title: Risk Factors for Hemorrhagic Complications following Pipeline Embolization Device Treatment of Intracranial Aneurysms: Results from the International Retrospective Study of the Pipeline Embolization Device.
abstract: OBJECTIVE
  Spontaneous intraparenchymal hemorrhage is a dreaded complication of unknown etiology following flow-diversion treatment. Using the International Retrospective Study of the Pipeline Embolization Device registry, we studied demographic, aneurysm, and procedural characteristics associated with intraparenchymal hemorrhage following Pipeline Embolization Device treatment.
  
  
  METHODS
  We identified patients in the International Retrospective Study of the Pipeline Embolization Device registry with intraparenchymal hemorrhage unrelated to index aneurysm rupture post-Pipeline Embolization Device treatment. The rate of intraparenchymal hemorrhage was determined by baseline demographics, comorbidities, aneurysm characteristics, and procedural characteristics (including anticoagulation use, platelet testing, number of devices used, sheaths, catheters, and guidewires). Categoric variables were compared with χ(2) testing, and continuous variables were compared with the Student t test.
  
  
  RESULTS
  Of 793 patients with 906 aneurysms, 20 (2.5%) had intraparenchymal hemorrhage. Fifteen intraparenchymal hemorrhages (75.0%) occurred within 30 days of treatment (median, 5 days; range, 0-150 days). Nine patients with intraparenchymal hemorrhage (45.0%) died, 10 (50.0%) had major neurologic morbidity, and 1 had minor neurologic morbidity (5.0%). Intraparenchymal hemorrhage was ipsilateral to the Pipeline Embolization Device in 16 patients (80%) and contralateral in 3 patients (15.0%). Variables associated with higher odds of intraparenchymal hemorrhage included treatment of ruptured aneurysms (OR, 4.44; 95% CI, 1.65-11.94; P = .005) and the use of ≥ 3 Pipeline Embolization Devices (OR, 4.10; 95% CI, 1.34-12.58; P = .04). The Shuttle sheath was not associated with intraparenchymal hemorrhage (OR, 0.97; 95% CI, 0.38-2.45; P = .95).
  
  
  CONCLUSIONS
  Spontaneous intraparenchymal hemorrhage following Pipeline Embolization Device treatment is a rare-but-devastating complication, with nearly all patients having morbidity or mortality. Variables associated with intraparenchymal hemorrhage included the use of multiple Pipeline Embolization Devices and treatment of ruptured aneurysms. The Shuttle, a device that was previously thought to be associated with intraparenchymal hemorrhage, was not associated with it.
authors.affiliation: From the Departments of Radiology (W.B., G.L., H.J.C., D.F.K.) brinjikji.waleed@mayo.edu.
authors.forename: W
authors.identifier: http://orcid.org/0000-0001-5271-5524
authors.initials: W
authors.lastname: Brinjikji
authors.affiliation: From the Departments of Radiology (W.B., G.L., H.J.C., D.F.K.) Neurosurgery (G.L., H.J.C., D.F.K.), Mayo Clinic, Rochester, Minnesota.
authors.forename: G
authors.identifier: http://orcid.org/0000-0003-1479-465X
authors.initials: G
authors.lastname: Lanzino
authors.affiliation: From the Departments of Radiology (W.B., G.L., H.J.C., D.F.K.) Neurosurgery (G.L., H.J.C., D.F.K.), Mayo Clinic, Rochester, Minnesota.
authors.forename: H J
authors.identifier: http://orcid.org/0000-0003-2590-3815
authors.initials: HJ
authors.lastname: Cloft
authors.affiliation: Department of Neurosurgery (A.H.S.), State University of New York, Buffalo, New York.
authors.forename: A H
authors.initials: AH
authors.lastname: Siddiqui
authors.affiliation: From the Departments of Radiology (W.B., G.L., H.J.C., D.F.K.) Neurosurgery (G.L., H.J.C., D.F.K.), Mayo Clinic, Rochester, Minnesota.
authors.forename: D F
authors.identifier: http://orcid.org/0000-0002-8495-0040
authors.initials: DF
authors.lastname: Kallmes
mesh_terms: D000328:Adult; D000368:Aged; D002543:Cerebral Hemorrhage / Q000453:epidemiology* / Q000209:etiology*; D004621:Embolization, Therapeutic / Q000009:adverse effects* / Q000295:instrumentation; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome