Pediatric Annals

Epidemiology and Prevention of Pediatric Traumatic Brain Injury

Frederick P Rivara, MPH

Abstract

The problem of childhood injuries has always been with us. In recent years, however, interest in trauma has dramatically increased for a number of reasons. Advances in medical care and public health have had a major impact on mortality and morbidity from a wide variety of infectious and other diseases. Similar changes have not occurred in trauma, and consequently, its relative importance has increased. An increasingly scientific approach to injury causation has led to progressively more effective prevention programs in specific areas. Finally, the interest of governmental agencies at the national and local level has been accompanied by an infusion of money for both research and prevention.

Head injuries are one of the most important subcategories of the injury problem. This article describes the magnitude of the problem, the groups at greatest risk, factors that increase the risk of head trauma, and the strategies that can be taken to decrease the impact of this problem on children, their families, and their communities.

DEFINITIONS

It is important to recognize that varying definitions of head trauma are used in the literature. "Head injury" or "head trauma" often includes injuries not affecting the brain itselfj ie, the scalp or skull. Although these nonbrain injuries may indeed be serious, they are rarely life threatening. Reporting systems that rely on "body part affected" to classify injuries that may include brain injuries, as well as those head and facial injuries not involving the brain, typically overestimate the true incidence of brain injury.

The term brain injury is generally defined as trauma with evidence of brain involvement. This usually presents as altered level of consciousness, ranging from symptoms of lethargy and drowsiness to coma and brain death. The severity of brain injury can be graded using physiological measures such as the Glasgow Coma Scale1 (GCS) and the Children's Orientation and Amnesia Test2 (COAT) or anatomic measures such as the Abbreviated Injury Scale3 (AIS). The physiological scales are most useful clinically and correlate well with prognosis and functional outcome. The anatomic scales usually are calculated after the fact and correlate better with risk of death and serve various research needs. Unfortunately, one type of scale cannot easily be mapped onto another type.

Severity of brain injury generally has been classified on the basis of the GCS at the time of admission to the hospital or emergency room. Mild injuries are usually described as those that have a GCS score of 13 to 15, moderate injuries have a GCS score of 9 to 12, and severe injuries have a GCS score of 8 or less. Patients with severe injuries are usually comatose.

MAGNITUDE OF THE PROBLEM

Fatalities

The number of fatal injuries due to brain injury is not accurately known. Widely disparate incidence rates are found depending on the data source and method of calculation. Based on death certificate information, the National Center for Health Statistics estimates that approximately 26% of trauma deaths, or some 7000 per year, are due to head trauma.4 Similar rates are found when applying the brain injury mortality rates from population-based studies in Minnesota5 and San Diego6 to the US population. However, case series, from trauma centers estimate that more than 75% of trauma deaths in children are due to brain injury, clearly making it the leading cause of trauma death.7

The case-fatality rate for pediatric brain injuries also varies widely depending on the inclusion criteria and the source of the cases. Probably, the biggest factor influencing rates is whether prehospital deaths are included. Since up to one half of brain injury fatalities occur at the scene of trauma, exclusion of these deaths can…

The problem of childhood injuries has always been with us. In recent years, however, interest in trauma has dramatically increased for a number of reasons. Advances in medical care and public health have had a major impact on mortality and morbidity from a wide variety of infectious and other diseases. Similar changes have not occurred in trauma, and consequently, its relative importance has increased. An increasingly scientific approach to injury causation has led to progressively more effective prevention programs in specific areas. Finally, the interest of governmental agencies at the national and local level has been accompanied by an infusion of money for both research and prevention.

Head injuries are one of the most important subcategories of the injury problem. This article describes the magnitude of the problem, the groups at greatest risk, factors that increase the risk of head trauma, and the strategies that can be taken to decrease the impact of this problem on children, their families, and their communities.

DEFINITIONS

It is important to recognize that varying definitions of head trauma are used in the literature. "Head injury" or "head trauma" often includes injuries not affecting the brain itselfj ie, the scalp or skull. Although these nonbrain injuries may indeed be serious, they are rarely life threatening. Reporting systems that rely on "body part affected" to classify injuries that may include brain injuries, as well as those head and facial injuries not involving the brain, typically overestimate the true incidence of brain injury.

