Morphometric Outcomes of Non-Syndromic Sagittal Synostosis following Open Middle and Posterior Cranial Vault Expansion.

PURPOSE: This study aims to quantify the change in three-dimensional skull morphometrics for patients with sagittal synostosis (SS) at presentation, after surgery, and at two-year follow-up.

METHODS: CT scans from 91 patients with isolated SS were age, gender, and race-matched to 273 controls. We performed vector analysis with linear regressions to model the impact of open middle and posterior cranial vault remodeling on cranial shape and growth.

RESULTS: Anterior cranial volume, bossing angle and frontal shape were not changed by surgery but normalized without surgical intervention by 2 years. Biparietal narrowing and middle cranial volume were corrected after surgery and maintained at 2 years. Occipital protuberance was improved after surgery and normalized at 2 years. Posterior cranial volume was decreased by the occipital remodeling and remained slightly lower than control volumes at 2 years whereas middle vault volume was larger than controls. Residual deformities that persisted at 2 years were decreased superolateral width at the level of opisthion, and increased anterosuperior height (vertex bulge). Linear models suggested older age at surgery resulted in more scaphocephaly and enlarged posterior cranial vault volumes at two years but did not impact other volume outcomes. Preoperative severity was the variable most predictive of 2-year morphometrics.

CONCLUSION: Initial severity of SS deformity was the best predictor of 2-year morphometric outcomes. Upper posterior cranial width decreases with time after surgery and an anterior vertex bulge can persist after open surgery, but frontal dysmorphology self-corrects without surgical intervention.LEVEL OF EVIDENCE: III.