Stroke

What is a stroke?

A stroke is when an area of the brain is deprived of its blood supply - usually because of a blockage or burst blood vessel - for long enough to cause vital brain tissue to die. It is essentially the same as what happens in the arteries leading to the heart when someone has a heart attack, which is why a stroke is now often described as a 'brain attack'.

If brain cells lose their supply of oxygen from the blood, they may be damaged or die. Dead brain cells cannot start working again. However, surrounding these dead cells is an area of tissue where blood supply is poor but not lost completely, so the nerve cells are receiving barely enough oxygen to stay alive.

One of the main aims of treating a stroke is to act fast enough to save this threatened brain tissue by restoring blood flow to the area and minimising the damage. As the inflammation and swelling caused by the stroke subside, brain cells near the dead cells may recover and begin working again.

There are two main types of stroke:

Ischaemic stroke
In this, the most common type of stroke, the artery is blocked by a blood clot, which interrupts the brain's blood supply.

This may be due to a cerebral thrombosis (sometimes called a thrombotic stroke), where a blood clot forms in one of the main arteries leading to the brain, or to a cerebral embolism (sometimes called an embolic stroke), in which a blood clot forms elsewhere in the body and is swept into the arteries serving the brain.

Fatty tissue or air bubbles may also form emboli which cause stroke, especially after major trauma or a head injury.

Another type of thrombotic ischaemic stroke is called a lacunar stroke. In this form, one of the tiny blood vessels deep inside the brain tissue becomes blocked, leading to the death of the small area of tissue that it supplies. Lacunar strokes are usually less severe.

Haemorrhagic stroke – Subacaranoid Heamorrahage
In this type of stroke, a blood vessel in or around the brain ruptures causing bleeding, or a haemorrhage. The build-up of blood presses on the brain, damaging its delicate tissue. Meanwhile, other brain cells in the area are starved of blood and damaged.

In an intracerebral haemorrhage, the bleeding occurs inside the brain itself. In a Subarachnoid haemorrage, the burst blood vessel bleeds into the Subarachnoid space surrounding the brain.

What is a Transient Ischaemic Attack (TIA)

A transient ischaemic attack, often known as a mini-stroke, is a brief episode where some brain function is temporarily lost because of a short-lived disruption of the blood supply.

Symptoms, such as weakness of a limb, last for just minutes (typically two to fifteen minutes) before the blood supply returns. As there is unlikely to be any permanent damage caused to the blood vessels often people will make a full recovery. If symptoms last under 24 hours this is deemed a TIA.

Traditionally it has been said that if symptoms last less than 24 hours its a TIA, but when symptoms persist for more than 24 hours then a stroke has occurred. But with more powerful and sophisticated brain-scanning techniques, it has become possible to show that permanent damage can usually be detected when symptoms last more than an hour or so.

TIAs are an important warning sign that all is not well with the blood supply to the brain. The risk of suffering a complete stroke within the first month after a TIA may be as high as 20 per cent, with the risk being even greater in the first few days following a TIA.

Why the brain needs a constant blood supply? The brain is the most complex organ in the body. It regulates absolutely everything your body does - breathing, moving, sweating, sleeping, waking, feeling, your moods, thoughts and speech.

To perform all these functions, the brain must have a constant supply of blood to deliver oxygen and nutrients to the brain cells. If the blood supply fails, as in a stroke, the brain cells become damaged or die within a very short space of time. Unlike other cells in the body, once they have been damaged, brain cells cannot regrow. An area of permanent damage within the brain is called cerebral infarction.

What are the causes of a stroke?

Each type of stroke has different causes. They include:

• Diseased arteries - blockage of the arteries is usually the result of athersclerosis, furring and narrowing of the artery walls with a mixture of cholesterol and other debris.
• Aneurysm - a weakened spot on an artery wall causes it to stretch. The vessel wall may become so thin it bursts, causing bleeding into the brain (sub-acharanoid heamorrahage).
• Atrial fibrillation - this kind of irregular heartbeat (arrhythmia) can cause a blood clot to form in the heart, which then travels to the brain.

Symptoms and warning signs of a stroke

The term stroke is apt because symptoms generally appear suddenly and without warning. The symptoms of a stroke and a transient ischaemic attack (TIA) are the same. They include:

• Sudden weakness, numbness or paralysis often down one side of the body, affecting the face, arm, leg or whole side
• Problems communicating, being unable to talk or understand what others are saying, or an alteration in speech, such as slurring words
• Sudden blurring, loss or disturbance of vision, especially in one eye
• Swallowing difficulties
• Dizziness, loss of balance or coordination
• Sudden severe headache

Other less obvious symptoms include difficulties in perception or thinking, mood swings and personality change.

If a stroke is suspected, it is vital to get medical help quickly. The sooner treatment is given, the less damage there is likely to be to the brain tissue and the better the odds of a good recovery. If you feel there has been a delay in you or a member of your family receiving appropriate treatment for a stroke you may have a claim for medical negligence.

The physical damage a stroke causes to the brain can have a wide range of effects. These will depend on the type of stroke and its severity, the part of the brain affected, the extent of brain damage and how quickly other brain cells take over the function of the damaged and dead ones. Around a third of strokes are fatal.

Effects may include:

• Weakness or paralysis, leading to difficulties with walking, movement or coordination. This often affects only one side of the body, known as hemiparesis or hemiplegia.
• Swallowing difficulties, which can cause trouble with eating or drinking. If this isn't managed, and food or liquid passes into the windpipe and lungs, it can result in chest infections such as pneumonia. Dehydration or constipation may also result.
• Speech or language difficulties, including difficulties in understanding, speaking (dysphasia, aphasia), reading, writing and calculation. Speech and language problems usually indicate damage to the left hemisphere of the brain.
• Cognitive difficulties, including problems caused by damage to areas of the brain controlling mental processes such as thinking clearly and logically, learning, paying attention, memory, decision making and forward planning.
• Behaviour changes, which may include being slower to react than before the stroke, excessive caution, disorganisation, difficulties adjusting to change and becoming confused or irritated.
• Difficulties with bowel or bladder control (urinary or faecal incontinence). These may be caused by a variety of different problems following stroke and can often be considerably improved or overcome with medical help and physiotherapy.
• Fatigue. Although a recognised phenomenon, the reason for fatigue isn't fully understood. There may be sleep disturbance caused by damage to areas of the brain controlling the body's sleep-wake cycle. It could also be linked to depression.
• Mood changes, including mood swings, irritability and laughing or crying, even when you don't feel particularly happy or sad. Depression is extremely common, with symptoms such as loss of appetite, insomnia, crying, low self-esteem and anxiety.
• Epilepsy affects around seven to 20 per cent of people who have strokes. This can usually be treated with anti-epileptic drugs.

If you think you may have a claim for medical negligence contact Head Injury UK for a no obligation review.