Changes in frontal morphology after single-stage open posterior-middle vault expansion for sagittal craniosynostosis

Background: There is controversy regarding whether the frontal bossing associated with sagittal synostosis requires direct surgical correction or spontaneously remodels after isolated posterior cranial expansion. The authors retrospectively measured changes in frontal bone morphology in patients with isolated sagittal synostosis 2 years after open posterior and midvault cranial expansion and compared these changes with those occurring in age-comparable healthy control groups. Methods: Forty-three patients age 1 year or younger (mean, 6 months) with sagittal synostosis underwent computed tomography scan digital analysis immediately after and 2 years after posterior-middle cranial vault expansion. Quantitative angular and linear measures were taken along the midsagittal and axial planes to capture both aspects of frontal bossing. The change in values over the 2 years were compared with healthy controls with normal computed tomography scans taken to rule out head trauma. Results: All measures indicative of frontal bossing decreased significantly from the time of posterior-middle vault expansion to 2 years postoperatively. Whereas the majority of patients at time of the operation had frontal bossing measures greater than two standard deviations outside the age-comparable control mean, almost all patients were within two standard deviations of the norm 2 years later. Lateral forehead bossing and anterior cranial growth was greater the older the patient was at the time of the operation, suggesting that the more time that passed before the operation, the more compensatory anterior fossa growth occurred. Central forehead position relative to the anterior cranial base was greatest in the younger patients at the time of operation, suggesting that a central forehead bulge was an early compensatory response to premature sagittal fusion. Conclusions: As a group, patients with sagittal synostosis start to normalize their forehead morphology within 2 years if an isolated posterior operation is performed at 1 year of age or younger, and this occurs by a combination of restriction of growth and reduction relative to patients without synostosis. This protocol decreases the risks of intraoperative positioning, forehead contour deformities, and two-stage operations.