Abstract: To explore the clinical features and neuro-imaging features in patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes. MethodsThe clinical manifestation and neuroimaging features of CT, MRI, MRA and MRS in 28 patients who were confirmed with MELAS syndrome by muscle biopsy were analyzed. ResultsThe clinical manifestations were migraine-like headache, seizures audiovisual deficit, strokes, cognitive regression and muscle weakness. Basal ganglia calcifications and low density lesions in the strokelike area were found by CT. Unilateral or bilateral multifocal lesions which had T1 and T2 prolongation with widening ventricles and cerebral atrophy were found by MRI, and they had no definite vascular territories but tended to fluctuate. The temporal and occipital lobes were most often involved and parietal and frontal lobes were secondary. Other parts such as thalami cerebellum and hippocampus can also be involved in which the cerebellum was most often. By MRS, a significant increase of Lac and a decrease of NAA were found, which was more significant in the centre area of the lesion than in the surrounding area. ConclusionMELAS syndrome can be diagnosed and differentially diagnosed based on features of clinical manifestations and neuroimaging, also it can be certified by muscle biopsies.

Key words: Mitochondrial myopathy, Encephalopathy, Lactic acidosis and strokelike episodes, Magnetic resonance imaging, Tomography, X-ray computed