A Multicenter, Prospective, Double-blind, Randomized Controlled Study on the Efficacy and Safety of Ischemic Preconditioning Therapy Versus Optimal Medical Therapy in Reducing the Recurrence of Ischemic Events in Symptomatic Moyamoya Disease

1. The patient is aged between 18 and 70 years old;
2. There is evidence from MRA, CTA or DSA, and the patient is professionally diagnosed with moyamoya disease or moyamoya syndrome;
3. The patient has ischemic symptoms related to moyamoya vasculopathy, including transient ischemic attack (TIA) and cerebral infarction (limb weakness, hemiplegia, paresthesia, speech disorder, etc. The symptoms may recur in the unilateral limb, or progress to bilateral attacks or alternating bilateral attacks);
4. After clinical evaluation, non-surgical treatment strategies such as drug therapy and risk factor management are planned to be adopted currently, and the patient is not planned to undergo cerebral blood flow revascularization within 6 months after randomization during screening;
5. The patient has signed the informed consent form.

Exclusion Criteria:

1. History of intracranial hemorrhage (such as subarachnoid hemorrhage, cerebral parenchymal hemorrhage and intraventricular hemorrhage) and other cerebrovascular diseases (such as intracranial aneurysm, cerebral arteriovenous malformation, arteriovenous fistula, etc.);
2. History of brain tumor, severe craniocerebral trauma, encephalitis, meningitis and other central nervous system inflammatory diseases, or other major craniocerebral diseases, any form of invasive brain treatment history and radiotherapy history;
3. Presence of severe or uncontrolled systemic diseases, or vital organ dysfunction that the investigator judges may significantly increase the subject's research risk or affect the completion of follow-up, including but not limited to severe cardiac insufficiency (ejection fraction \<50% or NYHA class III-IV cardiac function), severe liver function abnormality (such as ALT or AST > 2 times the upper limit of normal value), severe renal insufficiency (such as serum creatinine > 3 mg/dL), severe or uncontrolled respiratory diseases, severe non-cardiovascular comorbidities with expected survival time \<1 year;
4. There is a clear source of cardiogenic embolism, including rheumatic mitral or aortic valve stenosis, prosthetic valve, atrial fibrillation, atrial flutter, sick sinus syndrome, left atrial myxoma, patent foramen ovale, left ventricular mural thrombus, valve vegetation, congestive heart failure, bacterial endocarditis, or other cardiovascular diseases that affect study participation;
5. Uncontrolled severe hypertension, that is, seated systolic blood pressure >180 mmHg and/or diastolic blood pressure >110 mmHg after drug treatment;
6. Severe hemostatic disorder or severe coagulation dysfunction;
7. Contraindications to RIC treatment:

(1) Combined with upper extremity peripheral vascular disease or those judged by the investigator to be unsuitable for upper arm cuff compression, especially vascular lesions that may increase the risk of upper extremity ischemia, including known moderate to severe stenosis or occlusion of the subclavian artery, axillary artery, brachial artery, radial artery or ulnar artery, subclavian steal syndrome, and obvious symptoms of upper extremity ischemia; (2) There are local upper extremity conditions that may affect the safe implementation of RIC, including severe skin or soft tissue infection, skin breakage, unhealed wounds, recent upper extremity trauma or fracture, obvious hematoma, severe edema or lymphedema, arteriovenous fistula or hemodialysis access, PICC or other vascular access not suitable for compression, recent upper extremity deep vein thrombosis or thrombophlebitis, etc.; (3) Known history of allergy to RIC equipment or its constituent materials 8. Patients who refuse follow-up or cannot communicate due to severe mental illness; 9. Unfit for taVNS wearing due to skin breakage, infection, redness and swelling at the wearing site; 10. Pregnant and lying-in women; 11. Participate in other studies at the same period.