Five cross sections of brain scan with arrows pointing to areas showing subdural hematomasShare on Pinterest
Tonpor Kasa/Getty Images

A subdural hematoma is a collection of blood on your brain’s surface under the skull.

This type of bleeding usually happens after a head injury and can be either acute or chronic.

Subdural hematomas occur when a vein tears between your skull and your brain’s surface. A blood clot on the surface of the brain is also called a subdural hematoma.

Are subdural hematomas serious?

Subdural hematomas can be life-threatening, especially when they occur after a serious brain injury. Recovery after any severe brain injury is varied.

But the outcomes after subdural hematomas can depend on age, the type of hematoma, and how quickly treatment is given. Better outcomes are most common in:

  • younger adults
  • those who received treatment quickly
  • people with reactive pupils and higher levels of consciousness
  • those with only one area of bleeding on the brain, as opposed to multiple
  • those with a manageable amount of pressure on the brain


Acute subdural hematoma

If you sustain a major brain injury, the injured area can fill with blood and cause life-threatening symptoms. This is called an acute subdural hematoma. It’s the most dangerous type of subdural hematoma.

Acute subdural hematomas commonly form because of a severe head injury. They form quickly, and symptoms appear immediately.

Approximately 20 to 30 percent of people regain full or partial brain function after having an acute subdural hematoma.

About 50 to 90 percent of people who develop acute subdural hematomas die from the condition or its complications.

Chronic subdural hematoma

Chronic subdural hematomas develop due to minor head injuries. Many people who are diagnosed with them don’t even remember the exact event that caused the bleeding to start.

Older adults have higher rates of chronic subdural hematomas. This may be because the brain shrinks as you age, leaving extra space in the skull and allowing the veins to be more easily damaged during a head injury.

Symptoms of chronic subdural hematomas aren’t noticeable immediately and may not appear for several weeks. The most common symptom is headache, which is reported in up to 80 percent of cases.

Chronic subdural hematomas are easier to treat than acute subdural hematomas. But they can still cause life-threatening complications.

Acute subdural hematomas cause symptoms right away. Chronic subdural hematomas may not cause any symptoms at first but, over time, can lead to serious ones.

Common symptoms of a subdural hematoma are:

  • slurred speech
  • loss of consciousness or coma
  • loss of function on one side of the body
  • seizures
  • numbness
  • drowsiness
  • severe headaches
  • weakness
  • walking problems
  • visual problems
  • confusion
  • personality changes
  • nausea or vomiting

You should go to the doctor or emergency department right away if you or someone you’re caring for have any of these symptoms. These symptoms are also signs of other very serious health conditions. Symptoms of chronic subdural hematoma can be similar to the symptoms of dementia, stroke, tumors, or other problems in the brain.

Acute subdural hematomas are usually caused by a:

  • car accident
  • blow to the head
  • violent attack
  • serious fall

Chronic subdural hematomas are typically caused by mild or repeated head injuries. Some chronic subdural hematomas form with no apparent cause.

Who’s at risk?

Acute subdural hematomas generally occur in people who’ve recently had a brain injury. Up to 20 percent of people with traumatic brain injuries are found to also have a subdural hematoma.

Chronic subdural hematomas are most common in:

  • older adults who repeatedly fall and hit their heads
  • people taking anticoagulant medication, otherwise known as blood thinners
  • people with a history of heavy drinking or alcohol misuse


An acute subdural hematoma can only be treated in an operating room.

A surgical procedure called a craniotomy may be used to remove a large subdural hematoma. It’s normally used to treat acute subdural hematomas but may be used to treat chronic subdural hematomas in some cases.

In this procedure, your surgeon removes a part of your skull in order to access the clot or hematoma. They then use suction and irrigation to remove it.

For an acute subdural hematoma, a craniotomy may be a necessary life-saving procedure. But it still has risks. In one study, 18 percent of patients died within 30 days of the surgery.

Burr hole

A burr hole can be used to drain chronic subdural hematomas or acute ones that are smaller than 1 centimeter at the thickest point.

During the procedure to create a burr hole, your surgeon creates small holes in your skull and then places rubber tubes in them. The blood from the hematoma drains out through these holes.

Though recovery rates vary, 80 to 90 percent of patients experience significant brain function improvement after this procedure.


Your doctor may prescribe anti-seizure medications to treat or prevent seizures that the subdural hematoma might cause.

Medication may also be used to treat your brain injury. Corticosteroids are often prescribed to reduce inflammation in the brain.

A subdural hematoma can be diagnosed using imaging tests, like a CT or MRI scan. These scans provide your doctor with an in-depth look at your:

  • brain
  • skull
  • veins
  • other blood vessels

These scans can also reveal if there’s any blood on the surface of your brain.

Your doctor may also order a blood test to check your complete blood count (CBC). A CBC test measures your red blood cell count, white blood cell count, and platelet count. A low level of red blood cells can mean you’ve had significant blood loss.

Your doctor may also give you a physical exam to check your heart rate and blood pressure for evidence of internal bleeding.

Complications of subdural hematomas may occur soon after the injury or sometime after the injury has been treated. These include:

  • brain herniation, which puts pressure on your brain and can cause a coma or death
  • seizures
  • permanent muscle weakness or numbness

The level of complications depends on how badly the brain was injured during whatever accident caused the hematoma.

Other health issues may affect complications of either chronic or acute subdurals. People who take anticoagulants (blood thinners) are at higher risk of complications. People over the age of 65 also have a higher risk of complications, especially with chronic subdural hematomas.

Complications from subdural hematomas, including seizures, can still occur even after they’ve been removed and you’ve recovered from the immediate symptoms.

Subdural hematomas can be very serious and even deadly. This is especially true if they happen after a severe accident when the brain was badly injured.

It’s possible to regain full brain function after a subdural hematoma, especially for younger individuals and those who receive treatment quickly and have less severe bleeding.

Your overall outlook for recovery depends on the type of brain injury you have and where it’s located. Your doctor will create a treatment and recovery plan that’s best for you.