American Medical Association Family Medical Guide - American Medical Association [422]
Brain Injury
A minor head injury usually results in little or no damage to the brain and it heals rapidly and completely. However, a more forceful blow to the head can damage the brain even if the skull is not fractured. In these closed head injuries, the brain can strike the inside surface of the skull, resulting in damage. After a severe head injury, the brain may swell and press against the skull, causing more brain damage. In a small percentage of cases, brain damage is severe enough to cause permanent mental and physical disability or death. A severe head injury may also cause a cerebral hemorrhage (bleeding into the brain), which can lead to brain damage with symptoms resembling those of a stroke (see page 669). If the skull is fractured, bacteria or other microorganisms can enter the brain through the fracture and infect brain tissue, causing meningitis (see page 692). Severe brain injuries are most often caused by motor-vehicle collisions (especially those involving motorcycles), industrial work-related injuries, falls, fights, explosions, or gunshot wounds.
Symptoms
The symptoms of a brain injury may not appear immediately and depend on how badly the brain is damaged. A minor injury may cause a headache or dizziness that lasts for only a few days. Moderate injuries can progress over hours or days as the brain swells from the injury or from irritation from bleeding. severe injury can cause immediate unconsciousness, which can last hours, days, or weeks. A person who loses consciousness may be confused and dizzy when he or she regains consciousness. He or she also may have headaches, fatigue, muscle weakness, difficulty speaking, dilated pupils, and memory loss (especially of what happened immediately before the injury). A person may vomit or have a seizure in addition to the above symptoms. The injury can also cause bleeding in the membranes surrounding the brain or inside the brain. Symptoms of bleeding in the brain or a stroke—such as headache, weakness, confusion, and loss of consciousness—may develop hours or days after the injury.
The symptoms from a brain injury usually improve gradually as the injury heals. However, in severe cases, a person has permanent brain damage that causes lasting physical symptoms (such as paralysis) and decreased mental function. In some cases, a head injury can cause emotional problems such as depression that can develop long after the injury. Permanent brain damage after a severe head injury may also cause seizures as a result of scarring. The risk of seizures is increased if the skull has been penetrated and the brain has been injured directly.
Coma, Concussion, and Contusion
The following terms referring to brain injury or unconsciousness are frequently used and often confused:
• Coma A coma is a state of unconsciousness in which a person does not respond to stimulation. Coma results from a disturbance in or damage to areas of the brain involved in consciousness caused by disease, injury, or drugs.
• Concussion A concussion is an injury to the brain as the result of a blow to the head. A person may have loss of consciousness caused by a disturbance of the electrical activity in the brain. A mild concussion is a brief period of feeling stunned, sometimes with momentary loss of consciousness; the person may not remember the injury or what happened immediately before or after it. A severe concussion can cause prolonged unconsciousness, impairment of brain functions (including breathing, muscle strength, and coordination), dilated pupils, and a weak pulse.
• Contusion A contusion is a bruise of the brain as the result of an injury to the head. It may or may not be associated