121 Cortical Thickness | Crouzon DISCUSSION The primary aim of this study was to determine any association between cortical thickness and frontal versus occipital primary vault expansion in CP syndrome patients. Our secondary aim was to determine any relationship between synostosis pattern and cortical thickness. We hypothesized that cortical lobes beneath growth-restricted regions of the calvaria may be at an increased risk for thinning in CP patients and that targeted vault expansion may confer a protective advantage to these regions. This study failed to find any difference in effect between frontal and occipital primary vault expansions on global or lobar cerebral cortical thickness. In regard to synostosis pattern and cortical thickness, we found that lambdoid synostosis was associated with thinning across all brain regions, but particularly within the cingulate and frontal cortices. This leads us to question our hypothesis of localized growth restriction affecting proximate cortical lobes and consider how cranial shape contributes to pressure elevations and subsequent thinning in distant regions of the brain. Both frontal and occipital cranial vault procedures resulted in similar cortical thicknesses in this study. Previous work by Spruijt et al evaluated the effect of frontal versus occipital primary vault expansions on occipito frontal head circumference in an Apert and Crouzon cohort and found that occipital-first expansion resulted in greater circumferences and reduced postoperative incidence of papilledema.7, 16 A recent study has highlighted the importance of papilledema in syndromic craniosynostosis patients, demonstrating an association with global thinning of the cortex.16 The failure to find a direct association between primary cranial vault expansion type and cortical thickness in this study is most likely due to insufficient power. It is possible that occipital expansion resulted in fewer cases of papilledema than would otherwise be observed; however, the effect of surgery type alone was insufficient to result in detectable cortical thinning. This study was adequately powered to detect only a large difference in cortical thickness (0.37 mm), far exceeding that previously reported as a result of papilledema, between surgical treatment groups. With improved power we would expect more subtle cortical thickness changes to emerge, congruent with previous findings. Our secondary analysis showed lambdoid synostosis to result in thinning across all brain regions, with pronounced effects in the cingulate and frontal cortices. We expected to observe greater effect sizes between synostoses and corresponding cortical lobes (eg, coronal/frontal, lambdoid/occipital), but interestingly lambdoid involvement was associated with more thinning in the frontal cortex than the occipital. The largest effect sizes observed were those of lambdoid synostoses on the cingulate gyri. To date, lambdoid synostoses have been shown to result in localized brain dysmorphology such as increased rates of cerebellar tonsillar herniation.33, 34 This is likely due to the disproportionate cerebellar growth, which normally occurs in the 7
RkJQdWJsaXNoZXIy MTk4NDMw