[MELAS--mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes syndrome--two cases confirmed by biochemical and molecular investigations. Differential diagnosis of stroke causes].

Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes syndrome (MELAS) is a maternally inherited multisystem disease caused by mutations of the mitochondrial DNA. The characteristic clinical features are: encephalopathy manifesting as dementia and seizures, stroke-like episodes at young age (usually < 40), lactic acidosis and myopathy with ragged-red fibres. Other frequent manifestations include: sensorineural deafness, diabetes, hypoparathyroidism, peripheral neuropathy and cardiomyopathy. We present two patients with MELAS who were diagnosed 4 and 9 years respectively following the onset of the disease despite the characteristic clinical pictures. The differential diagnostics of inborn and acquired disorders causing stroke is included. We regard that mitochondrial diseases are still insufficiently known and are frequently misdiagnosed. The knowledge is indispensable for establishing diagnosis and accurate genetic counselling. Although there is no specific therapy for mitochondrial diseases to date, coenzyme Q and various vitamins as well as moderate degree exercise might be recommended.