The primary objective of this study is to estimate the safety of intra-arterial hypothermic magnesium sulfate infusion after endovascular thrombectomy in patients with acute ischemic stroke

Inclusion Criteria:

1. Age range of 18-80 years old (including critical value);
2. No gender restrictions;
3. The clinical diagnosis is acute ischemic stroke of the anterior circulation, and the site of acute occlusion of the responsible vessel is located in the intracranial segment of the internal carotid artery and the M1 or M2 segment of the middle cerebral artery;
4. The symptoms and signs are consistent with acute anterior circulation ischemic stroke, NIHSS≥6;
5. The time from onset to endovascular thrombectomy of acute ischemic stroke is within 24 hours;
6. Indications for endovascular thrombectomy of acute ischemic stroke: ① ASPECTS score ≥ 6 points, within 6 hours of onset; ② 6-16 hours after onset, meeting DEFUSE-3 criteria (infarct core volume < 70 mL, mismatch rate ≥ 1.8 and mismatch volume > 15 mL) or DAWN criteria (NIHSS ≥ 10 and infarct core volume < 31 mL); Or NIHSS ≥ 20 and infarct volume 31-51 mL); ③ Within 16-24 hours of onset, meet DAWN criteria (NIHSS ≥ 10 points and infarct core volume < 31mL); Or NIHSS ≥ 20 points and infarct volume 31-51 mL)
7. The mRS score before stroke is 0-1 points;
8. Written informed consent provided by the patients or their legal relatives.

Exclusion Criteria:

General exclusion criteria:

1. Clinical manifestations suggest the presence of intracranial cerebral parenchymal hemorrhage or subarachnoid hemorrhage (even if imaging results are normal);

2. During a stroke, accompanied by epilepsy, an accurate NIHSS score cannot be obtained;

3. Accompanied by coma or mental disorders, it may interfere with the assessment of neurological function;

4. History of allergy to iodinated contrast agents or history of anaphylactic shock;

5. Baseline blood glucose<50mg/dL (2.78mmol) or>400mg/dL (22.20mmol);

   *Acceptable fingertip blood glucose results

6. Baseline platelet count<50 × 10^9/L;

7. Recently (i.e. within 30 days prior to inclusion in the study), there has been a history of significant gastrointestinal or other clinically significant bleeding; Active bleeding, abnormal coagulation factors, or bleeding tendency (taking anticoagulant drugs with INR ≥ 3 or PT ≥ 3 × ULN; if the researcher believes that the subject has no coagulation dysfunction, there is no need to wait for coagulation test results to determine whether to enroll);

8. During a stroke, there may be fever or active infections that require systemic treatment (such as active pulmonary tuberculosis);

9. History of chronic heart failure with NYHA criteria>1; Uncontrolled hypertension (systolic blood pressure>180mmHg or diastolic blood pressure>105mmHg after standardized treatment), hypotension (systolic blood pressure ≤ 100mmHg after standardized treatment), unstable angina, myocardial infarction, or bypass or stent surgery within 6 months;

10. Accompanied by pulmonary diseases such as chronic obstructive pulmonary disease, tuberculosis, pneumonia, pneumothorax, atelectasis, pulmonary fibrosis, bronchopulmonary dysplasia, pleural effusion, acute respiratory distress syndrome, irregular breathing, etc;

11. Severe liver and kidney dysfunction, including but not limited to: cirrhosis, hepatic encephalopathy, ascites, renal failure or uremia (Ccr<25ml/min), hepatorenal syndrome, etc;

12. Pregnant or lactating women;

13. Patients with acute stroke within 48 hours after percutaneous cardiovascular and cerebrovascular intervention and major surgery;

14. Currently participating in interventional clinical trials and using research drugs or medical devices;

15. Participants may not be able to complete this study due to other reasons or may not be considered eligible for inclusion by the researchers;

Image exclusion criteria:

1. CTA/MRA/DSA shows excessive vessel curvature, which may hinder the delivery of interventional instruments;
2. Suspected cerebral vasculitis based on medical history and CTA/MRA/DSA;
3. Suspected aortic dissection based on medical history and CTA/MRA/DSA;
4. CTA/MRA/DSA confirmed multi vessel regional occlusion (such as bilateral anterior circulation or anterior/posterior circulation, extracranial carotid artery with intracranial tandem lesions), or clinical evidence of bilateral infarction or multi regional infarction;
5. CTA/MRA/DSA confirms moyamoya disease or moyamoya syndrome;
6. CT/MRI confirms significant effect of midline shift;
7. CT/MRI confirms the presence of intracranial tumors (excluding small meningiomas);
8. CT/MRI confirms the presence of intracranial hemorrhage.