ISCHEMIC PENUMBRA IN STROKE: EVOLUTION, VIABILITY AND THERAPY.

Resumo

Introduction: Ischemic stroke occurs due to the interruption of cerebral blood flow, leading to the formation of a central area of irreversible necrosis and a potentially recoverable peripheral region called the ischemic penumbra. This area represents functionally compromised, but still viable, brain tissue, constituting the main target of reperfusion therapies. Under the hypothesis that the evolution of the penumbra depends on ischemia time, collateral circulation, and rapid therapeutic intervention, it becomes relevant to question how these factors det ermine tissue viability, prognosis, and therapeutic possibilities in ischemic stroke. Objective: To analyze, through a narrative literature review, the evolution, tissue viability, neuroimaging identification, and therapies currently used in the penumbra p resentation in ischemic stroke. Materials and methods: A narrative review was conducted in PubMed, considering: the period 2016-2026; The search terms used were: “Ischemic Stroke”, “Penumbra”, and “Stroke” in Health Sciences, combined with the Boolean oper ators AND and OR; studies in humans available in English; systematic reviews, narratives, meta-analyses, and observational studies. Articles outside this period, duplicates, and those without a direct correlation to ischemic penumbra were excluded. The ana lysis, of an interpretative and descriptive nature, of the data comprised the thematic axes: Conceptual and evolutionary aspects of ischemic penumbra in stroke; Diagnostic aspects by neuroimaging; and Therapeutic approaches. Results: Based on the 12 studies analyzed, it was evidenced that ischemic penumbra constitutes hypoperfused and metabolically compromised brain tissue, still viable, characterizing itself as the main therapeutic target in acute ischemic stroke. It has been observed that its evolution is dynamic and time -dependent, especially on the efficiency of collateral circulation, and can persist for more than 24 hours in selected cases, with a progressive transition from the penumbra to the ischemic core in the absence of adequate reperfusion. Furt hermore, the use of advanced neuroimaging methods, such as magnetic resonance imaging with diffusion - perfusion mismatch and perfusion computed tomography, has proven fundamental for identifying the penumbra and stratifying patients, reinforcing an approach focused on tissue viability. From a therapeutic perspective, recent studies show that patients with a significant area of penumbra benefit from reperfusion therapies, such as intravenous thrombolysis and mechanical thrombectomy, even in late windows. Fin ally, important limitations were also identified, such as the variability in the criteria for defining the penumbra and the methodological heterogeneity among studies. Conclusion: It was possible to conclude that the assessment of tissue viability associated with the time window is essential for proposing therapeutic interventions that favor the rescue of brain tissue, in order to minimize severe neurological sequelae and enable a better prognosis for ischemic stroke patients.