Progressive Myoclonus Epilepsy: Distinctive MRI Changes in Cerebellar and Motor Networks

ABSTRACT Objective Progressive myoclonus epilepsy (PME) is a rare generalized epilepsy syndrome with a well‐characterized genetic basis. The brain networks that are affected to give rise to the distinctive symptoms of PME are less well understood. Methods Eleven individuals with PME with a confirmed...

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Bibliographic Details
Main Authors: Jillian M. Cameron, Remika Mito, Samuel F. Berkovic, Graeme D. Jackson
Format: Article
Language:English
Published: Wiley 2025-06-01
Series:Annals of Clinical and Translational Neurology
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Online Access:https://doi.org/10.1002/acn3.70010
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Summary:ABSTRACT Objective Progressive myoclonus epilepsy (PME) is a rare generalized epilepsy syndrome with a well‐characterized genetic basis. The brain networks that are affected to give rise to the distinctive symptoms of PME are less well understood. Methods Eleven individuals with PME with a confirmed genetic diagnosis and 22 controls were studied. MRI included diffusion acquisition using 64 directions, b = 3000 s/mm2. Fixel‐based analysis was used to identify white matter pathways with significant abnormality in structural connectivity, with subsequent tract segmentation and analysis. Region‐of‐interest and whole‐brain volumetric analysis of T1‐weighted images was performed. The relationship between structural connectivity measures and disease duration, and Unified Myoclonus Rating Scale was assessed. Results Analysis of structural connectivity revealed significantly reduced fiber density and fiber bundle cross‐section in white matter tracts in individuals with PME, with the most severe involvement of tracts within the cerebello‐thalamo‐cortical network, particularly the cerebello‐thalamic, thalamo‐cortical, cortico‐thalamic, and corticospinal tracts, as well as the splenium of the corpus callosum. By comparison with these abnormalities, cortico‐cortical association pathways were relatively preserved. There was reduced volume in the cerebellum, thalamus, brainstem, and mid‐anterior corpus callosum. Interpretation Individuals with PME have atrophy and changes in fiber tracts that predominantly affect the cerebello‐thalamic and motor systems, likely reflecting neuronal and axonal loss as part of a degenerative process. This imaging pattern is distinctive and accords well with the characteristic clinical, neuropathological, and neurophysiological features of the PMEs. The mechanism by which the PME genes affect these tracts is not yet known.
ISSN:2328-9503