Suspect Fabry disease in young individuals with posterior circulation stroke and few traditional risk factors, especially with renal or cardiac involvement. In sickle cell disease, chronic transfusions targeting hemoglobin S below 30% significantly reduce stroke risk in high-risk individuals identified by transcranial Doppler. In MELAS, avoid valproic acid and statins. Moyamoya management may include extracranial-intracranial bypass surgery to improve cerebral perfusion.

Enzyme replacement therapy for Fabry disease helps systemic symptoms; its impact on stroke risk reduction remains uncertain.Suspect Fabry disease in young individuals with posterior circulation stroke, few traditional risk factors, and renal or cardiac involvement.Sickle cell stroke mechanism: non-atherosclerotic large vessel disease with smooth muscle proliferation causing progressive arterial narrowing.Approximately 25% of sickle cell cases will have a stroke; ischemic strokes predominate in children, hemorrhagic in adults.Transcranial Doppler identifies high-risk sickle cell cases; chronic transfusions targeting hemoglobin S below 30% significantly reduce stroke risk.MELAS: stroke-like episodes before age 40, seizures, migraines, muscle weakness, hearing loss, diabetes, short stature.MELAS MRI: cortical lesions not conforming to vascular boundaries.MELAS inheritance: mitochondrial (maternal transmission only).MELAS treatment: supportive metabolic therapy; avoid valproic acid and statins.MELAS prognosis: progressive neurological decline and shortened life expectancy.Moyamoya disease: idiopathic; Moyamoya syndrome: secondary to an underlying condition; both appear identical on angiography.Moyamoya imaging: watershed infarcts and collateral vessel formation.