Late-Onset Moyamoya Disease Presenting With Acute Hemiparesis in a 77-Year-Old Patient: A Case Report.

Moyamoya is a progressive cerebrovascular condition leading to narrowing of the distal internal carotid artery (ICA) and its branches with subsequent development of abnormal collateral vessels around the ischemic brain area. Moyamoya disease is mostly encountered in children and young adults. It is rare in older patients with acute ischemic stroke and requires maintaining a broad differential diagnosis despite the presence of a rare cerebrovascular condition. A 77-year-old woman presented with left-sided weakness outside the thrombolysis window. Imaging revealed moyamoya vasculopathy and an acute right pontine infarct likely embolic in origin, while echocardiography showed an intra-atrial shunt. She was managed with dual antiplatelet therapy and supportive care before discharge to rehabilitation. Moyamoya disease in elderly patients is very rare and may represent a slowly progressing, long-standing process, where opportunities to diagnose it at an earlier age were missed. Secondary causes of moyamoya, including autoimmune disease and atherosclerotic arteriopathy, which is more prevalent in elderly patients, have to be considered. Appropriate choice of imaging modalities in acute ischemic stroke may help to narrow the differential diagnosis and influence further therapeutic approaches.