Intracranial atherosclerotic stenosis (ICAS) is a common cause of stroke, especially in East and South Asia, and is significantly associated with stroke recurrence and early neurological deterioration (END) despite aggressive medical management. Minor stroke (National Institutes of Health Stroke, NIHSS score ≤ 5) patients with ICAS often has higher risk of END. The early realization of blood flow patency is closely related to the improvement of patient outcomes. Submaximal balloon angioplasty (SBA) as a safer and simpler intervention which can improve cerebral blood flow. Thus, SBA may be an effective strategy for preventing END in acute ischemic stroke patients with ICAS.

Inclusion Criteria:

1. Over 18 years of age;
2. Minor ischemic stroke within 1 week of onset (NIHSS≤5);
3. Have received the best drug treatment (dual antibody, anti-plate combined with anticoagulation), but symptoms still have measurable fluctuations or progression (NIHSS increased by at least 1 point);
4. Symptoms fluctuate to the time of receiving balloon dilation within 24 hours;
5. The etiology was considered to be severe stenosis of the responsible vessels due to intracranial arteriosclerosis (70-99% stenosis), or perforator artery disease with severe stenosis of the carrier artery (confirmed by MRA, CTA or DSA);
6. Patients with first onset or past onset without sequelae such as limb paralysis should not affect the score of this NIHSS, and mRS Score of patients with past onset should be less than 2 points;
7. Patients or family members sign informed consent.

Exclusion Criteria:

1. Patients who have developed large intracranial vessel occlusion;
2. Intracranial hemorrhagic diseases in the past 3 months: cerebral hemorrhage, subarachnoid hemorrhage, etc.;
3. Non-atherosclerotic disease-related stenosis: arterial dissection, moya-moya disease, arterioinflammatory disease, etc.
4. Clotting disorders or systemic bleeding tendency or platelets less than 100,000;
5. Complicated with serious infection or liver, kidney and other serious diseases;
6. Patients with severe inability to control hypertension (systolic blood pressure >200mmHg or diastolic blood pressure >110mmHg);
7. Women who are pregnant, have a pregnancy plan or are breastfeeding;
8. Complicated with other serious diseases, life expectancy < 6 months; Other conditions deemed inappropriate for participation in this study.