The utility of diffusion tensor imaging tractography for post-operative evaluation of a patient with hemispherotomy performed for intractable epilepsy

Hemispherotomy is an effective treatment for patients with severe epilepsy caused by hemispheric abnormalities such as hemimegalencephaly or other dysplastic malformations. Here, we report a 5-year-old boy who experienced right-side hemiconvulsion due to left hemispheric cortical dysplasia. He presented with mild right hemiparesis that had been present since seizure onset. Ictal electroencephalogram obtained during the hemiconvulsion showed localized epileptic discharges in the left hemisphere. He underwent a left peri-insular hemispherotomy. Three months after surgery, clonic convulsions returned in the left leg and EEG-video monitoring showed localized epileptic discharges in the frontal region. Magnetic resonance images showed that the genu of corpus callosum was unsectioned and diffusion tensor imaging tractography confirmed the presence of callosal fibers in the genu of the corpus callosum. Clonic convulsion disappeared after additional section of the corpus callosum. Further studies are warranted to determine the utility of diffusion tensor imaging tractography on the assessment of subcortical fibers following disconnective epilepsy surgery.