[Mitochondrial diseases. Part II -- diagnosis and detailed review].

The diagnosis of mitochondrial disease (MD) requires biochemical investigations of body fluids, particularly with respect to lactate and pyruvate elevation. Cardiological and ophtalmological examinations may also be helpful, as well as cerebral imaging. Tissue sampling, especially muscle biopsy and DNA analysis are important. Neuropathological findings consist of nonspecific spongiform lesions of gray matter, neuronal loss and sometimes demyelination with different topographic patterns. Some, more frequently occurring mitochondrial diseases and therapeutic attempts are reviewed.