because it narrows your arteries and makes your blood more likely to clot.

If you stop smoking, you can reduce your risk of having a stroke by up to half. Not smoking will also improve your general health and reduce your risk of developing other serious conditions, such as lung cancer and heart disease.

Diet


A poor diet is a major risk factor for a stroke. High-fat foods can lead to the build-up of fatty plaques in your arteries and being overweight can lead to high blood pressure.

A low-fat, high-fibre diet is recommended, including plenty of fresh fruit and vegetables (five portions a day) and whole grains. You should limit the amount of salt you eat to no more than 6g (0.2oz) a day because too much salt will increase your blood pressure. Six grams of salt is about one teaspoonful.

There are two types of fat – saturated and unsaturated. You should avoid food containing saturated fats because these will increase your cholesterol levels.

Foods high in saturated fat include:
  • meat pies 
  • sausages and fatty cuts of meat 
  • butter 
  • ghee – a type of butter often used in Indian cooking 
  • lard 
  • cream 
  • hard cheese 
  • cakes and biscuits 
  • foods that contain coconut or palm oil.
However, a balanced diet should include a small amount of unsaturated fat, which will help reduce your cholesterol levels.

Foods high in unsaturated fat include:

Alcohol


Excessive alcohol consumption can lead to high blood pressure and an irregular heartbeat (atrial fibrillation). Both are major risk factors for stroke.

Because alcoholic drinks are rich in energy (high in calories) they also cause weight gain. Heavy drinking multiplies the risk of stroke by more than three times.

Preventive medications


If you've had an ischemic stroke or TIA, your doctor may recommend medications to help reduce your risk of having another stroke. These include:

Anti-platelet drugs. Platelets are cells in your blood that initiate clots. Anti-platelet drugs make these cells less sticky and less likely to clot. The most frequently used anti-platelet medication is aspirin. Your doctor can help you determine the right dose of aspirin for you.

Your doctor may also consider prescribing Aggrenox, a combination of low-dose aspirin and the anti-platelet drug dipyridamole, to reduce the risk of blood clotting. If aspirin doesn't prevent your TIA or stroke, or if you can't take aspirin, your doctor may instead prescribe an anti-platelet drug such as clopidogrel (Plavix).

Anticoagulants. These drugs, which include heparin and warfarin (Coumadin), reduce blood clotting. Heparin is fast acting and may be used over a short period of time in the hospital. Slower acting warfarin may be used over a longer term.

Warfarin is a powerful blood-thinning drug, so you'll need to take it exactly as directed and watch for side effects. Your doctor may prescribe these drugs if you have certain blood-clotting disorders, certain arterial abnormalities, an abnormal heart rhythm or other heart problems. Other newer blood thinners may be used if your TIA or stroke was caused by an abnormal heart rhythm.