title: Association of a Distal Intradural-Extracranial Posterior Inferior Cerebellar Artery Aneurysm With Chiari Type I Malformation: Case Report.
abstract: BACKGROUND
  Distal extracranial posterior inferior cerebellar artery (PICA) aneurysms are very rare lesions and have not been previously reported in association with a Chiari type I malformation (CMI).
  
  
  METHODS
  A 56-year-old woman with a distal, low-lying, intradural-extracranial PICA aneurysm presented with a subarachnoid hemorrhage and was treated with coil embolization. The patient presented again 1 month later with symptoms of a CMI and was found to have tonsillar herniation and a large syrinx that appeared to be exacerbated by the coil mass. The patient was re-treated with a suboccipital craniectomy, C1-2 laminectomy, aneurysm trapping and excision, end-to-end PICA anastomosis, and expansile duraplasty.
  
  
  CONCLUSIONS
  Although just a single case, important teaching points regarding the angiographic appearance of a CMI and treatment options for distal PICA aneurysms that are situated below the foramen magnum can be learned. A low-lying caudal PICA loop should trigger a workup for a CMI. Caution should be taken when using coil embolization for aneurysms in the high cervical spinal canal. Bypass with aneurysm trapping and excision may be a superior treatment option in these cases because the posterior fossa and high cervical canal can be concomitantly decompressed. To our knowledge, this is the only case reported of a distal intradural-extracranial PICA aneurysm associated with a CMI.
authors: Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York, New York.
authors: Justin R
authors: JR
authors: Mascitelli
authors: Sharona
authors: S
authors: Ben-Haim
authors: Srinivasan
authors: S
authors: Paramasivam
authors: Hekmat K
authors: HK
authors: Zarzour
authors: Robert J
authors: RJ
authors: Rothrock
authors: Joshua B
authors: JB
authors: Bederson
mesh_terms: D001139:Arnold-Chiari Malformation / Q000150:complications* / Q000000981:diagnostic imaging* / Q000628:therapy; D002531:Cerebellum / Q000098:blood supply / Q000000981:diagnostic imaging; D004621:Embolization, Therapeutic / Q000379:methods; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications* / Q000000981:diagnostic imaging* / Q000628:therapy; D008875:Middle Aged; D011859:Radiography