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Case report
Republished: Competitive flow diversion of multiple P1 aneurysms: proposed classification
  1. Mark Alexander MacLean1,
  2. Thien J Huynh2,
  3. Matthias Helge Schmidt2,
  4. Vitor M Pereira3,
  5. Adrienne Weeks1
  1. 1 Neurosurgery, Dalhousie University, Halifax, Nova Scotia, Canada
  2. 2 Department of Diagnostic Radiology, Dalhousie University, Halifax, Nova Scotia, Canada
  3. 3 Medical Imaging, Toronto Western Hospital, Toronto, Ontario, Canada
  1. Correspondence to Dr Adrienne Weeks; a.weeks{at}


We report the case of a patient with subarachnoid hemorrhage and three aneurysms arising from the posterior communicating artery (Pcomm)-P1 complex, treated with endovascular coiling and competitive flow diversion. The largest and likely ruptured Pcomm aneurysm was treated with traditional coiling. Two smaller potentially ruptured aneurysms arose from the distal right posterior cerebral artery (PCA) P1 segment. After a failed attempt to treat with conventional flow diversion across the PCA-P1 segment, the P1 aneurysms were successfully treated with competitive flow diversion distal to the PCA-P1 segment from Pcomm to the P2 segment. Over 12 months, competitive flow diversion redirected flow to the right PCA territory via the internal carotid artery-Pcomm-P2, reducing the size of the PCA-P1 segment and obliterating the P1 aneurysms. Competitive flow diversion treatment should be considered for aneurysms occurring at the circle of Willis when traditional methods are not feasible. Herein, we introduce a novel classification for competitive flow diversion treatment.

  • aneurysm
  • flow diverter
  • subarachnoid
  • technique
  • blood flow

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  • MAM and TJH are joint first authors.

  • Republishing Republished with permission from BMJ Case Reports. Published 03 June 2020; doi:10.1136/bcr-2019-015581.

  • Contributors Conception and design: AW and VMP. Acquisition of data: MAM and TJH. Analysis and interpretation of data: all authors. Drafting the article: AW, MAM. Critically revising the article: AW, MHM, MHS, TJH and VMP. Review of the final article prior to submission: all authors. Approval of the final version of the manuscript on behalf of all the authors: AW. Administrative/technical/material support: AW. Drawing of proposed classification scheme (Figure 5): AW. Study supervision: AW.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.