Microstructural Changes in Absence Seizure Children: A Diffusion Tensor Magnetic Resonance Imaging Study

Absence seizures are a subtype of epileptic seizures clinically characterized by transient alterations in states of consciousness and by electroencephalography indicating diffuse spike-wave discharges (SWD). Conventional brain magnetic resonance imaging (MRI) is not routinely used to establish the diagnosis, but rather to rule out other diseases. The present study investigated tissue integrity in children with SWD epilepsy using diffusion tensor imaging (DTI).

Magnetic resonance imaging (MRI)-DTI was conducted in 18 patients with absence seizures and 10 control participants. Brain areas were evaluated using diffusion maps, and fractional anisotropy (FA), mean diffusivity (MD), parallel diffusivity (λ||), and perpendicular diffusivity (λ⊥) values were extracted and analyzed. Tractography at the regions of abnormal diffusion indices was then reconstructed in each group, and tract symmetry was evaluated by an index of asymmetry (AI). Statistical analyses were performed using nonparametric Mann-Whitney U tests, with p values < 0.05 indicating statistical significance.

Compared to the control group, patients with SWD epilepsy had lower FA values and higher MD values at the genu of the corpus callosum. There was also a stronger negative correlation between MD and FA values at the genu of the corpus callosum in patients than in control participants. The AI for the fiber tracts through the genu of the corpus callosum in the SWD group was significantly higher than that of the control group, indicating that tract distribution was more asymmetric in patients with epilepsy. There were no significant differences between groups in diffusion indices for other brain areas.

We observed microstructural changes in the genu of the corpus callosum, as well as reduced FA values, increased λ⊥ values, increased MD values, and asymmetric distribution of fiber tracts, indicating that DTI is more sensitive than conventional MRI to detect brain abnormalities in children with absence seizures.