A mini stroke is also called a Transient Ischaemic Attack or TIA. It is a brief episode of dysfunction in the brain. Like a stroke, TIA’s onset is sudden, over a few seconds or minutes.
People having a mini stroke can experience a variety of symptoms. The most important are weakness on one side affecting the face, arm or leg – or all three – or speech disturbance, which can be slurring or decreased speech fluency or comprehension. These are the typical symptoms, but sometimes people can experience visual loss, dizziness or vertigo.
Patients having a mini stroke return to normal within minutes or hours after the event. This gives the false impression it may not be serious and patients do not always seek medical attention. But it is very important if you or someone in your family experiences any of the above symptoms, they immediately visit their nearest emergency department.
Why a mini stroke is serious
In a mini stroke, there is an interruption to the brain’s blood supply. As a consequence, some brain cells receive less oxygen and nutrients than they need. The period of poor blood flow can last from a few minutes to 24 hours. The longer it lasts, the more risk there is of brain cells dying.
Blood supply restriction to any body tissues is called ischaemia; an area of the brain where the cells are deprived of blood supply is called an ischaemic area. If the cells die this is called a stroke, or ischaemic attack, as opposed to a transient ischaemic attack. In a transient ischaemic attack though, brain function is impaired which causes symptoms, but the cells survive.
Anyone can have a mini stroke but it is more frequent in patients who have risk factors for blood vessel damage: old age, high blood pressure, diabetes, smoking and raised cholesterol levels.
Heart conditions leading to an irregular and fast heart rate, called atrial fibrillation, and disorders that mean blood has a tendency to form clots, are also causes of mini strokes. These are the same factors that can lead to a stroke.
Accompanying Article: How to recognise a stroke and what you should know about their treatment
A mini stroke is a strong warning of something more serious, like a stroke. Patients who have had a mini stroke are 10% more likely to have a stroke over the following four weeks. More than 40% of these happen in the first 48 hours.
Once a stroke does occur, treatment outcomes are much poorer. A large stroke in which a substantial volume of brain dies can be fatal, or produce a lifetime of disability. Potentially serious and disabling strokes can be prevented if a mini stroke is recognised. Adequate investigation and treatment will reduce the risk of a disabling stroke.
How to reduce risk of stroke
If a person has a mini stroke and is assessed in an emergency department, doctors will investigate to understand the cause of the event. Initial tests will include measuring a patient’s blood pressure and doing blood tests to exclude high cholesterol and diabetes.
A CT scan or MRI will be done, to provide a picture the brain. In a mini stroke, this should be normal, as the brain cells have survived. The brain scan is also done to exclude another diagnosis such as a brain tumour, which can also be the cause of the symptoms.
The doctor will also examine the neck arteries, with either a CT or an ultrasound, for a narrowing or blockage causing decreased blood supply to the brain. If there is a blockage, the doctor will decide whether this requires an operation.
She will check the patient’s heart to exclude a condition leading to clot formation. Factors that can cause clots to form in the heart include enlarged heart chambers, malfunction of the heart valves and an irregular heart rate.
The treatment of a mini stroke will include three different medications: a medicine to reduce the risk of blood clots, such as aspirin; a medication to decrease blood pressure, such as perindopril; and a cholesterol lowering drug, such as atorvastatin.
Almost all patients who have had a mini stroke should be on these three medications. Even with normal cholesterol or normal blood pressure, research shows these medications reduce risk of subsequent stroke. Other treatments may include help stopping smoking, diabetes treatment and advice about diet, exercise and weight loss.
The important message is; if you have sudden onset of weakness or speech disturbance seek urgent medical attention even if the symptoms improve quickly.