Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS): adolescent onset with severe cerebral edema.

A 19-year-old woman with long-standing sensorineural deafness, bilateral cataracts and mild clumsiness, presented with acute focal edema in the left temperoparieto-occipital area which required surgical decompression as a life-saving measure. Investigation revealed a persistent lactic acidemia and evidence of many ragged red fibres in a skeletal muscle biopsy specimen, suggesting a diagnosis of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome. The patient developed two further stroke-like episodes over a short period. One sibling died at the age of 14 years with a progressive neurological illness characterised by seizures, bilateral optic atrophy, ataxia, myoclonus and progressive dementia. The diagnosis of MELAS syndrome should be considered in young people presenting with stroke-like episodes that fail to conform to a given vascular territory, particularly if they have long-standing minor neurological abnormalities or a family history of obscure early onset neurological disease. The different clinical pictures in the two affected siblings in this family suggest that MELAS syndrome is part of a spectrum of inherited mitochondrial cytopathies rather than a discrete disease entity.