Injury to the head may damage the scalp, skull or brain, with results rangingfrom mild to fatal. Head injuries can be caused by traffic accidents,sports injuries, falls, workplace accidents, assaults, or firearms. About 70% of all accidental deaths are due to head injuries, as are most injury-related disabilities.
The brain can be damaged even if there is no external evidence of damage. A person who has had a head injury and who is experiencing the following symptoms should seek medical care immediately:
- Serious bleeding from the heador face
- Loss of consciousness, however brief
- Confusion and lethargy
- Lack of pulse or breathing
- Clear fluid drainage fromthe nose or ear.
A head injury may cause damage both from the direct physical injury and fromsecondary factors such as lack of oxygen, brain swelling, and disturbance ofblood flow. It can cause swirling movements throughout the brain, tearing nerve fibers and causing widespread bleeding or a blood clot. Swelling may raisepressure within the skull and can block the flow of oxygen to the brain.
Head injury may involve concussion, in which there is a brief loss ofconsciousness without visible structural damage to the brain. Initial symptoms of brain injury may also include: memory loss and confusion, vomiting, dizziness, partial paralysis or numbness, shock, and anxiety.
After a head injury, there may be a period of impaired consciousness followedby confusion and impaired memory with disorientation and a breakdown in theability to store and retrieve new information. Others experience temporary amnesia involving loss of memory of the weeks, months, or years before the injury. As the patient recovers, memory slowly returns. Post-traumatic amnesia refers to loss of memory for events during and after the accident. Epilepsy occurs in 2-5% of those who have had a head injury.
Closed head injury refers to brain injury without any penetrating injury to the brain. It may be the result of a direct blow to the head; of the moving head being rapidly stopped (as when it hits a windshield), or by the sudden deceleration of the head without striking anything. A moving head will cause a "contrecoup injury" where damage occurs on the side of the brain opposite thepoint of impact, as a result of the brain slamming into that side of the skull. Even when no object contacts the head, sudden deceleration can result in whiplash, causing delicate brain tissues to hit against the rough, jagged inner surface of the skull.
If the skull is fractured, bone fragments may be driven into the brain. Any object that penetrates the skull may implant foreign material and dirt into the brain, leading to infection.
A skull fracture is a medical emergency that must be treated promptly to prevent possible brain damage. Such an injury may be obvious if blood or bone fragments are visible, but there may also be no apparent damage. A fracture should be suspected if there is: blood or clear fluid leaking from nose or ears,unequal pupil size, bruises or discoloration around the eyes or behind the ears, swelling or depression of the part of the head.
If a blood vessel between the skull and the brain ruptures; leaking blood canform a clot, which can press against brain tissue. If the blood flow is notstopped, it can lead to unconsciousness and death. Symptoms of bleeding within the skull include: nausea and vomiting, headache, loss of consciousness, unequal pupil size, and lethargy.
If the head injury is mild, there may be no symptoms other than slight headache, or confusion, dizziness, and blurred vision. Up to 60% of patients who sustain a mild brain injury continue to experience a range of symptoms called "postconcussion syndrome," for as long as a year. This syndrome can involve apuzzling interplay of difficult-to-diagnose complaints, including: headache,dizziness, mental confusion, behavior changes, memory loss, depression, emotional outbursts, and cognitive deficits that impair functions such as awareness.
Damage in a severe head injury can be assessed with computed tomography scan(CT scan), magnetic resonance imaging (MRI), positron emission tomography (PET) scans, electroencephalograms (EEG), and routine neurological and neuropsychological evaluations.
A penetrating wound (such as caused by a bullet) may require surgery. If there is bleeding inside the skull, the blood may need to be surgically drained;if a clot has formed, it may need to be removed. Severe skull fractures alsorequire surgery.
In the event of long-term disability, there are a variety of treatment programs, including long-term rehabilitation, coma treatment centers, transitionalliving programs, behavior management programs, life-long residential or day treatment programs and independent living programs.
Patients with a mild head injury who experience symptoms are advised to seekout a specialist. A local chapter of a head-injury foundation can provide names of nearby experts.
Prompt diagnosis and treatment can alleviate some of the problems after a head injury. However, a patient's prospects for recovery may not be known for many months or even years. The outlook for a minor head injury is generally good, although symptoms can persist for a year or longer. This can limit abilityto work and cause strain in personal relationships.
Serious head injuries can be devastating, producing permanent mental and physical disability. Full healing may take five years or longer.
Many severe injuries could be prevented by wearing protective helmets duringcertain sports and occupations, and when riding bikes or motorcycles. Seat belts and airbags can prevent injuries.