Progressive encephalopathy in m.3243A > G/MT-TL1 mutation carriers: a quantitative EEG analysis

Area of Science:

• Neuroscience
• Genetics
• Mitochondrial Diseases

Background:

• The m.3243A>G/MT-TL1 mutation is linked to MELAS syndrome and milder MELAS-Spectrum Syndrome (MSS).
• Longitudinal EEG changes in individuals with this mutation are not fully understood.

Purpose of the Study:

• To systematically analyze longitudinal EEG changes in individuals with the m.3243A>G/MT-TL1 mutation.
• To investigate the impact of stroke-like episodes (SLEs) on EEG patterns.

Main Methods:

• Included adults with m.3243A>G/MT-TL1 mutation and at least two EEG recordings.
• Quantified EEG metrics: delta-theta/alpha energy ratio (ER), Higuchi fractal dimension (HD), and paroxysmal activities (AR).
• Assessed the effect of early SLEs using a linear mixed model.

Main Results:

• EEG energy ratio (ER) significantly increased over time in posterior regions.
• EEG after SLEs showed higher ER, lower HD, and an increasing AR trend.
• Quantitative EEG metrics revealed progressive disruption of posterior background rhythms.

Conclusions:

• Neurophysiological signs of progressive brain dysfunction occur independently of SLEs.
• Early SLE consequences include background slowing, reduced complexity, and increased paroxysmal abnormalities.
• Quantitative EEG analysis offers insights into MELAS and MSS progression.