The term brain injury is generally defined as trauma with evidence of brain involvement. This usually presents as altered level of consciousness, ranging from symptoms of lethargy and drowsiness to coma and brain death. The severity of brain injury can be graded using physiological measures such as the Glasgow Coma Scale1 (GCS) and the Children's Orientation and Amnesia Test2 (COAT) or anatomic measures such as the Abbreviated Injury Scale3 (AIS). The physiological scales are most useful clinically and correlate well with prognosis and functional outcome. The anatomic scales usually are calculated after the fact and correlate better with risk of death and serve various research needs. Unfortunately, one type of scale cannot easily be mapped onto another type.

Severity of brain injury generally has been classified on the basis of the GCS at the time of admission to the hospital or emergency room. Mild injuries are usually described as those that have a GCS score of 13 to 15, moderate injuries have a GCS score of 9 to 12, and severe injuries have a GCS score of 8 or less. Patients with severe injuries are usually comatose.

MAGNITUDE OF THE PROBLEM

Fatalities

The number of fatal injuries due to brain injury is not accurately known. Widely disparate incidence rates are found depending on the data source and method of calculation. Based on death certificate information, the National Center for Health Statistics estimates that approximately 26% of trauma deaths, or some 7000 per year, are due to head trauma.4 Similar rates are found when applying the brain injury mortality rates from population-based studies in Minnesota5 and San Diego6 to the US population. However, case series, from trauma centers estimate that more than 75% of trauma deaths in children are due to brain injury, clearly making it the leading cause of trauma death.7

The case-fatality rate for pediatric brain injuries also varies widely depending on the inclusion criteria and the source of the cases. Probably, the biggest factor influencing rates is whether prehospital deaths are included. Since up to one half of brain injury fatalities occur at the scene of trauma, exclusion of these deaths can artificially lower the case-fatality rate. In a population-based study, Kraus et al8 found a case-fatality rate of 6% for children under the age of 15 compared with a rate of 17% for brain injuries among all ages. On the other hand, of children admitted to the hospital in coma, the case-fatality rate in this same series was 59%. Michaud et al9 reported a 33% case-fatality rate for children 16 years of age or younger admitted to a regional trauma center with brain injury and a GCS score of 8 or less.

Nonfatal Injuries

More accurate data are currently available to estimate the incidence of overall brain injury occurring to children. The most recent and most rigorously collected data are those from a population-based study of San Diego residents in 1981 in which the incidence of brain injury for children and adolescents aged 0 to 19 years was 219.4 per 100 000 per year6 (Figure). These were brain injuries resulting in hospitalization and/or death; the rates include prehospital deaths. The exact number of head injuries requiring medical care but not admission is unknown, but would be expected to constitute a considerable number of cases. In emergency room surveillance studies, generally only 2% to 3% of children presenting with trauma require admission, ie, for every patient admitted, 30 to 50 are treated and discharged home.10

Figure. Age-specific brain injury rates per 100 000, by gender, San Diego County, California, 1981.

Figure. Age-specific brain injury rates per 100 000, by gender, San Diego County, California, 1981.

Gender

As with all types of trauma, males have approximately twice the rate of brain injuries than females.11 These differences appear very early in life during the preschool years and probably reflect a combination of differences in behavior between boys and girls, as well as differences in exposure to hazards resulting in injury. It is instructive to think of males as having excess rates of brain injury compared with females; if the rate in males were lowered to the rate in females, a significant number of injuries would be prevented.

Age

Generally, rates of brain injury are stable throughout childhood, but increase dramatically at the age of 15 years.6 This probably reflects changes in developmentally appropriate activities, particularly the acquisition of a driver's license and an increase in motor vehicle driving. Some studies also have demonstrated high rates of head injuries among preschool-aged children.11 These children have a high center of gravity and usually fall head-first, thus increasing the proportion of injuries that involve the head. In addition, parents also may be more concerned about relatively minor trauma in children of this age and will seek care more readily than for older children with the same degree of injury.

Variation With Race and Socioeconomic Status

Brain injury and death rates vary considerably by race and socioeconomic status. Among children less than 15 years old in the United States, death rates from unintentional injury are highest for Native Americans, followed by blacks, Hispanics, and then whites; Asians have the lowest rates.6 For all races, injury death rates are inversely related to income level, and much, if not all, of the difference seen in death rates between racial groups may be the result of differences in income.

