Here are four things to know about the ischemic penumbra in acute cerebral infarction

Original Zhang Qunying Medical neurology channel * only for medical professionals reference reading lay a solid foundation, review the old know the new.In the acute stage of cerebral infarction, various therapeutic measures with vascular recalculation as the core are mainly to rescue the abnormal nerve cells around the infarction due to ischemic injury, but not yet dead, so as to restore them to normal and promote the recovery of nerve function.The area of nerve tissue around an infarct that can still be treated is considered an ischemic penumbra.The ischemic penumbra has become the focus of acute cerebral infarction, and its clinical evaluation and treatment have received high attention from doctors in vascular neurology and related disciplines. Therefore, the author summarized the following according to the consensus of Chinese experts on the clinical evaluation and treatment of ischemic penumbra in acute cerebral infarction 2021 edition.Q1 What are the factors influencing the dynamic changes of ischemic penumbra?Table 1Q2 What are recommended guidelines for clinical prediction and influencing factors of ischemic penumbra?The guidelines are recommended as follows: ① In the acute stage of great artery occlusive cerebral infarction, neurological loss is mild, but in the early stage of neurological deterioration, or neurological loss is severe but the imaging infarcts are small, indicating the possible existence of ischemic penumbra, and clinical recognition should be strengthened (grade III recommendation, grade C evidence).② Ischemia duration, collateral circulation, risk factors of cerebrovascular disease, concomitant diseases and stroke complications affect the dynamic changes of ischemic penumbra, which should be paid attention to and actively intervened (grade II recommendation, grade C evidence).Q3 What is recommended by specialists in clinical imaging assessment of ischemic penumbra?Recommendations: ① For patients who plan to receive intravenous thrombolysis within 4.5 h of onset, plain CT scan should be performed as soon as possible to exclude bleeding, and multi-mode imaging examination to evaluate ischemic penumbra is not recommended to delay intravenous thrombolysis time (grade I recommendation, Grade A evidence).② For patients with unknown onset or more than 4.5 h from the last normal time, MRI can be used to assess the ischemic penumbra using FLAIR/DWI “mismatch” to screen for patients who may benefit from intravenous thrombolysis (grade II recommendation, Grade B evidence).③ CTA or MRA examination should be performed for patients who plan to receive intravascular thrombectomy within 6 h of onset to clarify vascular conditions (Grade I recommendation, Grade A evidence);Based on clinical symptoms, PLAIN CT and CTA (or MRI and MRA) results, intravascular thrombectomy may be considered when the NATIONAL Institutes of Health Stroke Scale (NIHSS) ≥6 and the Alberta Stroke Project’s early CT ASPECTS (ASPECTS) ≥6, or NIHSS≥8 and DWI high-signal volume ≤25 mL.Additional imaging such as perfusion imaging is not required to evaluate the ischemic penumbra (grade I recommendation, grade B evidence).(4) For patients with onset time of 6-16 h, CBF/CBV mismatch in CT mode should be used for qualitative evaluation of ischemic penumbra;Or according to DAWN or munitions 3 research criteria: Tmax > 6 s and rCBF < 30% were used to quantitatively evaluate the isCHEMIa-penumbra, and low-perfusion volume/infarct core > 1.8, infarct core ≤70 mL and ischemia-penumbra volume ≥15 mL were used to screen patients suitable for thrombolectomy (Grade I recommendation, Grade A evidence).⑤ For patients with onset time of 16-24 h or with unknown onset time, the “mismatch” of CBF/CBV in CT mode should be used for qualitative evaluation of ischemic penumbra, and suitable patients for thrombolectomy can be screened according to DAWN study criteria (grade ⅱ recommendation, grade B evidence).(6) Ai-assisted analysis software is helpful for rapid and automatic quantitative evaluation of infarct core and ischemic penumbra volume (grade ⅱ recommendation, Grade B evidence).⑦ Assessment of collateral circulation is helpful in determining the outcome of ischemic penumbra (grade ⅱ recommendation, grade B evidence).Q4 is recommended by specialists in the treatment of ischemic penumbra?Recommendations: ① For acute cerebral infarction with onset within 4.5 h, intravenous thrombolysis or bridging intravascular thrombectomy when necessary is recommended (grade I recommendation, Grade A evidence);Intravenous thrombolytic therapy is feasible for patients whose onset time is more than 4.5 h or whose onset time is unknown, and there is a “mismatch” in multi-mode imaging evaluation (Grade II recommendation, Grade B evidence).② For acute anterior circulation large vessel occlusion cerebral infarction within 6 h of onset, intravascular thrombectomy should be performed as soon as possible if there are indications and no surgical contraindications (Grade I recommendation, Grade A evidence);Intravascular thrombectomy is feasible for patients with anterior circulation great vessel occlusion more than 6 h[6-16 h (grade I recommendation, grade A evidence), 16-24 h (grade II recommendation, grade B evidence)] or with unknown onset time (grade II recommendation, grade B evidence) and with ischemic penumbra after rigorous clinical and imaging evaluation.③ For patients who have exceeded the time window of thrombolysis or intravascular thrombolysis or unconditional recanalization therapy, early individualized use of uricline or butylphthalide to promote collateral circulation opening can save the ischemic penumbra (level II recommendation, Level B evidence).④ Proper management of blood pressure and timely antiplatelet or anticoagulant therapy can improve the perfusion of ischemic penumbra (grade I recommendation, Grade A evidence).⑤ Active control of harmful factors such as hyperglycemia and hyperthermia and various complications of acute cerebral infarction is beneficial to the protection of ischemic penumbra (grade II recommendation, Grade B evidence).⑥ The effect of neuroprotective agents on ischemic penumbra remains unclear.The protective effect of edaravone dexcamphenol on ischemic penumbra via multi-target blocking of cerebral ischemia cascade is worthy of further clinical exploration (grade II recommendation, grade B evidence).Conclusion: In conclusion, ischemic penumbra is closely related to the aggravation and recovery of neurological dysfunction. Therefore, the aim of acute cerebral infarction therapy is to rescue the ischemic penumbra, and its treatment focuses on the early opening of occluted vessels, the protection and opening of collateral circulation, and the protection of ischemic nerve tissue.Imaging techniques such as CT or MRI have become a simple and rapid way to evaluate the ischemic penumbra and guide clinical management.It is believed that in the future, with the progress of diagnosis and treatment, there will be a more rapid, accurate and effective method to evaluate and rescue the ischemic penumbra and improve the prognosis of acute cerebral infarction.[1] Chinese Medical Doctor Association Branch of Neurology cerebrovascular division.Clinical evaluation and treatment of ischemic penumbra in acute cerebral infarction: a Chinese expert consensus [J]. Chinese Journal of Neuropsychiatry, 201,47(6):12.[2]Chinese Journal of Neurology,2018,51 (9) :666-682.[3] Chinese Stroke Association Cerebral Blood flow and metabolism division.Chinese guidelines for evaluation and intervention of cerebral collateral circulation in ischemic stroke (2017) [J]. Chinese Journal of Internal Medicine,2017,56 (6) :460-471.Article: Zhang Qunying review: Li Tuming, Deputy Chief physician Responsible EditorMr Surfaces in the medical community to the published content in the audit by the accurate and reliable, but not to the published content of timing, and the referenced data (if any) the accuracy and completeness of making any commitment and guarantee, also does not undertake because the content is outdated, the referenced data may be inaccurate or incomplete, and so on and so forth any responsibility.Parties concerned are requested to check separately before adopting or using this as the basis for decision making.Original title: “About acute cerebral infarction ischemic penumbra, these 4 points to know!”

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