Why does 'ischemic penumbra' salvage become difficult during a stroke as time progresses without reperfusion?

💡 Explanation

As ischemic duration increases, glutamate-mediated excitotoxicity causes irreversible damage, because excessive glutamate receptor activation leads to calcium overload and cell death; therefore, therapeutic intervention becomes less effective, rather than ATP demand or vasogenic edema being the primary limiting factors.

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