There are two types of subdural hematoma—acute and chronic. Acute subdural hematomas commonly form because of a severe head injury.
Chronic subdural hematomas develop due to a minor head injury. A blood clot on the surface of the brain is also called a subdural hematoma.
Subdural hematomas occur when a vein ruptures between the skull and the brain’s surface. When a person sustains a major brain injury, this area can fill with blood and cause life-threatening symptoms. This is called an acute subdural hematoma. It is the most dangerous type of subdural hematoma.
Acute subdural hematomas are usually caused by:
- a car accident
- a blow to the head
Acute subdural hematomas form quickly and the symptoms appear immediately.
Chronic subdural hematomas are caused by mild or repeated head injuries. These are common in elderly people who fall repeatedly with head injury. Symptoms of chronic subdural hematomas are not noticeable immediately and may not appear for several weeks.
Chronic subdural hematomas are easier to treat than acute subdural hematomas. Even so, they can still cause life-threatening complications. Some chronic subdural hematomas occur with no apparent cause.
Acute subdural hematomas cause symptoms right away. However, people with chronic subdural hematomas may have no symptoms at all.
Common symptoms of a subdural hematoma are:
- slurred speech
- the inability to speak
- loss of consciousness or coma
- numbness (may be in several areas of the body)
- visual problems
These symptoms are serious. If you develop difficulty speaking, numbness, severe headaches, weakness, or visual problems, you should see a doctor promptly.
A subdural hematoma can be diagnosed using imaging tests, such as a CT (computed tomography) scan or MRI (magnetic resonance imaging) scan. These scans provide your doctor with an in-depth look at your brain, skull, veins, and blood vessels. They can also reveal if there is any blood on the brain.
You may also be given a blood test to check your complete blood count. A complete blood count test measures your red blood cell, white blood cell, and platelet count. A low level of red blood cells can indicate significant blood loss.
Your doctor may also give you a physical examination to check your heart rate and blood pressure for evidence of internal bleeding.
An acute subdural hematoma can only be treated in an operating room. Your brain may swell because of your head injury, causing an increase of pressure in the head (intracranial pressure). If there is a build-up of pressure on the brain, a surgeon will relieve the pressure by drilling small holes in your skull.
A surgical procedure called a craniotomy may be used to remove a large subdural hematoma. It is normally used to treat acute subdural hematomas. In this surgical procedure, the surgeon removes a part of the skull in order to evacuate the clot or hematoma. The hematoma is removed using suction and irrigation.
A burr hole can also be used to drain smaller hematomas. First, the surgeon creates small holes in your skull and then places rubber tubes in them. The blood from the hematoma drains out through these holes.
Your doctor may prescribe anti-seizure medications to treat or prevent seizures that might be caused by the subdural hematoma. Medication may also be used to treat your brain injury. Corticosteroids are often prescribed to reduce inflammation in the brain.
Complications of subdural hematomas may occur soon after the injury, or sometime after the injury has been treated.
These complications may include:
- brain herniation (or pressure on the brain that can cause a coma or death)
- permanent muscle weakness or numbness
The extent of complications depends on the severity of the brain injury you sustained.
Your outlook for recovery depends on the type of brain injury you sustained and its location. The outlook for those with chronic subdural hematomas is fair.
Patients with acute subdural hematomas have a poor outlook. According to UCLA’s Neurosurgery department, about 50 to 90 percent of those with acute subdural hematomas die from the condition or its complications (UCLA). For those who recover, seizures can occur even after the subdural hematoma has been removed.