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Ischemic cortical lesions after permanent occlusion of individual middle cerebral artery branches in rats
1Department of Neurosurgery, New York University Medical Center, New York 10016.
Abstract:
Our study describes the anatomy of the middle cerebral artery (MCA) in 65 Sprague-Dawley rats and the spatial distribution of ischemic cortical lesions caused by occluding major MCA branches. The rats characteristically had at least two major MCA branches, frontal and parietal. Many rats had additional branches supplying the pyriform and temporal cortexes. Permanent occlusion of the frontal or parietal branches combined with 30 minutes of bilateral carotid artery occlusion produced visible Evans blue dye uptake by ischemic cortical areas after 24 hours. No lesions distal to the occlusion were apparent in 38% and 43% of rats with frontal and parietal branch occlusions, respectively; small lesions contiguous with the occlusion site were observed in 38% and 32% of the rats. Only 6% of the frontal and 7% of the parietal branch occlusions produced isolated distal infarcts as expected if these branches were end-arteries. Blood flow was reversed in arteries distal to the occlusion. We conclude that extensive collateral connections of the frontal and parietal MCA branches with other arterial systems protect the anterior and posterior cortical regions. In contrast, occlusions of the pyriform branch of the MCA invariably caused infarcts in the frontopyriform region. In about one third of the rats, frontal or parietal branch occlusions produced lesions involving much of the proximal MCA territory; the frontopyriform region was most consistently affected. Combined, these data suggest that the pyriform MCA branch is an end-artery and that the cortical region it supplies is prone to ischemic damage resulting from any reduction of blood flow through the main MCA trunk.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
The middle cerebral artery (MCA) in rats shows extensive collaterals protecting cortical regions, except for the pyriform branch which acts as an end-artery, leading to consistent ischemic damage in its territory.
Area of Science:
- Neuroscience
- Vascular Anatomy
- Cerebrovascular Research
Background:
- The middle cerebral artery (MCA) is a major cerebral vessel supplying the brain.
- Understanding MCA branching patterns and collateral circulation is crucial for stroke research.
Purpose of the Study:
- To investigate the anatomical variations of the MCA in Sprague-Dawley rats.
- To determine the susceptibility of different cortical regions to ischemia following MCA branch occlusion.
- To assess the role of collateral circulation in protecting against MCA-induced stroke.
Main Methods:
- Anatomical study of the MCA in 65 Sprague-Dawley rats.
- Occlusion of major MCA branches (frontal, parietal, pyriform).
- Combined with transient bilateral carotid artery occlusion.
- Assessment of ischemic cortical lesions using Evans blue dye uptake.
Main Results:
- Rats typically had frontal and parietal MCA branches; some had pyriform and temporal branches.
- Occluding frontal or parietal branches showed limited distal lesions due to collateral circulation.
- Occlusion of the pyriform MCA branch consistently resulted in frontopyriform infarcts, suggesting it is an end-artery.
- Blood flow reversal was observed distal to occluded arteries.
Conclusions:
- Extensive collateral connections of frontal and parietal MCA branches protect anterior and posterior cortical regions.
- The pyriform MCA branch functions as an end-artery, making its territory vulnerable to ischemia.
- Cerebral blood flow reduction affecting the main MCA trunk poses a significant risk to the frontopyriform region.