Bleeding inside the skull between the two outer membranes that surround the brain
- One type is more common in elderly people
- Contact sports and excessive alcohol consumption are risk factors
- Gender and genetics are not significant factors
In a subdural haemorrhage, a vein in the subdural space is torn due to a head injury. The subdural space lies between the two outer membranes of the three membranes that surround the brain. Subsequent bleeding into the subdural space causes a blood clot, known as a haematoma, to form. As the blood clot enlarges, it compresses the surrounding brain tissue, causing symptoms such as headache and confusion.
A subdural haemorrhage is a potentially life-threatening condition that requires prompt medical treatment. It is one of the most common causes of death from contact sports such as boxing.
What are the types?
After a head injury, bleeding may occur within minutes (acute subdural haemorrhage) or blood may build up slowly over a period of days or even weeks (chronic subdural haemorrhage).
An acute subdural haemorrhage may follow a severe blow to the head, the type of injury sustained in a road accident or while playing contact sports. Bleeding occurs immediately, and the blood clot enlarges quickly.
A chronic subdural haemorrhage can result from an apparently trivial head injury, especially in the elderly. Bleeding is slow, and it may be several months before the blood clot begins to cause symptoms. Chronic subdural haemorrhage often affects people who have frequent falls and therefore occurs more commonly in elderly people or in people who drink excessive amounts of alcohol. Disorders or treatments that impair blood clotting, such as treatment with drugs that prevent blood clotting, also increase the risk of chronic subdural haemorrhage.
What are the symptoms?
Symptoms may develop at any time between a few hours and a few months after the head injury, depending on whether the subdural haemorrhage is acute or chronic. In both types, symptoms are variable and often fluctuate in severity. The symptoms of acute subdural haemorrhage may include:
The symptoms of a chronic subdural haemorrhage may include:
Gradually developing confusion and drowsiness.
If any of the symptoms of acute or chronic subdural haemorrhage develop, seek medical attention immediately.
What might be done?
If your doctor suspects that you have a subdural haemorrhage, he or she will arrange for CT scanning or MRI of your brain to look for a clot. If the condition is confirmed, a surgical procedure in which blood is drained through small holes made in the skull (called burr holes) will probably be necessary.
If a chronic subdural haemorrhage is small and produces few symptoms, the affected person may be monitored with regular scans, and the clot may clear without the need for surgery.
In all cases, the prognosis is determined by the size and location of the clot. Many people recover rapidly, but some residual symptoms, such as weakness, may persist. If the haemorrhage has affected a large area of brain, the condition may be fatal.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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