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Quantitative Analysis of Change in Intracranial Volume After Posterior Cranial Vault Distraction and Frontal Orbital Advancement/Remodeling

Introduction: Patients with craniosynostosis with shortened occipitofrontal diameter are mainly treated with posterior cranial vault distraction osteogenesis (PVDO) in our institution. If further intracranial volume (ICV) expansion is needed, additional treatment with frontal orbital advancement (FOA) is done. On the contrary, frontal orbital remodeling (FOR) is done for better aesthetic results. In this study, post-treatment ICV changes in patients with craniosynostosis treated with these methods have been investigated. Methods: Patients who underwent FOA or FOR in addition to PVDO at Juntendo University Hospital between 2011 and 2017 were reviewed for patient characteristics and pre/postoperative ICV measurements using 3-dimensional computed tomography scans. Results: Nine patients aged from 5 months to 6 years 8 months at the time of PVDO were included. For PVDO, the ICV change was 113 to 328 mL, and the enlargement ratio of ICV was 109% to 152%. Two patients were further operated with FOA while the remaining 7 with FOR. With FOA, ICV change was 73 to 138 mL, while enlargement ratio of ICV was 107% to 114%. With FOR, ICV change was 3 to 45 mL (mean 20 mL), while enlargement ratio of ICV was 100% to 103%. Conclusion: The PVDO is our first line of treatment for ICV expansion and posterior cranial fossa decompression in patients with severe craniosynostosis. The FOA is performed if extra ICV increase is necessary. This approach seems to enable larger ICV expansions compared with other conventional methods. The FOR should be reserved for patients in whom adequate ICV levels are achieved with PVDO yet additional frontal reshaping is necessary.