Abstracts

Rationale: The cerebral operculum harbors areas essential for motor, sensory, auditory and language processing. Most of the evidence about opercular cortex ictal involvement emerged from the studies on temporal lobe and insular seizures propagation (Kahane et al., Avanzini G, Beaumanoir A, Mira L.Limbic seizures in children.John Libbey;2001;115-27; Isnard et al.,Epilepsia 2004;45:1079-90). Specific semiology as well as surgery outcome of epilepsies with seizures that start distinctly in the perisylvian operculum and secondarily involve insula or other structures are scarcely documented in literature. Methods: We retrospectively analyzed clinical semiology of opercular seizures based on video analysis correlated with SEEG ictal recordings and direct electrical stimulation (DES) of opercular cortex. Fifteen patients were included, based on the following criteria: opercular and insular structures were appropriately sampled, SEEG recordings demonstrated that the ictal discharge had origin in the opercular structures sparing the insular cortex at seizure onset and the follow up period after surgery comprised at least one year. We also compared semiology of seizures and general characteristics of patients suffering from seizures with suprasylvian (SSY) versus infrasylvian (ISY) opercular origin with focus on the symptom clustering, anatomo-electro-clinical correlations and results of surgery. Results: Hierarchical cluster analysis revealed that association of facial motor involvement, autonomic and somatosensory symptoms characterize the semiology of seizures originating in the perisylvian operculum. In the SSY group, significantly more patients had somatosensory auras and experienced early during their seizures facial motor involvement and speech arrest (p=0.001). In this group, seizures were significantly shorter in duration and occurred more often during sleep (p=0.001). The propagation of ictal discharge in the SSY group involved the insular structures but also the motor, premotor mesial cortex and anterior cingulate gyrus. In the ISY group, significantly more patients were able to warn at seizure onset (p=0.04) and had auditory auras (p=0.001). During the ictal period, they displayed more frequently staring and/or activity arrest and experienced loss of contact (p=0.04). SEEG study documented a multidirectional spreading of ictal discharges involving the insular cortex, suprasylvian operculum and temporal structures. Surgical resections were performed in 10 out of 15 patients due to functional restraints. Five patients (50%) were seizure free after a follow-up period of at least 24 months. Conclusions: Our study showed that a particular cluster of symptoms and signs characterizes perisylvian opercular seizures. Moreover, we pointed to a specific semiology that differentiates seizures starting in the SSY versus ISI border. Surgery could be successful in patients with seizures originating in the perisylvian operculum providing that complete removal of the epileptogenic zone is not interfering with the language eloquent network.