We report a 47-year-old woman who developed an ischemic stroke with diplopia and dysarthria. Emergency computed tomography (CT) showed no pathological findings, and magnetic resonance (MR) showed mild ischemic-degenerative lesions. MR angiography and angiogram showed severe stenosis of both internal carotid and main intracranial arteries with plenty collateral vessels with "puff of smoke" suggesting a moyamoya disease (MMD). Brain perfusion single-photon emission CT showed global diminished perfusion in the brain lobes and a marked relative hyperperfusion in the cerebellum. However, brain 18F-fluorodeoxyglucose-positron emission tomography showed physiological metabolism in the brain cortex with only slightly relative cerebellar hypermetabolism. MMD is a well-known arterial pathology that frequently develops with only mild symptoms until the middle age. Functional neuroimaging findings indicate a mismatch between brain glucose metabolism and brain perfusion, probably due to neuronal subclinical chronic ischemia in the brain cortex with preserved viability of neurons.