[Mitochondrial leukoencephalopathy of infancy: is it an early expression of Leigh syndrome?]

Leigh syndrome is probably the most frequent metabolic disorder in infancy and childhood. The classic form of the disease is characterized by bilateral lesions of basal ganglia and brainstem. The extensive involvement of white matter, without radiological basal ganglia abnormalities, is an unusual manifestation of the disease.

Four patients who presented the disease during the first year of life are described.

The four patients presented a stereotyped clinical picture, consisting of regression of already acquired psychomotor abilities and very prominent pyramidal signs. These clinical manifestations and results of neuroimaging studies suggested a primary leukodystrophy. Increased values of lactic and piruvic acids suggested a mitochondrial disorder. Enzymatic studies confirmed a mitochondrial respiratory chain deficiency in two patients, and a pyruvate dehydrogenase complex defect in the remaining two patients. The pathological findings in the latter two sisters were consistent with the characteristic microscopic lesions of Leigh syndrome, but with atypical distribution.

Diagnosis of Leigh syndrome must be taken into consideration in infants presenting with a leukodystrophic clinical and radiological pattern, despite the lack of basal ganglia involvement.