Severe brain injury can occur when the head suddenly and violently hits or is hit by an object, when an object pierces the skull and invades brain tissue, or when a sudden, violent stop or start causes the brain to knock against the interior of the skull.
The most common causes of severe brain injury include a blow to the head, a fall, assault or other violence, automobile accidents, and sports and recreational activities. These events can cause mass lesions, such as hematomas and contusions. A hematoma is a blood clot in the brain or on its surface, while a contusion is the bruising of brain tissue. These mass lesions cause damage to brain cells that inhibit their ability to communicate and function, which can leave a patient disabled to some degree.
Severe brain injury is characterized by unconsciousness and coma. The severity of the injury is directly related to the amount of time the patient spends unconscious. Other symptoms may include:
Degree and rate of recovery is highly dependent upon individual circumstances. The amount of time spent unconscious or in a coma, as well as how much is recovered within the first month, are good indicators of long-term recovery.