[l-arginine efficiency in MELAS syndrome. A case report]

Mitochondrial encephalomyopathy lactic acidosis and stoke-like episodes (MELAS) is a rare neurodegenerative disease caused by mutations of mitochondrial DNA.

We report the case of a 12-year-old child with MELAS syndrome who presented with recurrent migraine-like headache and sudden blindness suggesting stroke-like episodes. Furthermore, he developed progressive muscular impairment with bilateral hearing loss. Serum lactate and pyruvate levels were elevated and the muscle biopsy showed an aspect of red-ragged fibers with Gomori trichrome. Brain imaging showed calcifications of basal ganglia on the CT scan and a parieto-occipital high signal on diffusion-weighted MRI. A genetic analysis was not performed but the presence of hearing loss in the patient's mother was suggestive of maternal transmission. Stroke-like episodes in the form of migraine-like headache and blindness were the patient's major complaint and did not improve despite analgesic drugs. After oral administration of l-arginine at the dose of 0.4mg/kg per day, stroke-like symptoms totally and rapidly disappeared.

The efficiency of l-arginine in stroke-like episodes was initially reported then confirmed in a controlled study. The pathophysiology of stoke-like episodes and the mechanisms underlying the action of l-arginine are discussed.