title: Aneurysm of the distal posteroinferior cerebellar artery of extracranial origin: case report.
abstract: OBJECTIVE
  We describe a very rare case involving a ruptured intracranial aneurysm at the distal posteroinferior cerebellar artery (PICA) branching from the extracranial vertebral artery.
  
  
  METHODS
  A 53-year-old woman experienced the sudden onset of a severe occipital headache and vomiting. Computed tomographic scanning revealed subarachnoid and intraventricular hemorrhage. Cerebral angiography of the left vertebral artery demonstrated the left PICA branching from the extracranial segment of the extracranial vertebral artery at the level of C2; a saccular aneurysm arose from the intracranial portion of the distal PICA.
  
  
  METHODS
  Via the transcondylar approach, we were able to obtain adequate visualization without retracting important structures. To avoid injury to the anomalous PICA, the aneurysm was clipped.
  
  
  CONCLUSIONS
  Only four other cases of a distal aneurysm of the PICA branching from the extracranial vertebral artery have been reported in the literature. In all cases, the aneurysm originated at the intradural extracranial portion of the PICA. To our knowledge, the case presented here is the first report of a ruptured aneurysm at the level of the intracranial portion of the PICA branching from the extracranial segment of the vertebral artery.
authors.affiliation: Department of Neurosurgery, Chiba-Hokuso Hospital, Nippon Medical School, Chiba, Japan. kyongson@nms.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Kim
authors.forename: S
authors.initials: S
authors.lastname: Kobayashi
authors.forename: T
authors.initials: T
authors.lastname: Mizunari
authors.forename: A
authors.initials: A
authors.lastname: Teramoto
mesh_terms: D017542:Aneurysm, Ruptured / Q000175:diagnosis / Q000601:surgery*; D002531:Cerebellum / Q000098:blood supply* / Q000473:pathology / Q000601:surgery; D002533:Cerebral Angiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002532:Intracranial Aneurysm / Q000175:diagnosis / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D011183:Postoperative Complications / Q000000981:diagnostic imaging; D014711:Vertebral Artery / Q000002:abnormalities* / Q000473:pathology / Q000601:surgery