Moyamoya Disease

Moyamoya disease is a progressive cerebrovascular disorder characterized by bilateral stenosis and eventual occlusion of the terminal internal carotid arteries and their proximal branches (anterior and middle cerebral arteries). The stenosis results from fibrocellular intimal thickening (smooth muscle cell proliferation, not atherosclerosis) that gradually narrows the vessel lumen. In response to progressive ischemia, a fragile network of collateral blood vessels develops at the base of the brain, producing the characteristic 'puff of smoke' (moyamoya in Japanese) appearance on cerebral angiography. These collateral vessels are thin-walled and prone to rupture, causing hemorrhagic stroke, while the stenotic main arteries cause ischemic symptoms. Children typically present with ischemic strokes or transient ischemic attacks (hemiparesis, speech difficulty, often triggered by hyperventilation or crying which causes cerebral vasoconstriction from hypocapnia), while adults more commonly present with hemorrhagic stroke. The nurse performs serial neurological assessments, monitors for ischemic and hemorrhagic stroke symptoms, avoids hyperventilation in at-risk patients (prevents hypocapnia-induced vasoconstriction), manages blood pressure carefully (avoid hypotension which worsens ischemia, avoid hypertension which risks hemorrhage), maintains adequate hydration, and provides pre- and post-operative care for revascularization surgery...