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A subdural hematoma is a collection of blood on the surface of the brain.

Subdural hemorrhage

Subdural hematomas are usually the result of a serious head injury. When one occurs in this way, it is called an "acute" subdural hematoma. Acute subdural hematomas are among the deadliest of all head injuries. The bleeding fills the brain area very rapidly, compressing brain tissue. This often results in brain injury.

Subdural hematomas can also occur after a very minor head injury, especially in the elderly. These may go unnoticed for many days to weeks, and are called "chronic" subdural hematomas. With any subdural hematoma, tiny veins between the surface of the brain and its outer covering (the dura) stretch and tear, allowing blood to collect. In the elderly, the veins are often already stretched because of brain atrophy (shrinkage) and are more easily injured.

Some subdural hematomas occur without cause (spontaneously).

The following increase your risk for a subdural hematoma:

• Anticoagulant medication (blood thinners, including aspirin)
• Long term abuse of alcohol
• Recurrent falls
• Repeated head injury
• Very young or very old age

• Confused speech
• Difficulty with balance or walking
• Headache
• Lethargy or confusion
• Loss of consciousness
• Nausea and vomiting
• Numbness
• Seizures
• Slurred speech
• Visusal disturbances
• Weakness

In infants:

• Bulging fontanelles (the "soft spots" of the baby's skull)
• Feeding difficulties
• Focal seizures
• Generalized tonic-clonic seizure
• High-pitched cry
• Increased head circumference
• Increased sleepiness or lethargy
• Irritability
• Persistent vomiting
• Separated sutures (the areas where growing skull bones join)

Always get medical help after a head injury. Older persons should receive medical care if they shows signs of memory problems or mental decline. An exam should include a complete neurologic exam.

Your doctor may order a brain imaging study if you have any of the following symptoms:

• Confused speech
• Difficulty with balance or walking
• Headache
• Inability to speak
• Lethargy or confusion
• Loss of consciousness
• Nausea and vomiting
• Numbness
• Recent congitive decline in an elderly person, even without a history of brain injury
• Seizures
• Slurred speech
• Visual disturbance
• Weakness

A CT scan or MRI scan likely would be done to evaluate for the presence of a subdural hematoma.

The outlook following a subdural hematoma varies widely depending on the type and location of head injury, the size of the blood collection, and how quickly treatment is obtained.

Acute subdural hematomas present the greatest challenge, with high rates of death and injury. Subacute and chronic subdural hematomas have better outcomes in most cases, with symptoms often going away after the blood collection is drained. A period of rehabilitation is sometimes needed to assist the person back to his or her usual level of functioning.

There is a high frequency of seizures following a subdural hematoma, even after drainage, but these are usually well controlled with medication. Seizures may occur at the time the hematoma forms, or up to months or years afterward.

• Brain herniation (pressure on the brain severe enough to cause coma and death)
• Persistent symptoms such as memory loss, dizziness, headache, anxiety, and difficulty concentrating
• Seizures
• Temporary or permanent weakness, numbness, difficulty speaking

A subdural hematoma requires emergency medical attention. Call 911 or your local emergency number, or go immediately to an emergency room after a head injury.

Spinal injuries often occur with head injuries, so try to keep the person's neck still if you must move him or her before help arrives.

Always use safety equipment at work and play to reduce your risk of a head injury. For example, use hard hats, bicycle or motorcycle helmets, and seat belts. Older individuals should be particularly careful to avoid falls.

Heegaard WG, Biros MH. Head. In: Marx, JA, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 6th ed. Philadelphia, Pa: Mosby Elsevier; 2006: chap 38.