A Multicenter Retrospective Study Of Endovascular Therapy For Acute Middle Cerebral Artery M2 Occlusive Ischemic Stroke

Background and Objectives:Stroke as a common neurological severe disease,has received widespread attention in society,due to high disability rate,mortality rate,and high incidence.According to the Global Burden of Disease Study report that stroke has become the second leading cause of death in the world,and also the leading cause of disability.Among them,ischemic stroke accounts for 85% of all stroke patients.Ischemic stroke due to insufficient perfusion of brain tissue and vessel occlusion,resulting in ischemic necrosis and apoptosis of neurocyte.Thereby,neurological deficits occur,such as paralysis,aphasia,sensory disorder,conscious disturbance,ataxia,etc.Safe,effective and rapid revascularization of occlusive vessels and restoration of cerebral tissue perfusion are the key to the treatment of ischemic stroke.Intravenous thrombolysis is the classic treatment for acute ischemic stroke.It can open the occlusion vessels within 4.5 hours to achieve the purpose of reperfusion therapy.Due to the narrow treatment time window,low rate of vascular recanalization and high risk of bleeding,it is necessary to explore a more effective and safer treatment.Endovascular treatment has been confirmed by several prospective randomized controlled trials and recommended as the preferred treatment for acute ischemic stroke since 2015.The main subjects of these randomized controlled trials were anterior circulation proximal vascular occlusion.M2 segment occlusion is not discussed.The M2 segment of the middle cerebral artery is an important branch of the middle cerebral artery.Starting from the bifurcation of the M1 segment of the middle cerebral artery,ending in the circular sulcus of insula.M2 occlusion also can lead to severe clinical symptoms,and even death.At present,there are few studies on endovascular treatment of M2 occlusive,and there is no prospective RCT study published.Therefore,the endovascular treatment of middle cerebral artery M2 occlusion remains unclear.Some studies have suggested that the M2 segment and distal vessel have small diameters,thin vessel walls,distorted shape and more variation,so there is a high risk of endovascular treatment,and endovascular treatment is not recommended.Studies have also shown that endovascular treatment of acute middle cerebral artery M2 occlusive ischemic stroke is safe and effective.Therefore,the purpose of this study was to investigate the efficacy and safety of endovascular treatment of acute middle cerebral artery M2 occlusive ischemic stroke.Methods:Retrospectively analyze the clinical data of 103 patients with acute middle cerebral artery M2 occlusive ischemic stroke admitted from 19 comprehensive stroke centers in China from September 2013 to July 2018.All patients were onset to treatment for less than 6 hours.These patients were diagnosed with acute M2 occlusion by CTA,MRA or DSA.They were divided into endovascular treatment group(EVT group,65 cases)and non-endovascular treatment group(Non-EVT group,38 cases)according to the treatment methods.Observed the baseline data of two groups.The vascular recanalization rate,48 h acute re-occlusion rate and vascular perforation rate of EVT group were observed.Compared the two groups of patients at the 90 days modified rankin scale(mRS)score,mortality rate,incidence of symptomatic intracranial hemorrhage and subarachnoid hemorrhage.Then,subgroups were divided according to age,gender,onset to treatment time,intravenous thrombolysis,TOAST stroke classification,baseline NHISS score at onset,frequency of thrombectomy and ASTIN/SIR score.MRS scores of patients in the EVT group and Non-EVT group at 90 days were observed in each subgroup.Results:1.There were no significant differences in baseline data(age,gender,hypertension,hyperlipidemia,diabetes,atrial fibrillation,TIA,history of stroke,smoking,drinking,NHISS score,ASPECT score,TOAST classification,intravenous thrombolysis,onset to treatment time,etc.)between the EVT group and the Non-EVT group(P > 0.05).2.The vascular recanalization was successful in 57 patients of EVT group.The vascular recanalization rate was 87.7%,acute reocclusion rate was 7.7%,and vascular perforation rate was 1.5% in EVT group.3.The 90-day good outcome function(mRS?2)in the EVT group and the Non-EVT group had a prognostic rate of 64.6% vs 47.4%,respectively.There was no statistically significant difference(Z=-1.704,P=0.088).The 90-day mortality rate was 12.3% vs 18.4% in the two groups,and there was also no significant difference between the two groups(Z=0.822,P=0.365).4.Symptomatic intracranial hemorrhage occurred in 8 of the 65 patients in the EVT group and 5 of the 38 patients in the Non-EVT group,with no statistically significant difference in incidence(12.3% vs 13.2%,P=1.000).The incidence of subarachnoid hemorrhage was similar in both groups(3.1% vs 2.6%,P=0.109).5.Subgroup analysis results:For the onset to treatment time <4 hours group,the endovascular treatment group was better than the non-vascular treatment group in the 90-day good functional outcome(OR=0.343,95% CI: 0.134~0.877,P=0.023).For the r-tpa thrombolytic subgroup,patients receiving endovascular therapy after intravenous thrombolysis had a better prognosis of good outcome function at 90 days(OR: 0.043,95%ci: 0.056~0.998,P=0.043).For subgroup with NHISS scores ranging from 11 to 20,EVT was more effective than Non-EVT(OR: 1.667,95% CI: 0.333 to 0.510,P = 0.002).For patients with better collateral circulation(ASTIN/SIR>2),endovascular treatment was more likely to be effective in treatment(OR: 0.241,95% CI: 0.074 to 0.780,P=0.014).For subgroup with successful the first pass thrombectomy,endovascular treatment was more effective than non-endovascular treatment(OR: 0.318,95% CI: 0.127 to 0.794,P=0.013).In the other subgroups,the effect of the two treatments on the 90-day good outcome function was not significantly different(P>0.05).Conclusions:The efficacy and safety of EVT group are similar to that of Non-EVT group in patients with acute middle cerebral artery M2 occlusive ischemic stroke.However,there is a better propensity for the EVT group in terms of effectiveness.It has a good clinical outcome and vascular recanalization rate similar to M1 segment.Furthermore endovascular treatment may be more effective for patients with short onset time,severe clinical symptoms,endovascular treatment after intravenous thrombolysis,better collateral circulation,and just one-time successful bolting.