Subdural Hematoma


What Is It?

A subdural hematoma or hemorrhage is an accumulation of blood between the brain and its tough outer lining, caused by a ruptured blood vessel. A subdural hematoma is a close relative of other hemorrhages that can occur at the surface of the brain, including epidural hematoma and subarachnoid hemorrhage. These hemorrhage types each cause blood to collect beneath a different layer of the meninges, the three-layer protective covering of the brain. In the case of a subdural hematoma, blood collects immediately beneath the outermost layer, named the dura mater. A subdural hematoma is a threatening problem because it can compress the brain.

Most subdural hemorrhages are caused when trauma to the head damages tiny veins within the meninges. In young, healthy people, bleeding usually is triggered by a significant impact, such as might occur in a high-speed motor-vehicle accident. In contrast, older people may develop a subdural hemorrhage after minor trauma, such as a falling out of a chair. Bleeding within the head after a minor injury is also more common in people taking medications that thin the blood and in people who abuse alcohol or have seizures.

Subdural bleeding that develops shortly after a serious blow to the head is known as an acute subdural hemorrhage. Acute subdural hemorrhages develop in 5 percent to 20 percent of people with severe Head injury, typically those who fall from a considerable height. This type of bleeding occurs three times more often in men than in women. In acute subdural hemorrhage, the rapid accumulation of blood causes pressure to rise within the brain, and can result in loss of consciousness, paralysis or death. The force required to trigger this type of bleeding can cause several different injuries to the brain and spinal cord at the same time.

When bleeding develops slowly, typically over a period of weeks to months, it is known as a chronic subdural hemorrhage. This form of bleeding is much more common in the elderly, with most of those affected over age 50. The head trauma that causes chronic subdural hemorrhage is often minor, and up to one-half of those affected cannot recall a Head injury.


Acute subdural hemorrhage usually develops after severe head trauma. Injuries that result in a subdural hemorrhage are typically forceful enough to cause a temporary loss of consciousness (concussion). Bleeding associated with a subdural hemorrhage occurs slowly, because the damaged blood vessels are small veins. Usually, in the minutes to hours after Head injury, recovery from a concussion may be followed by a gradual loss of consciousness from subdural bleeding. Other common symptoms include severe headache, weakness of arms or legs on one side of the body, seizures and changes in vision or speech.

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

  • Mild headache
  • Nausea or vomiting
  • Change in personality
  • Memory loss
  • Loss of balance or difficulty walking
  • Double vision
  • Weakness, numbness or tingling in arms or legs

The symptoms caused by chronic subdural hemorrhage can mimic other common conditions, including strokes and brain tumors. Occasionally, the gradual onset of memory loss and personality changes can be mistaken for dementia.


All head injuries should be evaluated promptly by a physician, especially if there has been any loss of consciousness. A doctor usually will want to know:

  • How the injury occurred
  • What symptoms developed
  • Whether there have been head injuries in the past (since repeat injuries are more likely to cause serious damage)
  • Whether the person has other medical problems
  • What medications the person is taking
  • Whether the individual has been drinking alcohol or using drugs
  • Whether there are symptoms of other injuries (neck pain, shortness of breath, etc.)

The doctor will perform a thorough physical and neurological exam. He or she will check blood pressure and pulse; vision and the way the eyes respond to light; reflexes and balance; and the ability to answer questions and remember things. If there is suspicion of bleeding within the head, the doctor will order a computed tomography (CT) scan. This type of scan is the most effective way to determine the location and amount of bleeding, as well as any injuries to the brain, skull or neck.

A doctor may suspect a chronic subdural hemorrhage if an older patient develops new neurological symptoms, especially 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, severe brain injury and death can occur.

A chronic subdural hemorrhage develops over weeks to months. Symptoms may develop slowly and may be subtle.

As is the case with any brain injury, symptoms can be slow to go away after a subdural hematoma is treated, and some symptoms may be permanent. Occasionally, a subdural hematoma is small enough that doctors will allow the blood to deteriorate and to be reabsorbed gradually by the body without surgery. This process requires 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, and many others could be prevented with simple precautions or safety equipment.

To help prevent head injuries:

  • If you drink alcohol, drink in moderation. Never drive after drinking or using drugs.

  • If your job involves working high above the ground, use approved safety equipment to prevent accidental falls. Never work in a high place if you feel lightheaded or unsteady, if you have been drinking alcohol or if you are taking medication that can make you dizzy or affect your balance.

  • Have your vision checked regularly, since poor vision can increase your risk of falls and other types of accidents. This is especially true if you are elderly or if you work in high places.

  • If you are elderly, make sure to clear your home or apartment of hazards such as throw rugs and extension cords, which can cause you to trip and fall. If you feel unsteady on your feet, consider using a cane or walker.

  • If you play a contact sport such as football or soccer and you experience a significant Head injury, allow adequate time for healing before you start playing again. After a Head injury, the delicate veins beneath the dura mater can require up to 15 days to fully repair themselves, even if symptoms, such as headache, go away much sooner. A repeated injury that occurs during this fragile repair period is likely to result in hemorrhage. This is called the second impact syndrome.

Medications that thin the blood — including warfarin (Coumadin), aspirin and other anti-inflammatories — increase your risk of bleeding within the head. If you take blood thinners, make sure that you have close medical supervision with monitoring.


An acute subdural hemorrhage requires immediate medical attention. In most cases, emergency surgery must be performed to drain the hematoma and to control bleeding. Patients are monitored in an intensive-care unit with careful attention to breathing, blood pressure and neurological function. Occasionally, medications or controlled breathing through a ventilator is necessary to prevent swelling of the brain.

In contrast, only some chronic subdural hemorrhages require emergency treatment, and others do not require treatment at all. 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 for smaller hematomas that cause minimal or no symptoms.

People who develop a subdural hemorrhage are at risk of developing seizures, even after the hematoma has been treated. To prevent seizures, some physicians will prescribe anticonvulsant (antiseizure) medications for a year or longer.

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 any of the following symptoms:

  • Drowsiness or a decrease in alertness
  • Nausea or vomiting
  • Confusion or amnesia
  • Difficulty walking or poor coordination
  • Slurred speech
  • Double vision
  • Irrational or aggressive behavior
  • Seizures
  • Numbness or paralysis in any part of the body

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

  • Is elderly
  • Takes medications to thin the blood
  • Has a bleeding disorder
  • Has a history of heavy alcohol use


The prognosis for acute subdural hemorrhages generally is poor, often because of associated injuries to the brain, regardless of the size of the hematoma. Up to half of those with severe head injuries die, and many of those who survive may be left with permanent neurological problems. The prognosis is best in those with acute subdural hemorrhage who:

  • Are unconscious for only short periods of time
  • Have few neurological symptoms when evaluated by a doctor
  • Are younger than age 50
  • Do not abuse alcohol
  • Do not have other associated brain injuries
  • Receive prompt medical attention

In comparison, the prognosis for chronic subdural hemorrhage is quite favorable. Fewer than 10 percent of those affected die, and up to 80 percent are able to resume normal functioning. The prognosis is best in those who are awake, alert and have few neurological symptoms at the time of evaluation.

Johns Hopkins patient information

Last revised:

Diseases and Conditions Center

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.