title: Lack of aneurysm formation after carotid artery ligation in rabbits: a polymer MICROFIL® study.
abstract: BACKGROUND
  Previous studies have noted formation of saccular aneurysms along the distal basilar artery/P1 segments after carotid ligation in rabbits. In this prospective study we employed MICROFIL®, a polymer, which was used to fill the entire arterial tree, to examine the incidence of microaneurysm formation following right common carotid artery (RCCA) ligation in rabbits.
  
  
  METHODS
  RCCA ligation was performed in 18 New Zealand White rabbits for 0 day (n = 2), 3 weeks (n = 6), or 16 weeks (n = 10). Three control rabbits without carotid surgery were sacrificed at 4 weeks. At the time of sacrifice, MICROFIL® MV-122 yellow was injected through left CCA to fill cerebral vasculature. After gross photographs were taken, specimens were embedded, sectioned, and stained for histopathological evaluation. Tissue and sections were carefully evaluated for microaneurysm formation, defined as a localized dilatation of the vessel wall, associated with fragmentation or complete loss of the internal elastic lamina (IEL), and/or medial degeneration.
  
  
  RESULTS
  Gross examination with MICROFIL® opacification demonstrated no evidence of saccular aneurysm formation, but prominent perforating vessels were present in all 19 cases at, or adjacent to, the basilar terminus. Branches noted upon gross examination corresponded histologically to small, saccular contour defects, which demonstrated apparent loss of the IEL and apparent medial thinning. These observations, however, were a consequence of sectioning through the bases of perforating arteries, which simulated microaneurysm formation.
  
  
  CONCLUSIONS
  Unilateral carotid ligation does not induce microaneurysm formation at the basilar terminus in rabbits. Prominent perforating arteries as well as tissue injury from the processing may simulate "aneurysms" histologically.
authors: Neuroradiology Research Laboratory, Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors: Daying
authors: D
authors: Dai
authors: Yong Hong
authors: YH
authors: Ding
authors: Ramanathan
authors: R
authors: Kadirvel
authors: Arash Ehteshami
authors: AE
authors: Rad
authors: Debra A
authors: DA
authors: Lewis
authors: David F
authors: DF
authors: Kallmes
mesh_terms: D000783:Aneurysm / Q000175:diagnosis / Q000517:prevention & control*; D000818:Animals; D002340:Carotid Artery Diseases / Q000175:diagnosis / Q000517:prevention & control*; D004621:Embolization, Therapeutic / Q000379:methods*; D006490:Hemostatics / Q000627:therapeutic use; D008026:Ligation; D011817:Rabbits; D012826:Silicone Elastomers / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D006490:Hemostatics; D012826:Silicone Elastomers