A54-37 Unmasking Moyamoya: Hemiparesis Triggered by Normotension

Abstract Introduction Moyamoya disease is an infrequent cerebrovascular disorder (0.57 per 100,000 in the United States), characterized by progressive distal internal carotid artery stenosis and fragile collateral vessel formation, often resulting in stroke. Hypoperfusion-related symptoms are recognized, but normotension-triggered neurologic deficits requiring vasopressors are rarely reported. Description A 41-year-old male with a history of HIV and prior varicella-zoster meningitis presented with acute-onset left-sided weakness, facial droop, and dysarthria upon awakening. CT angiography revealed right M1 middle cerebral artery occlusion with moyamoya-like collaterals. Diagnostic cerebral angiography confirmed complete right M1 occlusion with robust pial collateralization (Suzuki Grade II) and mild left ICA involvement (Suzuki Grade I). In the ICU, he developed recurrent blood-pressure-dependent hemiparesis during normotension that resolved only with vasopressor-supported mean arterial pressure augmentation. Brain MRI demonstrated an acute right thalamocapsular infarct. Cardioembolic and hypercoagulable workup was unremarkable. He was transitioned to oral midodrine and fludrocortisone, with subsequent discharge for outpatient extracranial-intracranial bypass evaluation. Discussion The proposed mechanism of blood-pressure-dependent neurologic deficits in moyamoya is impaired autoregulation with limited vasodilatory reserve, resulting in pressure-dependent cerebral perfusion. In this setting, even modest MAP reductions can provoke deficits in chronically hypoperfused regions. Management focuses on individualized perfusion goals and avoidance of hypotension and hypocapnia; short-acting vasopressors may be used transiently as a bridge to definitive surgical revascularization. This abstract is funded by: None