Introduction: Intracranial atherosclerosis is an important cause of ischemic stroke, but there are few systematic examinations of the pathology of these lesions. In the current study, we examined post-mortem specimens of middle cerebral, vertebral, and basilar arteries to characterize the severity of lesions, and to identify potential differences between anterior versus posterior intracranial vasculature.
Hypothesis: We hypothesized that intracranial atherosclerosis has distinctive features, and that there are differences between anterior and posterior circulation lesions.
Methods: We examined the intracranial vasculature of 32 randomly-chosen autopsy cases aged 45 years or older. We used routine and immunostaining of pathologic material, and characterized the pathological features and plaque components of the lesions.
Results: Atherosclerotic lesions were identified in 122/128 (95.3%) of arteries studied. Features of complicated plaques were infrequently seen: Plaque hemorrhage was encountered in 15/128 (11.7%), neovascularity in 15/128 (11.7%), lumen thrombus in 17/128 (13.3%), macrophage infiltration in 26/128 (20.3%), and calcification in 38/128 (29.7%) of arteries. Posterior circulation arteries, compared to anterior circulation, had more concentric (versus eccentric) plaques, 68.8% (44/64) vs. 28.1% (18/64) (p<0.001), and more lumen thrombi 21.9% (14/64) vs. 4.7% (3/64) (p=0.008).
Conclusions: Intracranial atherosclerotic plaques were commonly present in this population, but the lesions generally lacked features of complicated plaques. Posterior circulation lesions had some identifiable differences compared to anterior circulation lesions. Further studies are needed to determine whether these characteristics indicate a distinctive atherosclerotic phenotype for the intracranial vasculature.