A head injury is any injury that results in trauma to the skull or brain. The terms traumatic brain injury and head injury are often used interchangeably in the medical literature. Because head injuries cover such a broad scope of injuries, there are many causes—including accidents, falls, physical assault, or traffic accidents—that can cause head injuries.
The number of new cases is 1.7 million in the United States each year, with about 3% of these incidents leading to death. Adults have head injuries more frequently than any age group resulting from falls, motor vehicle crashes, colliding or being struck by an object, or assaults. Children, however, may experience head injuries from accidental falls or intentional causes (such as being struck or shaken) leading to hospitalization. Acquired brain injury (ABI) is a term used to differentiate brain injuries occurring after birth from injury, from a genetic disorder, or from a congenital disorder.
Unlike a broken bone where trauma to the body is obvious, head trauma can sometimes be conspicuous or inconspicuous. In the case of an open head injury, the skull is cracked and broken by an object that makes contact with the brain. This leads to bleeding. Other obvious symptoms can be neurological in nature. The person may become sleepy, behave abnormally, lose consciousness, vomit, develop a severe headache, have mismatched pupil sizes, and/or be unable to move certain parts of the body. While these symptoms happen immediately after a head injury occurs, many problems can develop later in life. Alzheimer's disease, for example, is much more likely to develop in a person who has experienced a head injury.
Brain damage, which is the destruction or degeneration of brain cells, is a common occurrence in those who experience a head injury. Neurotoxicity is another cause of brain damage that typically refers to selective, chemically induced neuron/brain damage.
Head injuries are very common in alcoholics, either from traffic accidents, acts of violence or falls. A study showed that of 100 patients admitted as emergencies with head injuries, 58 were intoxicated, of whom 43 were alcohol dependent.