Atherosclerosis in the circle of Willis: Spatial differences in composition and in distribution of plaques.
Intracranial atherosclerosis is one of the main causes of ischemic stroke. However, the characteristics of intracranial arteries and atherosclerosis have rarely been studied. Therefore, we systematically investigated atherosclerotic changes in all arteries of the Circle of Willis (CoW).



Sixty-seven CoWs obtained at autopsy from randomly chosen hospital patients (mean age, 67.3 ± 12.5 years), of which a total of 1220 segments were collected from 22 sites. Atherosclerotic plaques were classified according to the revised American Heart Association classification and were related to local vessel characteristics, such as the presence of an external and internal elastic lamina and the elastic fibre density of the media.



181 out of the 1220 segments had advanced plaques (15%), which were mainly observed in large arteries such as the internal carotid, middle cerebral, basilar and vertebral artery. Only 11 out of 1220 segments (1%) showed complicated plaques (p < 0.001). Six of these were intraplaque hemorrhages (IPH) and observed only in patients who had cardiovascular-related events (p = 0.015). The frequency of characteristics such as the external elastic lamina and a high elastin fibre density in the media was most often associated with the vertebral artery. Only 3% (n = 33) of the CoW arteries contained calcification (p < 0.001), which were mostly observed in the vertebral artery (n = 13, 12%).



Advanced atherosclerotic plaques in the CoW are relatively scarce and mainly located in the 4 large arteries, and mostly characterized by an early and stable phenotype, a low calcific burden, and a low frequency of IPH.
Academic Medical Center, Department Pathology, Cardiovascular Research, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands. Electronic address: n.p.denswil@amc.uva.nl.
Nerissa P
NP
Denswil
Academic Medical Center, Department Pathology, Cardiovascular Research, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
Allard C
AC
van der Wal
Academic Medical Center, Department Pathology, Cardiovascular Research, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
Katja
K
Ritz
Academic Medical Center, Department Pathology, Cardiovascular Research, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
Onno J
OJ
de Boer
Academic Medical Center, Department Pathology, Cardiovascular Research, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
Eleonora
E
Aronica
Academic Medical Center, Department Pathology, Cardiovascular Research, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
Dirk
D
Troost
Academic Medical Center, Department Pathology, Cardiovascular Research, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands. Electronic address: m.j.daemen@amc.uva.nl.
Mat J A P
MJAP
Daemen
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001158:Arteries / Q000503:physiopathology; D050197:Atherosclerosis / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D001344:Autopsy; D002941:Circle of Willis / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D017540:Tunica Media / Q000473:pathology
Calcification; Circle of Willis; External elastic lamina; Internal elastic lamina; Intracranial atherosclerosis; Intraplaque haemorrhage; Plaque shape