Comprehensive craniometry for sagittal synostosis

Objective: Sagittal synostosis is the most common type of craniosynostosis, resulting in deformity with distinctive morphological characteristics. These include occipital narrowing, parietal narrowing, anteriorly shifted vertex with parietal depression, and exaggerated frontal bossing. The traditional cephalic index affords limited reliability in quantifying initial severity and correction. The purpose of this study was to conceptualize and evaluate a set of novel metrics based on optical surface scanning (OSS) technology used for cranial remolding orthosis (CRO) treatment.

Methods: The 25 most recent infants to receive CRO treatment for sagittal synostosis at a single center were reviewed retrospectively. All treated patients underwent the endoscope-assisted craniectomy technique without barrel staving. OSS representations of each patient's head were acquired perioperatively and at cessation of CRO treatment. A novel set of metrics were developed, comprising the occipital contour angle to assess severity of occipital narrowing; the vertex proportionality index to assess the anterior vertex relative to the depressed posterior anatomy; the parietal-temporal index to assess proximal cranial narrowing; and the sellion-frontal index as a measure of frontal bossing. The pre- and posttreatment results for all indices were compared against each other and against a control group of 33 nonsynostotic infants with grossly normal head shapes.

Results: Initial treatment group means for all 4 indices demonstrated significant variance against both the final treatment group means and the control group means. No statistically significant differences were observed in the group means for occipital contour angle, parietal-temporal index, and sellion-frontal index between the posttreatment and control cohorts, which was suggestive of mean correction to normative levels for these morphological considerations. Despite an appreciable mean correction of parietal depression in the final treatment group, the mean vertex proportionality index values remained statistically different from the control group.

Conclusions: Sagittal synostosis is characterized by several characteristic deviations from normocephaly. These are effectively improved by endoscope-assisted craniectomy with CRO intervention. Importantly, head shape abnormalities differ between patients, and the individual subject can present normatively for some deformational categories. Therefore, a multimetric approach is essential to quantify initial presentation and subsequent outcome. The introduction of novel OSS-enabled craniometry may facilitate more patient-centric management of this complex deformity. Specifically, features with the greatest deviation from normative standards can be identified, enabling creation of discrete treatment plans with respect to the focus and length of postoperative helmeting.