Date: October 2023.
Source: Plastic & Reconstructive Surgery-Global Open. 11(10S):45-46.
Presenter: Mario Blondin, MD. Track: Craniomaxillofacial/Head & Neck
Objective: Premature fusion is termed sagittal craniosynostosis (SC) and is described by a classic dysmorphology, scaphocephaly. Scaphocephaly results as bi-parietal expansion is inhibited and anterior and posterior compensatory elongation occurs. We recently used surface imaging modalities to develop regional measures quantifying elongation in the frontal bossing index (FBI) and occipital bullet index (OBI). Creating a width based measure, would allow the isolated measurement of the fundamental pathology of scaphocephaly. Further, it would allow for the creation of a global metric which could easily replace the familiar cephalic index. This combined system would allow surgeons to identify both global and regional morphology in scaphocephaly.
Materials and Methods: Surface imaging from CT scans or 3D photographs of 360 individuals with sagittal craniosynostosis and 221 normocephalic individuals was obtained. Cartesian grids were created on each individual’s surface mesh using equidistant sagittal and coronal planes. Grid intersections were used as reproducible landmarks to identify patterns in width restriction. Area under the curve (AUC) analyses was performed to identify trends in regional morphology and create measures capturing population differences. The most distinct was then used to create a vertex narrowing index (VNI). Using the FBI, OBI, and VNI, a measure of W/L analogous to the cephalic index was created (Scaphocephalic Index, SCI). Measure performance was evaluated using area under the curve (AUC) analyses. Finally, measurement was then automated.
Results: With regard to width, control crania were observed to round while those with SC consistently slope inward, with a more triangular appearance. Population differences increased as more superior regions were evaluated, with difference peaking just posterior to the AP midline at a height 70% of the way between the tragion and vertex. The VNI performed well with an AUC of 0.97, a sensitivity of 91.2% and a specificity of 92.2%. Index score is independent of age (<5 years), sex, and imaging modality. The measures can be simply combined to form a SCI. SCI measure performance was nearly perfect (AUC >0.999, Sensitivity >99%, Specificity >99%) in distinguishing control vs SC patients. The population means were 63(±5) and 88(±5) for the SC and control populations respectively.
Article: Creation of the Scaphocephalic Index.
Authors: Mario Blondin, MD, Griffin Bins, MD, Larry Zhou, Ryan Layton, Blake Dunson, Samuel Kogan, MD, Lisa David, MD, Christopher Runyan, MD, PhD.