ischemic penumbra

ischemic penumbra

an area peripheral to one of ischemia where metabolism is active but blood flow is diminished.
[L. paene, almost, + umbra, shadow]

ischemic penumbra

Neurology An ischemic zone in the brain at risk of infarction, which lies in a 'no-man's land' between a zone of low blood flow–< 25 ml/100 mg brain tissue/min and a zone where brain tissue is undergoing necrosis–flow–< 8 ml/100 mg/min. Cf Hemorrhagic stroke.
References in periodicals archive ?
rt-PA is a serine protease which can specifically bind fibrin to lyse the provaline-arginine junction, thus activating plasminogen, forming fibrinolytic enzyme, dissolving blood clots, promoting blood flow recovery in ischemic penumbra, saving nerve cells and promoting the recovery of nerve function in patients.15 In recent years, mild hypothermia has been recognized as an important method of neuroprotection.
[3] Studies suggest the likelihood of its neuroprotective action by reducing the levels of circulating and brain catecholamines and thus balancing the ratio between cerebral oxygen supplies, reducing excitotoxicity, and improving the perfusion in the ischemic penumbra. It reduces the levels of the glutamate responsible for cellular brain injury, especially in subarachnoid haemorrhage.
In physiological conditions, the diameter of the blood vessel is the main regulator of cerebral blood flow, while in blood vessel occlusion most of the penumbra perfusion originates from collaterals, which enables retrograde perfusion of the penetrating arterioles of the ischemic penumbra after AIS [28].
Modern imaging of the infarct core and the ischemic penumbra in acute stroke patients: CT versus MRI.
[2,13,16,18] This is particularly important on ischemic penumbra in which the level of the decline in the vascular supply was correlated with the ondulations of clinical symptoms.
Hyperglycemia disturbs collateral circulation of ischemic penumbra, increases the reperfusion injury, and has harmful effects on the outcome in stroke with major vessel occlusion via increasing blood brain barrier permeability, decreasing fibrinolytic activity, anaerobic glycolysis, and free radical production (22).
After 90 min of ischemia and 24 h of reperfusion, most neurons in the ischemic penumbra of the cerebral cortex appeared shrunken and deep stained in the IR group.
Main goal in treating ischemic stroke patients is to rescue the ischemic penumbra. The portion of hypothetical salvageable tissue is time dependent, but each patient presents a different amount of collateral blood flow, making the time window widely variable.
Endovascular treatment was indicated only in patients with a small proven ischemic deficit (defined as Alberta Stroke Program Early Computed Tomography Score [ASPECTS] [greater than or equal to] 6) (15, 17), or the presence of a salvageable tissue (ischemic penumbra) on perfusion CT (13), or of moderate-to-good collateral circulation on multiphase CT angiography (14).
Results: SWI is of guiding significance for thrombolytic therapy in stroke patients, it can predict the location and length of thrombus and ischemic penumbra. It is worthy of noting that susceptibility vessel sign (SVS) on SWI can be used to predict recanalization after thrombolytic therapy and whether it is better to implement endovascular thrombolectomy in combination or alone.
The Ischemic Penumbra, CRC Press, Boca Raton, FL, USA, 2007.
We confirmed the hypothesis that EA treatment could upregulate the protein quantities of EPO and EpoR in the ischemic penumbra after 24 h of MCAO.