Mitochondrial myopathy-encephalopathy-lactic acidosis-and strokelike episodes (MELAS) syndrome: CT and MR findings in seven children.

OBJECTIVE: The purpose of this study was to describe the imaging characteristics of mitochondrial myopathy-encephalopathy-lactic acidosis-and strokelike episodes (MELAS) syndrome. MATERIALS AND METHODS: Twelve CT scans and 15 MR images were retrospectively reviewed in seven patients with proven MELAS syndrome. Follow-up studies were performed in all patients, and the total follow-up period ranged from 3 months to 3 years. Images were analyzed in terms of lesion distribution, enhancement pattern, presence of mass effect or atrophy, calcification, and changes on follow-up studies. RESULTS: CT and MR imaging showed multiple cortical and subcortical infarctlike lesions, which crossed vascular boundaries, and various degrees of generalized cerebral and cerebellar atrophy. Lesions were distributed in the posterior, parietal, and occipital areas in six patients, the putamen in five, the caudate nucleus in two, the thalamus in two, the frontal lobe in two, the globus pallidus in one, and the brainstem in one. Contrast enhancement was noted in two of seven cases on MR images and in three of five cases on CT scans. In the early stage, infarctlike lesions showed swelling and mass effect. Lesions resolved with or without local tissue loss in five patients, and new lesions appeared in another part of the brain in five patients. Generalized atrophy progressed in six cases and was most severe in the posterior part of the cerebral hemispheres. CONCLUSION: Our results indicate that imaging findings of multiple migrating infarctlike lesions that are not limited to a specific vascular territory, especially in the basal ganglia and posterior part of the cerebral hemisphere in children, are diagnostic of MELAS syndrome.