Linear cortical cystic lesions: Characteristic MR findings in MELAS patients.

Abstract Background Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) is a progressive neurodegenerative disorder with stroke-like lesions. The common MRI findings are gyral swelling and high signal intensity on T2WI/FLAIR images crossing the vascular territories. We have observed a linear cystic lesion and a laminar necrosis in the affected cortices of MELAS patients. Herein, we evaluated these cortical MRI findings in each subtype of mitochondrial disease. Patients and methods We retrospectively reviewed the MRI findings of 71 consecutive patients with clinically and genetically confirmed mitochondrial diseases. The cortical cystic lesions and laminar necrotic lesions were evaluated on T1, T2, and FLAIR images in each subtype of mitochondrial disease, as were their clinical and other imaging characteristics. Results The cortical cystic lesion was observed in 21 of the 71 patients (29.6%) with mitochondrial diseases. Laminar necrosis was detected in only three patients (4.2%). MELAS was the most frequent subtype with cortical cystic lesions, accounting for 81.0%, and all showed the linear pattern except for one patient whose pattern was beaded-like. Conclusion A cortical linear cystic lesion was a common MRI finding in our series of patients with mitochondrial disease, especially in those with MELAS, but laminar necrosis was not. These findings can help differentiate MELAS from infarction.