Objective: The present study investigated the electroclinical features and epileptogenic networks of parietal operculum seizures (POS) by using stereoelectroencephalography (SEEG) intracerebral recordings. Methods: Comprehensive presurgical evaluation data of seven patients with drug-resistant epilepsy with POS were analyzed retrospectively. Stereoelectroencephalography-recorded seizures were processed visually and quantitatively by using epileptogenicity mapping (EM), which has been proposed to ergonomically quantify the epileptogenicity of brain structures with a neuroimaging approach. Results: Six patients reported initial somatosensory or viscerosensitive symptoms. !dal clinical signs comprised frequently nocturnal hypermotor seizures and contralateral focal motor seizures, including tonic, tonic-clonic, or dystonic seizures of the face and limbs. lnterictal and ictal scalp EEG provided information regarding lateralization in the majority of patients, but the discharges were widely distributed over perisylvian or "rolandic-like" regions and the vertex. Furthermore, two subgroups of epileptogenic network organization were identified within POS by SEEG, visually and quantitatively, using an EM approach: group 1 (mesial frontal/dngulate networks) was observed in three patients who mainly exhibited hypermotor seizures; group 2 (perisylvian networks) was observed in four patients who mainly exhibited contralateral focal motor seizures. Conclusion: This study indicated that POS could be characterized by initial specific somatosensory sensations, followed by either frequently nocturnal hypermotor seizures or contralateral focal motor seizures. The distinctive seizure semiology depended on the organization of two primary epileptogenic networks. (C) 2018 Elsevier Inc. All rights reserved.