RESUMO
Mitochondnal encephalomyopathies are multisysternic diseases affecting predominantly the CNS and skeletal muscLes by mitochondrial dysfunction. Mitochondrial diseases include three distinct syndromes: mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS): myoclonus epilepsy associated with ragged-red fibers (MERRF):and chronic progressive external ophthalmoplegia(CPEO). A characteristic abnormality called "ragged-red fibers" is usually seen on histochemical evaluation of muscle biopsy specimens in these diseases. The characteristic clinical presentations of MELAS are short stature, recurrent stroke like episodes, migraine-like headache, sensorineural hearmg loss, glucose intolerance and neuropathy. We now report a case of MELAS syndrome confirmed by demonstrating "ragged-red fibers" and abnormal mitochondria in muscle biopsy.