Correlation between degree of sagittal suture fusion and surrogates of elevated intracranial pressure in sagittal craniosynostosis

Abstract

OBJECTIVE Sagittal craniosynostosis constricts transverse skull growth, with possible neurocognitive sequelae. While the degree of sagittal suture fusion has been shown to influence the degree of dysmorphology, it is unknown if it impacts functional findings, including elevated intracranial pressure (ICP). The purpose of this study was to determine associations between the degree of sagittal suture fusion and optical coherence tomography (OCT) surrogates suggestive of increased ICP in patients with nonsyndromic sagittal craniosynostosis. METHODS Three-dimensional CT head images of patients with sagittal craniosynostosis were analyzed in Materialise Mimics and parietal bones were manually isolated to determine the percentage fusion of the sagittal suture. Retinal OCT was performed prior to the cranial vault procedure with analysis for thresholds that correlate with elevated ICP. The degree of sagittal suture fusion was compared with OCT retinal parameter measurements using Mann-Whitney U-tests, Spearman’s correlations, and multivariate logistic regression models controlled for age. RESULTS Forty patients (31 males) with nonsyndromic sagittal craniosynostosis at a mean (± SD) age of 3.4 ± 0.4 months were included in this study. OCT surrogates of elevated ICP (maximal retinal nerve fiber layer [RNFL] thickness and maximal anterior projection [MAP]) were not associated with total sagittal suture fusion (p > 0.05). Maximal RNFL thickness was positively associated with increased percentage of posterior one-half (rho = 0.410, p = 0.022) and posterior one-third (rho = 0.417, p = 0.020) sagittal suture fusion. MAP was also positively associated with increased percentage of posterior one-half (rho = 0.596, p < 0.001) and posterior one-third (rho = 0.599, p < 0.001) sagittal suture fusion. Multivariate logistic regression models revealed increased percentage of posterior one-half (p = 0.048) and posterior one-third (p = 0.039) sagittal suture fusion predicted ICP > 20 mm Hg. CONCLUSIONS Increased percentage fusion of the posterior sagittal suture, but not total suture, was positively associated with retinal changes indicative of increased ICP. These findings suggest suture fusion leading to increased ICP may be region specific.