Definition of Subdural hematoma :

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

Causes, incidence, and risk factors:

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