Do human intracranial arteries lack vasa vasorum? A comparative immunohistochemical study of intracranial and systemic arteries

Abstract

Vasa vasorum are adventitial vessels that play a role in pathogenesis of atherosclerosis, aneurysm, vasculitides, and graft vascular disease. The existence of vasa vasorum in human intracranial arteries is not yet well defined. The specific aims of this study are to determine whether the human intracranial arteries have vasa vasorum, whether their existence is related to the thickness of tunica media as is in systemic vessels, and whether they are acquired in reaction to pathological conditions, such as atherosclerosis and arterial occlusion. Human intracranial internal carotid (i-ICA), vertebral (i-VA), basilar (BA) and middle cerebral arteries (MCA) from adults, children and newborns were examined. Systemic vessels of comparable medial thickness were used as controls. Immunohistochemical staining for Factor VIII and CD 31 was used to identify the endothelial cells. Human intracranial arteries in neonates, children and adults do not have vasa vasorum, although their medial thickness is comparable to their systemic counterparts with vasa vasorum. Only in adults did the proximal intracranial segments of i-ICA and i-VA reveal a few vasa vasorum-like vessels with unusually large diameter. They were more frequently seen in atherosclerosis and thrombotic but again limited to the proximal segments of i-ICA and i-VA. Completely obstructed bilateral carotid arteries in a child with sickle cell disorder revealed a rich adventitial neovascularization in the proximal intracranial part of the vessel. It is not yet known whether obstruction of the distal segments may create similar neovascularizations. Adventitial neovascularizations seen in the proximal i-ICA and i-VA may represent a focal intracranial extension of the vascular pathologies involving the extracranial segments of major cerebral arteries.

Gadolinium Enhancement of Atherosclerotic Plaque in the Middle Cerebral Artery: Relation to Symptoms and Degree of Stenosis

“…Unlike extracranial arteries, which are surrounded by solid tissue, intracranial arteries have littleto-no vasa vasorum. 24,25 This finding is consistent with the hypothesis that the vasa vasorum in the intracranial artery does not necessarily have an obligatory role in lesion development during the early stages of atherosclerosis. As atherosclerosis progresses to an advanced stage, the vasa vasorum develops in the proximal-to-distal segments.…”

Pathology of Atherosclerosis and Stenting

“…37 The existence of vasa vasorum is more common in the proximal arteries (vertebral, internal carotid, and basilar arteries) than in the distal middle cerebral and anterior cerebral arteries. 38 Moreover, vasa vasorum are found more frequently in aged patients with severe atherosclerosis and those with cerebrovascular diseases.…”

Genetic endothelial systems biology of sickle stroke risk

“…2,8 Stroke pathogenesis does not simply involve sickling in the vasa vasorum because vessels in the CoW do not have vasa vasorum. 9 Our hypothesis predicts that those children with sickle cell anemia who develop CoW disease and are therefore at-risk for ischemic stroke have inherited different polymorphisms (affecting endothelial gene expression) from each other, but polymorphisms that exert similar downstream effects on the relevant biologic systems involved in CoW disease development. Indeed, HLA linkage 10 and sib-pair analysis 11 have suggested a familial predisposition to stroke in sickle cell anemia.…”