Abstracts

Nocturnal hypermotor seizures (NHS) are considered highly suggestive of a frontal lobe onset, and more specifically of a mesial frontal origin. This is even more true when such an epileptic pattern affects several members of the same family, suggesting the syndrom of autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). Electrophysiological evidences of the frontal origin of such seizures are scarce, however. We report in this study three patients with either sporadic NHS or ADNFLE in whom invasive monitoring demonstrated the insular origin of seizures. We identified the three patients presented in this study among the 486 patients who underwent a stereoelectroencephalography (SEEG) procedure in the epilepsy surgery departments of Grenoble and Lyon, and reviewed their detailed clinical and intra-cranial EEG findings. 14 to 15 intracranial electrodes were stereotactically implanted in all three patients, and mainly targeted the mesial and lateral frontal lobe structures. Based on electroclinical evidences, most electrodes were placed in the same hemisphere, with one exploring the anterior part of the insula ipsilateral to the suspected epileptogenic zone in all patients. All three patients presented with predominantly nocturnal seizures which started between three and nine years of age. No remarkable past history was noted in two patients, whereas the third one presented with a typical familial history of ADNLFE. All three patients exhibited prominent ictal motor activity, consistent with the diagnosis of hypermotor seizures, including bicycling, pelvic thrusting, and turning over. Shouting, grimacing, and facial expression of fear were also commonly observed during seizures, the latter being usually of short duration without post-ictal confusion. In the two sporadic cases, SEEG data clearly identified a very active and focal interictal focus as well as the origin of ictal discharges in the anterior insula [italic](either right or left-sided). [/italic]In the patient with ADNFLE, seizures originated almost simultaneously from the left anterior insula and the ispilateral frontal operculum. Seizures always rapidly propagated to the mesial frontal lobe, concommitantly with the onset of hypermotor activities. Sporadic cryptogenic epilepsy characterized by nocturnal hypermotor seizures, as well as ADNFLE, can be associated with an ictal onset zone located within the insula rather than within the frontal lobe proper. Taking into consideration previous observations from our groups in temporal plus epilepsy, it appears that depending on the portion of the insula where seizures arise, the latter can alternatively mimick temporal or frontal lobe epilepsy.