title: Successful flow reduction surgery for a ruptured true posterior communicating artery aneurysm caused by the common carotid artery ligation for epistaxis.
abstract: BACKGROUND
  Carotid artery occlusion can lead to the development of rare true posterior communicating artery (PCoA) aneurysms because of hemodynamic stress on the PCoA. Surgical treatment of these lesions is challenging.
  
  
  METHODS
  The authors report a case of a true PCoA aneurysm that developed and ruptured 37 years after ligation of the ipsilateral common carotid artery for epistaxis. The lesion was successfully treated with clipping of the distal M1 segment of the middle cerebral artery (MCA) after the occipital artery-radial artery free graft-MCA bypass, which led to extreme reduction in collateral flow through the PCoA. A cortical branch, located just proximal to the obliteration site, functioned as a sufficient flow outlet. The aneurysm shrank, and the patient has been doing well without any symptoms for 5 years after surgery.
  
  
  CONCLUSIONS
  M1 obliteration combined with high-flow extra-intracranial bypass might be a promising option for a true PCoA aneurysm, and therapeutic design that leaves a sufficient flow outlet on the M1 is mandatory to avoid unexpected occlusion of the M1 and its perforators.
authors.affiliation: Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Yamao
authors.affiliation: Department of Neurosurgery, National Cerebral and Cardiovascular Research Center Hospital, Osaka, Japan.
authors.forename: Jun C
authors.initials: JC
authors.lastname: Takahashi
authors.affiliation: Department of Neurosurgery, National Cerebral and Cardiovascular Research Center Hospital, Osaka, Japan.
authors.forename: Tetsu
authors.initials: T
authors.lastname: Satow
authors.affiliation: Department of Neurosurgery, Graduate School of Medical Sciences, Kyusyu University, Fukuoka, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Iihara
authors.affiliation: Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Miyamoto
keywords: Common carotid artery ligation; extra-intracranial bypass; flow reduction; true posterior communicating artery aneurysm