Chronic subdural hematoma

Alternative names:

subdural hematoma, chronic; subdural hemorrhage, chronic

Definition:

A brain disorder involving a collection of blood in the space between the inner membranes that cover the brain and the outer membrane covering of the brain, with symptoms occurring 2 weeks or more after the causative injury.

Causes, incidence, and risk factors:

Subdural means below the dura (the dura mater is the outer membrane covering the brain).

Chronic subdural hematoma develops when blood veins that are located between the membranes covering the brain slowly leak blood after a head injury. The head injury could be as obvious as a traumatic accident or as seemingly trivial as a minor bump to the head. In many cases, the head injury may not even be remembered. The blood collects into a mass (hematoma) that presses on the brain tissue. This causes loss of brain function, which may progressively worsen as the hematoma enlarges. The symptoms develop gradually because the leakage of blood is gradual and the hematoma forms slowly.

Risks include head injury, very young or old age, chronic use of aspirin or blood thinner (anti-coagulant) medication, and alcoholism or chronic alcohol use. Other important factors include a history of any disorder that may increase the risk of falling, and organic brain syndromes where confusion and cognitive impairment are already present and may mask symptoms of chronic subdural hematoma.

Chronic subdural hematoma occurs in about 1 out of 10,000 people. It is most common in infants and the elderly, especially people over age 75, but it may occur in people of all ages.