L-arginine improves the symptoms of stroke-like episodes in MELAS

Based on the hypothesis that mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes ( MELAS) are caused by impaired vasodilation in an intracerebral artery, the authors evaluated the effects of administering L-arginine, a nitric oxide precursor. Patients were administered L-arginine intravenously at the acute phase or orally at the interictal phase. L-Arginine infusions significantly improved all strokelike symptoms, suggesting that oral administration within 30 minutes of a stroke significantly decreased frequency and severity of strokelike episodes.