Progressive Changes in Brain Morphology in People With Idiopathic Generalized Epilepsy

Idiopathic generalized epilepsy (IGE) is typically responsive to treatment, yet some people remain poorly controlled despite multiple antiseizure medication trials. Whether this subgroup shows progressive structural brain changes remains uncertain. We aimed to investigate whether people with poorly controlled chronic IGE exhibit progressive morphological brain alterations and how these differ from those in early-stage IGE.

This longitudinal case-control neuroimaging study included 2 cohorts: an early-stage IGE group from West China Hospital (Chengdu, China) and a chronic IGE group from the National Hospital for Neurology and Neurosurgery (London, United Kingdom). Participants had a history of generalized seizures and no focal pathology. Matched healthy controls were drawn from 3 public imaging data sets. Participants underwent 2 high-resolution T1-weighted MRI scans at least 12 months apart. Cortical thickness and hippocampal and subcortical volumes were measured on paired scans. Longitudinal changes were assessed using linear mixed-effects models, correcting for age and interscan interval. Structural covariance analysis was conducted to examine inter-regional relationships over time, focusing on thalamo-cortical coupling.

Forty-two people with early-stage IGE and 67 with chronic IGE were recruited from 2 separate epilepsy centers, and 109 matched controls were included. The early-stage IGE group showed progressive atrophy limited to the left putamen. Chronic IGE was associated with widespread cortical thinning, primarily in frontal and temporal regions, and thickening in posterior and occipital areas. Subcortical atrophy involves the putamen, thalamus, and pallidum. People with ongoing generalized tonic-clonic seizures showed thickening in the precentral gyrus and additional thinning in the frontal cortex and precuneus. Photosensitive IGE was associated with thickening in the lingual gyrus and occipital cortex. Valproate use was associated with attenuated structural changes in motor, visual, and subcortical regions. Increased structural covariance was observed between the left thalamus and left lingual gyrus in chronic IGE.

Chronic IGE, particularly with persistent generalized tonic-clonic seizures or photosensitivity, is associated with more extensive progressive brain changes compared with matched controls. Valproate may have a protective association with these structural changes, although further validation is needed. Longitudinal MRI may help monitor disease progression and treatment effects in poorly controlled IGE.