Shape analysis of the sphenoid bone in Apert syndrome using 3D CT scans

ABSTRACT

Apert syndrome is a rare acrocephalosyndactyly syndrome characterised by craniosynostosis, midface hypoplasia and syndactyly of the hands and feet. The majority of cases arise as the result of one of two mutations of the fibroblast growth factor receptor 2 gene (FGFR2). Due to the involvement of both the cranial and the facial sutures, the keystone of the craniofacial skeleton, the sphenoid bone, is affected by the disease process and as a result is dysmorphic. This may significantly affect craniofacial morphology but it is recognised that there are marked variations in this between different affected individuals. This is a retrospective study examining the morphology of the sphenoid bone using three dimensional reconstructions of computed tomography (CT) scan data. Shape analysis was performed using generalised Procrustes analysis and principal component analysis (GPA/PCA). Comparisons were made between the individuals with Apert syndrome and a group of normal individuals, and between the two genotypic groups. The sphenoid bone in those with Apert syndrome showed marked differences in morphology compared to the normal individuals with a restriction in height and increased angulation of the lesser wings; however, there were no consistent differences between the two genotypic groups. It is possible that fronto-orbital advancement (FOA) surgery indirectly releases the sphenoid bone and allows compensatory growth in this direction.