What is a subdural hematoma?
A subdural hematoma is a type of bleed inside your head. It's a type of bleed that occurs within your skull but outside the actual brain tissue. The brain has three membrane layers or coverings (called meninges) that lie between the bony skull and your brain tissue. The purpose of the meninges is to cover and protect the brain.
If you have a subdural hematoma, you have experienced a tear in a blood vessel, most commonly a vein, and blood is leaking out of the torn vessel into the space below the dura mater membrane layer. This space is called the subdural space because it is below the dura. Bleeding into this space is called a subdural hemorrhage.
Other names for subdural hematoma are subdural hemorrhage or intracranial hematoma. More broadly, it is also a type of traumatic brain injury (TBI).
How common are subdural hematomas?
Subdural hematomas occur in up to 25% of people with head injuries.
Are subdural hematomas serious?
Yes, a subdural hematoma can be a serious event. Occasionally, the bleed is slow and the body is able to absorb the pooled blood. However, if the hematoma is severe, the buildup of blood can cause pressure on the brain. This pressure can lead to breathing problems, paralysis and death if not treated.
Because you don’t immediately know how severe a brain bleed is until further testing, all blows to the head should be considered a serious event. If you hit your head, get checked out at a hospital.
Are there different types of subdural hematomas?
Yes. Doctors sort subdural hematomas by how fast they develop, how much bleeding occurs, and how much damage the bleeding causes. The types of subdural hematoma are:
- Acute: This is the most dangerous type of subdural hematoma. Symptoms are severe and appear right after a head injury, often within minutes to hours. Pressure on the brain increases quickly as the blood pools. If not diagnosed and treated quickly, you could lose consciousness, become paralyzed or even die.
- Subacute: Symptoms usually appear hours to days or even weeks after the head injury. A subacute subdural hematoma can occur with a concussion.
- Chronic: This type of hematoma is more common in older people. Bleeding occurs slowly and symptoms may not appear for weeks or months. Even minor head injuries can cause chronic subdural hematomas. Due to the delay in developing symptoms, an older person may not even recall how their head injury happened. Also, the changes can be so subtle and occur so slowly that symptoms may not be noticed by the older person or their friends or family.
Are some people more likely to get a subdural hematoma?
Although anyone can get a subdural hematoma from an accidental head injury, certain groups of people are at higher risk. Subdural hematomas are more common in:
- Older adults: As we age, our brains shrinks within our skull and the space between the skull and brain widens. This causes the tiny veins in the membranes between the skull and the brain to stretch. These thinned, stretched veins are more likely to tear in the event of even a minor head injury, such as a fall out of a chair.
- Athletes who play contact sports: Football players and others who play high-impact sports and who might take a blow to the head have an increased risk of a hematoma.
- People who take blood thinners: Blood thinners slow down the clotting process or prevent blood from clotting at all. If blood doesn’t clot, bleeding can be severe and long-lasting, even after a relatively minor injury.
- Hemophiliacs: Hemophilia is an inherited bleeding disorder that prevents blood from clotting. People with hemophilia have a higher risk of uncontrolled bleeding after an injury.
- People with alcohol use disorder and people who drink lots of alcohol: Drinking too much alcohol causes liver damage over time. Damaged livers can’t produce enough of the proteins that help the blood to clot, which increases the risk of uncontrolled bleeding.
- Babies: Babies don’t have strong neck muscles to protect themselves from trauma to the head. When someone abuses a baby by shaking him or her, the baby can develop a subdural hematoma. This type of injury is called shaken baby syndrome.
Symptoms and Causes
How do subdural hematomas happen?
Head injuries cause most subdural hematomas. If you fall and hit your head or take a blow to the head in a car or bike accident, a sporting activity or have another type of head trauma, you are at risk for developing a subdural hematoma.
What are the symptoms of subdural hematoma?
Because a subdural hematoma is a type of traumatic brain injury (TBI), they share many symptoms. Symptoms of a subdural hematoma may appear immediately following trauma to the head, or they may develop over time – even weeks to months.
Signs and symptoms of a subdural hematoma include:
- Headache that doesn’t go away. (Headache is usually severe in the case of acute subdural hematoma.)
- Confusion and drowsiness.
- Nausea and vomiting.
- Slurred speech and changes in vision.
- Dizziness, loss of balance, difficulty walking.
- Weakness on one side of the body.
- Memory loss, disorientation, and personality changes, especially in older adults with chronic subdural hematoma.
- Enlarged head in babies, whose soft skulls can enlarge as blood collects.
As bleeding continues and the pressure in the brain increases, symptoms can get worse. Symptoms, at this point, include:
- Breathing problems.
- Loss of consciousness and coma.
Sometimes people have no symptoms immediately following a head injury. This is called a lucid interval. They develop symptoms days later. Also, it’s important to know that subdural hematomas that develop more slowly (the chronic type) might be mistaken for other conditions, such as a brain tumor or stroke.
Special note about head injury and symptoms in seniors: Some of the symptoms of subdural hematoma in older people, like memory loss, confusion, and personality changes, could be mistaken for dementia. The older person may not remember hitting their head. Sometimes, people forget because they are disoriented. Other times, the injury was minor and may have occurred weeks before symptoms appeared. They should still see their healthcare provider for evaluation.
Diagnosis and Tests
How are subdural hematomas diagnosed?
