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August 21, 2017 E-Pearl of the Week: MELAS

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August 21, 2017

MELAS

MELAS (“Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like episodes”) is one of the most common mitochondrial disorders. The 2012 Japanese diagnostic criteria are divided into category A: seizures, headaches with vomiting, hemiplegia, cortical blindness, and acute focal lesions in neuroimaging; and category B: high plasma or cerebrospinal fluid (CSF) lactate, mitochondrial abnormalities in muscle biopsy and a MELAS-related gene mutation. For a definitive diagnosis of MELAS the patient should meet at least two category A and two category B criteria.1 Stroke-like episodes are secondary to metabolic infarcts due to defects in neuronal metabolism. They do not follow vascular territories, and they show a predilection for the parietal, temporal and occipital lobes. The affected areas have elevated lactate peaks on MR spectroscopy and diffusion restriction on MRI. More than 80% of patients have the m.3243A>G mutation in the mitochondrial tRNA gene.2 Treatment involves intravenous L-arginine infusion during the acute attack, and oral arginine interictally, which help reverse and prevent attacks respectively.2 Other supplements (coenzyme Q10, citrulline, idebenone, edaravone, multivitamins) are also used to improve mitochondrial respiratory complex function and reduce levels of reactive oxygen species. Drugs that cause mitochondrial dysfunction should be avoided, particularly valproic acid.1

References:

  1. El-Hattab AW, Adesina AM, Jones J, Scaglia F. MELAS syndrome: Clinical manifestations, pathogenesis, and treatment options. Mol Genet Metab 2015; 116: 4-12.
  2. Lorenzoni PJ, Werneck LC, Kay CS, Silvado CE, Scola RH. When should MELAS (Mitochondrial myopathy, Encephalopathy, Lactic Acidosis, and Stroke-like episodes) be the diagnosis? Arq Neuropsiquiatr 2015; 73: 959-967.

Submitted by Alfonso Sebastian López-Chiriboga, MD - Department of Neurology, Mayo Clinic.

Dr. López-Chiriboga reports no disclosures.

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