Microstructural alterations of white matter in juvenile myoclonic epilepsy

Juvenile myoclonic epilepsy (JME) is a common type of idiopathic generalized epilepsy that is characterized by myoclonic jerks of the upper limbs and generalized tonic-clonic seizures. Frontal cognitive dysfunctions and abnormal coupling of the thalamocortical system have been found in neuropsychological and neuroimaging studies. This study intended to explore white matter (WM) measurement changes in JME using MRI. Twenty-six patients with JME and 25 healthy controls (HC) were recruited for the acquisition of diffusion MRI and structural MRI data. Then, a tract-based spatial statistics approach was used to investigate the disease effects on WM microstructural diffusion characteristics. Subsequently, the associations between clinical features and characteristics of the tracts that connect the impacted regions were also evaluated. Compared with HC, JME showed an increased mean diffusivity in the anterior corpus callosum connected to the bilateral frontal lobe. Decreased axial diffusivity was observed in the body of the corpus callosum connected to the bilateral supplementary motor area as well as, in the region connecting the left thalamic radiation, the superior longitudinal fasciculus and corticospinal tract. Furthermore, the microstructural metrics of the tracts connecting these regions, especially the projection fibres that connect the cerebral cortex, subcortical regions and cerebellum, were correlated with disease duration. These findings likely reflect the alterations in WM microstructural connectivity, which may be associated with frontal cognitive and motor dysfunction in JME. In addition, the projection fibres connecting these impacted regions are progressively affected by the disease duration. Based on our findings, we propose that the cerebellum may play a potential role in the pathomechanism of JME.