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Updated: Jun 27, 2026
Modeling Mitochondrial Disease Using Brain Organoids: A Focus on Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like Episodes
Published on: October 10, 2025
Serial diffusion imaging in a case of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes
Charalampos Tzoulis1, Laurence A Bindoff
1Department of Neurology, Haukeland University Hospital, Bergen, Norway. chtzoulis@yahoo.com
Background And Purpose:
Most diffusion MRI studies of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episode stroke-like lesions report high- or normal-apparent diffusion coefficient, and this has been used to differentiate stroke-like lesion from ischemic stroke. There are, however, 3 recent reports of restricted diffusion in the acute phase of the stroke-like lesions. The purpose of our study was to investigate this apparent paradox.
Methods:
We performed 9 serial MRI covering 2 stroke-like episodes in a 36-year-old man with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episode caused by the common mitochondrial DNA mutation 3243A>G.
Results:
We found clear evidence of initial restricted diffusion in the stroke-like lesions, which gradually evolved to high-apparent diffusion coefficient as lesions aged. Evolution was, however, asynchronous with both high- and low-apparent diffusion coefficients temporally coexisting.
Conclusions:
Our findings suggest that cytotoxic edema does occur early in the course of a stroke-like lesions and that its presence or, conversely, the absence of vasogenic edema, should not weaken the possibility of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episode in favor of ischemic stroke.
Insights
Stroke-like lesions in mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episode (MELAS) initially show restricted diffusion, contrary to prior beliefs. This finding is crucial for accurate diagnosis, differentiating MELAS from ischemic stroke.
Area of Science:
- Neuroimaging
- Neurology
- Mitochondrial Diseases
Background:
- Diffusion MRI is key for differentiating MELAS stroke-like lesions from ischemic stroke, typically showing high or normal apparent diffusion coefficients.
- Recent studies report restricted diffusion in acute MELAS stroke-like lesions, creating a diagnostic paradox.
Observation:
- Serial MRI was performed on a patient with MELAS due to the 3243A>G mitochondrial DNA mutation during two stroke-like episodes.
- The study tracked the evolution of diffusion characteristics within the stroke-like lesions over time.
Findings:
- Initial restricted diffusion was observed in acute MELAS stroke-like lesions.
- Lesions evolved to show high apparent diffusion coefficients as they aged.
- Both restricted and high apparent diffusion coefficients were observed concurrently during the evolution of lesions.
Implications:
- Cytotoxic edema occurs in the early stages of MELAS stroke-like lesions.
- The presence of restricted diffusion does not exclude MELAS and should be considered in differential diagnosis with ischemic stroke.
