MITOCHONDRIAL ENCEPHALOMYOPATHY, LACTIC-ACIDOSIS, STROKE-LIKE EPISODES (MELAS) - CLINICAL, RADIOLOGICAL, PATHOLOGICAL, AND GENETIC OBSERVATIONS

We reviewed 10 patients (5 males, 5 females) with mitochondrial enceph alomyopathy, lactic acidosis, and stroke-like episodes. The age of sym ptom onset ranged from 3 months to 12 years. All had lactic acidosis, multiple stroke-like events with secondary neurological deficits, radi ological changes of progressive brain infarction, and muscle biopsy sh owing ragged-red fibers. In patients with earlier onset of symptoms (< 2 yr), involvement tended to be more diffuse, with failure to thrive a nd early onset of delayed development. Patients whose symptoms appeare d later tended to have focal neurological deficits with migraine-like headache, and a rate of cognitive regression reflecting the rapidity o f disease progression. Radiological changes included multiple areas of infarction with initial predilection for parietal occipital areas, pr ogressing to generalized atrophy. Pathological findings in muscle biop sies included type 1 fiber predominance, ragged-red fibers, increased intermyofibrillar lipid deposition, and abnormal mitochondria. Four pa tients showed mitochondrial DNA tRNA mutation at position 3,243. No di fference was noted in clinical, radiological, or pathological findings in patients with and without this mutation, suggesting that multiple sites of point mutation may give rise to mitochondrial encephalomyopat hy, lactic acidosis, and stroke-like episodes.