Correlation of Adventitial Vasa Vasorum with Intracranial Atherosclerosis: A Postmortem Study

Abstract

Background and purpose: Vasa vasorum (VV) have been believed to be rare or non-existent in small-caliber intracranial arteries. In a series of human cerebral artery specimens, we identified and examined the distribution of VV in association with co-existing intracranial atherosclerosis.

Methods: We obtained cerebral artery specimens from 32 consecutive autopsies of subjects aged 45 years or above. We scrutinized middle cerebral artery (MCA), vertebral artery (VA), and basilar artery (BA) for the presence of adventitial VV. We described the distribution of VV, and the characteristics of co-existing atherosclerotic lesions.

Results: Among 157 intracranial arteries, adventitial VV were present in 74 of the 157 specimens (47%), involving MCA (n=13, 18%), BA (n=14, 19%), and VA (n=47, 64%). Although qualitatively these 74 adventitial VV distributed similarly in arteries with or without atherosclerotic lesions (disease-free arteries n=4/8; arteries of pre-atherosclerosis n=17/42; and arteries of progressive atherosclerosis n=53/107), the presence of adventitial VV in intracranial VA was associated with a heavier plaque load (1.72±1.66 mm2 vs. 0.40±0.32 mm2, P<0.001), severer luminal stenosis (25%±21% vs. 12%±9%, P=0.002), higher rate of concentric lesions (79% vs. 36%, P=0.002), and denser intraplaque calcification (44% vs. 0%, P=0.003). Histologically, intracranial VA with VV had a larger diameter (3.40±0.79 mm vs. 2.34±0.58 mm, P<0.001), thicker arterial wall (0.31±0.13 mm vs. 0.23±0.06 mm, P=0.002), and a larger intima-media (0.19±0.09 mm vs. 0.13± 0.04 mm, P=0.003) than VA without VV.

Conclusion: s Our study demonstrated the distribution of adventitial VV within brain vasculature and association between vertebral VV and progressive atherosclerotic lesions with a heavier plaque load and denser intraplaque calcification.

Keywords: Angiogenesis; Atherosclerosis; Vasa vasorum.

Figure 1.

Vasa vasorum in adventitia of cerebral arteries (arrows). (A) Middle cerebral artery (H&E stain). (B) Basilar artery (H&E stain). (C) Vertebral artery (H&E stain). (D) Immunochemical staining for von Willebrand factor revealed multiple vasa vasorum (short arrows).

Figure 2.

Plaque composition in intracranial arteries. (A) Intraplaque hemorrhage (asterisks) (H&E stain). (B) Calcification (arrowheads) (H&E stain). (C) Macrophage infiltration (long arrows) (CD68 antibodies staining). (D) Lumen thrombi (asterisk) (H&E stain).