Radiation-free 3D head shape and volume evaluation after endoscopically assisted strip craniectomy followed by helmet therapy for trigonocephaly

Abstract

IntroductionRadiation-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 for mean volume and shape change evaluation of the head utilizing 3D photos after endoscopically assisted trigonocephaly surgery. MethodsWe performed a mean head shape and volume evaluation on age grouped 3D photos (n = 86) of children who underwent endoscopically assisted strip craniectomy with helmet therapy. We used CT-scans 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. ResultsThe 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. ConclusionUsing a novel technique we were able to objectively evaluate head shape and volume using stereophotogrammetry after endoscopically assisted strip craniectomy. The A/T-ratio and volume growth pattern of endoscopically treated patients is near identical to that of the normal reference group.