title: The foramen magnum in isolated and syndromic brachycephaly.
abstract: BACKGROUND
  Though the foramen magnum (FM) is often altered in complex craniosynostosis, no study analysed the FM dimensions in patients with brachycephaly specifically.
  
  
  METHODS
  We measured the FM area, sagittal and transverse diameters on preoperative CT scans in patients with bicoronal synostosis (n = 40) and age-matched control group (n = 18). Our study included 16 children with FGFR3 p.Pro250Arg mutation (mean age 6.1 months), 10 with TWIST-1 mutation (mean age7.6 months) and 14 patients with isolated bicoronal synostosis (mean age 6.1).
  
  
  RESULTS
  We observed a significantly smaller FM area in FGFR3 group compared to control group and isolated brachycephaly group (p = 0.001 and p = 0.038, respectively). The mean FM area in FGFR3 group was 426.13 mm(2) (p = 0.001), while in TWIST-1 group was 476.34 mm(2) (p = 0.103), and in isolated brachycephaly group 489.43 mm(2) (p = 0.129) compared to control group: 528.90 mm(2). The posterior segment of the sagittal diameter of the FM and its width as well as the bi-interoccipital synchondrosis diameters were significantly smaller in FGFR3 group compared to control group. In TWIST-1 group, the only altered dimension was the FM anterior segment of the sagittal diameter (p = 0.008). We did not observe any significant alteration of FM in patients with isolated brachycephaly compared to control group.
  
  
  CONCLUSIONS
  The FM area is significantly altered in FGFR3-related brachycephaly, whereas in patients with Saethre-Chotzen syndrome (TWIST-1 mutation) the mean FM area is similar to control group. This study confirms the importance of FGFRs on FM growth whereas TWIST-1 seems to have a minor role.
authors.affiliation: Unité de Chirurgie Craniofaciale, Service de Neurochirurgie, Centre de Référence National Dysostoses Crâniofaciales, Hôpital Necker, APHP, Université Paris Descartes, Paris, France, federico.dirocco@nck.aphp.fr.
authors.forename: Federico
authors.initials: F
authors.lastname: Di Rocco
authors.forename: Dana
authors.initials: D
authors.lastname: Dubravova
authors.forename: Jawad
authors.initials: J
authors.lastname: Ziyadeh
authors.forename: Christian
authors.initials: C
authors.lastname: Sainte-Rose
authors.forename: Corinne
authors.initials: C
authors.lastname: Collet
authors.forename: Eric
authors.initials: E
authors.lastname: Arnaud
mesh_terms: D003398:Craniosynostoses / Q000000981:diagnostic imaging* / Q000601:surgery*; D005260:Female; D005539:Foramen Magnum / Q000000981:diagnostic imaging* / Q000601:surgery*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D013577:Syndrome; D014057:Tomography, X-Ray Computed / Q000379:methods