Thread by @DharSaty

Ischemic penumbra:
The part of an Ac ischemic stroke that is at risk of progressing to infarction but is still salvageable if reperfused. Located around an infarct core which represents the tissue which has already infarcted or is going to infarct regardless of reperfusion.
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In this small cohort, the penumbra system was able to revascularize the site of primary occlusion in all of the treated subjects enrolled into the study, resulting in a revascularization rate of 100%.
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ajnr.org/content/29/7/1…

Saving the penumbra is the goal of acute ischaemic stroke therapy. Reperfusing the brain before infarct growth is completed will salvage the residual penumbra and reduce final infarct size.

academic.oup.com/brain/article/…

Normal perfusion 60-70 mL/100 g of brain tissue/minute, and when flow is ⬇️ to 25 mL/100 g/min, aerobic metabolism cannot be maintained & loss of function occurs. Prolonged ischemia ➡️ stereotypical series of biochemical events ➡️ cell death
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ncbi.nlm.nih.gov/pmc/articles/P…

On MRI, comparison of PWI & DWI better predictor of ischemic penumbral tissue vs conventional T1 and T2 images. It was reported that PWI within 6 h of stroke onset had a sensitivity of 95% & a specificity of 100% in detecting the salvageable tissue.
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journals.sagepub.com/doi/10.1177/17…

Imaging parameters (especially infarct core volume) were better predictors of good or bad clinical outcome following thrombolytic treatment than time to treatment, & that CTP improves the identification of patients who benefit from tPA from those who are less likely to.
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Computerized tomography perfusion may be able to predict treatable ischemic penumbra and the risk of Hemorrhagic transformation after Mechanical thrombectomy in patients with Acute ischemic stroke.
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jnis.bmj.com/content/10/3/2…

The dynamic nature of ischemic penumbra implicates that infarct core eventually expands into penumbra over time without reperfusion, dictating relative short therapeutic windows and limiting the impact of current reperfusion intervention.
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experts.unthsc.edu/en/publication…