title: Characteristics of distal posteroinferior cerebellar artery aneurysms.
abstract: OBJECTIVE
  Distal posteroinferior cerebellar artery (PICA) aneurysms are rare and have not been well investigated previously. We report our series of 24 patients with 27 distal PICA aneurysms.
  
  
  METHODS
  All patients with distal PICA aneurysms that were surgically treated at Shinshu University Hospital and its affiliated hospitals between 1983 and 2001 were reviewed retrospectively. Data relating to clinical, radiological, and intraoperative findings were analyzed.
  
  
  RESULTS
  In our series, distal PICA aneurysms reached an incidence of 0.28 and 0.38% of all intracranial aneurysms and ruptured aneurysms, respectively. There were 23 ruptured and 4 unruptured distal PICA aneurysms. Of these, 74.1% were saccular, 7.4% fusiform, and 18.5% dissecting aneurysms. Primarily the telovelotonsillar segment of the PICA was affected. Usually, the surgical outcome was favorable and was influenced by the obstructive hydrocephalus and the preoperative grade. It was sometimes difficult to detect the ruptured distal PICA aneurysm on the initial angiogram, and an extracranial origin of the PICA was sometimes observed.
  
  
  CONCLUSIONS
  This review summarizes the presentation and outcome of a large series of 24 patients with 27 distal PICA aneurysms, and we conclude that distal PICA aneurysms are benign entities compared with vertebral artery-PICA aneurysms. Characteristics that should be considered in the treatment of distal PICA aneurysms are discussed.
authors.affiliation: Department of Neurosurgery, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Tetsuyoshi
authors.initials: T
authors.lastname: Horiuchi
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Hongo
authors.forename: Junpei
authors.initials: J
authors.lastname: Nitta
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Kusano
authors.forename: Shigeaki
authors.initials: S
authors.lastname: Kobayashi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002531:Cerebellum / Q000098:blood supply* / Q000000981:diagnostic imaging* / Q000601:surgery; D002533:Cerebral Angiography; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D012189:Retrospective Studies; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed