What Is A Mini-Stroke? What Is A Transient Ischemic Attack (TIA)?

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Main Category: Stroke
Also Included In: Neurology / Neuroscience;  Cardiovascular / Cardiology
Article Date: 16 Sep 2009 - 2:00 PDT

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A mini-stroke, or transient ischemic attack (TIA) occurs when there is a temporary drop in the blood supply to the brain, depriving it of essential oxygen. The patient experiences stroke-like symptoms, although they don't last as long. A mini-stroke only lasts a few minutes and disappears within a day.

In other words, a TIA is like a stroke, produces similar symptoms, but only lasts a few minutes and causes no permanent damage.

Health experts say a TIA may be a warning. Approximately 30% of people who have a TIA eventually go on to have a stroke. Half of that 30% have a stroke within a year of their TIA. Although some may call it a warning, it may also be seen as an opportunity to take steps to prevent a full blown stroke.

According to Medilexicon's medical dictionary, a Transient Ischemic Attack is "a sudden focal loss of neurologic function with complete recovery usually within 24 hours; caused by a brief period of inadequate perfusion in a portion of the territory of the carotid or vertebral basilar arteries."

What are the signs and symptoms of a TIA (mini-stroke)?

A symptom is something the patient experiences or reports, such as a headache, while a sign is something others detect, such as a rash. The signs and symptoms of a TIA are represented by the abbreviation FAST (Face, Arms, Speech, Time):

• Face - the face may fall on one side as some of the facial muscles become paralyzed. The patient's eye or mouth may droop, and he/she may be unable to smile properly.


• Arms - arm weakness or numbness might make it hard for the patient to either raise both arms, or to keep them raised.


• Speech - speech may be slurred and garbled.


• Time - when you see at least one of these symptoms it is Time to dial emergency services (911 in USA, 999 in UK).

If signs and symptoms last more than 24 hours or cause lasting brain damage, it's considered a stroke. Do not wait 24 hours to find out!

Being able to identify the signs and symptoms present in FAST is especially important if you live with somebody in a high risk group, such as an elderly person, or an individual with hypertension (high blood pressure) or diabetes.

Other signs and symptoms include:

• Dizziness
• Difficulty talking
• Difficulty understand what others are talking about
• Swallowing difficulties
• Very bad headache
• Paralysis, numbness or weakness on one side of the body
• In severe cases, loss of consciousness

If you or somebody else has at least three of these signs and symptoms medical attention should be sought immediately.

TIA symptoms are temporary and should disappear within 24 hours. They may last from a couple of minutes to 15 minutes. TIA sufferers experience varying symptoms, depending on which part of the brain is affected.

In some cases a TIA may be a prelude to a full stroke, in which case permanent and possibly serious damage occurs. Prompt medical attention and treatment significantly reduces the risk of experiencing another TIA or stroke.

In other words - if think that you, or somebody else, is having a TIA, get medical attention immediately.

What are the causes of a TIA?

• Disruption of blood supply to the brain
  
  Two main blood vessels - the carotid arteries - supply blood to the brain. These arteries branch off into many smaller blood vessels which provide the whole of the brain with essential nutrients, such as blood, glucose, and oxygen. A TIA can occur if one of the smaller blood vessels becomes blocked, depriving that part of the brain of oxygen-rich blood.
  
  In the case of a TIA, the blocked blood supply is temporary and the affected part of the brain soon returns to normal. When a full stroke occurs the oxygen-rich blood supply is disrupted for much longer, causing brain cells to die.
  
  Blood supply to parts of the brain is usually disrupted because of a narrowing of the arteries (stenosis) or the formation of a blood clot.


• Atherosclerosis
  
  Atherosclerosis causes arteries to narrow (stenosis). Fatty deposits (plaque) develop on the inner lining of blood cells, causing them to become hardened, thickened and less flexible - resulting in more difficulties with blood flow.


• Blood clots
  
  A blood clot can disrupt the supply of oxygen-rich blood to parts of the brain. Blood clots are usually caused by:
  
  
  • Heart conditions - congestive heart muscle disease or atrial fibrillation are common causes of blood clots.
  
  
  • Blood conditions - leukemia (blood cell cancer), sickle cell anemia, hyperlipidemia (high blood fat levels), polycythemia (very thick blood), or thrombocyemia (overproduction of blood platelets) are common causes of blood clots.
  
  
  • Infections - phlebitis can cause blood clots.
  
  An embolism can cause a TIA, and even a full blown stroke. A blood clot from a blood vessel in another part of the body becomes dislodged and travels into one of the arteries that supplies blood to the brain.


• Hemorrhage (internal bleeding)
  
  A minor brain hemorrhage (small amount of bleeding in the brain) can cause a TIA; however, this is rare.

What are the risk factors for TIA?

There are some risk factors we can change, and others we can't.

Risk factors we cannot change:

• A family history - people with a family history of TIA or stroke, i.e. people with a close relative who has had a stroke or TIA, have a higher risk of experiencing one themselves.


