PURPOSE: Cortical dysplasia (FCD) is a frequent cause of epilepsy in childhood. Two major pathological variants are distinguished, FCD type I and II. The aim of the study was to characterize differences between FCD type I and II with respect to imaging and EEG findings, clinical and neuropsychological presentations, and surgical outcome. METHODS: Forty children with refractory epilepsy and histopathologically confirmed FCD were retrospectively analyzed. FCD type I was identified in 24 and FCD type II in 16 patients. RESULTS: Characteristic MRI abnormalities in FCD type I included subtle white matter signal changes and regional reduction of the white matter volume. Typical MRI findings in FCD type II were increased cortical thickness, transmantle sign, gray-white matter junction blurring, fluid-attenuated inversion recovery (FLAIR) and proton density (PD) gray matter signal changes as well as T1w, and PD white matter signal changes. Continuous EEG slowing was significantly more common in patients with FCD type I. Children with FCD type I presented with lower levels of intelligence and were suffering more often from maladaptive behavior and behavioral disorders. Surgical outcome was significantly worse in the FCD type I group (seizure freedom was achieved in 21% FCD type I patients and in 75% FCD type II subjects, p < 0.001). CONCLUSIONS: Clinically important differences were found in children with distinct histopathological subtypes of FCD. Due to prominent neuropsychological deficits and worse seizure outcome, treatment strategies in FCD type I are more challenging than previously reported and these children should be recognized and specifically addressed within the incoherent group of patients with malformative brain disorders.

Clinic for Neurosurgery and Neuroradiology Behandlungszentrum Vogtareuth Vogtareuth Germany

Department of Neuropathology and Neuropathological Reference Center for Epilepsy Surgery University Hospital Erlangen Erlangen Germany

Department of Pediatric Neurology Charles University 2nd Medical School Motol Hospital Prague Czech Republic

Department of Radiology Olgahospital Stuttgart Stuttgart Germany

Epilepsy Center Department of Neurology University Hospital Erlangen Erlangen Germany

Epilepsy Center for Children Neuropediatric Clinic and Clinic for Neurorehabilitation Behandlungszentrum Vogtareuth Vogtareuth Germany