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Head Injury

Definition

Injury to the head may damage the scalp, skull, or brain. The most important consequence of head injury is traumatic brain injury. Head injury may occur either as a closed head injury such as the head hitting a car's windshield, or as a penetrating head injury such as when a bullet pierces the skull. Both may cause damage that ranges from mild to profound. Very severe injury can be fatal because of profound brain damage.

Description

External trauma to the head is capable of damaging the brain, even if there is no external evidence of damage. More serious injuries can cause skull fracture, blood clots between the skull and the brain, or bruising and tearing of the brain tissue itself.

Injuries to the head can be caused by traffic accidents, sports injuries, falls, workplace accidents, assaults, or bullets. Most people have had some type of head injury at least once in their lives, but rarely do they require a hospital visit.

Each year, approximately two million people suffer from a serious head injury. Up to 750,000 of them are severe enough to require hospitalization. Brain injury is most likely to occur in males between ages 15 and 24, usually as a result of car and motorcycle accidents. About 70% of all accidental deaths are due to head injuries, as are most of the disabilities that occur after trauma.

A person who has had a head injury and who is experiencing the following symptoms should seek immediate medical care:

• serious bleeding from the head or face
• loss of consciousness, however brief
• confusion and lethargy
• lack of pulse or breathing
• clear fluid drainage from the nose or ear

Causes and symptoms

A head injury may cause damage both from the direct physical injury to the brain and from secondary factors such as lack of oxygen, brain swelling, and disturbance of blood flow. Both closed and penetrating head injuries can cause swirling movements throughout the brain, tearing nerve fibers and causing widespread bleeding or a blood clot in or around the brain. Swelling may raise pressure within the skull (intracranial pressure) and may block the flow of oxygen to the brain.

Head trauma may cause a concussion, in which there is a brief loss of consciousness without visible structural damage to the brain. In addition to loss of consciousness, initial symptoms of brain injury may include:

• memory loss and confusion
• vomiting
• dizziness
• partial paralysis or numbness
• shock
• anxiety

After a head injury, there may be a period of impaired consciousness, followed by a period of confusion and impaired memory with disorientation and a breakdown in the ability to store and retrieve new information. Others may experience temporary (retrograde) amnesia following head injury. As a person recovers, memory slowly returns. Post-traumatic amnesia refers to loss of memory for events during and after an accident.

Epilepsy occurs in 2-5% of those who have experienced a head injury. It is much more common in people who have had severe or penetrating injuries. Most cases of epilepsy appear immediately after an accident or within the first year. They become less likely with increased time following an accident.

Closed head injury

Closed head injury refers to brain trauma without any penetrating injury to the brain. It may be the result of a direct blow to the head, of a moving head being rapidly stopped, or by a sudden deceleration of the head without striking another object. The kind of injury the brain receives in a closed head injury is determined by whether or not the head was unrestrained upon impact and the direction, force, and velocity of the blow. If a head was resting on impact, the maximum damage will be found at the impact site. A moving head will cause a contrecoup injury in which the brain damage occurs on the side opposite the point of impact, as a result of the brain slamming into that side of the skull. A closed head injury also may occur without the head being struck, such as when a person experiences whiplash, because the brain is of a different density than the skull, and can be injured when delicate brain tissues hit against the rough, jagged inner surface of the skull.

Penetrating head injury

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 an infection.

Skull fracture

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. It is possible for a fracture to have occurred without any apparent damage. A skull fracture should be suspected if any of the following are observed:

• 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 part of the head

Intracranial hemorrhage

Bleeding (hemorrhage) inside the skull may accompany a head injury and cause additional damage to the brain. A blood clot (hematoma) may occur if a blood vessel between the skull and the brain ruptures. When the blood leaks out and forms a clot, it can press against brain tissue, causing symptoms that may arise within a few hours to a few weeks after the injury. If the clot is located between the bones of the skull and the covering of the brain (dura), it is called an epidural hematoma. If the clot is between the dura and the brain tissue itself, the condition is called a subdural hematoma. In other cases, bleeding may occur deeper inside the brain. This condition is called intracerebral hemorrhage, or intracerebral contusion.

If the blood flow within the skull is not stopped, it can lead to unconsciousness and death. The signs and symptoms of bleeding within the skull include:

• nausea and vomiting
• headache
• loss of consciousness
• unequal pupil size
• lethargy

Post-concussion syndrome

If a head injury is mild, there may be no symptoms other than a slight headache, or there also may be confusion, dizziness, and blurred vision. While the head injury may seem to have been quite mild, in many cases symptoms persist for days or weeks. Up to 60% of persons who sustain a mild brain injury continue to experience a range of symptoms called post-concussion syndrome, for as long as six months or a year after the injury.

