Reorganization of the primary somatosensory area in epilepsy associated with focal cortical dysplasia

A 5‐year‐old boy with focal cortical dysplasia was referred to our hospital because of epileptic seizures. He showed mild weakness of the left hand without sensory disturbance. Brain MRI revealed extensive cortical dysplasia with pachygyria and microgyria around the right central sulcus. On EEG examination, interictal spikes were noted over the right fronto/centro/parietal region. A 37‐channel magnetometer revealed that the sources of the spikes were in a small, restricted region of the normal frontal lobe adjacent to the dysplastic brain. Somatosensory evoked magnetic fields indicated that the location of the current source of N20 was in the same area. Our patient shows a unique case of plasticity and reorganization of the somatosensory function due to cortical dysplasia.