Morphometric Outcomes of Nonsyndromic Sagittal Synostosis following Open Middle and Posterior Cranial Vault Expansion

Abstract

Background: This study aimed to quantify the change in three-dimensional skull morphometrics for patients with sagittal synostosis at presentation, after surgery, and at 2-year follow-up. Methods: Computed tomography scans from 91 patients with isolated SS were age-, sex-, and race-matched with those from 273 controls. The authors performed vector analysis with linear regressions to model the effect 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 occipital remodeling and remained slightly lower than control volumes at 2 years, whereas middle vault volume was larger than in 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 2 years but did not affect other volume outcomes. Preoperative severity was the variable most predictive of 2-year morphometrics. Conclusions: Initial severity of sagittal synostosis 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. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.