RESUMO
MELAS syndrome is a rare but distinct clinical entity belonging to a group of mitochondrial encephalomyopathies characterized by the tetrad of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes. We experienced a case of MELAS syndrome in an 8 year-old boy who showed headache, pain of the eyeball, vomiting, stroke-like episodes such as visual disturbance and dysarthria, myoclonic seizure, confusion, and walking disturbance. His serum lactate level was elevated up to 48 mg/dl. MRI findings showed high signal intensities T2-weighted image and low signal intensities in T1-weighted image in the right thalamus and parietooccipital lobe and bilateral symmetric high signal intensity in T1-dweighted image in the basal ganglia. We have seen the dispersed ragged-red fibers with modified Gomori trichrome staining on light microscope, and abundant and dysmorphic mitochondria on electon microscope in the specimen of muscle biopsy. esis of SLE.