How Injury Damages Are Assessed
Friday, March 25, 2005
Variables that determine the outcome of TRAUMATIC BRAIN INJURY include mechanism of injury, age of the child, severity of injury, and extent of secondary injury. Children have a better outcome after TRAUMATIC BRAIN INJURY than do adults. The outlook for both survival and recovery is best for elementary-school-age children, compared to preschoolers and adolescents. Young children often suffer diffuse, multiple injuries from child abuse, and many adolescents suffer high-impact injury in a motor vehicle collision. In contrast, injury to elementary-school-age children is generally focal and less severe.
Infants may be more severely affected by head injury because of their relatively large head size compared to the rest of the body, limited head control, and immature nervous system. Disruption of neural circuits in the immature brain may impair normal developmental sequences permanently.
Both the initial injury and the subsequent physiologic response to injury are significant determinants of outcome. Primary brain injury occurs at the time of the trauma and irreversibly injures and kills brain cells as the result of impact or acceleration-deceleration forces. Because primary brain injury is irreversible and therefore untreatable, the goal of management is to prevent or minimize secondary brain injury.
In addition to damaging brain parenchyma directly at the initial impact, TRAUMATIC BRAIN INJURY triggers a common pathway to neuronal death that involves posttraumatic ischemia, energy failure, excitotoxicity, mitochondrial failure, and oxidative stress.9 There is great investigative interest in mitigating many of these secondary damaging factors. Most current treatment strategies in the intensive care unit, however, focus on relieving increased intracranial pressure from cerebral swelling by means of upright head positioning, osmotic diuresis, ventriculostomy, and, in some medical centers, craniectomy.
Investigators have examined a variety of acute prognostic indicators of outcome. Injury severity scoring systems have usually been used to predict morbidity and mortality in the pediatric ICU. In general, more severe and persistent disability is predicted by a lower Glasgow Coma Scale score at the time of injury, a longer period of coma, a longer period between injury and return of short-term memory, and more diffuse and deeper lesions seen on brain imaging. However, exceptions occur for many reasons, which should prompt caution in predicting a dire outcome early in the acute injury period. For example, comorbid conditions such as untreated hydrocephalus or multiple fractures that require continued narcotics may delay emergence of arousal and awareness. Pediatric critical care specialists often are surprised by a visit from a former patient whose extent of recovery they would not have predicted based on the patient's condition in the ICU.
Preinjury history of learning and attention problems, psychiatric illness, and substance abuse predict a worse outcome. A positive social situation with a supportive family, on the other hand, enhances recovery.10 Social supports encourage return to school or employment, participation in community activities, and a better adaptation to varying degrees of disability.
Once acute medical and surgical problems have been treated and stabilized, the child who has a TRAUMATIC BRAIN INJURY is usually transferred to a specialized unit or facility for intensive rehabilitation. Rehabilitation is a comprehensive treatment program aimed at maximizing independent functioning by reducing impairment and disability.11 Impairment is a loss of a specific body function such as muscle coordination, speech, or mental processing. Disability is the resulting difficulty in performing the corresponding activity, such as walking, communication of needs, and completing school assignments.
The goals of acute inpatient rehabilitation are to restore the child's independence in mobility, communication, and self-care (feeding, grooming, toileting). When these goals have been reached to some extent, or it appears that the child is reaching a plateau in the rate of improvement, discharge may be considered.
One or two months of inpatient rehabilitation is usually necessary to establish and maintain the most rapid recovery. Insofar as plasticity of the injured brain is feasible, intense rehabilitation would most logically have its greatest impact on reestablishing or facilitating alternate neural pathways as soon as possible after injury.
The rehabilitation program should include continued monitoring for persistent or new medical problems; at least three hours of physical, occupational, and speech therapy a day; cognitive retraining; and a variety of other treatment modalities, including recreation therapy, augmentative technology, and education.
