head injury

Head Injury 

Definition

Injury to the head may damage the scalp, skull or brain. The most important consequence of head trauma 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, 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.

However, each year about two million people suffer from a more serious head injury, and 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 medical care immediately:

• 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 experience temporary amnesia following head injury that begins with memory loss over a period of weeks, months, or years before the injury (retrograde amnesia). 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; it is much more common in people who have had severe or penetrating injuries. Most cases of epilepsy appear right after the accident or within the first year, and become less likely with increased time following the accident.

Closed 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, such as when a person's head hits a windshield in a car accident; or by the sudden deceleration of the head without its 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 the head is resting on impact, the maximum damage will be found at the impact site. A moving head will cause a "contrecoup injury" where 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. This type of injury occurs 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, but it's possible for a fracture to have occurred without any apparent damage. A skull fracture should be suspected if there is:

• blood or clear fluid leaking from the 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 from 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 (from the word for bruising).

In any case, if the blood flow is not stopped, it can lead to unconsciousness and death. The symptoms of bleeding within the skull include:

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

Postconcussion syndrome

If the head injury is mild, there may be no symptoms other than a slight headache. 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 patients who sustain a mild brain injury continue to experience a range of symptoms called "postconcussion syndrome," 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) scans, electroencephalograms (EEG), and routine neurological and neuropsychological evaluations.

Doctors use the Glasgow Coma Scale to evaluate the extent of brain damage based on observing a patient's ability to open his or her eyes, respond verbally, and respond to stimulation by moving (motor response). Patients 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.

Patients 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 patient complaints 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 all may be normal because the damage is so subtle. In many cases, these tests can't detect the microscopic damage that occurs when fibers are stretched in a mild, diffuse injury. In this type of injury, the axons lose some of their covering and become less efficient. This mild injury to the white matter reduces the quality of communication between different parts or the brain. A PET scan, which evaluates cerebral blood flow and brain metabolism, may be of help in diagnosing mild head injury.

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

Treatment

If a concussion, bleeding inside the skull, or skull fracture is suspected, the patient 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 the problems that result. A penetrating wound may require surgery. Those 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 the patient 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 as a result of head injury, there are a variety of treatment programs 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, proper diagnosis and treatment can help alleviate some of the problems after a head injury. However, it usually is difficult to predict the outcome of a brain injury in the first few hours or days; a patient's prognosis may not be known for many months or even years.

The outlook for someone with a minor head injury generally is 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. This can limit a person's ability to work and cause strain in personal relationships.

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 can be very slow, and it may take five years or longer to heal completely. 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.

As researchers learn more about the long-term effects of head injuries, they have begun to uncover links to later conditions. A 2003 report found that mild brain injury during childhood could speed up expression of schizophrenia in those who were already likely to get the disorder because of genetics. Those with a history of a childhood brain injury, even a minor one, were more likely to get familial schizophrenia than a sibling and to have earlier onset. Another study in 2003 found that people who had a history of a severe head injury were four times more likely to develop Parkinson's disease than the average population. Those requiring hospitalization for their head injuries were 11 times as likely. The risk did not increase for people receiving mild head injuries.

Prevention

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

Key terms

Computed tomography scan (CT) — A diagnostic technique in which the combined use of a computer and x rays produce clear cross-sectional images of tissue. It provides clearer, more detailed information than x rays alone.

Electroencephalogram (EEG) — A record of the tiny electrical impulses produced by the brain's activity. By measuring characteristic wave patterns, the EEG can help diagnose certain conditions of the brain.

Magnetic resonance imaging (MRI) — A diagnostic technique that provides high quality cross-sectional images of organs within the body without x rays or other radiation.

Positron emission tomography (PET) scan — A computerized diagnostic technique that uses radioactive substances to examine structures of the body. When used to assess the brain, it produces a three-dimensional image that reflects the metabolic and chemical activity of the brain.

Resources

Periodicals

"Childhood Head Injury Tied to Later Schizophreia." The Brown University Child and Adolescent Behavior Letter June 2003: 5.

"Link to Head Injury Found." Pain & Central Nervous System Week June 9, 2003: 3.

Organizations

American Epilepsy Society. 342 North Main Street, West Hartford, CT 06117-2507. (860) 586-7505. http://www.aesnet.org.

Brain Injury Association. 1776 Massachusetts Ave. NW, Ste. 100, Washington, DC 20036. (800) 444-6443.

