The cortical sources of face selective N170: a simultaneous multi-scale EEG study

Abstract published in Clinical Neurophysiology, 130(7):e70, July 2019International audienceThe sudden onset of a face image leads to a prominent face-selective response in human scalp electroencephalographic (EEG) recordings, peaking 170 ms after stimulus onset at occipito-temporal (OT) scalp sites: the N170 (or M170 in magnetoencephalography). According to a widely held view, the main cortical source of the N170 lies in the fusiform gyrus (FG), whereas the posteriorly located inferior occipital gyrus (IOG) would rather generate earlier face-selective responses. Here, we report neural responses to upright and inverted faces recorded in a unique patient using multicontact intracerebral electrodes implanted in the right IOG and in the OT sulcus above the right lateral FG (LFG). Simultaneous EEG recordings on the scalp identified the N170 over the right OT scalp region. The latency and amplitude of this scalp N170 were correlated at the single-trial level with the N170 recorded in the lateral IOG, close to the scalp lateral occipital surface. In addition, positive component maximal around the latency of the N170 (a P170) was prominent above the internal LFG, whereas this region typically generates an N170 (or “N200”) over its external/ventral surface. This suggests that electrophysiological responses in the LFG manifest as an equivalent dipole oriented mostly along the vertical axis with likely minimal projection to the lateral OT scalp region. Altogether, these observations provide evidence that the IOG is a major cortical generator of the face-selective scalp N170, qualifying the potential contribution of the FG and questioning a strict serial spatiotemporal organization of the human cortical face network

Localizing value of interictal electrical source imaging: who are the best candidates?

Abstract published in Clinical Neurophysiology 130(7):e70, July 2019International audienceBackground: High resolution EEG combined to electrical source imaging has taken up a promising place in this pre-surgical investigation due to its ability to localize epileptic sources in the individual anatomical space and in a non-invasive way.Objectives: We aimed to prospectively assess the anatomical concordance of electric source localizations of interictal discharges with the epileptogenic zone (EZ) estimated by stereo-electroencephalography (SEEG) according to different subgroups.Methods: In a prospective multicentric observational study, we enrolled 85 consecutive patients undergoing pre-surgical SEEG investigation. Electric source imaging was performed before SEEG. Anatomical concordance between ESI and EZ was defined according to 36 predefined sublobar regions. ESI was interpreted blinded to- and subsequently compared with SEEG estimated EZ.Results: A total of 74 patients were finally analyzed. A total of 38 patients had temporal and 36 extra-temporal lobe epilepsy. MRI was positive in 52. 41 patients had malformation of cortical development, 33 had another or an unknown aetiology. In the overall cohort, ESI completely or partly localized the EZ in 85%: full concordance in 13 cases and partial concordance in 50 cases. The rate of ESI full concordance with EZ was significantly higher in:– frontal lobe epilepsy (46%);– cases of negative MRI (36%) and;– MCD (27%).Conclusion: We demonstrated that ESI more accurately estimated the EZ in subgroups of patients who are often the most difficult cases in epilepsy surgery: frontal lobe epilepsy, negative MRI and the presence of MCD

Localizing value of interictal electrical source imaging: who are the best candidates?

Abstract published in Clinical Neurophysiology 130(7):e70, July 2019International audienceBackground: High resolution EEG combined to electrical source imaging has taken up a promising place in this pre-surgical investigation due to its ability to localize epileptic sources in the individual anatomical space and in a non-invasive way.Objectives: We aimed to prospectively assess the anatomical concordance of electric source localizations of interictal discharges with the epileptogenic zone (EZ) estimated by stereo-electroencephalography (SEEG) according to different subgroups.Methods: In a prospective multicentric observational study, we enrolled 85 consecutive patients undergoing pre-surgical SEEG investigation. Electric source imaging was performed before SEEG. Anatomical concordance between ESI and EZ was defined according to 36 predefined sublobar regions. ESI was interpreted blinded to- and subsequently compared with SEEG estimated EZ.Results: A total of 74 patients were finally analyzed. A total of 38 patients had temporal and 36 extra-temporal lobe epilepsy. MRI was positive in 52. 41 patients had malformation of cortical development, 33 had another or an unknown aetiology. In the overall cohort, ESI completely or partly localized the EZ in 85%: full concordance in 13 cases and partial concordance in 50 cases. The rate of ESI full concordance with EZ was significantly higher in:– frontal lobe epilepsy (46%);– cases of negative MRI (36%) and;– MCD (27%).Conclusion: We demonstrated that ESI more accurately estimated the EZ in subgroups of patients who are often the most difficult cases in epilepsy surgery: frontal lobe epilepsy, negative MRI and the presence of MCD

Développement de nouveaux cristaux non linéaires pour la conception de dispositifs laser solides émettant dans l'ultraviolet

National audienceUne technique prometteuse pour la réalisation de dispositifs laser solides émettant dans l'ultraviolet consiste à disposer en cascade plusieurs cristaux non linéaires générant des sommes de fréquence à partir d'une émission laser fondamentale située dans le proche infra-rouge. Cependant, à ce jour, peu de cristaux non linéaires offrent la possibilité de générer de manière efficace des longueurs d'onde voisines ou inférieures à 250 nm. Dans ce but, les plus gros efforts de recherche actuels s'orientent vers des cristaux contenant des groupements borate. Après une description des principaux cristaux non linéaires proposés pour ce type d'application, nous présenterons les études que nous menons sur des matériaux de type fluoroborate, dérivés des oxoborates de terre rare et de calcium TrCa4O(BO3)3 (Tr = terre rare), et sur des matériaux de structure huntite TrMe3(BO3)4 (Me = Al, Ga, Sc)

