<p>　Moyamoya disease is a rare cerebrovascular disease of unknown origin that causes stenooclusive changes in major intracranial arteries and chronic cerebral ischemia. Although no fundamental cure exists, revascularization surgery can improve cerebral ischemia. Recent studies have shown that patients with moyamoya disease suffer from central nervous system (CNS) interstitial fluidopathy. Imaging findings of CNS interstitial fluidopathy reported in this disease include enlarged perivascular spaces, white matter hyperintensity, medullary streaks, interstitial free water measured with multi-shell diffusion magnetic resonance imaging, an index of diffusivity along the perivascular spaces, choroid plexus perfusion, and volume. These changes are, at least in some parts, reversible if revascularization surgery improves the cerebral ischemia. Decreased arterial input may result in disrupted function of intramural peri-arterial drainage pathways and the glymphatic system, and thus, disrupted CSF homeostasis. Because arterial input is a driving force of waste clearance in the brain, it is reasonable to infer that disrupted CSF homeostasis under chronic cerebral ischemia induces pathological changes in Alzheimer’s disease. However, regarding this aspect serum biomarkers and positron emission tomography studies have not revealed amyloid beta accumulation in patients with moyamoya disease. Further studies are required to investigate whether CSF interstitial fluidopathy in moyamoya disease should be the treatment target for neuronal damage induced by chronic cerebral ischemia.</p>