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Subdural hematoma

Medically reviewed by Last updated on Jun 24, 2023.

What is Subdural hematoma?

Harvard Health Publishing

A subdural hematoma occurs when a blood vessel near the surface of the brain bursts. Blood builds up between the brain and the brain's tough outer lining. The condition is also called a subdural hemorrhage.

In a subdural hematoma, blood collects immediately beneath the dura mater. The dura mater is the outermost layer of the meninges. The meninges is the three-layer protective covering of the brain.

A subdural hematoma is a life-threatening problem because it can compress the brain.

Subdural hematoma

Most subdural hemorrhages result from trauma to the head. The trauma damages tiny veins within the meninges.

In young, healthy people, bleeding usually is triggered by a significant impact. This type of impact might occur in a high-speed motor vehicle accident.

In contrast, older people may bleed after only a minor trauma. For example, it might happen from falling out of a chair.

A subdural hematoma is also more common in people

An acute subdural hemorrhage is bleeding that develops shortly after a serious blow to the head. Blood accumulates rapidly, causing pressure to rise within the brain. This can result in loss of consciousness, paralysis, or death.

When bleeding develops slowly, it is known as a chronic subdural hemorrhage. Bleeding may develop over a period of weeks to months.

This form of bleeding is much more common in older people. The head trauma that causes chronic subdural hemorrhage is often minor. Many of those affected cannot recall a head injury.


Acute subdural hemorrhage usually develops after severe head trauma. Injuries that result in this condition are typically forceful enough to cause a temporary loss of consciousness.

Usually, in the minutes to hours after head injury, the person recovers consciousness. Then, the person gradually loses consciousness again, this time from subdural bleeding.

Other common symptoms of an acute subdural hemorrhage include

Chronic subdural hemorrhages produce more subtle symptoms. These symptoms may continue for more than a month before the diagnosis is recognized.

These symptoms include

The symptoms caused by chronic subdural hemorrhage can mimic other common conditions. For example, they may resemble strokes and brain tumors. Occasionally, the gradual memory loss and personality changes can be mistaken for dementia.


All head injuries should be evaluated promptly by a physician. This is especially true if there has been any loss of consciousness.

A doctor usually will want to know

The doctor will perform a thorough physical and neurological exam. He or she will check

If the doctor suspects bleeding in the head, he or she will usually order a computer tomography (CT) scan. A CT scan is the fastest way to determine the location and amount of bleeding. It can also identify any injuries to the brain, skull, or neck. If needed, a brain MRI might also be performed.

A doctor may suspect a chronic subdural hemorrhage if an older patient develops new neurological symptoms. This is more likely if there has been a fall or minor trauma to the head.

Expected duration

An acute subdural hemorrhage develops over minutes to hours. If not diagnosed and treated promptly, it can cause severe brain injury and sometimes death.

A chronic subdural hemorrhage develops over many days to weeks. The symptoms may be subtle and develop so slowly that the person and family are not alarmed.

As is the case with any brain injury, symptoms can be slow to go away after treatment. Some symptoms may be permanent.

Occasionally, a subdural hematoma is small enough that you may not need surgery to remove the blood. The blood will be reabsorbed gradually by the body. This process may require a few months. But it is sometimes the safest treatment plan.


Accidents, including head injuries, are the leading cause of death in young people. Many of these accidents are related to drugs and alcohol. Many others could be prevented with simple precautions or safety equipment.

To help prevent head injuries:

"Blood-thinning" medications increase your risk of bleeding within the head. Examples include


An acute subdural hemorrhage requires immediate medical attention. In most cases, emergency surgery must be done to drain the hematoma and to control bleeding.

In contrast, only some chronic subdural hemorrhages require emergency surgery. Most physicians will recommend surgery for larger hemorrhages and those that cause neurological symptoms. However, treatment with bed rest, medications, and observation may be reasonable in some cases. This may be the case for smaller hematomas that cause minimal or no symptoms.

People who develop a subdural hemorrhage are at risk of seizures. Seizures may occur even after the hematoma has been treated.

When to call a professional

Call for emergency assistance if you find someone unconscious at an accident scene.

Also seek immediate attention if someone with a head injury experiences

Even if a head injury appears minor, with mild symptoms, certain people are at high risk of serious bleeding. Call a doctor or go to an emergency room immediately if a person with head injury also:


The outlook for acute subdural hemorrhages generally is guarded and some people die even with prompt surgery. Usually there are injuries to other parts of the brain from the trauma. This tends to be true regardless of the size of the hematoma. Many of those who survive may be left with permanent neurological problems.

The prognosis for an acute or chronic subdural hematoma is best in people who:

The prognosis for chronic subdural hemorrhage is quite favorable. Most people are able to resume their level of previous functioning.

Additional info

National Institute of Neurological Disorders and Stroke

Brain Injury Association of America

Learn more about Subdural hematoma

Treatment options

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.