Orbital Anthropometrics Correct to Age-Matched Values after Strip Craniectomy in Metopic Craniosynostosis

BACKGROUND: Children with metopic craniosynostosis have distinct orbital dysmorphologies that include perceived hypotelorism and a symmetric, elliptical orbital aperture canted toward the synostosed suture. The extent to which hypotelorism is a true skeletal difference or, rather, perceived hypotelorism in the setting of trigonocephaly has been previously debated (1). Additionally, maneuvers to address the intercanthal distance during traditional fronto-orbital advancement procedures yield inconsistent results on orbital anthropometrics. The purpose of this study is to expand on our previous work by detailing pre- and post-operative orbital anthropometrics among a cohort of metopic synostosis patients undergoing endoscopic strip craniectomy (ESC) compared to age-matched controls. We aim to (1) detail the presence/absence of true skeletal hypotelorism in young infants with metopic synostosis and (2) define the role of ESC in restoring orbital anthropometric parameters to normal values. METHODS: A retrospective, cohort study was performed at a single center over a three-year (2020 – 2023) period. Using Slicer software, a three-dimensional craniometric analysis was performed on preoperative and one-year postoperative CT images of children with metopic craniosynostosis and age-matched peers. Twelve craniometric parameters were obtained. Age-matched children with normocephalic head shapes who underwent CT scan for other reasons than to rule-out craniosynostosis were utilized for comparison. RESULTS: Nine children were included as subjects in the study and fourteen children were included as controls. The mean age of subjects at pre-operative CT scan was 69.3 days and 72.3 days for controls. The mean age of subjects at post-operative CT scan was 14.8 months and 14.3 months for controls, for a mean follow-up of 11.4 months after ESC. 64 orbits were analyzed. Pre-operative subject Dacryon to Dacryon (Da-Da) measurements showed a significant difference from controls (12.2 ± 0.54 millimeters v. 15.4 ± 0.53 millimeters; p=0.0007), while post-surgery, there was no significant difference (16.11 ± 0.67 millimeters v. 15.10 ± 0.50 mm; p=0.2392). Similarly, Zygomaticofrontal suture to Zygomaticofrontal suture (ZF-ZF) measurements revealed a significant pre-operative difference (61.3 ±1.25 millimeters v. 67.2 ± 2.38 millimeters; p=0.0238) with post-operative normalization (76.0 ± 1.22 millimeters v. 76.0 ± 1.19 millimeters; p=0.9767). The supraorbital notch to anterior nasal spine to supraorbital notch (SON-ANS-SON) angle also indicated significant pre-operative differences (39.9 ± 0.96 degrees v. 60.1 ± 3.06 degrees; p=0.0001), with post-operative measurements showing no significant difference from controls (49.6 ± 1.39 degrees v. 55.3 ± 2.00 degrees; p=0.0674). CONCLUSIONS: Previous work demonstrated improvement in interdacryon distance before and after endoscopic strip craniectomy. The present effort shows that orbital hypotelorism in young infants with metopic synostosis is a true skeletal difference from age-matched controls that corrects after endoscopic strip craniectomy.