Traumatic Brain Injury Health Article

Demographics

Estimates for the number of Americans living today who have had a TBI range from between 2.5 and 6.5 million, making it a major public health problem costing the United States more than $48 billion annually. A recent review suggests that the incidence of TBI in the United States is between 180 and 250 per 100,000 population per year, with even higher incidence in Europe and South Africa.

Although TBI can affect anyone at any age, certain age groups are more vulnerable because of lifestyle and other risk factors. Males ages 15 to 24, especially those in lower socioeconomic levels, are most likely to become involved in high-speed or other risky driving, as well as physical fights and criminal activity. These behaviors increase the likelihood of TBI associated with automobile and motorcycle accidents or with violent crimes.

Infants, children under five years of age, and adults 75 years and older are also at higher risk for TBI than the general population because they are most susceptible to falls around the home. Other factors predisposing the very young and the very old to TBI include physical abuse, such as violent shaking of an infant or toddler that can result in shaken baby syndrome.

Causes and symptoms

Accidents, especially motor vehicle accidents, are the major culprit implicated in TBI. Because accidents are the leading cause of death or disability in men under age 35, and because over 70% of accidents involve injuries of the head and/or spinal cord, this is not surprising. In fact, transportation accidents involving automobiles, motorcycles, bicycles, and pedestrians account for half of all TBIs and for the majority of TBIs in individuals under the age of 75. At least half of all TBIs are associated with alcohol use. Sports injuries cause about 3% of TBIs; other accidents leading to TBI may occur at home, at work, or outdoors.

In those age 75 and older, falls are responsible for most TBIs. Other situations leading to TBI at all ages include violence, implicated in about 20% of TBIs. Firearm assaults are involved in most violent causes of TBI in young adults, whereas child abuse is the most common violent cause in infants and toddlers. In the shaken baby syndrome, a baby is shaken with enough force to cause severe countrecoup injury.

The symptoms of TBI may occur immediately or they may develop slowly over several hours, especially if there is slow bleeding into the brain or gradual swelling. Depending on the cause, mechanism, and extent of injury, the severity of immediate symptoms of TBI can be mild, moderate, or severe, ranging from mild concussion to deep coma or even death.

With concussion, the injured person may experience a brief or transient loss of consciousness, much like fainting or passing out, or merely an alteration in consciousness described as "seeing stars" or feeling dazed or "out of it." On the other hand, coma refers to a profound or deep state of unconsciousness in which the individual does not respond to the environment in any meaningful way.

When a person with TBI regains consciousness, some symptoms are immediately apparent, while others are not noticed until several days or weeks later. Symptoms which may be obvious right away after mild TBI include headache, changes in vision such as blurred vision or tired eyes, nausea, dizziness, lightheadedness, ringing in the ears, bad taste in the mouth, or altered sense of smell which is usually experienced as loss of the sense of taste.

Approximately 40% of patients with TBI develop postconcussion syndrome within days to weeks, with symptoms including headache, dizziness or a sensation of spinning (vertigo), memory problems, trouble concentrating, sleep disturbances, restlessness, irritability, depression, and anxiety. This syndrome may persist for a few weeks, especially in patients with depression, anxiety, or other psychiatric symptoms before the TBI.

With more severe injuries, there may also be immediate numbness or weakness of one or more limbs, blindness, deafness, inability to speak or understand speech, slurred speech, lethargy with difficulty staying awake, persistent vomiting, loss of coordination, disorientation, or agitation. In addition to some of these symptoms, young children with moderate to severe TBI may also experience prolonged crying and refusal to nurse or eat.

While the injured person is preoccupied with headache or pain related to other physical trauma, symptoms such as difficulty in thinking or concentrating may not be evident. Often these more subtle symptoms may appear only when the individual attempts to return to work or to other mentally challenging situations. Similarly, personality changes, depression, irritability, and other emotional and behavioral problems may initially be attributed to coping with the stress of the injury, and they may not be fully appreciated until the individual is recuperating at home.

Seizures may occur soon after a TBI or may first appear up to a year later, especially when the damage involves the temporal lobes. Other symptoms which may appear immediately or which may be noticed only while the individual is returning to usual activities are confusion, fatigue or lethargy, altered sleep patterns, and trouble with memory, concentration, attention, and finding the right words or understanding speech.