The symptoms of postconcussion syndrome can result in a puzzling interplay of behavioral, cognitive, and emotional complaints that can be difficult to diagnose, including:

• headache
• dizziness
• mental confusion
• behavior changes
• memory loss
• cognitive deficits
• depression
• emotional outbursts

Diagnosis

The extent of damage in a severe head injury can be assessed with computed tomography (CT) scan, magnetic resonance imaging (MRI), positron emission tomography (PET) scan, electroencephalograms (EEG), and routine neurological and neuropsychological evaluations.

Physicians use the Glasgow Coma Scale to evaluate the extent of brain damage based on observing a person's ability to open his or her eyes, respond verbally, and respond to stimulation by moving (motor response). Persons can score from three to 15 points on this scale. People who score below eight when they are admitted usually have suffered a severe brain injury and will need rehabilitative therapy as they recover. In general, higher scores on the Glasgow Coma Scale indicate less severe brain injury and a better prognosis for recovery.

Persons with a mild head injury who experience symptoms are advised to seek out the care of a specialist. Unless a family physician is thoroughly familiar with medical literature in this newly emerging area, experts warn that there is a good chance that a complaint after a mild head injury will be downplayed or dismissed. In the case of mild head injury or postconcussion syndrome, CT and MRI scans, electroencephalograms (EEG), and routine neurological evaluations may all be normal because the damage is so subtle. In many cases, these tests cannot detect the microscopic damage that occurs when fibers are stretched in a mild, diffuse injury, in which the axons in the brain lose some of their covering and become less efficient. This mild injury to the white matter reduces the quality of communication between different parts and the brain. A PET scan, which evaluates cerebral blood flow and brain metabolism, may be of help in diagnosing mild head injury, although many experts still considered this to be an experimental procedure.

Persons with continuing symptoms after a mild head injury should call a local chapter of a head-injury foundation that can refer them to the best nearby expert.

Treatment

If a concussion, bleeding inside the skull, or skull fracture is suspected, a person should be kept quiet in a darkened room, with head and shoulders raised slightly on pillow or blanket.

After initial emergency treatment, a team of specialists may be needed to evaluate and treat any problems that result. A penetrating wound may require surgery. Those individuals with severe injuries or with a deteriorating level of consciousness may be kept hospitalized for observation. 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 also require surgery. Supportive care and specific treatments may be required if a person experiences further complications. People who experience seizures, for example, may be given anticonvulsant drugs, and people who develop fluid on the brain (hydrocephalus) may have a shunt inserted to drain the fluid.

In the event of long-term disability that occurs as a result of head injury, a variety of treatment programs are available, including long-term rehabilitation, coma treatment centers, transitional living programs, behavior management programs, life-long residential or day treatment programs, and independent living programs.

Prognosis

Prompt diagnosis and treatment can help alleviate some of the problems after a head injury. However, it is usually difficult to predict the outcome of a brain injury in the first few hours or days. A person's prognosis may not be known for many months or even years.

The outlook for someone with a minor head injury is generally good, although recovery may be delayed, and symptoms such as headache, dizziness, and cognitive problems can persist for up to a year or longer after an accident.

Serious head injuries can be devastating, producing permanent mental and physical disability. Epileptic seizures may occur after a severe head injury, especially a penetrating brain injury, a severe skull fracture, or a serious brain hemorrhage. Recovery from a severe head injury may take five years or longer to completely heal. Risk factors associated with an increased likelihood of memory problems or seizures after head injury include age, length and depth of coma, duration of post-traumatic and retrograde amnesia, presence of focal brain injuries, and initial Glasgow Coma Scale score.

Health care team roles

First aid may be given by emergency medical technicians. Physicians trained in emergency medicine often provide initial care in a hospital. Neurosurgeons and neurologists may be asked to assist with care. Rehabilitation specialists such as physicians, physical therapists, speech therapists, or occupational therapists may provide rehabilitation. Nurses provide supportive care throughout, including 24-hour care, home nursing care, and patient education.

Prevention

Many severe head injuries could be prevented by wearing protective headgear during certain sports, or helmets when riding a bike or motorcycle. Seat belts and airbags can prevent many head injuries that result from motor vehicle accidents. Appropriate protective headgear should always be worn on the job where head injuries are a possibility.

Resources

BOOKS

Adams, Raymond D., Maurice Victor, and Allan H. Ropper. Adams and Victor's Principles of Neurology, 6th ed. New York: McGraw Hill, 1997.

