title: Microsurgical anatomy of the extracranial-extradural origin of the posterior inferior cerebellar artery.
abstract: OBJECTIVE
  The authors describe the microsurgical anatomy of the posterior inferior cerebellar artery (PICA) with an extradural origin and discuss its importance as a common variation.
  
  
  METHODS
  The microsurgical anatomy of paired PICAs with an extradural origin were examined.
  
  
  CONCLUSIONS
  Five to 20% of PICAs have an extradural origin. In the case described, both PICAs arose extradurally from the third segment of the vertebral artery (VA). Both origins were less than 1 cm proximal to the site at which the VA penetrated the dura, and neither PICA gave rise to extradural branches. Extradurally, the PICAs coursed parallel to the VA and the C-1 nerve and the three structures penetrated the dura together. Intradurally, the PICAs remained lateral and posterior to the brainstem, whereas, in the common PICA configuration, the first segment of the PICA courses anterior to the medulla. Neither PICA sent branches to the anterior brainstem, which is commonly found in PICAs with an intradural origin. There were no soft-tissue or bone anomalies.
authors.affiliation: Department of Neurological Surgery, University of Florida, Gainesville 32610-0265, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: Fine
authors.forename: A
authors.initials: A
authors.lastname: Cardoso
authors.forename: A L
authors.initials: AL
authors.lastname: Rhoton
mesh_terms: D001158:Arteries / Q000033:anatomy & histology; D002531:Cerebellum / Q000098:blood supply* / Q000601:surgery; D004388:Dura Mater / Q000033:anatomy & histology / Q000098:blood supply; D006801:Humans; D008866:Microsurgery; D014711:Vertebral Artery / Q000033:anatomy & histology