An intracranial hematoma is a collection of blood within the skull. It's usually caused by a blood vessel that bursts in the brain. It may also be caused by trauma such as a car accident or fall. The blood may collect in the brain tissue or underneath the skull, pressing on the brain. Some head injuries, such as one that causes only a short period of unconsciousness, can be minor. However, an intracranial hematoma is potentially life-threatening. It usually requires immediate treatment. This might include surgery to remove the blood.