Experimental investigation of encephalomyosynangiosis using gyrencephalic brain of the miniature pig: histopathological evaluation of dynamic reconstruction of vessels for functional anastomosis. Laboratory investigation.
OBJECTIVE
Encephalomyosynangiosis (EMS) is a surgical treatment for moyamoya disease that is widely used to provide increased intracranial blood flow via revascularization by arterial anastomosis from the external carotid artery. However, the angiogenic mechanism responsible for the revascularization induced by EMS has not been systematically evaluated. In this study the authors investigated the chronological angiogenic changes associated with EMS to clarify the favorable factors and identify revascularization mechanisms by using an experimental internal carotid artery occlusion (ICAO) model in the miniature pig.


METHODS
Fourteen miniature pigs were used, 11 of which underwent ICAO before transcranial surgery for EMS was performed. Animals were allowed to recover for 1 week (4 pigs) or 4 weeks (7 pigs) after EMS. Control group animals were treated in the same way, but without occlusion (3 pigs). Magnetic resonance imaging, angiography, and histological investigation were performed.


RESULTS
One week after EMS, on histological examination of both the ICAO and control groups it was found that the transplanted temporal muscle had adhered to the arachnoid via a granulation zone, which was enriched with immune cells such as macrophages associated with the angiogenic process. Four weeks after EMS, angiography and histological examination of the ICAO group showed patent anastomoses between the external carotid artery and the cortical arteries without any detectable boundary between the temporal muscle and the cerebral cortex. In contrast, histological examination of the control group found scar tissue between the cerebral cortex and temporal muscle.


CONCLUSIONS
The initial step for formation of anastomoses resembles the process of wound healing associated with repair processes such as active proliferation of macrophages and angiogenesis within the new connective tissue. Functional revascularization requires a suitable environment (such as tissue containing vascular beds) and stimulus (such as ischemia) to induce vascular expansion.
Nakamura
Mitsunobu
M
Department of Neurosurgery, Gunma University Graduate School of Medicine, Maebashi, Japan.
Imai
Hideaki
H
Konno
Kenjiro
K
Kubota
Chisato
C
Seki
Koji
K
Puentes
Sandra
S
Faried
Ahmad
A
Yokoo
Hideaki
H
Hata
Hidekazu
H
Yoshimoto
Yuhei
Y
Saito
Nobuhito
N
D000714:Anastomosis, Surgical; D000818:Animals; D002340:Carotid Artery Diseases / Q000601:surgery; D002533:Cerebral Angiography; D002540:Cerebral Cortex / Q000098:blood supply; D002548:Cerebral Revascularization / Q000379:methods*; D008279:Magnetic Resonance Imaging; D009072:Moyamoya Disease / Q000601:surgery*; D018919:Neovascularization, Physiologic / Q000502:physiology; D013552:Swine; D013556:Swine, Miniature; D013703:Temporal Muscle / Q000098:blood supply; D014945:Wound Healing