Bailes, Julian E., Mark R. Lovell, and Joseph C. Maroon. Sports Related Concussion. St. Louis, MO: Quality Medical Publishing, 1998.

Parker, Rolland S. Concussive Brain Trauma: Neurobehavioral Impairment and Maladaptation. Boca Raton, FL: Lewis Publishers, 2000.

Rizzo, Matthew, and Daniel Tranel. Head Injury and Postconcussive Syndrome. London: Churchill Livingstone, 1996.

Wrightston, Philip, and D. M. A. Gronwall. Mild Head Injury: A Guide to Management. New York: Oxford, 1999.

PERIODICALS

Bailes, J. E., and R. C. Cantu. "Head Injury in Athletes." Neurosurgery 48, no. 1 (2001): 26-45.

Centers for Disease Control and Injury. "Facts about Concussion and Brain Injury and Where to Get Help." 〈http://webapp.cdc.gov/IXPRESS/PUBSPROD/NCIPC+BOOK/NCIPC.DML〉.

Guskiewicz, K. M., N. L. Weaver, D. A. Padua, and W. E. Garrett. "Epidemiology of Concussion in Collegiate and High School Football Players." American Journal of Sports Medicine 28, no. 5 (2000): 643-50.

Maroon, J. C., et al. "Cerebral Concussion in Athletes: Evaluation and Neuropsychological Testing." Neurosurgery 47, no. 3 (2000): 659-69.

Proctor, M. R., and R. C. Cantu. "Head and Neck Injuries in Young Athletes." Clinics in Sports Medicine 19, no. 4 (2000): 693-715.

Reece, R. M., and R. Sege. "Childhood Head Injuries: Accidental or Inflicted?" Archives of Pediatric and Adolescent Medicine 154, no. 1 (2000): 11-15.

ORGANIZATIONS

American Academy of Neurology. 1080 Montreal Avenue, St. Paul, MN 55116. (651) 695-1940. (651) 695-2791. 〈http://www.aan.com/〉. info@aan.org.

American Academy of Pediatrics. 141 Northwest Point Boulevard, Elk Grove Village, IL 60007-1098. (847) 434-4000. (847) 434-8000. 〈http://www.aap.org/default.htm〉. kidsdoc@aap.org.

American College of Emergency Physicians. P.O. Box 619911, Dallas, TX 75261-9911. (800) 798-1822. (972) 550-0911. (972) 580-2816. 〈http://www.acep.org/〉. info@acep.org.

American College of Osteopathic Emergency Physicians. 142 E. Ontario Street, Suite 550, Chicago, IL 60611. (312) 587-3709. (800) 521-3709. (312) 587-9951. 〈http://www.acoep.org〉.

Brain Injury Association. 105 North Alfred Street, Alexandria, VA 22314. (800) 444-6443. (703) 236-6000. (703) 236-6001. 〈http://www.biausa.org/Sportsfs.htm〉. prevention@biausa.org.

Emergency Nurses Association. 915 Lee Street, Des Plaines, IL 60016-6569. (800) 900-9659. (847) 460-4001. 〈http://www.ena.org/about/index.htm〉.

International Brain Injury Association. 1150 South Washington Street, Suite 210, Alexandria, VA 22314. (703) 683-8400. (703) 683-8996. 〈http://www.internationalbrain.org/〉. info@internationalbrain.org.

National Center for Injury Prevention and Control. Centers for Disease Control and Prevention, Mailstop F41, 4770 Buford Highway NE, Atlanta, GA 30341-3724. (770) 488-4031. (770) 488-4338. 〈http://www.cdc.gov/ncipc/dacrrdp/tbi.htm〉. dardinfo@cdc.gov.

OTHER

American Academy of Family Physicians. 〈http://familydoctor.org/handouts/458.html〉.

American Academy of Pediatrics. 〈http://www.aap.org/policy/ac9858.html〉.

Brain Injury Association. 〈http://www.biausa.org/〉.

Glasgow Coma Score. 〈http://www.trauma.org/scores/gcs.html〉.

Head Injury Association of Waterloo-Wellington, Canada. 〈http://www.ahs.uwaterloo.ca/∼cahr/headfall.html〉.

Head Injury Hotline. 〈http://www.headinjury.com/faqpcs.htm〉.

Pashby Sport Concussion Safety Website. 〈http://www.concussionsafety.com/〉.

University of California Los Angeles. 〈http://neurosurgery.ucla.edu/Diagnoses/BrainInjury/BrainInjuryDis_6.html〉.

University of Missouri Health Center. 〈http://www.muhealth.org/∼neuromedicine/concussion.shtml〉.