Cerebrovascular reserve (CVR), defined as the increase in cerebral blood flow (CBF)in response to a vasodilatory stimulus, is known to reflect the compensative capacity of the brain to maintain adequate blood flow in the face of decreased perfusion due to arterial stenosis. CVR dysfunction has been identified as an independent risk factor for ischemic stroke. Limb remote ischemic preconditioning （LRIC) has been suggested as a protective therapeutic modality against brain ischemia. So it is worth to detect whether LRIC can improve the CVR ability in ischemic cerebrovascular disease patients.

Inclusion Criteria:

- (1)Symptomatic intracranial arterial stenosis measuring >=50% by angiography or >=70% by ultrasound, CT angiography (CTA), or magnetic resonance angiography (MRA);(2)Age range 18-80 years;(3)Compared with normal brain tissue, the reduction of cerebral glucose metabolism (CGM) and/ or cerebral blood flow (CBF) in the focal area>=8%;(4)Stable vital signs, normal renal and hepatic functions; (5)No hemorrhagic tendency;(6)Subject or his or her legally authorized representative was able to provide an informed conised.

Exclusion Criteria:

-(1)Uncontrolled hypertension (defined as systolic blood pressure>=200 mmHg despite medications at enrollment); (2)Any vascular, soft tissue, or orthopedic injury (eg, superficial wounds and fractures of the arm) that contraindicated bilateral arm ischemic preconditioning;(3)Peripheral vascular disease (especially subclavian arterial and upper limb artery stenosis or occlusion); (4)Hematologic disease;(5)Severe or unstable concomitant disease;(6)Can not tolerate LRIC treatment;(7)No informed consent.