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Analysis of acute stroke-like lesions in MELAS: Distribution, potential boundaries and spreading pattern

Huada Tang1, Junyu Liu1, Xiying Cai1

  • 1Department of Neurology, Peking University First Hospital, 8 Xishiku Street, Xicheng District, Beijing, 100034, China.

Neuroimage. Reports
|July 2, 2026
PubMed
Abstract

Insights

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) stroke-like lesions (SLLs) spread freely within cortical regions but are restricted between them. Synaptic density influences lesion spread in MELAS.

Area of Science:

  • Neuroimaging
  • Neurology
  • Genetics

Background:

  • Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) is characterized by reversible cortical edema during acute phases.
  • The underlying mechanisms of cortical lesions in MELAS are not fully understood.
  • Analyzing MRI findings can offer insights into MELAS lesion pathogenesis.

Purpose of the Study:

  • To investigate the spatial distribution and spreading patterns of stroke-like lesions (SLLs) in MELAS.
  • To explore the relationship between synaptic density and SLLs in MELAS patients.
  • To elucidate the mechanisms of cortical lesion development in MELAS.

Main Methods:

  • Retrospective analysis of 61 MRI scans from 55 MELAS patients (2013-2024).
  • High-resolution cortical segmentation for spatial distribution analysis of SLLs.
  • Non-negative independent component analysis (nnICA) to identify SLL components.
  • Spearman's rho test for correlation between synaptic density and lesion load.
  • Diffusion model to analyze SLL spreading behavior.

Main Results:

  • Peak SLL involvement frequency observed in the left temporo-occipital lobe; no hemispheric bias in distribution.
  • Identified 8 independent cortical SLL components.
  • Positive correlation between the probability map and synaptic density map (Spearman's rho = 0.32, p < 0.001).
  • Directed-Effect Coefficient showed a proportional relationship with the Dilation Coefficient (r = 0.76).

Conclusions:

  • MELAS SLLs demonstrate free intra-regional and restricted inter-regional spreading patterns on the cortex.
  • Identified components suggest potential boundaries influencing lesion spread.
  • Lesion spreading is impeded in cortical areas with lower synaptic density.
Keywords:
MELAS syndrome/complications/∗diagnosis/∗physiopathologyMagnetic resonance imagingNon-negative independent component analysis/nnICASpreading patternStroke-like lesions

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