This is a prospective, multicenter, randomized controlled clinical study aimed at evaluating the efficacy of butylphthalide in improving the severity of cerebral edema and prognosis in patients with acute anterior circulation large vessel occlusion after endovascular treatment.

Inclusion Criteria:

1. Age ≥18 years.
2. Time from onset to randomization within 24 hours.
3. Confirmed occlusion of the internal carotid artery or the M1 segment of the middle cerebral artery by digital subtraction angiography (DSA).
4. NIHSS score ≥10 at onset, or NIHSS score >8 at 1 hour post-procedure (for those able to cooperate with NIHSS assessment), or CT-ASPECTS score 3-7 immediately post-procedure.
5. Received endovascular treatment with successful reperfusion (mTICI ≥2b).
6. Signed informed consent form by the subject or their legally authorized representative.

Exclusion Criteria:

1. Pre-stroke modified Rankin Scale (mRS) score ≥2.
2. Immediate post-procedure CT indicating PH2 hemorrhagic transformation or subarachnoid hemorrhage.
3. Immediate post-procedure CT indicating cerebral herniation or planned decompressive craniectomy.
4. History or evidence of intracerebral hemorrhage, subarachnoid hemorrhage, arteriovenous malformation, cerebral aneurysm, or brain tumor.
5. Evidence (clinical or radiological) of concurrent infarction in the contralateral cerebral hemisphere that, in the investigator's judgment, may affect functional prognosis.
6. Clinical or radiological evidence of vertebral or basilar artery occlusion.
7. History of severe renal impairment (e.g., on dialysis) or estimated glomerular filtration rate (eGFR) <30 mL/min/1.73 m²; severe hepatic disease or alanine aminotransferase (ALT) >3× the upper limit of normal, or total bilirubin >2× the upper limit of normal.
8. Use of butylphthalide within 7 days prior to enrollment.
9. Known allergy to butylphthalide.
10. Pregnancy.
11. Breastfeeding women who do not agree (or whose legally authorized representative does not allow) to discontinue breastfeeding during the study drug administration period and for 7 days thereafter.
12. Participation in other purely observational stroke studies, or expected survival <6 months unrelated to the current stroke, or unlikely to comply with follow-up requirements.
13. Currently receiving another investigational drug with the same or similar mechanism of action as the study drug.
14. Any condition that, in the investigator's opinion, makes the subject unsuitable for participation in the study.