MRI FINDINGS OF MITOCHONDRIAL DISEASES IN INFANTS AND CHILDREN

The relationship of mitochondrial dysfunction to human diseases has been reported extensively over the past century. Compared to the former, the MRI findings of mitochondrial diseases are less mentioned. To know their neuroimaging findings might provide an alternative method to suspect the mitochondrial diseases.

From 1983 to December 2005, we collected 50 cases, 29 male and 21 female, aged from 3 months to 14 years. The diagnosis of mitochondrial diseases was made by clinical manifestations together with abnormal muscle mitochondrial morphologies by histochemical stains and electron microscopic examination,±oral glucose lactate stimulation test and mitochondrial gene determination. Those patients included 14 Leigh syndrome, 2 Kearns-Sayre syndrome, 3 mitochondrial encephalopathy lactic acidosis stroke-like episode, 1 myoclonic epilepsy with ragged red fibers, 1 fatal infantile mitochondrial myopathy, 3 fatty acid oxidation defects, 4 mitochondrial cardiomyopathy±myopathy, 1 Leber hereditary optic neuropathy, 1 mitochondrial neuropathy gastrointestinal encephalopathy, 1 dystonia deafness syndrome, 1 chronic progressive external ophthalmoplegia, 1 Pearson syndrome, 17 unclassified syndromes. Among them, five cases had not done brain MRI.

In our series, 8 out of 45 cases (17.78%) showed normal result, 7 out of 45 cases (15.56%) showed nonspecific findings in terms of cortical atrophy, ventriculomegaly, or generalized brain atrophy, 16 cases showed abnormal signals over the basal ganglion, 13 cases showed abnormal signals over the brainstem, 4 cases showed abnormal signals over the cerebellum, 13 cases showed abnormal signals over the cortical neurons, 5 cases showed abnormal white matter, and 3 cases showed remarkable infarction.

In our experience, mitochondrial diseases in infants and children had diverse brain MRI findings. Mitochondrial diseases should be included in the differential diagnosis when brain MRI showed the lesions over the brainstem, basal ganglion, or white matter. Subtle changes over the brainstem, especially dorsal aspect, were one of significant findings in the mitochondrial diseases of young children.