The cause of intracranial bleeding (hemorrhage) usually is a head injury, often resulting from automobile, motorcycle or bicycle accidents, falls, assaults, and sports injuries. Mild head trauma is more likely to cause a hematoma if you're an older adult, especially if you're taking an anticoagulant or antiplatelet drugs, such as aspirin. You can have a serious injury even if there's no open wound, bruise or other outward sign of damage.

A hematoma may occur as a subdural hematoma, an epidural hematoma or an intraparenchymal hematoma.

Subdural hematoma

This occurs when blood vessels — usually veins — rupture between your brain and the outermost of three membrane layers that cover your brain (dura mater). The leaking blood forms a hematoma that compresses the brain tissue. If the hematoma keeps enlarging, a progressive decline in consciousness occurs, possibly resulting in death.

The three types of subdural hematomas are:

  • Acute. This type is the most dangerous. It's generally caused by a severe head injury, and signs and symptoms usually appear immediately.
  • Subacute. Signs and symptoms take time to develop, sometimes days or weeks after your injury.
  • Chronic. The result of less severe head injuries, this type of hematoma may cause much slower bleeding, and symptoms can take weeks to appear. You might not recall injuring your head.

All three types require medical attention as soon as signs and symptoms appear, or permanent brain damage may result.

The risk of subdural hematoma is greater for people who:

  • Take aspirin or anticoagulants daily
  • Abuse alcohol
  • Are elderly

Epidural hematoma

Also called an extradural hematoma, this type occurs when a blood vessel — usually an artery — ruptures between the outer surface of the dura mater and the skull. Blood then leaks between the dura mater and the skull to form a mass that compresses the brain tissue.

Some people with this type of injury remain conscious, but most become drowsy or comatose from the moment of trauma. An epidural hematoma that affects an artery in your brain can be deadly unless you get prompt treatment.

Intraparenchymal hematoma

This type of hematoma, also known as intracerebral hematoma, occurs when blood pools in the brain. After a head trauma, there may be multiple severe intraparenchymal hematomas.

The trauma that causes intraparenchymal hematomas often is responsible for so-called white matter shear injuries — torn axons in the brain's white matter. Axons carry electrical impulses, or messages, from the neurons in the brain to the rest of the body. When this connection is sheared, serious brain damage can result.

Jun. 25, 2014

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