1 1 要旨 42 34 mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes MELAS 2014 11 12 MRI L-L-Arg 1.0 g/kg 14 L-Arg 1.0 g/kg L-Arg MELAS A 34-year-old woman experienced a stroke-like episode and was diagnosed with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS). By the end of November 2014, she suffered from cognitive decline, although there had been no recurrence of strokes till then. Her symptoms progressed steadily to the

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... nt that her ability to communicate was lost and then she was hospitalized in the beginning of December 2014. On magnetic resonance imaging (MRI) high-intensity areas from the left temporal to the occipital region was shown, which stretched to the left precentral gyrus region within several days, with associated limb-kinetic apraxia. The treatment consisted of daily high-dose L-arginine of 1.0 g/kg/day for 14 days by intravenous administration. After starting the treatment, modest improvement was observed, so the dosage of L-arginine was reduced. But later she experienced the recurrence of symptoms with cortical blindness and agitation, and a right occipital lesion was also identified. So, daily high-dose L-arginine of 1.0 g/kg/day began to be used again. Her neurological symptoms gradually improved, and all the lesions that had been seen on the MR images disappeared. We confirmed from the result that clinical and radiologic reversal of stroke-like episodes in an adult MELAS patient occurred with daily L-arginine.