title: Chiari I anatomy after ventriculoperitoneal shunting: posterior fossa volumetric evaluation with MRI.
abstract: BACKGROUND
  Cephalocranial disproportion was said to be responsible for Chiari I malformation after ventriculoperitoneal shunt. We aimed to evaluate if the volumetric characteristics of Chiari I after a ventriculoperitoneal shunt was due to a general volumetric reduction and if it is restricted to the posterior fossa.
  
  
  RESULTS
  Our results show that the posterior fossa volume, cisternal, clival length, and posterior cranial fossa volume ratio were reduced in the shunted group compared to the controls (p<0.05). Cerebellar and supratentorial volumes were similar between both groups. Craniocaudal extent, inferior, and superior tonsillar herniations were greater in the shunted group than control (p<0.05). The frontal occipital horn ratio in both groups was within normal range.
  
  
  CONCLUSIONS
  Chiari I anatomy after a ventriculoperitoneal shunt could develop in children and we propose a "posterior cranial fossa disproportion" rather than a "cephalocranial disproportion."
authors.affiliation: Department of Anatomy, University of Ibadan, Ibadan, Nigeria.
authors.forename: Ferdnand C
authors.initials: FC
authors.lastname: Osuagwu
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Lazareff
authors.forename: Shayan
authors.initials: S
authors.lastname: Rahman
authors.forename: Suzie
authors.initials: S
authors.lastname: Bash
mesh_terms: D001139:Arnold-Chiari Malformation / Q000473:pathology* / Q000601:surgery*; D002675:Child, Preschool; D003388:Cranial Fossa, Posterior / Q000473:pathology* / Q000601:surgery*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D017287:Ventriculoperitoneal Shunt / Q000379:methods*