These same trends are seen with brain injury. The incidence of head injury among nonwhites is nearly 50% higher than among whites. In the San Diego study, stratifying by median family income essentially eliminated the racial and ethnic differences in brain injury rates.12 The reasons for the increased risk of poor children probably include both decreased supervision, lower levels of information about and use of prevention strategies (such as bicycle helmets), and exposure to more hazardous environments such as high-rise tenements (leading to falls from windows) and higher volume, fester moving traffic (resulting in pedestrian injuries).

CAUSES OF BRAIN INJURY

The major causes of pediatric brain injury are falls, motor vehicle crashes, and recreational activities. The relative importance of these varies with age and reflects developmental changes in activities as well as skills, and hence exposure to risk.

Falls

Injuries from falls account for 35% of pediatric brain injuries requiring hospital admission or resulting in death.6 Among injuries of all types, falb are the most common reason for a visit of a child or an adolescent to an emergency room.10 In one statewide population-based study, falls accounted for 29% of hospital admissions for an incidence of 97 per 100 000 annually.13 This varied significantly by age, with the rate of hospitalization for fall-related trauma highest for adolescents and lowest for preschool-aged children. However, 42% of tall-related trauma among preschoolers involved head injury compared with only 14% of fell trauma in adolescents. Most of the fells resulting in brain injury, particularly among young children, were fells from heights. A recent series of case reports on fells in children examined the relationship between height of the fell and severity of injury, particularly brain injury.14,15 Toddlers and older children usually escape severe injury in fells from heights of less than 10 feet; severe brain injuries occurring to children with reported fells of less than 10 feet bear careful investigation for the possibility of child abuse. However, infants and children under the age of 2 years may not have the same degree of resistance to severe injury from low fells. Epidural hematomas in particular can occur in infants from falls of less than 4 feet.

Motor Vehicle Collisions

Motor vehicles account for approximately one quarter of pediatric brain injuries. Among children under the age of 15, the majority of these injuries occur to nonoccupants, ie, bicyclists and pedestrians. Bicycles account for approximately one fifth of head injuries requiring admission for children under the age of 15 years.6 Pedestrian injuries are the most important cause of death from trauma in the 5- to 9-year-old age group and are second only to cancer as a cause of death in this age. The majority of children who die from pedestrian injuries have significant brain injuries. In contrast, the majority of motor vehicle injuries to adolescents occur as occupants, reflecting the pattern in adults.

Recreational

Sports and recreational causes account for approximately 21% of brain injuries to children and adolescents.6 One half of these are bicycle accidents not involving collision with a motor vehicle; the remainder occur during organized and unorganized sports and on playgrounds. Falls from playgrounds account for the majority of serious playground-related injuries.

Assaults

One in 10 brain injuries to children are due to assaults. An important subcategory of these are injuries from child abuse. Among children under the age of 2, 24% of head injuries (brain and skull) requiring hospital admission in one series were due to abuse.16 More than one half of these were subdural hematomas; more than one third of patients in this series also had acute or healing long-bone fractures. Subdural hemorrhages in young children are much more common from child abuse than from unintentional injury; in contrast, epidural hematomas are more typically found in children with blunt unintentional trauma. Retinal hemorrhage rarely occurs in unintentional injury in children; its presence usually implies the child is the victim of the shaken-impact syndrome.

PREVENTION

The number of patients with serious disability or death from brain injuries is not likely to decrease solely because of better medical care. More than two thirds of patients who die of brain injury do so before ever reaching a hospital.6 For those patients who do survive, medical care is directed to preventing secondary brain injury. Few resources are available for direct treatment of neurons damaged in the initial impact. Prevention of the injury from occurring in the first place appears to be the only answer for a large number of these patients (Table).