Family Caregiver Alliance. 425 Bush St., Ste. 500, San Francisco, CA 94108. (800) 445-8106. http://www.caregiver.org.

Head Injury Hotline. PO Box 84151, Seattle WA 98124. (206) 621-8558. http://www.headinjury.com.

Head Trauma Support Project, Inc. 2500 Marconi Ave., Ste. 203, Sacramento, CA 95821. (916) 482-5770.

National Head Injury Foundation. 333 Turnpike Rd., Southboro, MA 01722. (617) 485-9950.

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head injury,

any traumatic damage to the head resulting from blunt or penetrating trauma of the skull. Blood vessels, nerves, and meninges can be torn. Bleeding, edema, and ischemia may result. See also concussion.

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head

1. the anterior or superior part of a structure or organism, in vertebrates containing the brain and the organs of special sense. See also skull, caput.

2. one animal; used in reference to farm livestock, e.g. ten head of cattle.

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articular head

an eminence on a bone by which it articulates with another bone.

head bail

see headstock.

head bob

the patient is unable to keep the head still while at rest, it makes an involuntary, usually at regular intervals, short, quick downward movement then recovers.

head bot

see cephenemyia.

head cap

of spermatozoon, formed by the collapse of the acrosomial vesicle over the nucleus.

head carriage

includes at attention, drooping, rotated, deviated.

head catarrh

malignant catarrhal fever.

head clamp

see headstock.

head collar

a leather halter-like piece of harness consisting of a poll strap, nose band and usually a rope shank.

head cover

hood or cap used by surgical personnel to reduce contamination of the surgical area by hair and associated flora.

head deviation

the poll-nose axis is turned laterally so that the animal walks in circles but there is no disturbance of balance. Occurs in lesions of the neck and of the cerebral cortex.

fetal head lateral deviation

the fetal head is deviated laterally to lie against the shoulder of the fetus, the front feet and the lateral aspect of the neck being presented to the pelvic inlet; a dystocia which can only be relieved by repulsion of the fetus and the return of the head to between the front feet.

fetal head ventral deviation

the head of the fetus is flexed ventrally so that the fore feet and the dorsum of the neck are presented to the pelvic inlet; a dystocia which can only be relieved by repulsion of the fetus and lifting of the head into the pelvic canal.

head grit

jaundice, photosensitization and hepatic injury in lambs caused by Narthecium ossifragum poisoning.

head injury

traumatic injury to the head resulting from a fall or violent blow. Such an injury may be open or closed and may involve a brain concussion, skull fracture, or contusions of the brain.

head mange

see notoedric mange.

nerve head

the optic disk.

head nod

see head bob (above).

head picking

a form of cannibalism in which birds pick at and injure each other's wattles, combs, eyes; beak trimming reduces the problem but does not prevent the vice.

head posture

see head carriage (above).

head pressing

persistent pushing with the head against a fixed object. Part of the dummy syndrome as in hepatic encephalopathy or encephalitis.

head process

the elongating cephalic tissues which represent the first step in the development of the fetal body.

head rotation

twisting of the head around the axis from the poll to the nose. To be differentiated from deviation of the head. Caused usually by lesions of the vestibular apparatus on one side. The animal walks in circles and has problems maintaining its balance.

head shaking

common in dogs and cats with acute inflammation or foreign bodies in the external ear canal. May be a cause of auricular hematoma. Seasonal head shaking is seen in horses mainly during spring, worsening in summer. A trigeminal neuritis caused by increased levels of melatonin is the suspected cause in some. Allergic rhinitis may also be an underlying cause.

head shy

said of a horse that tries to avoid having its head handled or its headstall put on.

head stall

see head collar (above).

head tilt

includes rotation and deviation.

Head tilt. By permission from Nelson RW, Couto CG, Small Animal Internal Medicine, Mosby, 2003

head tremor

a feature of cerebellar lesions.

head twist injury

injury to cervical vertebrae may occur in horses as a result of a fall with the head and neck under the body.

head's zones

in acupuncture the zones of human skin which are responsive to abnormalities in each of the vital organs.

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Patient discussion about head injury.

Q. What is a concussion? How do you treat it? My child fell and hit his head and passed out. We went to the hospital and they say it’s a concussion and he’ll be fine. Can some one explain what it is exactly?

A. When your brain gets hit hard- this is concussion. But there’s a nice short video about it with a nice pediatrician that explains it:
http://www.5min.com/Video/Dealing-with-Baby-Head-Injuries-7104