title: Tourniquet parent artery occlusion after flow diversion.
abstract: BACKGROUND
  The Pipeline Embolization Device (PED) is increasingly used for both on- and off-label purposes for treatment of intracranial aneurysms. The device gradually slows flow of blood into the aneurysm, but the high metal coverage of PED promotes endothelialization of the device. Occasionally, this leads to in-stent stenosis that is clinically well tolerated. We present a multi-institutional Pipeline series that includes three cases of gradual asymptomatic occlusion within the PED and parent vessel.
  
  
  METHODS
  Institutional databases at each participating center were searched for patients treated with the PED. Patients with at least 50% stenosis or occlusion were selected and all relevant clinical and radiographic data were reviewed.
  
  
  RESULTS
  A total of 326 cases performed by five neurointerventionalists across four institutions were reviewed. Among these there were three cases of complete occlusion and two cases of stenosis of more than 50%, for an occlusion rate of 0.9%. All patients were clinically asymptomatic.
  
  
  CONCLUSIONS
  A gradual tourniquet-like occlusion can occur following placement of the PED, leading to vessel occlusion. This has been clinically well tolerated by patients in our series due to the formation of pial collaterals as the stenosis progresses, likely due to ischemic preconditioning. Small parent vessel, pre-existing stenosis, fusiform pathology, overlapping devices, and suboptimal antiplatelet therapy seem to be predisposing factors. Further experience and follow-up will allow us to characterize the risk factors and optimize post-procedural therapy for these patients.
authors.affiliation: Department of Neurosurgery, Baylor College of Medicine, Houston, Texas, USA.
authors.forename: Visish M
authors.identifier: http://orcid.org/0000-0001-7673-6805
authors.initials: VM
authors.lastname: Srinivasan
authors.affiliation: Department of Neurosurgery, University of South Florida, Tampa, Florida, USA.
authors.forename: Maxim
authors.identifier: http://orcid.org/0000-0001-7264-4233
authors.initials: M
authors.lastname: Mokin
authors.affiliation: Northwest Neurosurgical Associates, Boise, Idaho, USA.
authors.forename: Edward A M
authors.initials: EAM
authors.lastname: Duckworth
authors.affiliation: Department of Radiology, Baylor College of Medicine, Houston, Texas, USA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Radiology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: Ajit
authors.initials: A
authors.lastname: Puri
authors.affiliation: Department of Neurosurgery, Baylor College of Medicine, Houston, Texas, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Kan
mesh_terms: D000328:Adult; D000368:Aged; D002533:Cerebral Angiography / Q000639:trends; D002561:Cerebrovascular Disorders / Q000000981:diagnostic imaging* / Q000209:etiology; D004621:Embolization, Therapeutic / Q000009:adverse effects* / Q000295:instrumentation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000209:etiology; D012189:Retrospective Studies; D015607:Stents / Q000009:adverse effects*; D014111:Tourniquets; D016896:Treatment Outcome
keywords: Aneurysm; Complication; Flow Diverter; Vessel Wall