Rate of craniometric change following suture release in patients with metopic and sagittal craniosynostosis.

OBJECTIVE

Craniosynostosis is a congenital disorder resulting from the premature fusion of cranial sutures in the infant skull. This condition results in significant cosmetic deformity and can impede neurodevelopment, if left untreated. Currently, rates of craniometric change following minimally invasive surgery have only been examined for sagittal craniosynostosis. A better understanding of postoperative skull adaptations in other craniosynostosis subtypes is needed to objectively categorize surgical outcomes and guide length of cranial orthosis therapy.

METHODS

Eleven patients with sagittal and 8 with metopic craniosynostosis treated using endoscopic strip craniectomy and postoperative helmet orthoses were retrospectively reviewed. Using semiautomated image analysis of top-down orthogonal 2D photographs, the following craniometrics were recorded before surgery and at postoperative visits: cephalic index (CI), cranial vault asymmetry index (CVAI), anterior arc angle (AAA), posterior arc angle (PAA), anterior-middle width ratio (AMWR), anterior-posterior width ratio (APWR), left-right height ratio (LRHR), sagittal Hu moment (Sag-Hu), and brachycephaly Hu moment (Brachy-Hu). These craniometrics were then normalized to photograph-based measurements of normocephalic patients and the rates of change between metopic and sagittal craniosynostoses were compared.

RESULTS

Patients with sagittal craniosynostosis exhibited significantly lower CI, lower PAA, higher AMWR, higher APWR, lower Sag-Hu, and higher Brachy-Hu preoperatively compared to patients with normocephalic craniosynostosis. Patients with metopic craniosynostosis exhibited lower AAA and AMWR preoperatively compared to normocephalic subjects. Sagittal and metopic patients had a rapid initial change in normalized CI or AAA, respectively. Craniometric rates of change that significantly differed between metopic and sagittal patients were found in AAA (p < 0.001), AMWR (p < 0.001), and APWR (p < 0.0001). Metopic patients had a prolonged AAA change with a significantly different rate of change up to 6 months postoperatively (median at 3 months = 0.027 normalized units/day, median at 6 months = 0.017 normalized units/day, and median at > 6 months = 0.007 normalized units/day), while sagittal CI rate of change at these time points was not significantly different.

CONCLUSIONS

Patients with metopic craniosynostosis have a prolonged rate of change compared to patients with sagittal craniosynostosis and may benefit from longer helmet use and extended postoperative follow-up. Categorizing craniometric changes for other craniosynostosis subtypes will be important for evaluating current treatment guidelines.