Original articlePredicting neuropsychologic outcome after traumatic brain injury in children
Introduction
Pediatric traumatic brain injury is a primary cause of death and disability of children and adolescents [1]. For the estimated 135,000 children who survive traumatic brain injury in the United States each year, diffuse and widespread injury may cause intellectual, behavioral, and functional impairment [2], [3]. Treatment of brain injury in pediatric patients is complicated by the limited predictive power of injury severity indicators for long-term intellectual and neuropsychologic outcome. The more commonly used clinical indicators of injury severity have included the Glasgow Coma Scale score [4], duration of impaired consciousness and duration of posttraumatic amnesia [5], presence of nonreactive pupils [6], and brain imaging techniques [7]. Individually, these methods, when used to characterize the nature and severity of traumatic brain injury, account for a major portion of the variance in prediction of long-term cognitive and behavioral outcome [5]. Clinical indicators become more effective predictors when combined, correctly classifying up to 80% of patients as having either mild or severe injury [8].
Findings from several studies indicate that metabolite ratios assessed through use of proton magnetic resonance spectroscopy (MRS) are reliable predictors of long-term neurologic outcome after a variety of acute brain insults in children [9], [10], [11], [12], [13], [14]. Brain metabolites assessed with MRS and often expressed as ratios include the following: (1) N-acetyl aspartate (NAA) found in neurons; (2) creatine and phosphocreatine (Cre) that reflect energy metabolism; (3) choline-containing compounds (Cho) released during membrane disruption; and (4) presence of lactate indicating a disturbance in cerebral energy metabolism. A recent study from our group used MRS taken from occipital gray matter to examine 53 infants and children who had sustained traumatic brain injury [9]. We found that reductions in NAA/Cre and NAA/Cho ratios, increases in Cho/Cre, and the presence of lactate significantly correlated with a poor long-term neurologic outcome. This study and others, however, relied on relative broad categories of outcome assessment based on use of the Pediatric Cerebral Performance Category Scale score or the Glasgow Outcome Scale score. Although some studies in adults have correlated neuropsychologic test results with spectroscopy [15], similar data have not been reported in children.
The current study evaluated whether changes in MRS metabolite ratios after traumatic brain injury are predictive of long-term intellectual and neuropsychologic function, and whether the predictive power of these indicators provided greater prediction than traditional clinical indicators alone or in combination. Specific areas of impairment traditionally evaluated after traumatic brain injury and therefore included in this study are intellectual function and memory [16], [17], [18], [19], [20], [21], [22], [23], linguistic abilities [19], [24], [25], [26], [27], planning and attention [19], [28], [29], visuospatial processing, and sensorimotor abilities [16], [18], [19], [30], [31].
Section snippets
Materials and methods
Children between the ages of 3 and 19 years (mean 9.4 ± 5.6 years) who were treated for traumatic brain injury at Loma Linda University Children’s Hospital between 1 and 7 years before the current assessment were asked to participate in the study. The protocol was approved by the Institutional Review Board of Loma Linda University Medical Center. Inclusion criteria included children who: (1) had sustained a nonpenetrating traumatic brain injury because of accidental or nonaccidental trauma
Participant characteristics
There were 86 children who met the inclusion criteria for participation in this study; 31 could be contacted and 22 (with parental consent) participated in the study. There were no significant differences between the children who participated and those who declined with regard to clinical or MRS variables with the exception that children in the study had a higher mean Cho/Cre ratio. With regard to children who were unable to be contacted, one variable, presence of nonreactive pupils, was
Discussion
When a child suffers a traumatic brain injury, those involved in the child’s care desire to accurately estimate whether and to what extent the injury will impair future function. A reliable estimate of long-term function can help parents and health care professionals develop a plan that will aid the child’s recovery to the greatest extent possible. Prediction can motivate more intensive and targeted intervention. However, inherent in prediction is a responsibility that it not be used in order
Acknowledgements
The authors wish to thank Matt L Riggs, PhD, for his help with the statistical analysis.
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