LA NEURORADIOLOGIA DELLE MALATTIE MITOCONDRIALI

MR and CT scans of the brain performed in 45 patients with various mitochondrial disorders were reviewed. In Leigh's disease, brainstem abnormalities were more common than putaminal lesions; they were found mainly in the medulla oblongata, in the pontine tegmentum, in the periaqueductal area and in the deep white matter of the cerebellum also involving the dentate nuclei. Lesions in the subthalamic nuclei were characteristic of COX deficiency. In MELAS, the first lesions usually involved the posterior regions of the cerebral hemispheres. Fading of the abnormalities was sometimes observed, but, with repeated stroke-like episodes, lesions also occurred in the cerebellum, basal ganglia, fronto-parietal cortex, with development of severe atrophy. Calcifications in the basal ganglia and cerebellar atrophy may precede the onset of stroke-like episodes. Basal ganglia calcifications may also be found in MERRF and Kearns-Sayre syndrome. In Kearns-Sayre syndrome, abnormalities in the subcortical white matter of the cerebral hemispheres and in basal ganglia, thalami, and dorsal upper brainstem may be seen. Abnormalities observed in fatty acids beta-oxidation deficiency and in Leber's optic atrophy are also described. In chronic progressive external ophthalmoplegia, minimal cerebellar atrophy may be present, but in this disorder MR scan of the brain is usually normal. Cases not classifiable in the most characteristic mitochondrial encephalopathies may be observed, with various MRI abnormal findings. The MRI abnormalities observed may often suggest the diagnosis of mitochondrial disorder and, in the appropriate clinical setting, may even suggest a specific syndrome.