Head injury – Wikipedia, the free encyclopedia

Any injury that results in trauma to the scalp, skull, or brain can be classified as a head injury. The terms traumatic brain injury and head injury are often used interchangeably in medical literature.[1] This broad classification includes neuronal injuries, hemorrhages, vascular injuries, cranial nerve injuries, and subdural hygromas, among many others.[2] These classifications can be further categorized as open (penetrating) or closed head injuries. This depends on if the skull was broken or not.[3] Because head injuries cover such a broad scope of injuries, there are many causesincluding accidents, falls, physical assault, or traffic accidentsthat can cause head injuries. Many of these are minor, but some can be severe enough to require hospitalization.[4]

The incidence (number of new cases) of head injury is 1.7 million people in the United States alone each year. About 3% of these incidences lead to death. Adults suffer head injuries more frequently than any age group. Their injuries tend to be due to falls, motor vehicle crashes, colliding or being struck by an object, and assaults. Children, however, tend to experience head injuries due to accidental falls and intentional causes (such as being struck or shaken). Head injury usually occurs in toddlers as they learn to walk. Head trauma is a common cause of childhood hospitalization.[5]

Unlike a broken bone where trauma to the body is obvious, head trauma can sometimes be obvious or discrete. 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.[3] While these symptoms happen right after head injury occurs, many problems can develop later in life. Alzheimers disease, for example, is much more likely to develop in a person who has experienced a head injury.[6]

Head injuries include both injuries to the brain and those to other parts of the head, such as the scalp and skull.

Head injuries can be closed or open. A closed (non-missile) head injury is where the dura mater remains intact. The skull can be fractured, but not necessarily. A penetrating head injury occurs when an object pierces the skull and breaches the dura mater. Brain injuries may be diffuse, occurring over a wide area, or focal, located in a small, specific area.

A head injury may cause skull fracture, which may or may not be associated with injury to the brain. Some patients may have linear or depressed skull fractures.

If intracranial hemorrhage occurs, a hematoma within the skull can put pressure on the brain. Types of intracranial hemorrage include subdural, subarachnoid, extradural, and intraparenchymal hematoma. Craniotomy surgeries are used in these cases to lessen the pressure by draining off blood.

Brain injury can be at the site of impact, but can also be at the opposite side of the skull due to a contrecoup effect (the impact to the head can cause the brain to move within the skull, causing the brain to impact the interior of the skull opposite the head-impact).

If the impact causes the head to move, the injury may be worsened, because the brain may ricochet inside the skull causing additional impacts, or the brain may stay relatively still (due to inertia) but be hit by the moving skull (both are contrecoup injuries).

Specific problems after head injury can include[citation needed]:

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Head injury - Wikipedia, the free encyclopedia