How Healthy Is the Acutely Reperfused Ischemic Penumbra?

Abstract

Because it is the main determinant of clinical recovery, early reperfusion of the ischemic penumbra has become the mainstay of acute stroke therapy. Although early permanent recanalization can be associated with spectacular and complete recovery, some patients in fact exhibit delayed or incomplete recovery, even despite small infarcts on late structural imaging. This might result from tissue inflammation and selective neuronal death/damage, two probably inter-related cellular events well described in the animal literature, precluding full functional restoration in the salvaged penumbra. However, impact of these processes on recovery may be complex because of the interplay with ongoing plasticity and the possible promoting effect of inflammation on the latter. Preliminary results from imaging studies of inflammation and selective neuronal loss after middle cerebral artery territory stroke, using radioligands of the central benzodiazepine receptor and the activated microglia, respectively, reviewed here, suggest these phenomena also exist in man, although their relationship with acute-stage hypoperfusion and their impact on clinical recovery, if any, remain poorly understood. Furthermore, their inter-relationships in the salvaged penumbra have not been addressed. Better understanding of these potentially harmful processes might help to maximize benefits from thrombolysis, and could also have implications for patients who enjoy spontaneous recanalization.

Comparison of 10 Different Magnetic Resonance Perfusion Imaging Processing Methods in Acute Ischemic Stroke

“…Histologic evidence of damage may occur outside the T2-visible lesion. 30,31 Functional outcome is more relevant to stroke services and patients. The true final damage being greater than just the T2-visible lesion might explain why, in this study, the correlations between baseline PWI lesion and functional outcome were strongest for rMTT measures.…”

Decreased Chronic-Stage Cortical 11 C-Flumazenil Binding After Focal Ischemia-Reperfusion in Baboons

“…After clip removal, there was marked reperfusion, as expected for the eventually surviving penumbra. 2 Thus, the observed FMZ changes likely reflect subtle neuronal damage in the reperfused at-risk tissue.…”

“…1,2 Because spontaneous reperfusion can also rescue the penumbra, 3 SNL has implications beyond thrombolysis. SNL is important because it may affect functional outcome and may be preventable.…”

Neurogenic neuroprotection: Future perspectives

“…For the purposes of this review, the penumbra area has been defined as the risk zone for cellular death that is sensitive to therapeutic procedures ( Figure 1) [10][11][12][13][14][15][16][17]. There are no anatomical markers that clearly map the penumbra region, and its borders may overlap with the adjacent necrosis area.…”