There are a few principles of prevention that should be understood. The etiologic agent of injury is the transfer of energy to tissues in an amount and at a rate that exceeds their threshold for injury. Anything that can decrease the amount and rate of energy transfer will decrease the severity of injury to the brain, if not prevent it entirely. A second principle is that injury prevention strategies that rely as much as possible on "passive" or automatic strategies are likely to be much more stressful from a public health perspective than are those strategies that are based solely on behavior change. Behavior change is difficult to achieve, particularly among those at greatest risk, eg, adolescents, the poor, and those who are intoxicated. Passive strategies are particularly effective in these groups who otherwise might not be reached by prevention. Finally, any injury prevention strategy, regardless of its focus, is likely to be far more effective if it is given as a specific message than if it is part of a more diffuse, "shotgun" approach to the injury problem. Pediatricians have told patients and their parents for years to "be careful" and to "childproof the home." The physician is likely to be much more effective if specific advice is given instead, such as "use a car seat, buy and use a bike helmet, and throw out the baby walker."

The following are some specific strategies that have proven effective and lend themselves to application by pediatric health providers in the office and community setting.

Safety Helmets

Bicycles are a ubiquitous part of childhood, yet they are not without their risks. Approximately 550 000 persons a year require emergency room care for bicycle-related trauma, and more than 900 of these individuals die from their injuries; children and adolescents are the groups at greatest risk.17 Approximately one third of emergency room visits, two thirds of hospitalizations, and three fourths of deaths related to bicycling involve brain injury.18

These injuries are easily preventable through the use of bicycle helmets. A case-control study conducted in Seattle demonstrated that bicycle helmets decrease the risk of head injury by 85% and the risk of brain injury by 88%; unhelmeted riders are eightfold more likely to have a brain injury than are helmeted bicyclists. This is enormously effective, especially when compared with many other injury prevention strategies.

Important barriers to helmet use are lack of awareness about the risks of bicycling and the effectiveness of helmets; the cost of helmets, particularly for low-income families and families with multiple children; and the perception of negative pressure from peers. Fortunately, strategies to address these barriers to use have been developed, and programs to increase bicycle helmet use have been successful. These have included educational programs, discount coupons, helmet subsidies, role-modeling by parents and sports figures, and more recently, mandatory helmet legislation. Pediatricians and other health-care providers have played integral roles in many bicycle helmet promotion programs. Educational programs have been able to increase helmet use by children in the community to more than 40%. 17 Similar results also have been achieved by mandatory-use legislation. Using combined education, cost reduction, and legislation may yield the highest rate of helmet use. Where this has been done in places such as the state of Victoria in Australia, helmet use rates as high as 70% among school-aged children have been achieved. Subsidies for helmet purchasers can be cost effective in terms of averting the cost of brain injuries. Such strategies should be considered by managed care organizations, health insurance plans, and community programs.

Table

TABLEInjury Prevention Strategies

TABLE

Injury Prevention Strategies

Use of helmets also can potentially prevent brain injuries occurring in other sports and recreational activities. For example, studies of equestrian injuries show that brain injuries account for approximately 75% of deaths and 55% to 100% of hospitalizations.19 Helmet use in baseball and football is pervasive. Helmets also should be used in horseback riding, roller blading, skateboarding, hockey, and perhaps in roller skating, skiing, and sledding. Most of the serious and fatal injuries in these sports are brain injuries. The promotion of helmets for these other activities is appropriate, but to some degree will depend on the production of low-cost and attractive helmets that meet appropriate standards. Manufacturers must address the barriers to helmet use identified by participants in these sports. Helmets are generally perceived as being hot, uncomfortable, unattractive and too costly. The development of a multi-purpose sports helmet, that parents could buy and ask the child to use for a variety of sports, would be a step in the right direction.

Falls

Brain injuries from fells occur in a variety of ways. One important cause is fells from playground equipment onto unprotected surfaces. The energy generated in a fall and transmitted to the brain is a function of both the height of the equipment and the energy absorbing potential of the surface. The severity of injuries can be decreased markedly by lowering the height of equipment to no greater than 5 feet and by using materials such as sand, pea gravel, or wood chips under the equipment. These surfacing materials must be placed at sufficient depth and be properly maintained if they are to be maximally effective. A recent survey of playground equipment in Boston found that more than one third of playground equipment such as swings and climbers were placed over surfaces such as concrete, asphalt, or packed dirt. However, of the two thirds that were placed over appropriate surfaces, none of the surfaces were adequately maintained with material to the right depth.20

Another type of completely preventable fall injury is that involving baby walkers. These usually involve children 6 to 18 months of age felling down stairs in these walkers. More than 20 000 infants are treated in hospital emergency rooms annually for treatment of baby walker injuries. Head injuries are the most common serious injuries sustained by these children. Walker use is extremely common, with more than 1.5 million sold each year in the United States. Mishaps are also very common; surveys of parents reveal that 30% to 40% of children have some sort of mishap in a baby walker.21 These devices offer no developmental advantage to infants and may in feet retard normal walking. Efforts are now being made to ban the manufacture and sale of these devices. Health-care providers should strongly counsel parents about baby walkers.

