Transient ischemic attack

What is it?

According to the NINDS and MedlinePlus: a transient ischaemic attack (often called a "mini-stroke") is a "stroke that lasts only a few minutes", occurring when the blood supply to part of the brain is temporarily blocked. The CDC states that blood flow is blocked for a short time "usually no more than 5 minutes", and that these are sometimes called "warning strokes".

The difference from stroke: the NHS says the symptoms are the same but last minutes to hours and clear completely within 24 hours, whereas in a full stroke blood flow to the brain is disrupted for longer and causes more severe damage. The CDC stresses that there is no way to know whether symptoms at their start come from a transient attack or a major stroke, and that a transient attack is "a medical emergency just like a major stroke".

Causes

The NHS says that the blockage responsible for most transient attacks is usually caused by a blood clot that forms elsewhere in the body and travels to the vessels supplying the brain, and may also be caused by pieces of fatty material or air bubbles, and very rarely a small bleed in the brain. Clots form in arteries that have narrowed or become blocked over time through the build-up of fatty deposits (plaques), known as atherosclerosis.

Atrial fibrillation (one of the heart rhythm disorders) can lead to clots forming that leave the heart and lodge in the brain's vessels (NHS). The NINDS states that the blockage in a transient attack breaks up and dissolves on its own.

Risk factors

According to the NINDS: anyone can have one, but it is more common in older people. Risk factors include high blood pressure, cigarette smoking, heart disease, carotid or peripheral artery disease, diabetes, excessive alcohol, and excess weight and obesity.

The NHS adds: high cholesterol and atrial fibrillation, age (more common over 55), and descent from South Asian, African or Caribbean backgrounds. MedlinePlus lists controlling blood pressure and cholesterol among the means of prevention.

Symptoms

Symptoms appear suddenly (NINDS, MedlinePlus): numbness or weakness in the face, arm or leg, especially on one side of the body; difficulty speaking or understanding speech; vision problems in one or both eyes, or double vision; difficulty walking; dizziness; loss of balance and coordination; confusion.

The FAST test as the NHS presents it: Face may droop on one side and the person cannot smile; Arms, the person may not be able to lift both arms and keep them raised; Speech may be slurred, garbled or absent; Time to call an ambulance immediately. In the B.E. F.A.S.T. version, the CDC adds loss of balance and changes in vision. Other symptoms the NHS mentions include sudden loss of vision, vertigo, paralysis on one side and difficulty swallowing.

Duration: most symptoms go away within an hour, and may last up to 24 hours (NINDS, MedlinePlus). The CDC cautions that many people ignore the attack because it goes away, even though it is "a sign of a serious condition that will not go away without medical help".

How is it diagnosed?

The doctor can diagnose a transient attack based on the symptoms and medical history, with a physical examination looking for heart, vascular, muscle and nerve problems, and may request brain imaging by MRI or CT scan (NINDS). The NHS states that brain scans are not always necessary, and are usually done if the part of the brain affected is unclear, and that MRI is the most used.

Other tests according to the NHS: measuring blood pressure because high pressure can lead to transient attacks; blood tests to detect high cholesterol or diabetes; an electrocardiogram to measure the heart's electrical activity; and ultrasound imaging of the carotid arteries to detect narrowing or blockage of the neck arteries leading to the brain.

Timing of assessment: the NHS recommends that a specialist assess the case within 24 hours of symptom onset, and states that the medical team may give an antiplatelet medicine as soon as it is suspected unless there is a medical reason against it. Detailed procedures differ between health systems, and do not take any medicine on your own.

Treatment

The treatment categories usually used are listed here; this is not a prescription. The doctor chooses the plan according to each person's condition; do not change any medicine or dose without a specialist.

The NINDS says the transient attack itself needs no treatment because the blockage breaks up and dissolves by itself; the aim is to lower the risk of stroke: starting exercise, trying to lose weight, quitting smoking, and controlling blood pressure. The CDC states that recognising and treating transient attacks lowers the risk of a major stroke.

Medicine categories according to the NHS (the doctor chooses what suits your condition): antiplatelets, which reduce platelets sticking together and forming clots; anticoagulants, usually given to those whose attack was caused by a clot from the heart (often with atrial fibrillation), both carrying a risk of bleeding; blood-pressure-lowering medicines (thiazide diuretics, angiotensin-converting enzyme inhibitors, calcium channel blockers and beta blockers), and two or more may be combined; and statins for high cholesterol. The NINDS and MedlinePlus mention blood thinners and anticoagulants. Do not start or stop any medicine without the doctor.

Surgery: if the neck arteries are blocked, the patient may need surgery to open them (NINDS); the NHS describes carotid endarterectomy, i.e. removing part of the lining of the carotid arteries together with the blockage to restore blood flow, and says it greatly lowers the risk of stroke.

Follow-up

After the attack, control of risk factors continues: high cholesterol, blood pressure, atrial fibrillation and diabetes through lifestyle changes and medicines when needed (NHS); the NINDS stresses the need to treat conditions such as high blood pressure, heart disease and high cholesterol. This page does not cover detailed follow-up schedules.

Driving: the NHS advises stopping driving immediately after the attack and not returning until the doctor agrees; the rules on driving after an attack differ between countries.

Complications

The most important consequence is the risk of stroke: according to the NINDS about a third of those affected will have a severe stroke at some point in the future. According to the CDC, more than a third of those who have a transient attack and receive no treatment have a major stroke within a year, and up to 10% to 15% within 3 months. The NHS describes it as a warning of the risk of a full stroke in the near future.

Prevention

According to the NHS: the best prevention is a healthy diet, regular exercise, not smoking and not drinking excessive alcohol. A low-fat, high-fibre diet is usually advised, including at least 5 portions of fruit and vegetables a day and whole grains, with salt no more than 6 grams a day (about one teaspoon), and at least 150 minutes a week of moderate-intensity activity or 75 minutes of vigorous activity, with strengthening exercises two days a week. These are general NHS recommendations and may differ between countries, and the doctor decides what suits you.

MedlinePlus mentions avoiding smoking and excessive alcohol, a healthy diet, regular exercise, and controlling blood pressure and cholesterol; the NINDS mentions weight loss and blood pressure control.

Living with it

What to do when symptoms occur: call an ambulance immediately, and do not drive to the hospital or let anyone drive you (NINDS, CDC), and note the time symptoms appeared because it helps doctors choose treatment (CDC). Even if symptoms go away while waiting for the ambulance, assessment in hospital is essential (NHS).

After assessment: keep to the doctor's medicine plan and lifestyle changes, because recognising and treating transient attacks lowers the risk of a major stroke (CDC). This page does not cover living after an attack in detail.

Common questions