Direct evidence of nonadherence to antiepileptic medication in refractory focal epilepsy

International audienceThe adherence to medication in drug-resistant focal epilepsy (RFE) remains largely unknown. The present work aimed to assess the frequency of recent adherence to antiepileptic drugs (AEDs) in patients with RFE. This prospective observational study screened all patients with RFE, admitted to the Nancy University Hospital between April 2006 and September 2008, for a 5-day hospitalization without AED tapering. The adherence to AEDs was assessed by measuring serum drug levels on day 1 (reflecting the recent "at home" adherence) and day 5 (reflecting the individual reference concentration when drug ingestion was supervised). A patient was considered nonadherent if at least one of their serum drug levels was different between days 1 and 5. The day-1 value was considered different from day 5 when it was at least 30% lower (underdosed) or 30% higher (overdosed). Nonadherent patients were classified as under-consumers in the case of one or more underdosed day-1 values, over-consumers in the case of one or more overdosed day-1 values, or undefined if they exhibited both underdosed and overdosed day-1 values. Forty-four of the 48 screened patients were included. Eighteen (40.9%) of 44 patients were nonadherent. Among them, 12 (66.7%) were over-consumers, 4 (22.2%) were under-consumers, and 2 (11.1%) were undefined nonadherents. The study indicates that recent adherence to antiepileptic medication in this group of patients with RFE is poor. Overconsumption is the most frequent form of nonadherence in this population and should be specifically assessed to prevent its possible consequences in terms of AEDs dose-dependent adverse events

Stereoelectroencephalography and surgical outcome in polymicrogyria-related epilepsy: A multicentric study

OBJECTIVE: We aimed to (1) assess the concordance between various polymicrogyria (PMG) types and the associated epileptogenic zone (EZ), as defined by stereoelectroencephalography (SEEG), and (2) determine the postsurgical seizure outcome in PMG-related drug-resistant epilepsy. METHODS: We retrospectively analyzed 58 cases: 49 had SEEG and 39 corticectomy or hemispherotomy. RESULTS: Mean age at SEEG or surgery was 28.3 years (range, 2-50). PMG was bilateral in 9 (16%) patients and unilateral in 49, including 17 (29%) unilobar, 12 (21%) multilobar, 15 (26%) perisylvian, and only 5 (9%) hemispheric. Twenty-eight (48%) patients additionally had schizencephaly, heterotopia, or focal cortical dysplasia. The SEEG-determined EZ was fully concordant with the PMG in only 8 (16%) cases, partially concordant in 74%, and discordant in 10%. The EZ included remote cortical areas in 21 (43%) cases and was primarily localized in those in 5 (10%), all related to the mesial temporal structures. All but 1 PMG patient with corticectomy or hemispherotomy had a unilateral PMG. At last follow-up (mean, 4.6 years; range, 1-16), 28 (72%) patients remained seizure free. Shorter epilepsy duration to surgery was an independent predictor of seizure freedom. INTERPRETATION: PMG-related drug-resistant epilepsy warrants a comprehensive presurgical evaluation, including SEEG investigations in most cases, given that the EZ may only partially overlap with the PMG or include solely remote cortical areas. Seizure freedom is feasible in a large proportion of patients. PMG extent should not deter from exploring the possibility of epilepsy surgery. Our data support the early consideration of epilepsy surgery in this patient group. Ann Neurol 2017;82:781-794

Atlas mondial des cercaires

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Long-term efficacy and safety of eslicarbazepine acetate monotherapy for adults with newly diagnosed focal epilepsy: An open-label extension study

Objective: To assess the efficacy, safety, and tolerability of eslicarbazepine acetate (ESL) monotherapy during long-term treatment. Methods: An open-label extension (OLE) study was conducted in adults completing a phase 3, randomized, double-blind, noninferiority trial, during which they had received monotherapy with either once-daily ESL or twice-daily controlled-release carbamazepine (CBZ-CR) for newly diagnosed focal epilepsy. In the OLE study, all patients received ESL (800-1600 mg/d) for 2 years. Primary efficacy outcome was retention time (from baseline of the OLE study). Secondary efficacy assessments included seizure freedom rate (no seizures during the OLE study) and responder rate (≥50% seizure frequency reduction from baseline of double-blind trial). Safety assessments included evaluation of treatment-emergent adverse events (TEAEs). Results: Of 206 randomized patients, 96 who received ESL in the double-blind trial (ESL/ESL) and 88 who received CBZ-CR in the double-blind trial (CBZ-CR/ESL) were treated with ESL monotherapy (89.3% overall). Treatment retention time was similar between groups, with low probability of ESL withdrawal overall (80% in both groups throughout the study. Incidence of serious TEAEs was similar between groups (7.3% vs 5.7%; 0% vs 1.1% possibly related), as were the incidences of TEAEs considered at least possibly related to treatment (17.7% vs 18.2%) and TEAEs leading to discontinuation (3.1% vs 4.5%). The types of TEAEs were generally consistent with the known safety profile of ESL. Significance: ESL monotherapy was efficacious and generally well tolerated over the long term, including in patients who transitioned from CBZ-CR monotherapy. No new safety concerns emerged