The aims of this study were to evaluate longitudinal metabolite changes in traumatic brain injury (TBI) subjects and determine whether early magnetic resonance spectroscopic imaging (MRSI) changes in discrete brain regions predict 1year neuropsychological outcomes. Three-dimensional (3D) proton MRSI was performed in pediatric subjects with complicated mild (cMild), moderate, and severe injury, acutely (6-17 days) and 1-year post-injury along with neurological and cognitive testing. Longitudinal analysis found that in the cMild/Moderate group, all MRSI ratios from 12 regions returned to control levels at 1 year. In the severe group, only cortical gray matter regions fully recovered to control levels whereas N-acetylaspartate (NAA) ratios from the hemispheric white matter and subcortical regions remained statistically different from controls. A factor analysis reduced the data to two loading factors that significantly differentiated between TBI groups; one included acute regional NAA variables and another consisted of clinically observed variables (e.g., days in coma). Using scores calculated from the two loading factors in a logistic regression model, we found that the percent accuracy for classification of TBI groups was greatest for the dichotomized attention measure (93%), followed by Full Scale Intelligence Quotient at 91%, and the combined memory Z-score measure (90%). Using the acute basal ganglia NAA/creatine (Cr) ratio alone achieved a higher percent accuracy of 94.7% for the attention measure whereas the acute thalamic NAA/Cr ratio alone achieved a higher percent accuracy of 91.9% for the memory measure. These results support the conclusions that reduced NAA is an early indicator of tissue injury and that measurements from subcortical brain regions are more predictive of long-term cognitive outcome.

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Objective The study aimed to assess (1) whether the severity of a TBI affects performance on a measure of memory, and (2) whether FSIQ, VIQ, and PIQ moderate recovery following TBI, over time, after controlling for severity of injury. Method TBI patients (n = 60) were recruited from admissions to the Loma Linda University Children’s Hospital (LLUCH). Indicators of memory and learning were assessed with the CMS for all the children (ages 6 to 16), while overall cognitive abilities were assessed with the WASI-II. These data are a component of a larger neuropsychology assessment battery collected at 3 and 12 months post-injury. Results Simple Linear Regression was conducted in SPSS. Results indicated that severity of injury explained a significant amount of the variance in participant’s performance on overall memory at the initial evaluation (R2 = .154). As severity of injury increased by one-point, general memory declined by .392 points, 95%CI [.820, 3.233] (p < .001). Three moderation analyses using model one of the PROCESS macro for SPSS were conducted to assess whether FSIQ, VIQ, or PIQ moderated recovery from TBI over time. We controlled for the severity of injury. FSIQ, VIQ, and PIQ did not significantly moderate verbal, nonverbal, or general memory recovery of moderate-to-severe TBI over time (ps > .05). Conclusions Results of the study suggest that, after controlling for severity of injury, FSIQ, VIQ, and PIQ did not significantly moderate recovery following a TBI. Given that research suggests that higher premorbid IQ is associated with more favorable outcomes, further investigation is warranted.

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