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Original research
Meta-analysis of treatment outcomes of posterior circulation non-saccular aneurysms by flow diverters
  1. Satoshi Kiyofuji1,
  2. Christopher S Graffeo1,
  3. Avital Perry1,
  4. Mohammad Hassan Murad2,
  5. Kelly D Flemming3,
  6. Giuseppe Lanzino1,
  7. Leonardo Rangel-Castilla4,
  8. Waleed Brinjikji5
  1. 1 Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, USA
  2. 2 Evidence-based Practice Center, Mayo Clinic, Rochester, Minnesota, USA
  3. 3 Department of Cerebrovascular Neurology, Mayo Clinic, Rochester, Minnesota, USA
  4. 4 Department of Neurosurgery, Wayne State University, Detroit, Michigan, USA
  5. 5 Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
  1. Correspondence to Dr. Waleed Brinjikji, Department of Radiology, Mayo Clinic, Rochester, MN 55905, USA; Brinjikji.Waleed{at}


Introduction Non-saccular aneurysms of the posterior circulation are uncommon but highly dangerous lesions. Flow diverter stents have been demonstrated to be effective treatments of various anterior circulation aneurysms, particularly large and giant proximal internal carotid artery aneurysms. However, evidence regarding the treatment of non-saccular posterior circulation aneurysms with flow diverters is lacking.

Methods A systematic literature review of the English language literature since 2007 was conducted using PubMed, MEDLINE, and Embase. Keywords and MeSH terms included flow diversion, flow diverter, pipeline, surpass, intracranial aneurysm, vertebrobasilar, and non-saccular. Case reports were excluded. Angiographic and clinical outcomes were pooled using a random effects meta-analysis.

Results 13 retrospective non-comparative studies reporting 129 patients and 131 aneurysm treatments were included. The average number of flow diverters per aneurysm was 4.33. Immediate complete or near complete occlusion of the aneurysm occurred in 25% (95% CI 1% to 60%), and long term occlusion in 52% (29–76%). Periprocedural stroke occurred in 23% of cases. Good long term neurologic outcome (modified Rankin Scale score ≤2) was achieved in 51% (95% CI 31% to 71%). Overall mortality was 21% (95% CI 7% to 38%) and morbidity was 26% (12%–42%). Retreatment was required in 5% (95% CI 0% to 14%). Good neurologic outcome rate was higher in vertebral artery aneurysms (83%) than other locations (18–33%).

Conclusions Flow diversion is a feasible and efficacious treatment for non-saccular aneurysms in the posterior circulation. However, the intervention carries a significant risk of periprocedural stroke, and is still associated with high overall mortality. Further studies are needed to identify significant treatment risk factors and optimize patient selection.

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  • Contributors SK collected studies, collected, cleaned, and analyzed the data, and drafted and revised the paper. CSG and AP collected studies, analyzed the data, and revised the draft paper. MHM monitored the data collection, analyzed the data, and revised the draft paper. KDF analyzed the data and revised the draft paper. GL and LR-C revised the draft paper. WB designed the study, monitored the data collection, analyzed the paper, and drafted and revised the paper. He is the guarantor.

  • Competing interests None declared.

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