Stroke
1. Ischaemic Stroke
This is the most common type of stroke. Here, the artery is blocked by a blood clot, which interrupts the brain's blood supply. This may be due to a cerebral thrombosis where a blood clot forms in the main artery leading to the brain, or to a cerebral embolism in which a blood clot forms elsewhere in the body and is swept into the arteries supplying blood to the brain.
Haemorrhagic Stroke
In this type of stroke a blood vessel in or around the brain ruptures causing bleeding. The build up of blood presses on the brain damaging its delicate tissue, while other brain cells in the area are starved of blood and damaged.
In an intra-cerebral haemorrhage the bleeding occurs inside the brain itself. In a subarachnoid hemorrhage the burst blood vessel bleeds into the subarachnoid space surrounding the brain.
Transient Ischaemic Attack (TIA)
A transient ischaemic attack, often known as a mini-stroke, is when the blood supply to the brain is interrupted for a shorter period of time - anything from a few minutes to 24 hours - followed by complete recovery. It can be a warning sign of an impending stroke.
The brain needs a constant blood supply, as it is the most complex organ in the body. It regulates absolutely everything your body does - breathing, moving, sleeping, waking, your speech, sweating, your etc. 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.
What causes strokes?
Some other illnesses and medical conditions increase the risk of stroke. They include:
- High blood pressure - persistent, untreated hypertension - the medical term for high blood pressure - is the major risk factor for stroke and TIA (transient ischaemic attack). Keep a regular check on your blood pressure with an accurate and reliable personal blood pressure monitor.
- Cardiovascular problems - existing diseased blood vessels, angina, heart attack or a previous TIA’s and atrial fibrillation increase the risk of stroke.
- Diabetes - diabetes doubles the risk of a stroke.
Each of the types of stroke has different causes. Ischaemic strokes are caused by:
Blockage of the arteries- This is usually the result of atherosclerosis, i.e. furring and narrowing of the artery walls with a sludge-like mixture of cholesterol and other debris.
Haemmorhagic strokes can be caused by an aneurysm . This is a weakened spot on an artery wall that causes it to stretch a bit like a balloon. The vessel wall may become so thin and stretched it bursts causing bleeding into the brain .
Atrial fibrillation can also cause a person to suffer a stroke. This is a kind of irregular heartbeat (arrhythmia). It can cause a blood clot to form in the heart which can shear off and travel to the brain.
Areas of the brain affected
The brain is divided into two hemispheres, each of which controls the opposite side of the body and different areas of activity.
The left hemisphere for example controls cognition (thinking), language and movement and sensation on the right side of the body.
The right hemisphere controls functions involved in more visual-spatial skills such as the ability to judge distances, size, form, the awareness of where things are in space and movement and sensation on the left side of the body.
What are the short and long term effects of a stroke?
The physical damage stroke causes to the brain can have a wide range of effects that will depend on the type of stroke and its severity, and the part of the brain affected. Around a third of strokes are fatal. Effects may include:
- Weakness (hemiparesis) or paralysis (hemiplegia) - these can lead to difficulties in walking, movement, balance and coordination. These usually affect one side of the body.
- Swallowing difficulties - these can cause trouble with eating or drinking which, if not managed, can result in dehydration, constipation or chest infections including pneumonia, caused by food passing into the windpipe.
- Speech or language difficulties - that include difficulties in understanding, speaking, reading, writing and calculation known as dysphasia or aphasia. Speech and language problems are usually a result of damage to the brain's left hemisphere.
- Lack of feeling - or loss of awareness of objects on one side of the body, known as left- or right-sided neglect, depending on the side affected.
- Problems of perception - these can include trouble recognising or being able to use everyday objects such as a kettle or teapot, difficulties telling the time, and problems interpreting what the eyes see, even where vision is not affected.
- Cognitive difficulties - these include 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 - these may include being slower to react than before the stroke, excessive caution, finding it difficult to adjust 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. These can often be considerably improved or overcome with medical help and physiotherapy.
- Fatigue -The reason for fatigue is not fully understood. There may be sleep disturbance caused by damage to areas of the brain controlling the body's sleep-wake cycle and it could also be linked to depression, which is also common following a stroke.
- Mood changes - these include mood swings, laughing or crying even when you do not feel particularly happy or sad as well as symptoms such as loss of appetite, insomnia, crying, low self-esteem and anxiety that can all be signs of depression.
- Post-stroke pain - a small number of people develop a burning, shooting, throbbing pain that does not respond to painkillers following a stroke.
Symptoms may go on for anything from several minutes to 24 hours or longer, but no matter how long they last it is vital to get medical help quickly as the sooner stroke is diagnosed and treated, the less damage there is likely to be to the brain tissue and there is a better chance of a good recovery.
Please bear in mind that most people who have strokes do not experience all of these symptoms.
