A subdural haematoma is a serious brain condition that is caused when blood collects between the skull and the surface of the brain. The blood puts the brain under pressure, which can trigger a wide range of symptoms including:
- vomiting (being sick)
- mental confusion
- coma
See subdural haematoma – symptoms for more information
A subdural haematoma occurs when a blood vessel in the space between the skull and the brain (the subdural space) is ruptured. Blood escapes from the ruptured blood vessel, leading to the formation of a blood clot (haematoma), which places pressure on the brain and may cause brain damage.
See subdural haematoma – causes for more information
Types of subdural haematoma
There are two main types of subdural haematoma:
- The haematoma forms immediately after the initial injury (acute subdural haematoma).
- The haematoma forms over a period of two to three weeks after the initial injury (chronic subdural haematoma).
The two types are discussed in more detail below.
Acute subdural haematoma
Acute subdural haematomas are the most serious type of subdural haematoma. They usually occur after severe, high-impact head injuries, often caused motor vehicle accidents, falls and physical assaults.
An acute subdural haematoma is a medical emergency that requires immediate admission to a hospital.
Surgery is usually required to remove the haematoma.
Chronic subdural haematoma
Chronic subdural haematomas are more commonly seen in older people. It is thought that they occur because the natural aging process makes the brain more vulnerable to injury in some people.
This means that even a minor injury can cause bleeding inside the subdural space (in around half of all cases, the injury is so minor that the person cannot remember it).
The symptoms of a chronic subdural haematoma often develop weeks, rather than days, after the initial injury because our brain usually shrinks as we get older, creating more subdural space for the haematoma to expand before it causes any noticeable symptoms.
Chronic subdural haematomas may also be regarded as a medical emergency. Surgery is usually required.
See subdural haematoma – treatment for more information.
Outlook
Acute subdural haematoma carries a high risk of death. Age is an important factor that affects a person’s outlook. For example, people who are:
- under 40 years old have a 20% risk of dying
- 40 to 80 years old have a 65% risk of dying
- 80 years old or over have a 88% risk of dying
People who survive an acute subdural haematoma usually take a long time to recover from the effects of the haematoma. The recovery time will depend on the severity of the haematoma. There can also sometimes be permanent physical and mental disablities.
The outlook for chronic subdural haematoma is much better than the outlook for acute subdural haematoma. However, the condition still carries a moderately high risk of death. An estimated 1 in 20 people will die within the first 30 days after having surgery to treat a chronic subdural haematoma.
See subdural haematoma – recovery for more information