Definitions, symptoms and causes of stroke and TIA
What is a stroke?
A stroke is a brain attack similar to a heart attack, and is mostly caused by a blockage of a blood vessel to part of the brain.
In a minority of cases it can be caused by an area of bleeding into the brain, referred to as a haemorrhagic stroke and it should be treated as a medical emergency. The sooner a suspected stroke patient is seen by a doctor, a diagnosis made and treatment started, the greater the likelihood of recovery.
What is a transient ischaemic attack (TIA)?
A transient ischaemic attack (TIA) is a set of symptoms that occur as a result of a temporary lack of blood supply to the brain.
Typically the symptoms last only a few minutes and then completely resolve. It is important you contact your GP straight away so that you can be referred to our TIA clinic as soon as possible.
If your symptoms last more than a few minutes, you should call 999 and be assessed in our emergency department. We will assess whether you are high or low risk depending on your symptoms. If you are high risk, we will assess you within 24 hours. If you are low risk we will assess you within one week.
Most TIA patients will not require admission to hospital and will be assessed and managed as an outpatient.
If your symptoms last more than 24 hours, this is considered to be a stroke and you will require admission to hospital for a medical and therapy assessment.
Strokes can affect people in different ways depending on which part of the brain has been affected. Symptoms you may notice include:
- weakness of an arm or a leg
- a change in sensation to an arm or leg
- drooping of one side of the face (facial weakness)
- a change in speech (slurring of speech or jumbled speech) or understanding speech (dysphasia)
- lack of awareness of part of the body (neglect)
- a loss of coordination
- visual loss.
Face: ask the person to smile. Is there a drooping of the mouth on one side of the face?
Arm: ask the person to raise both arms. Does one arm drift downward?
Speech: can the person speak clearly and understand what is said to them?
Time: call 999 if they show any of the above symptoms.
If the symptoms last longer than a few minutes, you should call 999 for an immediate assessment as the patient may be suitable for clot busting treatment.
If the symptoms completely resolve within a few minutes, the patient may have experienced a transient ischaemic attack (TIA). This can be a warning sign for a potentially more serious stroke. You should therefore contact your GP immediately or attend an emergency department for an urgent referral to the TIA service.
Causes of a stroke
An ischaemic stroke can be caused by several kinds of disease. The most common problem is the narrowing of the arteries in the head or neck. If the arteries become too narrow, blood cells may collect and form blood clots. These blood clots can block the artery where they are formed (thrombosis) or can dislodge and become trapped in arteries closer to the brain (embolism).
Another cause of a stroke is blood clots coming from the heart, which can occur as a result of an irregular heartbeat, heart attack or abnormalities of the heart valves. While these are the most common causes of ischaemic stroke, there are many possible causes, including:
- high blood pressure
- cigarette smoking
- diabetes mellitus
- irregular heart rhythm
- high cholesterol
- lack of exercise
- unhealthy diet
- previous history of stroke
- previous history of a heart attack or angina
- history of peripheral vascular disease (poor arterial circulation to the legs)
- use of illegal drugs
- traumatic injury to the blood vessels of the neck
- disorders of blood clotting
What is atrial fibrillation (AF) and how does this cause strokes?
Atrial fibrillation (AF) is the most common heart rhythm disturbance encountered by doctors. NHS 2011 figures suggest AF affects in excess of one million people across the UK, although this is considered to be an under estimation due to delayed detection and diagnosis.
Adults of any age can be affected, however it is more common as people get older. It affects around 10% of people in the over 65 year old age group. Atrial fibrillation is not a life-threatening heart rhythm problem, but it can be troublesome and often requires treatment.
Atrial fibrillation occurs when chaotic electrical activity develops in the upper chambers or atria, and completely takes over from the sinus node. As a result the atria no longer beats in an organised way and pumps less efficiently. The AV node will stop some of these very rapid impulses from travelling to the ventricles, but the ventricles will still beat irregularly and possibly rapidly.
The main risk associated with AF is stroke. This occurs because the atria are fibrillating and not beating in a coordinated way. The lack of sufficient contraction means that the blood in the atria becomes stagnant and can form clots. These clots can break off and travel anywhere in the body, including the brain, and cause a stroke.
You may not have any symptoms and the AF may be picked up by a doctor or nurse checking your pulse or performing a heart tracing (ECG). You may however notice palpitations, dizziness, breathlessness or chest pain.
For more information on AF and its treatment please see www.atrialfibrillation.co.uk