Minor strokes

What is a minor stroke?

A stroke is caused by a blood clot or a haemorrhage (bleed) in the brain.

A stroke is a general term for an event which disrupts the blood supply (and therefore the oxygen supply) to an area of the brain. It may occur when a blood vessel to the brain is blocked, for example by a blood clot (preventing any blood reaching a part of the brain – this is called an ischaemic stroke, and it accounts for nearly 90 per cent of stroke) or when a blood vessel is damaged and blood leaks out into the brain tissue (a haemorrhagic stroke, about ten per cent of strokes).

This may result in a brief or more permanent disturbance of brain function, depending on how much of the brain is affected, how long the disruption of blood supply lasts and how much of the brain tissue is damaged.

A stroke occurs when part of the brain suddenly loses it’s blood supply and is damaged or destroyed. It can be caused by a blood clot forming elsewhere in the body, breaking off and travelling through the circulation until it blocks one of the arteries where it cuts off the flow of blood to part of the brain. Another common cause is a blood vessel in the brain (which may be abnormally shaped or damaged) bursting or leaking, spilling blood into the delicate tissues of the brain and disrupting flow, or bleeding into the membrane layers that surround the brain.

There is no formal definition of a minor stroke but the term is often used to describe a stroke where there is only limited disruption of the brain’s blood supply and where symptoms are relatively short-lived.

A very brief event is known as a transient ischaemic attack or TIA (and sometimes referred to as a mini-stroke). This is defined as a sudden, localised neurological deficit that lasts for less than 24 hours, is presumed to be of vascular origin, and is limited to an area of the brain or eye supplied by a specific artery. Many specialists argue that TIAs cause symptoms that last a matter of minutes or at least no more than an hour or two and that symptoms lasting up to 24 hours are a full stroke.

Causes of a minor stroke

Other less common causes include bubbles of fat, air or even amniotic fluid which form during an accident (for example when a major bone is broken) or during pregnancy and labour, which can travel through the circulation and block the arteries.

Symptoms of a minor stroke

"Someone who has had a stroke is undoubtedly unwell, and the length of recovery will depend on the severity of the stroke," according to a spokeswoman for the Stroke Association's advisory service. "But the effects of a stroke on an individual will depend entirely on where the stroke happens in the brain. For some people, their face will be paralysed, in others their speech will slur - again, it depends on where it happens and it's down to the doctor's clinical judgement to decide where the stroke occurred."

A stroke typically causes:

• Movement problems with weakness of the limbs or face, affecting one side of the body.
• Sensory problems such as some loss of vision or sensory changes in the skin.
• Communication problems : speech may be slurred or lost completely. The person may also have problems processing speech, and may find it difficult to understand what is said to them or find the right words to use themselves.
• Confusion.
• Swallowing difficulties: the action of the muscles which control swallowing and prevent food and liquid entering the breathing tubes may be lost.
• Nearly one in three strokes are fatal.

Exact symptoms will depend which part of the brain is damaged. A stroke in the cerebellar area of the brain for example, may cause problems with balance. The severity of a stroke can range from the minor - some numbness or tingling - to the severe - where the patient may be completely paralysed down one side and unable to speak at all.

In a minor stroke symptoms are more limited and usually improve more quickly and more completely. In a TIA symptoms resolve very rapidly and the person usually feels back to normal within 10-15 minutes.

The FAST test

The Stroke Association suggest the FAST test to recognise a stroke. It involves checking for:

• FACIAL weakness: Can the person smile? Has their mouth or eye drooped?
• ARM weakness: Can the person raise both arms?
• SPEECH problems: Can the person speak clearly and understand what you say?
• TIME to call 999.

It’s important to recognise a stroke and get treatment as quickly as possible, to maximise the chances that treatment will limit the extent of damage to the brain.

Treatment of a minor stroke

The aim of treatment in a stroke is to improve blood supply to the critical area of the brain if possible, to support the patient through the acute phase and then to help them recover from any permanent damage by offering rehabilitation therapy which helps the brain relearn basic functions such as movement or speech.

If a person can get medical attention very quickly after the start of a stroke (usually within four hours) it may, in certain cases, be possible to use thrombolytic or 'clot-busting' therapy. These are drugs which dissolve the obstructing clot and restore blood flow to the brain’s tissues but they are not suitable for everyone and they have a significant risk of causing bleeding which can make the stroke worse.

In most cases, people with a stroke should be treated on a stroke unit in a hospital – research has shown that those people treated on these specialist units, where there is input from specially trained doctors, nurses, physiotherapists, speech and language therapists (SALTs) and other staff, do much better in the long run.

If there is lasting damage to the brain, the person may benefit from a programme of rehabilitation which specifically addresses their symptoms and needs. After a minor stroke most people can expect to make a fairly complete recovery but this may take a number of weeks.

Another important aspect of treatment is called secondary prevention. Once a person has had a stroke they are increased risk of another one but a variety of treatments can reduce this risk and prevent a further stroke.

• First, lifestyle advice to cut down risks for stroke such as smoking (smoking doubles the risk of a stroke) or binge drinking. Regular exercise and a balanced diet also help to reduce risk.
• Drugs to lower blood cholesterol levels. After a stroke, the aim should be to get cholesterol levels as low as possible. Most people benefit from taking a drug such as a statin to control cholesterol.
• Drugs to control blood pressure.
• Treatment for abnormal heart rhythms: in some abnormal rhythms, especially a common one called atrial fibrillation, blood clots can form in the chambers of the heart and then break off to travel up to the brain. Treatment to control the hearts rhythm may reduce this risk.
• Drugs to thin the blood and reduce the risk of clot formation. These include a small daily dose of aspirin in most patients and the use of the anti-coagulant warfarin especially if there is atrial fibrillation.
• In some cases the clots that cause a stroke originate from atheromatous narrowing of the carotid arteries in the neck, called carotid stenosis. Surgery may be needed to open this narrowing and improve blood flow.

Transient ischemic attacks, or TIAs, are also known as warning strokes because although people recover fully from them, they are an important sign that the person is at greatly increased risk of a full stroke. In the first month after a TIA, five per cent of patients will have a stroke, while the risk in the first year after a TIA is ten per cent. The risk in the four years following a TIA is seven times greater than normal. So TIAs should never be ignored but represent a warning that the person needs to be thoroughly checked out.