See related article, pages 1751–1758. Since the ischemic penumbra was discovered and since a therapeutic window for acute ischemic stroke has been postulated, stroke experts are looking for safe and effective drugs to treat as many acute ischemic stroke patients as possible. Maturation of ischemic damage is a complex process, triggered by hypoperfusion at critical levels and spontaneously evolving toward cell death. It is a self-perpetuating process in which some critical steps (such as ion pumps failure and iNOS production) maintain and enhance the process.1 Reperfusion may reverse the ischemic cascade but, at the same time, induces a further damage. The risk/benefit ratio of reperfusion depends on the amount of penumbral salvageable tissue, that is “individual” and only partially predictable.2,3 Spontaneous reperfusion may occur, and symptoms may reverse, partially or totally, but the percentages of spontaneous reperfusion so far reported account for approximately the 24% of all stroke cases.4 A review of published articles about cerebral angiography in stroke reported that the percentage of spontaneous reperfusion …