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Introduction Increasing use of CT examinations has led to concerns of possible negative cognitive effects for children. The objective of this study is to examine if the ionizing radiation dose from a CT head scan at the age of 6–16 years affects academic performance and high school eligibility at the end of compulsory school. Materials and methods A total of 832 children, 535 boys and 297 girls, from a previous trial where CT head scan was randomized on patients presenting with mild traumatic brain injury, were followed. Age at inclusion was 6–16 years (mean of 12.1), age at follow up 15–18 years (mean of 16.0), and time between injury and follow up one week up to 10 years (mean of 3.9). Participants’ radiation exposure status was linked with the total grade score, grades in mathematics and the Swedish language, eligibility for high school at the end of compulsory school, previously measured GOSE-score, and their mothers’ education level. The Chi-Square Test, Student’s t-Test and factorial logistics were used to analyze data. Results Although estimates of school grades and high school eligibility were generally higher for the unexposed, the results showed no statistically significant differences between the exposed and unexposed participants in any of the aforementioned variables. Conclusions Any effect on high school eligibility and school grades from a CT head scan at the age of 6–16 years is too small to be detected in a study of more than 800 patients, half of whom were randomly assigned to CT head scan exposure.

IntroductionIncreasing use of CT examinations has led to concerns of possible negative cognitive effects for children. The objective of this study is to examine if the ionizing radiation dose from a CT head scan at the age of 6-16 years affects academic performance and high school eligibility at the end of compulsory school.Materials and methodsA total of 832 children, 535 boys and 297 girls, from a previous trial where CT head scan was randomized on patients presenting with mild traumatic brain injury, were followed. Age at inclusion was 6-16 years (mean of 12.1), age at follow up 15-18 years (mean of 16.0), and time between injury and follow up one week up to 10 years (mean of 3.9). Participants' radiation exposure status was linked with the total grade score, grades in mathematics and the Swedish language, eligibility for high school at the end of compulsory school, previously measured GOSE-score, and their mothers' education level. The Chi-Square Test, Student's t-Test and factorial logistics were used to analyze data.ResultsAlthough estimates of school grades and high school eligibility were generally higher for the unexposed, the results showed no statistically significant differences between the exposed and unexposed participants in any of the aforementioned variables.ConclusionsAny effect on high school eligibility and school grades from a CT head scan at the age of 6-16 years is too small to be detected in a study of more than 800 patients, half of whom were randomly assigned to CT head scan exposure.

Injuries to the immature optic radiation (OR) are associated with thinning of the retinal nerve fiber layer and corresponding visual field (VF) defects. The aim of the current study was to seek evidence for causal retrograde trans-synaptic degeneration by exploring the correspondence between the localization and extension of the injury to the OR and the structure of the macular ganglion cell complex, and the relation to VF function. Seven adults (age range 18–35) with visual dysfunction secondary to white-matter damage of immaturity and six healthy adults (age range 22–33) underwent magnetic resonance imaging (MRI). Fiber tractography was used to generate the geniculate projections to the dorsal and ventral striate cortex, delineated by retinotopic functional MRI mapping. The structure of the macular ganglion cell complex was measured with optical coherence tomography. The tractography showed overlaps between the dorsal and ventral geniculo-striate projections. However, in four patients with inferior VF defects, the dorsal projections were to a large extent traversing the space normally solely occupied by ventral projections. This is consistent with structural changes to the OR and suggests of re-organization upon injury. Diffusion parameters were significantly different between patients and controls, and most pronounced in the dorsal geniculo-striate projections, with a pattern indicating primary injury. The macular ganglion cell complex was significantly thinner in the patients and most pronounced in the superior sectors; a pattern particularly evident in the four patients with inferior VF defects. The ratio of the mean thickness of the macular ganglion cell complex in the superior and inferior sectors significantly correlated with the axial and mean diffusivities in the contra- and ipsilateral dorsal striate projections. The results suggest a causal link between injuries to the superior portion of the immature OR and secondary thinning in the macular ganglion cell complex, resulting in inferior VF defects.