Subdural hematoma: Bleeding into the space between the dura (the brain cover) and the brain itself. This space is called the subdural space. If the hematoma puts increased pressure on the brain, neurological abnormalities including slurred speech, impaired gait, and dizziness may result and progress to coma and even death.
Subdural hematomas can be caused by minor accidents to the head, major trauma, or the spontaneous bursting of a blood vessel in the brain (aneurysm). Acute subdural hematomas are usually due to severe head trauma. Chronic subdural hematomas may be very insidious. They usually go unnoticed, sometimes for 2 to 4 weeks: When they do cause problems, the incident that caused the bleeding is often long past. Symptoms include increasing daily headache, fluctuating drowsiness or confusion, and mild weakness on one side of the body. Subdural hematomas are more common in alcoholics and patients over 50 years of age. In infants, subdural hematomas can cause the fontanel to bulge and the head circumference to enlarge.
Diagnosis is usually confirmed by MRI or CT scan. Treatment is by trepanation -- drilling through the skull to drain the excess blood.