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Morphological Analyses of the Arterial Supply to the Brain

The following abstract was presented as part of London Health Research Day 2016.

Research Area: Circulatory and Respiratory Health
First Author: Emily Kyle
Supervisor(s): Drs. Kem Rogers and Vladimir Hachinski

Stroke is one of the leading causes of mortality and morbidity in North America. Specifically, lacunar infarcts, which occur within deeper cortical regions of the brain, account for up to 25% of all stroke incidence. These regions of the brain are supplied by short penetrating arteries (SPAs) that arise perpendicularly from their main arterial supply, such as the lateral lenticulostriate arteries which supply part of the basal ganglia. The penetrating arteries travel only a short distance before their systolic pressure must be reduced to capillary pressure. In contrast, the long circumferential arteries (LCAs) that supply the superficial cerebral cortex have a long course and oblique branching pattern, which permits a more gradual reduction in intraluminal pressure as the capillary bed is approached. This study compares the morphological design of the short vessels and the longer circumferential vessels to determine whether their structure reflects their different vascular pressure dynamics.

The objective of this study is to quantitatively assess the morphology of the SPAs and LCAs. 

SPAs within the brainstem and mammillary bodies (inferior surface of the brain) will have a thicker tunica adventitia and a smaller luminal diameter compared to LCAs within the cortex.

Materials and Methods:
Histological sections from the cortex, mammillary bodies, and brainstem were stained with Masson’s trichrome and scanned with an Aperio ScanScope AT Turbo at 40x. Using Aperio ImageScope, four arterial measurements were obtained from an average of 40 vessels per section: thickness of the tunica adventitia; combined breadth of the tunica intima and media; luminal diameter; and the arterial luminal circumference.

The preliminary results indicate that, in general, for the same luminal diameter, SPAs at the inferior surface of the brain and adjacent to the brainstem have a thicker tunica adventitia and a thinner combined tunica intima and media as compared to the LCAs that supply the cortex. The results also indicate that, for the same luminal diameter, arteries at the inferior surface of the brain have a thicker tunica adventitia than arteries adjacent to the brainstem.

Discussion and Conclusions:
We have demonstrated a reliable quantitative method to assess cerebral arteries and have shown clear differences between the morphology of the SPAs and LCAs. This method is now being used to investigate age-related arterial changes and the relationship between vessel morphology and various diseases, including hypertension and lacunar infarcts.