Most serious brain injuries involve fells from heights, . usually from open windows. In New York City, the number of serious and fetal injuries from such fells at one time approached almost epidemic proportions. Spiegel and Lindaman developed a preventive program using lightweight, inexpensive bars that could be installed easily in windows.22 This program reduced fall-related deaths by 47% in children younger than 16 years of age. This simple intervention is applicable to other locales as well.

Motor Vehicle Trauma

Prevention of brain injury to motor vehicle occupants should involve preventing the crash from occurring in the first place and protecting occupants involved in crashes as much as possible.

Perhaps the single biggest controllable risk factor for motor vehicle crashes in adolescents is alcohol. A number of studies indicate that as many as 40% of adolescents are intoxicated at the time of a motor vehicle crash. Unfortunately, many adolescents, perhaps as many as 40% of those intoxicated at the time of an injury, have chronic alcohol problems.23 AU individuals beyond childhood who are admitted with serious trauma should have blood tested for alcohol; those with positive tests must be evaluated further for chronic alcohol abuse. While this may seem unnecessary to some and even inappropriate to others, the frequency of alcohol abuse among teenagers and the devastating consequences that can result demand that we as physicians screen and treat alcohol abuse like any other disease. Few of us would fail to do a screening test for a problem in which 40% of tlie results were positive; none would fail to diagnose and treat a potentially fatal disorder that occurred in more than 20% of a group of patients.

The use of occupant restraints is clearly an effective strategy for preventing injury if a crash does occur. Seat restraints can prevent up to 90% of serious and fetal injuries to children under the age of 5. Lap and shoulder belts can prevent approximately 45% of serious and fatal injuries to older children and adolescents. These devices must be used correctly; misuse of child seats is still a common problem. Likewise, use of lap shoulder belts on a young child is inappropriate and dangerous. Serious brain and spinal cord injuries have been reported from the use of such restraints in young children. Airbags are a complementary strategy to seat restraints; they are particularly effective because they are passive strategies that operate automatically without the need for behavior change of the driver or occupant. They are a particularly attractive injury prevention strategy for adolescents, in whom seat belt use tends to be lower than for younger children.

Pedestrian injuries are a difficult problem, particularly in the 5- to 9-year-old age group. As mentioned above, it is the most common cause of death from trauma in this age group and one of the leading causes of severe brain injury. The problem is a complex one that requires community-wide approaches for solution. A combination of active and passive strategies are required and involve changes in the environment, in the teaching of pedestrian skills, in our attitudes toward risk, and in motor vehicle design. Young children have clear developmental limitations in their ability to safely negotiate traffic. A young child's inability to assess distances and speeds, combined with his or her normal impulsiveness, results in unsafe traffic behavior among those younger than 11 or 12 years of age. Children's traffic skills can be improved by training; however, even after training, the majority of young children still have risky behavior.24

Community approaches should focus primarily on decreasing the speed of traffic, enforcing laws governing pedestrian-motor vehicle interaction, and separating the pedestrian from the traffic. This may require rethinking in how communities view traffic and reordering of priorities given to pedestrians. However, where it has been done in countries such as Sweden, child pedestrian fatality rates are one third to one half those in the United States.

CONCLUSION

Brain injuries, like other injuries to children, do not occur at random. Certain children and adolescents are at high risk, primarily because of the hazard of their environment, the difficulty of the task relative to their skills at the time, or the lack of use of preventive measures. The impact of brain injuries on children and their families and the relative inability to treat this problem emphasizes the role that prevention must take. Many effective strategies are available; it is up to us to see that they are implemented.

