Transient ischemic attack

• Sudden weakness, numbness or paralysis in your face, arm or leg, typically on one side of your body
• Slurred or garbled speech or difficulty understanding others
• Sudden blindness in one or both eyes or double vision
• Dizziness, loss of balance or coordination

You may have more than one TIA, and the recurrent signs and symptoms may be similar or different depending on which area of the brain is involved. If signs and symptoms last longer than 24 hours or cause lasting brain damage, it's considered a stroke.

Causes

A transient ischemic attack has the same origins as that of an ischemic stroke, the most common type of stroke. In an ischemic stroke, a clot blocks the blood supply to part of your brain. In a transient ischemic attack, unlike a stroke, the blockage is brief and there is no permanent damage.

The underlying cause of a TIA often is a buildup of cholesterol-containing fatty deposits called plaques (atherosclerosis) in an artery or one of its branches that supply oxygen and nutrients to your brain. Plaques can decrease the blood flow through an artery or lead to the development of a clot. Other causes include a blood clot moving to your brain from another part of your body, most commonly from your heart.

Risk factors

Some risk factors for transient ischemic attack and stroke can't be changed. Others, you can control.

Risk factors you can't change

You can't change the following risk factors for transient ischemic attack and stroke. But knowing you're at risk can motivate you to change your lifestyle to reduce other risks.

• Having a family history. Your risk may be greater if one of your family members has had a TIA or a stroke.
• Being 55 years old or older. Your risk increases as you get older, especially after age 55.
• Being a man. Men have a slightly higher likelihood of TIA and stroke than women do, but more than half of deaths from stroke occur in women.

Risk factors you can take steps to control

You can control or treat a number of risk factors, including:

• High blood pressure. A systolic blood pressure of 140 millimeters of mercury (mm Hg) or higher, or a diastolic pressure of 85 mm Hg or higher increases your risk.
• Cardiovascular disease. This includes heart failure, a heart defect, heart infection or abnormal heart rhythm.
• Carotid artery disease. The blood vessels in your neck that lead to your brain become clogged.
• Peripheral artery disease (PAD). The blood vessels that carry blood to your arms and legs become clogged.
• Cigarette smoking. Smoking increases your risk of blood clots, raises your blood pressure and contributes to the development of cholesterol-containing fatty deposits in your arteries (atherosclerosis).
• Physical inactivity. Engaging in 30 minutes of moderate intensity exercise most days helps reduce risk.
• Diabetes. Diabetes increases the severity of atherosclerosis — narrowing of the arteries due to accumulation of fatty deposits — and the speed with which it develops.
• Poor nutrition. Eating too much fat and salt, in particular, increases your risk of TIA and stroke.
• High cholesterol — a total cholesterol level of 200 milligrams per deciliter (mg/dL), or 5.2 millimoles per liter (mmol/L), or higher increases your risk of TIA and stroke.
• High levels of homocysteine. Elevated levels of this amino acid in your blood can cause your arteries to thicken and scar, which makes them more susceptible to clogs.
• Obesity. A body mass index of 30 or higher and a waist circumference greater than 35 inches in women or 40 inches in men increases risk.
• Heavy drinking. If you drink alcohol, limit yourself to no more than two drinks daily if you're a man and one drink daily if you're a woman.
• Use of illicit drugs. Avoid cocaine and other drugs.
• Use of birth control pills. If you use any hormone therapy, talk to your doctor about how the hormones may affect your risk of TIA and stroke.

Diagnosis

Because a transient ischemic attack is short-lived, your doctor may diagnose a TIA based just on the medical history of the event rather than on anything found during a general physical and neurological examination. To help determine the cause of your TIA and to assess your risk of stroke, your doctor may rely on the following:

• Physical examination and tests. Your doctor may check for risk factors of stroke, including high blood pressure, high cholesterol levels, diabetes, and high levels of the amino acid homocysteine. Your doctor may also use a stethoscope to listen for a whooshing sound (bruit) over your arteries that may indicate atherosclerosis. Or your doctor may observe cholesterol fragments (emboli) in the tiny blood vessels of your retina, at the back of your eye, during an eye examination using an ophthalmoscope.
• Carotid ultrasonography. A wand-like device (transducer) sends high-frequency sound waves into your neck. After the sound waves pass through your tissue and back, your doctor can analyze images on a screen to look for narrowing or clotting in the carotid arteries.
• Computerized tomography (CT) scanning. CT scanning of your head uses X-ray beams to assemble a composite, 3-D look at your brain.
• Computerized tomography angiography (CTA) scanning. Scanning of the head may also be used to noninvasively evaluate the arteries in your neck and brain. CTA scanning uses X-rays, similar to a standard CT scan of the head, but may also involve injection of a contrast material into a blood vessel.
• Magnetic resonance imaging (MRI). This procedure, which uses a strong magnetic field, can generate a composite, 3-D view of your brain.
• Magnetic resonance angiography (MRA). This is a method of evaluating the arteries in your neck and brain. It uses a strong magnetic field, similar to MRI.
• Transesophageal echocardiography (TEE). During this procedure, a flexible probe with a transducer built into it is placed in your esophagus — the tube that connects the back of your mouth to your stomach. Because your esophagus is directly behind your heart, very clear, detailed ultrasound images can be created, allowing a better view of some things, such as blood clots, that might not be seen clearly in a traditional echocardiography exam.
• Arteriography. This procedure gives a view of arteries in your brain not normally seen in X-ray imaging. A radiologist inserts a thin, flexible tube (catheter) through a small incision, usually in your groin. The catheter is manipulated through your major arteries and into your carotid or vertebral artery. Then, the radiologist injects a dye through the catheter to provide X-ray images of the arteries in your brain.

References

http://www.nhs.uk/conditions/transient-ischaemic-attack/pages/introduction.aspx

http://www.mayoclinic.org/diseases-conditions/transient-ischemic-attack/basics/definition/con-20021291

http://www.mayoclinic.org/diseases-conditions/transient-ischemic-attack/basics/definition/con-20021291