[A case of mitochondrial encephalomyopathy characterized by repeated stroke-like episodes]

We reported a case of mitochondrial encephalomyopathy with repeated stroke-like episodes. A 33-year-old single male was admitted to our hospital because of stroke-like episodes with visual field defect, hemiplegia and convulsion repeated seven times for the past seven years. There were no abnormalities on the physical examination. He was hallucinative and perseverative and had mental deficiency. Muscle weakness and atrophy were not prominent, and generalized hyporeflexia were present without pathological reflexes. Myoclonus was not observed. Serum CK and blood gas analysis were normal (pH 7.398). Although blood levels of lactate and pyruvate were almost within normal limit, lactate was elevated by 20WATT-15 minutes exercises. On the contrary, the CSF levels of lactate and pyruvate were elevated markedly. CT of the brain revealed the presence of the low density areas in the right occipital and the left frontal lobes. Cranial 4 vessels studies were unremarkable. EEG showed the diffuse slowness with spike and wave complex. CT of the muscles were normal. A specimen obtained from the left biceps brachii muscle showed ragged-red fibers without obvious myogenic or neurogenic changes, and accumulations of abnormal mitochondria with paracrystalline inclusion bodies were observed by electron microscopy. However, mitochondrial abnormalities were not seen in the vessel walls in the biopsied muscle. Activities of complex I + III, II + III, IV in mitochondria were normal. Clinical features of this case were consistent with MELAS. However, this case showed no muscle weakness, short stature and lactic acidosis which characterize MELAS, and the onset of this case was later than those cases that were reported before.