Characterization of Regional Morphological Changes in Sagittal Craniosynostosis Following Endoscopic Strip Craniectomy With Post-operative Helmeting: Predictors for Success

BACKGROUND: Sagittal craniosynostosis (SC) restricts craniofacial growth perpendicular to the sagittal plane resulting in scaphocephaly. The cranium grows in the anterior-posterior dimension causing disproportionate changes, which can be corrected with either cranial vault reconstruction (CVR) or endoscopic strip craniectomy (ESC) combined with post-operative helmet therapy. ESC is performed at an earlier age, and studies demonstrate benefits in risk profile and morbidity compared to CVR, with comparable results if the post-operative banding protocol is strictly upheld. We aim to identify predictors of successful outcome and, using three-dimensional (3D) imaging, assess cranial changes following ESC with post-banding therapy. MATERIALS AND METHODS: A single institution retrospective review was performed from 2015-19 for patients with SC who underwent ESC. Patients received immediate post-operative 3D photogrammetry for helmet therapy planning and implementation as well as post-therapy 3D imaging. Using these 3D images, the cephalic index (CI) for study patients was calculated before and after helmet therapy. In addition, Deformetrica™ was used to measure volume and shape changes of pre-defined anatomic skull regions (frontal, parietal, temporal, & occipital) based on the pre- and post-therapy 3D imaging results. Fourteen institutional raters evaluated the pre- and post-therapy 3D imaging in order to determine the success of the helmeting therapy. RESULTS: Twenty-one SC patients met our inclusion criteria. Using 3D photogrammetry, 14 raters at our institution rated 16 of the 21 patients to have had successful helmet therapy. There was a significant difference in CI following helmet therapy with both groups, but there was no significant difference in CI between the "successful" and "unsuccessful" groups. Furthermore, the comparative analysis demonstrated that the parietal region had a significantly higher change in mean RMS distance when compared to the frontal or occipital regions. CONCLUSION: For patients with SC, 3D photogrammetry may be able to objectively recognize nuanced findings not readily detectable when using CI alone. The greatest changes in volume were observed in the parietal region, which falls in line with treatment goals for SC. Patients deemed to have unsuccessful outcomes were found to be older at time of surgery and initiation of helmet therapy. This suggests that early diagnosis and management for SC may increase the likelihood of success.