title: Development of profound Chiari I malformation and cerebellar tissue loss and resolution following shunting of posterior fossa extra-axial cyst. Case report.
abstract: BACKGROUND
  Chiari I malformation can be due to a multitude of etiologies such as craniosynostosis or hydrocephalus. A posterior fossa extra-axial cyst (PFEAC) appears to be an extremely rare cause of this form of hindbrain herniation.
  
  
  METHODS
  Herein, we report a case of PFEAC that presented with no Chiari I malformation and then presented months later with a significant Chiari I malformation. Following shunt placement of a PFEAC, striking reversal of the Chiari malformation as well as reconstitution of the cerebellum was noted.
  
  
  CONCLUSIONS
  Patients with PFEAC might develop a Chiari I malformation and this might be treated with shunting of the PFEAC alone.
authors.affiliation: Seattle Science Foundation, 550 17th Avenue, James Tower, Suite 600, Seattle, WA, 98122, USA.
authors.forename: Rabia
authors.initials: R
authors.lastname: Khan
authors.affiliation: Seattle Science Foundation, 550 17th Avenue, James Tower, Suite 600, Seattle, WA, 98122, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Oakes
authors.affiliation: Seattle Science Foundation, 550 17th Avenue, James Tower, Suite 600, Seattle, WA, 98122, USA. shanet@seattlesciencefoundation.org.
authors.forename: R Shane
authors.initials: RS
authors.lastname: Tubbs
authors.affiliation: Pediatric Neurosurgery, Children's of Alabama, Birmingham, AL, USA.
authors.forename: W Jerry
authors.initials: WJ
authors.lastname: Oakes
mesh_terms: D001139:Arnold-Chiari Malformation / Q000209:etiology* / Q000601:surgery*; D001927:Brain Diseases / Q000150:complications* / Q000601:surgery; D002531:Cerebellum / Q000473:pathology; D002557:Cerebrospinal Fluid Shunts; D002675:Child, Preschool; D003388:Cranial Fossa, Posterior / Q000473:pathology / Q000601:surgery; D003560:Cysts / Q000150:complications*; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000209:etiology / Q000601:surgery
keywords: Hindbrain herniation; Posterior fossa CSF collection; Surgery; Tonsillar ectopia; Treatment