• Age - people aged 55 years or more have a higher risk of TIAs compared to younger people. The older you get, the higher the risk becomes.


• Sex - males have a slightly higher risk of stroke and/or TIA than women.


• Ethnic origin - people of black African ancestry have a higher risk of stroke and TIA than others.

Risk factors we can change:

• Hypertension - people with high blood pressure have a significantly higher risk of developing a TIA, compared to people of normal blood pressure. Hypertension means the patient's systolic blood pressure is 140 mm hg or higher, and diastolic pressure is mm hg or higher.


• Cardiovascular disease - people with cardiovascular diseases have a higher risk of stroke and/or TIA. This includes a heart defect, heart failure or arrhythmia (abnormal heart rhythm).


• Carotid artery disease - this is when the blood vessels in the neck that lead to the brain are clogged.


• PAD (peripheral artery disease) - people whose blood vessels that carry blood to their arms and legs become clogged have a higher risk of stroke and TIA.


• Smoking - smoking increases the risk of various diseases and conditions, including TIA, stroke, blood clots, heart attack, cardiovascular disease, cancer, erectile dysfunction, and blindness in old age.


• Sedentary lifestyle - people who are physically inactive have a significantly higher risk of stroke or TIA compared to people who do 30 minutes of moderate exercise at least 5 times per week.


• Diabetes - patients with diabetes are more likely to suffer from atherosclerosis (narrowing of the arteries due to a build up of fatty deposits), raising the risk of stroke or TIA. This is especially the case if the diabetes is poorly controlled.


• Bad diet - people who consume too much bad qualtiy fat and/or salt have a higher risk of stroke and TIA.


• Blood cholesterol levels - if your blood cholesterol level is at least 200 mg/dL or 5.2 mmol/L you have a higher risk of TIA or stroke.


• Homocysteine levels - homocysteine is an amino acid produced by the body. It is usually a byproduct of consuming meat. It is made from another amino acid, methionine, and then is concerted into other amino acids. Elevated levels of homocysteine in the blood can make the arteries thicken and scar, and more susceptible to clogs, resulting in a higher risk of stroke and TIA.


• Bodyweight - obese people have a significantly higher risk of stroke or TIA than people of normal body weight.


• Alcohol - people who drink large quantities of alcohol regularly are much more likely to have a stroke or TIA than people who never drink or drink within recommended limits.


• Illegal drugs - some illegal drugs, such as cocaine, can raise the risk of stroke or TIA if taken often enough.

How is a TIA diagnosed?

Anybody who has signs and symptoms of a TIA should seek medical attention immediately. As TIAs do not last very long it is most likely the patient will have no symptoms by the time he/she gets to see the doctor.

The GP (general practitioner, primary care physician) or hospital doctor may need to carry out a neurological examination, even if symptoms have gone. This will include some simple tasks to check skills, such as memory and coordination. While being examined the patient will be asked questions regarding symptoms, such as how long they lasted, what they were like, and how they affected the patient. This will help the doctor discard any other conditions which may have similar symptoms.

If the GP, or non-specialized doctor or health care professional believes the patient may have had a TIA he/she will be referred to a neurologist for further testing. A neurologist is a doctor specialized in the diagnosis and treatment of disorders of the nervous system - the brain, spinal cord and the nerves. In the UK and many other countries the patient may be referred to a neurologist who specializes in strokes, or a specialist TIA clinic.

The specialist may order a number of tests designed to identify the underlying factors or conditions which may have caused the TIA.

• Blood tests
  
  
  • Blood pressure - the patient's blood pressure will be checked for hypertension.
  • Blood clotting test - this is to find out how likely the patient's blood is to clot.
  • Blood cholesterol test - this test determines whether the patient's blood cholesterol level is high.


• Electrocardiogram (ECG) - this device records the electrical activity and rhythms of the patient's heart. Electrodes are attached to the patient's skin and impulses are recorded as waves are displayed on a screen (or printed on paper). The test may also reveal any damage to the heart from a heart attack.


• Echocardiogram - this is an ultrasound scan that checks the pumping action of the patient's heart. This test also helps distinguish systolic heart failure from diastolic heart failure (the heart is stiff and does not fill properly). Sound waves are used to create a video image of the patient's heart, which helps the doctor see how well the heart is pumping. The doctor measures the percentage of blood pumped out of the patient's left ventricle (the main pumping chamber) with each heartbeat - this measurement is called the ejection fraction.


• Chest X-ray - this test helps the doctor rule out any other illness or health condition.


• Computerized tomography (CT) scan - a scanning device that creates a 3-D image that can show aneurysms, bleeding, or abnormal vessels within the brain. It can also reveal whether there is a tumor.


• Magnetic resonance imaging (MRI) scan - a magnetic field generates a 3-D view of the brain. An MRI can often give a more detailed view of the brain than a CT scan, and can help the doctor identify any brain damage.


• Ultrasound - a wand waved over the carotid arteries in the neck can provide a picture that indicates any narrowing or clotting.

What are the treatment options for TIAs?

