Epileptic networks in patients with bitemporal epilepsy: the role of SEEG for the selection of good surgical candidates.
In this study we investigated the electrical characteristics of seizures recorded by stereo-EEG (SEEG) in a cohort of patients with bitemporal lobe epilepsy (BTLE), in the attempt to verify the presence/absence of different seizure patterns and to identify good surgical candidates.



We retrospectively reviewed 14 consecutive patients with medically refractory BTLE confirmed by scalp video-EEG (VEEG) recording of bitemporal independent or non-lateralizing seizure onset. All patients had a comprehensive evaluation including history and neurologic examination, MRI, scalp VEEG and SEEG monitoring. Neuropsychological, Wada testing and FDG-PET were performed in most patients. When temporal lobe resection was performed (7 cases), the postoperative follow-up was of at least 1year.



Intracranial EEG (SEEG) revealed that only 4/14 (29%) patients were suffering of unilateral TLE. Two groups of patients with distinct SEEG patterns of seizures were identified: a temporo-mesial origin of seizures was the only SEEG pattern observed in 8 patients (Group 1); in 6 patients seizures originated from multiple onset zones in mesial and lateral temporal cortex or from extra-temporal cortex (Group 2). All patients of group 1 (except one who refused surgery) underwent surgery and had a favorable outcome (6 Engel class I; one Engel's class II). The side of surgery was not necessarily the one responsible for the majority of recorded seizures. It was chosen on the basis of MRI findings and consistency of data from presurgical functional investigations, mostly memory assessment and Wada test.



In patients with suspected BTLE, SEEG proved to be useful in identifying the origin of seizures. Good surgical outcome can be obtained after unilateral resection in patients with bilateral independent seizure onsets or sequential mesial temporal involvement on SEEG if the side of surgery is chosen considering multimodal data.
IRCCS Institute of Neurological Sciences, Bologna, Italy. Electronic address: lidia3@gmail.com.
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L
Di Vito
Department of Functional Neurology and Epileptology, Hospices Civils de Lyon, Lyon 1 University, Lyon 69500, France; Lyon Neuroscience Research Centre (CRNL), INSERM U1028/CNRS UMR5292, Lyon, France. Electronic address: francois.mauguiere@univ-lyon1.fr.
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F
Mauguière
Department of Functional Neurology and Epileptology, Hospices Civils de Lyon, Lyon 1 University, Lyon 69500, France; Lyon Neuroscience Research Centre (CRNL), INSERM U1028/CNRS UMR5292, Lyon, France. Electronic address: helene.catenoix@chu-lyon.fr.
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H
Catenoix
Department of Functional Neurology and Epileptology, Hospices Civils de Lyon, Lyon 1 University, Lyon 69500, France; Lyon Neuroscience Research Centre (CRNL), INSERM U1028/CNRS UMR5292, Lyon, France; Epilepsy Institute (IDEE), Lyon, France. Electronic address: sylvain.rheims@univ-lyon1.fr.
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S
Rheims
Department of Functional Neurosurgery, Neurological Hospital Hospices Civils de Lyon, Lyon 1 University, Lyon 69003, France; Lyon Neuroscience Research Centre (CRNL), INSERM U1028/CNRS UMR5292, Lyon, France. Electronic address: pierre.bourdillon@neurochirurgie.fr.
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P
Bourdillon
Department of Functional Neurology and Epileptology, Hospices Civils de Lyon, Lyon 1 University, Lyon 69500, France. Electronic address: alexandra.montavont@chu-lyon.fr.
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A
Montavont
Department of Functional Neurology and Epileptology, Hospices Civils de Lyon, Lyon 1 University, Lyon 69500, France; Lyon Neuroscience Research Centre (CRNL), INSERM U1028/CNRS UMR5292, Lyon, France. Electronic address: jean.isnard@chu-lyon.fr.
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J
Isnard
D000328:Adult; D001931:Brain Mapping; D000069279:Drug Resistant Epilepsy / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D000069280:Electrocorticography; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013702:Temporal Lobe / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery*; D016896:Treatment Outcome
Bitemporal lobe epilepsy; Epilepsy surgery; Epileptic networks; SEEG