A subdural hematoma is an increase in pressure within the skull that happens when blood collects in the space between the skull and the brain. The bleeding is usually caused by torn veins in the brain following a head injury.

Symptoms of a subdural hematoma, which can develop rapidly or slowly, include:

• Severe headache.
• Confusion.
• Seizures.
• Loss of motor function, such as the ability to walk normally.

If the bleeding is severe, symptoms may develop within minutes or hours. In babies, one or both of the two soft spots on the head (fontanelles) bulge.

If the bleeding is minimal, symptoms may not develop for weeks. Even after the bleeding has stopped and the blood has clotted, fluid from surrounding tissues can be absorbed into the space, slowly increasing the pressure within the skull.