When the doctor has identified what caused the TIA his/her aim is to treat it, thus minimizing the risk of a subsequent stroke. The doctor may prescribe medication which lowers the risk of a blood clot, or recommend surgery or an angioplasty; this will depend on the cause of the TIA.

Medications

The type of medication(s) prescribed will depend on what caused the TIA, how severe it was, and what part of the brain was affected.

• Anti-platelet drugs
  
  These make the platelets less likely to stick together. When a blood vessel has a lesion platelets start forming clots by initially sticking to each other.


• Aspirin and dipyridamole - drugs, such as aspirin make the platelets less sticky and lower the risk of undesirable blood clots. Aspirin is commonly prescribed because it is cheap and has few side-effects. Some doctors may prescribe Aggrenox - this drug contains both aspirin as well as dipyridamole, another anti-platelet medication. Some doctors may recommend ticlopidine (Ticlid).
  
  Side effects of aspirin may include:
  • Indigestion
  • Nausea
  • Stomach irritation
  
  
  Side effects of dipyridamole may include:
  • Diarrhea
  • Dizziness
  • Headaches
  • Nausea


• Clopidogrel - the doctor may prescribe clopidogrel (Plavix) if the patient experienced severe side effects from taking aspirin, had a further TIA despite taking aspirin, or has arterial disease.
  
  Side effects of clopidogrel may include:
  • Abdominal pain
  • Bleeding
  • Bruising
  • Diarrhoea
  • Indigestion


• Anticoagulants
  
  Examples of anticoagulants are warfarin (Coumadin) and heparin. Warfarin can be used long-term, while heparin is used short-term. Patients on anticoagulants need to be monitored closely.


• Warfarin - this is the most commonly used anticoagulant for the prevention of subsequent TIAs. The doctor has to make sure that warfarin thins the patient's blood enough, but not so much that there is a risk of internal bleeding. Patients will have to undergo regular blood tests (INR - international normalized ratio tests).
  
  The most serious undesirable side effect of warfarin is bleeding. Any patient on warfarin who has any of the following symptoms should tell his/her doctor immediately:
  
  -- Blood in urine
  -- Blood in feces (either specs of blood, or feces are black)
  -- Severe bruising
  -- Nosebleeds that persist for more than ten minutes
  -- Blood in vomit
  -- Coughing up blood
  -- Unexplained headaches
  -- Bleeding from the vagina
  -- Heavy or increased bleeding during menstruation
  


• Medications for hypertension - hypertension (high blood pressure) needs to be controlled as it is an important risk factor for stroke and TIA. There are many different types of antihypertensive drugs. A doctor may prescribe one, or a combination. If the patient is unfit and overweight hypertension can often be brought down by losing weight, doing exercise, getting at least 7 hours good quality sleep every night, and eating a well balanced healthy diet.


• Cholesterol medication - high blood cholesterol levels significantly increase a patient's risk of stroke and TIA. As with hypertension, losing weight, following a well balanced diet, doing regular exercise, and sleeping at least 7 hours every night can help bring cholesterol levels back to normal. Sometimes medications are necessary and the patient may be prescribed a statin, which helps reduce the production of cholesterol.

Surgery - Carotid endarterectomy - this operation involves removing part of the lining of the damaged carotid artery, as well as any blockage that has accumulated in the artery. The carotid arteries deliver blood to the brain. When plaques (fatty deposits) accumulate inside them they become narrow and hard, making it more difficult for blood to flow through them (atherosclerosis).

This operation is not suitable for patients whose arteries are nearly completely blocked. Even some patients with partial blockage may not be suitable for this procedure because of the risk of stroke during the operation.

Prevention of TIAs or mini-strokes

The measures below can help you reduce your risks of having a mini-stroke (TIA), stroke, or a recurrent TIA:

• Give up smoking - the moment you stop smoking your risk of stroke, TIA and many other conditions and diseases goes down significantly, and continues dropping each month.


• Diet - follow a well balanced diet, with plenty of fruit and vegetables, whole grains, fish, poultry and very lean meat. Avoid all junk foods and foods with bad fats, such as saturated and trans fats.


• Salt (sodium) intake - if you have high blood pressure, or tend to have high blood pressure, avoid salty foods and do not add salt to your cooking.


• Physical exercise - exercise moderately for at least 30 minutes five times a week. Check with your doctor whether you can do this.


• Sensible alcohol consumption - either don't drink alcohol at all, or stay within the daily recommended limits.


• Body weight - if you are overweight or obese and can bring your body weight down to normal for your height and age your risk of stroke or TIA will go down dramatically, as will your risk of developing several other diseases and conditions.


• Illegal drugs - many illegal drugs, such as cocaine, significantly raise your risk of stroke and TIA. Even illegal drugs which are seen not to be particularly harmful are made without inspectors and quality control guarantees (you really don't know what is in them). Avoiding them may help reduce your risks.


• Diabetes - good diabetes control, i.e. following your diabetes treatment properly, greatly reduces your risks of stroke and TIA.


• Sleep - make sure you get at least 7 hours good quality, continuous sleep every day.

Written by Christian Nordqvist


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