Mitochondrial Leukodystrophy: an Unusual Manifestation of Leigh's Disease. A Report of Three Cases and Review of the Literature.

Leigh's disease is an inherited, progressive neurodegenerative disorder of infancy and early childhood. This metabolic disease is biochemically and genetically a heterogeneous disorder with defects involving various enzymes involved in the respiratory chain mechanism. Due to the multitude of enzyme defects known to occur in patients afflicted with Leigh's disease, this condition is known to have a variable clinical, pathological and radiological pattern of presentation. Isolated deficiency of cytochrome oxidase (COX) enzyme is one of the commonest abnormalities seen in patients afflicted by Leigh's disease. A primary white matter pattern of involvement representing a mitochondrial leukodystrophy is rare. Symmetric hyperintensities on T2WI involving the subthalamic nuclei and brainstem have been reported in patients with COX deficiency with SURF 1 mutations and are considered almost a hallmark of Leigh's disease with COX deficiency. We describe three cases of Leigh's disease with a primary white matter involvement diagnosed at our institution on the basis of clinical features, radiological appearance and laboratory findings.