Vascular corrosion casts mirroring early morphological changes that lead to the formation of saccular cerebral aneurysm: an experimental study in rats.
OBJECTIVE
The formation of cerebral aneurysms involves complex processes and little is known about the mechanisms by which they originate, grow, and rupture. The purpose of this study was to identify early ultrastructural morphological changes that lead to the formation of experimental cerebral aneurysms.


METHODS
Twenty male Sprague-Dawley rats were subjected to cerebral aneurysm induction (renal hypertension and right common carotid artery ligation); 10 intact rats served as the control group. The animals were killed after 2 months, and a vascular corrosion cast of their cerebral arteries was prepared and screened for aneurysm development by using a scanning electron microscope. Sequential morphological changes observed at the cerebral artery bifurcation in response to hemodynamic shear stress included endothelial changes, intimal pad elevation, and saccular dilation. Endothelial cell changes were the first observed morphological changes; they were followed by various degrees of artery wall dilation. No aneurysmal changes developed in any of the control rats. Of the 20 surgically treated rats, 11 displayed aneurysmal changes. In five of these animals only changes in the endothelial cell imprints could be identified. In the other six rats morphological changes in endothelial cells were associated with different stages of aneurysmal dilation.


CONCLUSIONS
This is the first study to demonstrate in vivo early morphological changes that lead to the formation of cerebral aneurysms. The morphological findings indicate the principal role of endothelial cells in the pathogenesis of cerebral aneurysms and suggest that hemodynamic shear stress and blood flow patterns may precipitate these early changes.
Jamous
Mohammad A
MA
Department of Neurosurgery, School of Medicine, The Institute of Health Bioscience, The University of Tokushima, Tokushima City, Japan. neuros@clin.med.tokushima-u.ac.jp
Nagahiro
Shinji
S
Kitazato
Keiko T
KT
Satoh
Koichi
K
Satomi
Junichiro
J
D000818:Animals; D016319:Corrosion Casting; D002532:Intracranial Aneurysm / Q000473:pathology*; D008297:Male; D008855:Microscopy, Electron, Scanning; D051381:Rats; D017207:Rats, Sprague-Dawley; D013314:Stress, Mechanical