title: Morphological aspects of blister aneurysms and nuances for surgical treatment.
abstract: OBJECTIVE
  Blister aneurysms of the supraclinoid part of the internal carotid artery (ICA) are known for their high morbidity and mortality rates related to treatment, regardless of whether the treatment is surgical or endovascular. However, this grim prognosis is based on results that indiscriminately group all blister aneurysms together without taking into account the heterogeneous appearance of these lesions. The goal of this study was 2-fold: to determine whether different blister aneurysm morphologies present different pitfalls, which would then require different surgical strategies, as well as to determine whether there are identifiable subgroups of these types of aneurysms based on morphology.
  
  
  METHODS
  The authors reviewed the charts, cerebral catheter angiograms, surgical reports, and intraoperative videos of all ICA blister aneurysms treated surgically at the Centre Hospitalier de l'Université de Montréal from 2005 to 2012 to investigate whether there was a relationship between morphology and pitfalls, and whether different surgical strategies had been used according to these pitfalls. During this review process the authors noted 4 distinct morphological aspects. These 4 aspects led to a review of the English and French literature on blister aneurysms in which imaging was available, to determine whether other cases could also be classified into the same 4 subgroups based on these morphological aspects.
  
  
  RESULTS
  The retrospective review of the authors' series of 10 patients allowed a division into 4 distinct subtypes: Type I (classic), Type II (berry-like), Type III (longitudinal), and Type IV (circumferential). These subtypes may at times be progressive stages in the arterial anomaly, and could represent a continuum. Each subtype described in this paper presented its own pitfalls and required specific surgical adaptations. Upon reviewing the literature the authors retained 35 studies involving a total of 61 cases of blister aneurysms, and all cases were able to be classified into 1 of these 4 distinct subtypes.
  
  
  CONCLUSIONS
  Although they share some common characteristics, blister aneurysms may be divided into distinct subtypes, suggestive of a continuum. Such a classification with a detailed description of each type of blister aneurysm would allow for better recognition to anticipate complications during intervention and better assess the different treatment strategies according to the subtypes.
authors.affiliation: Division of Neurosurgery, Centre Hospitalier de l'Université de Montréal, Quebec, Canada; and.
authors.forename: Michel W
authors.initials: MW
authors.lastname: Bojanowski
authors.affiliation: Division of Neurosurgery, Centre Hospitalier de l'Université de Montréal, Quebec, Canada; and.
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Weil
authors.affiliation: Division of Neurosurgery, Centre Hospitalier de l'Université de Montréal, Quebec, Canada; and.
authors.forename: Nancy
authors.initials: N
authors.lastname: McLaughlin
authors.affiliation: Division of Neurosurgery, Centre Hospitalier de l'Université de Montréal, Quebec, Canada; and.
authors.forename: Chiraz
authors.initials: C
authors.lastname: Chaalala
authors.affiliation: Division of Neurosurgery, Centre Hospitalier de l'Université de Montréal, Quebec, Canada; and.
authors.forename: Elsa
authors.initials: E
authors.lastname: Magro
authors.affiliation: Division of Neurosurgery, Centre Hospitalier de l'Université de Montréal, Quebec, Canada; and.|Department of Neurosurgery, Cantonal Hospital of St. Gallen, Switzerland.
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Fournier
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D017542:Aneurysm, Ruptured / Q000473:pathology / Q000601:surgery; D002343:Carotid Artery, Internal / Q000473:pathology / Q000601:surgery; D016893:Carotid Stenosis / Q000601:surgery; D002404:Catheterization; D002533:Cerebral Angiography; D018450:Disease Progression; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000145:classification* / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods; D012189:Retrospective Studies; D013345:Subarachnoid Hemorrhage / Q000145:classification / Q000473:pathology / Q000601:surgery; D016896:Treatment Outcome; D055815:Young Adult
keywords: ICA = internal carotid artery; blister aneurysm; cerebral aneurysm morphology; clipping; subarachnoid hemorrhage; surgical technique; vascular disorders