What is a subdural hematoma?
A subdural hematoma is a buildup of blood on the surface of the brain. The blood builds up in a space between the protective layers that surround your brain.
Your brain sits within a bony skull. Inside your skull are several layers called the meninges. These layers cover and protect the brain. The outermost covering, just inside the skull, is a tough, fibrous layer known as the dura mater, usually just called the “dura.” On the inside of the dura is a layer called the arachnoid. Closest to the brain is a membrane called the pia. Cerebrospinal fluid (CSF), which fills the space inside the meninges, also helps cushion your brain.
The dura lines the skull and surrounds the brain. In a subdural hematoma, the blood seeps between the dura and the arachnoid layers, collecting inside the brain’s tough outer lining. This bleeding typically comes from a blood vessel that breaks within the space around the brain. This most commonly happens because of a head injury. The blood may press against the brain and damage the delicate tissue. A subdural hematoma can be life-threatening.
Subdural hematoma is not uncommon. It happens in some people who receive a severe head injury. Younger men are most likely to get these types of injuries. Older adults and babies are also at risk for a subdural hematoma because their veins surrounding the brain are more likely to tear. About a third of subdural hematomas happen in older adults.
What causes a subdural hematoma?
The most common cause for a subdural hematoma is head injury, such as from a car crash, fall, or violent attack. This sudden impact can strain the blood vessels within the dura, causing them to rip and bleed. Sometimes small arteries break within the subdural space as well. In some people, the brain shrinks (often from aging) and the subdural space gets bigger. This can make the blood vessels more likely to break. Possible causes for a subdural hematoma include:
- Head injury, such as from accidents or violence—most common among younger people
- Brain shrinking (atrophy)—more common among older adults
- Being on medicines to prevent blood clots, such as warfarin, aspirin, and other blood thinners
- Cerebrospinal fluid leaking
What are the risks for a subdural hematoma?
A subdural hematoma is most commonly the result of head injury. So people at risk of car crashes or falls are most at risk for this problem. You may have an increased risk of subdural hematoma due to:
- Head injury, such as from car crashes, falls, or sudden changes in speed
- Playing high-impact sports
- Advanced age, which increases the likelihood of brain shrinkage and thus more vulnerable blood vessels
- Alcohol abuse
- Previous brain injury
- Use of blood-thinning medicine
- Violence, such as “shaken baby syndrome”
- Cerebrospinal fluid leak (rare)
- Blood vessel rupture at a weak or bulging spot, known as a cerebral aneurysm (rare)
- Tumor (rare)
- Bleeding disorders, such as hemophilia (rare)
What are the symptoms of a subdural hematoma?
A subdural hematoma may cause symptoms right away (acute), or it may slowly grow and cause symptoms at a later time. You may notice the symptoms weeks after an injury or blood vessel breaking (chronic).
Signs and symptoms of a subdural hematoma may include:
- Balance or walking problems
- Nausea or vomiting
- Passing out (losing consciousness)
- Speech difficulties
- Vision problems
- Weakness or numbness that may come and go
How is a subdural hematoma diagnosed?
An acute subdural hematoma is an emergency. You will need a thorough physical exam, including a check of your reflexes as well as your head, eyes, and neck. Doctors usually check for any weakness or signs of brain problems. You may be asked when you first noticed the symptoms. Your doctor may ask you to do some simple things, such as touching your finger to your nose.
Doctors generally do a CT scan of your head to look for signs of bleeding. It is very important to identify the location of the bleeding. You may need to have one or more tests, such as:
- Blood tests to look for bleeding disorders and measure clotting function
- Blood tests to look for other possible causes of your symptoms
- More imaging of your blood vessels (angiography) to find underlying problems
- MRI scan to get more details about the bleeding
- Rapid CT scan to look for bleeding and to see if it is pressing on the brain
Diagnosis of subdural hematomas often occurs in emergency rooms.
How is a subdural hematoma treated?
Doctors often treat subdural hematomas with surgery to relieve the pressure on the brain. Your doctor may use a variety of surgeries to treat the hematoma, such as:
- Cutting a flap of skull open to remove the blood (craniotomy)
- Drilling a hole in the skull to allow the blood to drain (burr hole)
If your subdural hematoma is small, doctors might closely monitor it instead of doing surgery right away. In this case, you will likely stay in an intensive care unit. You may need:
- Insertion of a sensor inside your head to measure your intracranial pressure
- Medicines to control symptoms
- Repeated CT scans to observe the hematoma
- Stop taking blood-thinning drugs (such as warfarin) if you normally take them
- Vitamin K therapy (which can reverse the effects of some blood-thinning drugs)
Can a subdural hematoma be prevented?
Protecting yourself from head injuries may help prevent subdural hematomas. It is important to wear a helmet when riding a motorcycle, scooter, bicycle, or skateboard. Wearing seatbelts when in a car and using safety equipment in dangerous situations may help protect your head from injury. You can take steps to avoid falls.
When should I call the doctor?
A subdural hematoma is an emergency. If you or someone else has had a head injury and has the symptoms listed above, you should call 911 or go to the nearest emergency room.
A subdural hematoma is a collection of blood that forms on the surface of the brain. The blood may press against the brain and damage the delicate tissue. A subdural hematoma can be life-threatening.
- A chronic subdural hematoma may happen in older people after a minor head injury.
- A subdural hematoma may follow a severe head injury.
- Doctors often treat subdural hematomas with surgery to relieve the pressure on the brain.
- If you have a subdural hematoma, you need emergency treatment.
- Symptoms may happen right away or develop over weeks.
Tips to help you get the most from a visit to your healthcare provider:
- Know the reason for your visit and what you want to happen.
- Before your visit, write down questions you want answered.
- Bring someone with you to help you ask questions and remember what your healthcare provider tells you.
- At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your healthcare provider gives you.
- Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
- Ask if your condition can be treated in other ways.
- Know why a test or procedure is recommended and what the results could mean.
- Know what to expect if you do not take the medicine or have the test or procedure.
- If you have a follow-up appointment, write down the date, time, and purpose for that visit.
- Know how you can contact your healthcare provider if you have questions.