Advances in cerebrovascular reserve function assessment for moyamoya disease

Moyamoya disease (MMD) is a rare cerebrovascular disease characterised by gradual progressive stenosis and occlusion of the terminal internal carotid arteries, anterior cerebral arteries and proximal middle cerebral arteries bilaterally. This pathology leads to the formation of a compensatory and fragile collateral vascular network at the brain's base. With disease progression, MMD may result in ischaemic or haemorrhagic stroke. However, the lack of reliable and effective methods to assess disease progression leaves many patients at high risk of stroke without timely clinical intervention. Therefore, determining the disease course and assessing stroke risk are critical. Cerebrovascular reserve (CVR) reflects the ability of brain tissue to increase blood flow under stress. CVR evaluation assists clinicians in understanding MMD severity, guiding therapeutic decisions and determining prognosis. This narrative review analyses recent literature, highlights the advantages and disadvantages of various CVR assessment techniques, and discusses the interplay between CVR and MMD. In addition, it examines the role of CVR in evaluating disease progression and associated treatments.