The next possible secondary injury as the result of a traumatic injury and after the primary brain injury has occurred, is a hematoma. A hematoma is a pool of blood that forms in the body. If the blood vessels in the brain are broken by the impact of a blow to the skull, they may leak, forming a hematoma. A hematoma can cause brain injury by directly damaging nerves or by causing increased pressure in the brain, which also squeezes nerves. The treatment for a hematoma is to surgically drain the blood.