REFERENCES

1. Teasdale G, Jennett B. Assessment ci coma and impaired consciousness: a practical scale, lancet. 1974;2:81-84.

2. Ewing-Cobbs L, Levin HS, Fletcher JM, Miner ME, Eisenberg HM. The Children's Orientation and Amnesia Test: relationship to severity of acute head injury and to recovery of memory. Neurosurgery. 1990,27:683-691.

3. Committee on Injury Scaling. The Abbreviated Injury Scale, 1990 Revision. Morton Giove, HI: American Association fer Automotive Medicine; 1990.

4. Sosin DM, Sacks JJ, Smith SM. Head injury-associated deaths in the United States from 1979 to 1986. JAMA. 1989;262:2251-2255.

5. Annegers JF, Grabow JD, Kurland LT, et al. The incidence, causes and secular trends in head injury in Olmsted County, Minnesota, 1935-1974- Neurology. 1980-30:912919.

6. Kraus JF, Rock A, Hemyari P. Brain injuries among infants, children, adolescents and young adults. Am J Dis Child. 1990;144:684-691.

7. Mayer T, Walker M, Johnson D, et al. Causes of morbidity and mortality in severe pediatric trauma. JAMA. 1981;245:719-721.

8. Kraus JF, Fife D, Conroy C. Pediatric brain injuries: che nature, clinical course, and early outcomes in a defined US population. Pediatrics. 1987;79:501-507.

9. Michaud LJ, Rivara FP1 Grady MS, Reay DT. Predictors of survival and severity of disability after severe brain injury in children. Neurosurgery. 199231:254-264.

10. Rivara FP, Calonge N, Thompson RS. Population based study of unintentional injury incidence and Impact during childhood. Am J Public Health. 1989;79:990-994.

11. Rivara FP, Bergman AB, LoGerfo J, Weiss NS. Epidemiology of childhood injuries, H: sex différences in injury rates. Am/ Dis Chad. 1982;136:502-506.

12. Kraus JF, Fife D, Ramstein K, Conroy C, Cox P. The relationship of family income to the incidence, causes, and outcomes of serious brain injury, San Diego County, California. Am/ PiASc Health. 1986;76:1345-1347.

13. Rivara FP, Alexander B, Johnston B1 Soderberg R. Population-based study of fall injuries in children and adolescents. Pediatrics. 1993;92:61-63.

14. Chadwick DL, Chin S. Salerno C, Landsverk J, Kitchen L. Deaths from falls in children: how far is fetal?; Trauma. 1991;31:1353-1355.

15. Williams RA. Injuries in infants and small children resulting from witnessed and corroborated free fells. J Trauma. 1991;31:1350-1352.

16. Duhaime AC, Alario AJ, Lewander J, et al. Head injury in very young children: mechanisms, injury types, and ophthalmologic findings in 100 hospitalized patients younger than 2 years erf age. Pediatrics. 1992;90:179-185.

17. Bicycle helmet promotion programs - Canada, Australia, United States. MM\&T?. 19SO;42:203, 209-210.

18. Thompson RS, Rivara FP, Thompson DC. A case-control study of the effectiveness of bicycle safety helmets. N Engl J Med. 1989;320:1361-1367.

19. Nelson DE, Bixby-Hammetr D. Equestrian injuries in children and young adults. Am J Dis ChM. 1992;146:611-614.

20. Bond MT, Peck MG. The risk of childhood injury on Boston's playground equipment and surfeces. Am J Public Health. 1993;83:731-733.

21. Board of Trustees, AMA. Use of infent walkers. Am; Dis Child. 1991;145:933-934.

22. Spiegel CN, Lindaman FC Children can't fly: a program to prevent childhood morbidity and mortality from window fells. Am J Public Health. 1977:67:1 143-1 147.

23. Rivara FP, Gurney JG, Ries RK, Seguin DA. Copase MK, Jurkovich GJ. A descriptive study of trauma, alcohol and alcoholism in young adults. ; Adolesc Health. 1992;13:663-667.

24. Rivara FP. Child pedestrian injuries in the United States. Current status of the problem, potential interventions and future research needs. Am J Dis Child. 1990;144:692-696.

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Injury Prevention Strategies

10.3928/0090-4481-19940101-06

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