[Focal cortical dysplasia at the primary somatosensory cortex could manifest both intractable partial epilepsy and cortical reflex myoclonus].

We report a 31-year-old patient who suffered from the left foot motor seizure since 6 years of age. In addition to spontaneous seizures, the seizures tended to be triggered by somatosensory stimulus to the left foot. Recently, he developed irregular myoclonic jerks of the left foot. Neurologically, he had mild impairment of fine movements of the left foot, but otherwise no weakness or sensory disturbance was noted. Interictal spikes were frequently recorded at the vertex region, where ictal discharges also started during the video-EEG monitoring. Electrical stimulation of the left tibial nerve evoked giant cortical components of somatosensory evoked potentials and C-reflex. Magnetoencephalographic study of both interictal and jerk-locked averaged spikes located the equivalent current dipole of both activities at the left foot primary somatosensory cortex (SI), where 3 tesla MRI revealed a focal abnormality consistent with focal cortical dysplasia. The present non-invasive investigation suggests that focal cortical dysplasia at SI could manifest intrinsic, autonomous, epileptogenicity as well as extrinsic, stimulus-sensitive, hyperexcitability, which are clinically manifested as spontaneous seizures and cortical reflex myoclonus, respectively.