S8A-08 SESSION 8A: METOPIC SYNOSTOSIS RADIATION-FREE 3D HEAD SHAPE AND VOLUME EVALUATION AFTER ENDOSCOPICALLY ASSISTED STRIP CRANIECTOMY FOLLOWED BY HELMET THERAPY FOR TRIGONOCEPHALY

Abstract

Introduction: Radiation-free 3D post-operative sequential follow-up in craniosynostosis is hindered by the lack of consistent markers restricting evaluation to subjective comparison. However, using the computed cranial focal point (CCFP), it is possible to perform correct sequential image superposition and objective evaluation. We used this technique to evaluate the result of endoscopically assisted trigonocephaly surgery, looking at the mean volume and shape change of the head utilizing 3D photos. Methods: We performed a mean head shape and volume evaluation on age grouped 3D photos of 40 children who underwent endoscopically assisted strip craniectomy followed by helmet therapy at the Craniofacial team Nijmegen. We used CTscans of healthy children as reference. We performed a mean shape evolution analysis and calculated the anterior fossa to total volume ratio (A/T-ratio). The volume- and A/T-ratio pattern were compared with the reference group Results: The mean anterior fossa volume evolved from 336 ml (33.4% A/T-ratio) pre-surgery to 664 ml(36.0% A/T-ratio) at 37–48 months post-surgery. Both groups have a near similar volume- and A/T-ratio pattern over time. The first 18 months show a predominant growth around the resected metopic suture. Between 18 and 24 months we observed mostly anterior orbital rim growth. From 24 months till 36–48 months the head grows predominantly at the temporal area. The least outward growth was observed at the temporal bones. Conclusion: Using a novel technique we were able to objectively evaluate head shape and volume using stereophotogrammetry after endoscopically assisted strip craniectomy followed by helmet therapy. The A/T-ratio and volume growth pattern of endoscopically treated patients is near identical to that of the normal reference group.