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Published on: May 6, 2021
Impact of stroke co-morbidities on cortical collateral flow following ischaemic stroke
Ifechukwude J Biose1,2, Deborah Dewar1, I Mhairi Macrae1
1Stroke and Brain Imaging, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
Insights
Acute hyperglycemia and chronic hypertension impair collateral blood flow restoration after stroke. This hinders recovery and worsens stroke outcomes by affecting the brain
Area of Science:
- Neuroscience
- Cerebrovascular Research
- Stroke Pathophysiology
Background:
- Acute hyperglycemia and chronic hypertension are known to worsen stroke outcomes.
- The impact of these comorbidities on collateral perfusion, crucial for penumbral survival, remains poorly understood.
Purpose of the Study:
- To investigate the influence of acute hyperglycemia and chronic hypertension on cortical perfusion recovery following permanent middle cerebral artery occlusion (pMCAO).
- To assess the role of cortical collaterals in perfusion restoration under these comorbid conditions.
Main Methods:
- Laser-speckle contrast imaging (LSCI) was employed to measure cortical perfusion in spontaneously hypertensive stroke-prone rats (SHRSP) and normotensive Wistar rats.
- Permanent middle cerebral artery occlusion (pMCAO) was induced to model ischemic stroke.
- Cortical perfusion was monitored over 180 minutes post-occlusion in animals with and without hyperglycemia or hypertension.
Main Results:
- Following pMCAO, cortical perfusion initially decreased then gradually recovered over 3.5 hours, mediated by cortical collaterals.
- Acute hyperglycemia in normotensive rats and chronic hypertension in SHRSP attenuated this perfusion recovery.
- Inhaled nitric oxide did not affect cortical perfusion in hypertensive rats post-pMCAO.
Conclusions:
- Hyperglycemia at the time of arterial occlusion and pre-existing hypertension impair the dynamic recruitment of cortical collaterals after stroke.
- This impairment in collateral blood flow restoration may contribute to the negative impact of these comorbidities on stroke outcomes.
Abstract:
Acute hyperglycaemia and chronic hypertension worsen stroke outcome but their impact on collateral perfusion, a determinant of penumbral life span, is poorly understood. Laser-speckle contrast imaging (LSCI) was used to determine the influence of these stroke comorbidities on cortical perfusion after permanent middle cerebral artery occlusion (pMCAO) in spontaneously hypertensive stroke prone rats (SHRSP) and normotensive Wistar rats. Four independent studies were conducted. In animals without pMCAO, cortical perfusion remained stable over 180 min. Following pMCAO, cortical perfusion was markedly reduced at 30 min then gradually increased, via cortical collaterals, over the subsequent 3.5 h. In the contralateral non-ischaemic hemisphere, perfusion did not change over time. Acute hyperglycaemia (in normotensive Wistar) and chronic hypertension (SHRSP) attenuated the restoration of cortical perfusion after pMCAO. Inhaled nitric oxide did not influence cortical perfusion in SHRSP following pMCAO. Thus, hyperglycaemia at the time of arterial occlusion or pre-existing hypertension impaired the dynamic recruitment of cortical collaterals after pMCAO. The impairment of collateral recruitment may contribute to the detrimental effects these comorbidities have on stroke outcome.
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