title: Why are aneurysms of the posterior inferior cerebellar artery so unique? Clinical experience and review of the literature.
abstract: BACKGROUND
  Aneurysms of the posterior inferior cerebellar artery (PICA) are rare lesions. The anatomical behaviour of the artery itself is complex and characterised by a multitude of variations. The same holds true for the aneurysms discovered there. Dissecting aneurysms can be found from the PICA origin to the distal artery berry. They have a wider range of clinical and radiographical presentations and their surgical treatment requires more than one standard approach.
  
  
  METHODS
  We encountered 14 patients with PICA aneurysms within two surgical series of a total of 1345 cerebral aneurysm patients (1 %). In this patient group of the last 27 years only 3 of the 14 were distal aneurysms ("true" PICA aneurysms)
  
  
  RESULTS
  The 14 patients harboured 15 aneurysms (9 right-sided and 6 left-sided). The female/male ratio of the patients was 9/5, the mean age 52.7 years. 13 of them had sustained an SAH. 7/14 patients were hypertensive, in 10 patients at least one of putative cerebrovascular risk factors was found. From the 15 aneurysms treated, 11 were typical berry aneurysms, 4 dissecting aneurysms. The aneurysms ranged in size from 5 to 20 mm (mean 9.1). 11 aneurysms were located within the anterior medullary segment, 1 in the tonsillomedullary and 2 in the telovelomedullary segments. All patients were surgically treated, 10 in a semi-sitting position via a suboccipital craniotomy, 4 in the prone position. 13 aneurysms were clipped, two were treated differently. Two patients died due to their bad preoperative clinical status.
  
  
  CONCLUSIONS
  The clinical, radiographical and surgical approaches to PICA aneurysms still represent a challenge.
authors.affiliation: Donauspital, Vienna, Austria. g.kleinpeter@billrothhaus.at
authors.forename: G
authors.initials: G
authors.lastname: Kleinpeter
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D002531:Cerebellum / Q000098:blood supply*; D002536:Cerebral Arteries / Q000473:pathology* / Q000601:surgery*; D003399:Craniotomy; D005260:Female; D006801:Humans; D015994:Incidence; D002532:Intracranial Aneurysm / Q000473:pathology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods*; D011187:Posture; D011379:Prognosis; D012307:Risk Factors; D012737:Sex Factors; D013345:Subarachnoid Hemorrhage / Q000209:etiology* / Q000601:surgery*; D016896:Treatment Outcome