How can we explain the frontal presentation of insular lobe epilepsy? The impact of non-linear analysis of insular seizures.
For a decade it has been known that the insular lobe epilepsy can mimic frontal lobe epilepsy. We aimed to clarify the pattern of functional coupling occurring during the frontal presentation.



We analyzed five insular lobe epilepsy patients. Frontal semiology was predominant for three of them, whereas insular semiology was predominant for the two others. We applied the non-linear regression analysis to stereoelectroencephalography-recorded seizures. A directed functional coupling index was calculated during clonic discharge periods that were accompanied either with frontal or insular semiology.



We found significant functional coupling between the insula and mesial frontal/cingulate regions, with the former being a leader region for seizures propagation. Extra-insular regions showed significantly less or even no coupling with the mesial hemispheric regions. The three patients with frontal semiology showed strong couplings with the mesial frontal as well as cingulate regions, including the medial orbitofrontal cortex, pre-SMA/SMA, and the anterior to posterior cingulate. The two patients with the insular semiology only showed couplings between the insula and cingulate regions.



The frontal semiology was expressed by strong functional couplings between the insula and mesial frontal regions.



The insular origin of seizure should be considered in cryptogenic mesial frontal epilepsies.
Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Université Lyon 1, Lyon F-69000, France; Hospices Civils de Lyon, Neurological Hospital, Department of Functional Neurology and Epileptology, Lyon F-69003, France; Central Integration of Pain (NeuroPain) Lab-Lyon Neuroscience Research Center, INSERM U1028, CNRS, UMR5292, Université Claude Bernard, Bron F-69677, France. Electronic address: hagiwara-kyu@umin.ac.jp.
Koichi
K
Hagiwara
Université Lyon 1, Lyon F-69000, France; Hospices Civils de Lyon, Neurological Hospital, Department of Functional Neurology and Epileptology, Lyon F-69003, France; Lyon Neuroscience Research Centre, INSERM U1028, CNRS UMR5292, Brain Dynamics and Cognition Team, Lyon F-69000, France.
Julien
J
Jung
Université Lyon 1, Lyon F-69000, France; Lyon Neuroscience Research Centre, INSERM U1028, CNRS UMR5292, Brain Dynamics and Cognition Team, Lyon F-69000, France.
Romain
R
Bouet
Hospices Civils de Lyon, Neurological Hospital, Department of Functional Neurology and Epileptology, Lyon F-69003, France.
Chifaou
C
Abdallah
Université Lyon 1, Lyon F-69000, France; Hospices Civils de Lyon, Neurological Hospital, Department of Functional Neurosurgery, Lyon F-69003, France; Central Integration of Pain (NeuroPain) Lab-Lyon Neuroscience Research Center, INSERM U1028, CNRS, UMR5292, Université Claude Bernard, Bron F-69677, France.
Marc
M
Guénot
Central Integration of Pain (NeuroPain) Lab-Lyon Neuroscience Research Center, INSERM U1028, CNRS, UMR5292, Université Claude Bernard, Bron F-69677, France; Centre D'évaluation et de Traitement de la Douleur, Hôpital Neurologique, Lyon F-69000, France.
Luis
L
Garcia-Larrea
Université Lyon 1, Lyon F-69000, France; Hospices Civils de Lyon, Neurological Hospital, Department of Functional Neurology and Epileptology, Lyon F-69003, France; Central Integration of Pain (NeuroPain) Lab-Lyon Neuroscience Research Center, INSERM U1028, CNRS, UMR5292, Université Claude Bernard, Bron F-69677, France.
François
F
Mauguière
Université Lyon 1, Lyon F-69000, France; Hospices Civils de Lyon, Neurological Hospital, Department of Functional Neurology and Epileptology, Lyon F-69003, France; Central Integration of Pain (NeuroPain) Lab-Lyon Neuroscience Research Center, INSERM U1028, CNRS, UMR5292, Université Claude Bernard, Bron F-69677, France.
Sylvain
S
Rheims
Université Lyon 1, Lyon F-69000, France; Hospices Civils de Lyon, Neurological Hospital, Department of Functional Neurology and Epileptology, Lyon F-69003, France; Central Integration of Pain (NeuroPain) Lab-Lyon Neuroscience Research Center, INSERM U1028, CNRS, UMR5292, Université Claude Bernard, Bron F-69677, France.
Jean
J
Isnard
D000293:Adolescent; D004569:Electroencephalography / Q000379:methods*; D004827:Epilepsy / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017711:Nonlinear Dynamics; D012640:Seizures / Q000175:diagnosis / Q000503:physiopathology*; D055815:Young Adult
Directed functional coupling; Insular lobe seizure; Mesial frontal propagation; Non-linear regression analysis; Stereoelectroencephalography (SEEG)