First, your healthcare provider will do a thorough physical and neurological exam. Your healthcare provider will ask you about your head injury (when and how it occurred, review your symptoms and other medical problems, review medications you are taking and ask about other lifestyle habits). The neurology exam will include blood pressure checks, vision testing, balance and strength testing, as well as reflex tests and a memory check.
If your healthcare provider thinks you may have a subdural hematoma, they will order a computed tomography (CT) scan or magnetic resonance imaging (MRI) scan of your head. These imaging tests allow healthcare providers to see clear pictures of the brain and determine the location and amount of bleeding or other head and neck injuries.
Management and Treatment
What are the treatments for subdural hematoma?
Healthcare providers treat larger hematomas with decompression surgery. A surgeon drills one or more holes in the skull to drain the blood. Draining the blood relieves the pressure the blood buildup causes on the brain. Additional surgery may be needed to remove large or thick blood clots if present. Usually, healthcare providers leave a drain in place for several days following surgery to allow the blood to continue draining.
Sometimes hematomas cause few or no symptoms and are small enough that they don’t require surgical treatment. Bed rest, medications and observation may be all that is needed. The body can absorb the small amount of blood over time, usually a few months. Your healthcare providers may order regular imaging tests (such as an MRI) to monitor the hematoma and make sure it is healing.
What are the side effects of subdural hematoma treatment?
Side effects from decompression surgery include an increased risk of bleeding, infection and blood clots. Your healthcare providers will monitor you closely after surgery.
What are the complications of having a subdural hematoma?
Without treatment, large hematomas can lead to coma and death. Other complications include:
- Brain herniation: Increased pressure can squeeze and push brain tissue so it moves from its normal position. A brain herniation often leads to death.
- Repeated bleeding: Older adults who are recovering from a hematoma have a higher risk of another hemorrhage. Older brains don’t recover as quickly as younger brains. Also, as we age, our brains shrink and the space between the skull and brain widens. This further stretches the tiny thin veins between the outer membrane layers of the brain and skull and makes the older brain more vulnerable to future bleeding if another head injuries occur.
- Seizures: Seizures may develop even after a hematoma has been treated.
How can you prevent a subdural hematoma?
Although it may not be possible to prevent a hematoma as a result of an accident, you can reduce your risk by:
- Protecting your head: Use your seatbelt and always wear a helmet when riding a bike or a motorcycle. If you play high-impact or contact sports, always wear a helmet. Use safety gear if you work off the ground or at a job with a high risk of head injury.
- Resting after a head injury: If you’ve had a concussion, rest and allow your brain time to recover. Your healthcare provier will tell you how long to rest before returning to work or previous activities. Remember, a chronic subdural hematoma may not show symptoms for days, weeks and even months.
- Removing tripping hazards from your home – especially if you are elderly. Get rid of throw rugs; make sure electrical cords are tucked out of the way; add handrails to all stairs; add lights to stairways, hallways and dark areas; and position furniture so you always have something to hold on to as you walk through your home. Use a cane or walker if you walking is unstable.
- Having your vision checked regularly to prevent falls and accidents.
- Having your healthcare provider or pharmacist do a medication review. These professionals can check the side effects of your medications to make sure they don’t cause dizziness or loss of balance. If they do, doses can be changed or a different drug may be able to be prescribed.
- Drinking responsibly: Excessive alcohol consumption makes your brain more likely to bleed when injured. Avoid drinking more than two beverages containing alcohol per day.
- Being careful when taking blood thinners: Even minor head injuries can cause a subdural hematoma in people who take blood thinners. Talk to your healthcare provider about needed precautions if you are on these medications. Examples include aspirin, warfarin, heparin and newer blood thinners like dabigatran (Pradaxa®), rivaroxaban (Xarelto®), apixiban (Eliquis®) and edoxaban (Savaysa®).
Outlook / Prognosis
What can I expect if I have a subdural hematoma?
If you have a subdural hematoma, your prognosis depends on your age, the severity of your head injury and how quickly you received treatment. About 50% of people with large acute hematomas survive, though permanent brain damage often occurs as a result of the injury. Younger people have a higher chance of survival than older adults.
People with chronic subdural hematomas usually have the best prognosis, especially if they have few or no symptoms and remained awake and alert after the head injury.
Older adults have an increased risk of developing another bleed (hemorrhage) after recovering from a chronic subdural hematoma. This is because older brains cannot re-expand and fill the space where the blood was, leaving them more vulnerable to future brain bleeds with even minor head injuries.
When should I get emergency medical assistance if I’ve had a head injury?
A subdural hematoma is always a risk after a head injury. If you or someone you know has any of the following symptoms after a head injury, call 911 or seek medical attention immediately.
- Loss of consciousness (friend or witness needs to call 911).
- Slurred speech.
- Nausea or vomiting.
- Change in alertness/drowsiness.
- Balance/walking problems.
- Double vision.
- Weakness or numbness in any part of the body.
- Severe headache.
People at increased risk of a subdural hematoma – even though the head injury appears minor – should also get immediate medical attention. These people include:
- Older people.
- People who take blood-thinning drugs or have diseases that make clotting difficult (like hemophilia, von Willebrand disease).
- People who drink a lot of alcohol.
Subdural hematomas can be life-threatening. If you have a head injury, get immediate medical attention. Don’t wait to “see if symptoms develop.” It’s better to be safe, than sorry.