Publications by authors named "Louise Tyvaert"

37 Publications

Brain F-FDG PET for the diagnosis of autoimmune encephalitis: a systematic review and a meta-analysis.

Eur J Nucl Med Mol Imaging 2021 Mar 7. Epub 2021 Mar 7.

Department of Nuclear Medicine and Nancyclotep Imaging Platform, Université de Lorraine, CHRU Nancy, Rue du Morvan, 54500 Vandoeuvre-les-Nancy, F-54000, Nancy, France.

Objective: To consolidate current understanding of detection sensitivity of brain F-FDG PET scans in the diagnosis of autoimmune encephalitis and to define specific metabolic imaging patterns for the most frequently occurring autoantibodies.

Methods: A systematic and exhaustive search of data available in the literature was performed by querying the PubMed/MEDLINE and Cochrane databases for the search terms: ((PET) OR (positron emission tomography)) AND ((FDG) OR (fluorodeoxyglucose)) AND ((encephalitis) OR (brain inflammation)). Studies had to satisfy the following criteria: (i) include at least ten pediatric or adult patients suspected or diagnosed with autoimmune encephalitis according to the current recommendations, (ii) specifically present F-FDG PET and/or morphologic imaging findings. The diagnostic F-FDG PET detection sensitivity in autoimmune encephalitis was determined for all cases reported in this systematic review, according to a meta-analysis following the PRISMA method, and selected publication quality was assessed with the QUADAS-2 tool.

Results: The search strategy identified 626 articles including references from publications. The detection sensitivity of F-FDG PET was 87% (80-92%) based on 21 publications and 444 patients included in the meta-analysis. We also report specific brain F-FDG PET imaging patterns for the main encephalitis autoantibody subtypes.

Conclusion And Relevance: Brain F-FDG PET has a high detection sensitivity and should be included in future diagnostic autoimmune encephalitis recommendations. Specific metabolic F-FDG PET patterns corresponding to the main autoimmune encephalitis autoantibody subtypes further enhance the value of this diagnostic.
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http://dx.doi.org/10.1007/s00259-021-05299-yDOI Listing
March 2021

Recurrent seizures of autoimmune origin: emerging phenotypes.

J Neurol 2021 Feb 27. Epub 2021 Feb 27.

Department of Neurology, University Hospital of Nancy, Nancy, France.

Objective: Recurrent seizures of autoimmune origin (AEp) are one of the most frequent causes of recurrent seizures or suspected epilepsy of unknown cause. The aim of this study was to identify specific phenotypes corresponding to AEp.

Methods: We retrospectively reviewed features of patients with recurrent seizures of unknown cause and investigated for suspected AEp (January 2015-May 2018). Patients were separated in: (1) AEpAb+: AEp with positive autoantibodies; (2) AEpAb-: suspected AEp (inflammatory central nervous system (CNS) profile) without autoantibodies; (3) NAEp: epilepsy without CNS inflammation.

Results: Eighty-nine epileptic patients underwent a CSF antibody detection. From the remaining 57 epileptic patients (32 excluded for a differential diagnosis), 61.4% were considered as AEp. 21% were AEpAb+ (4 NMDAR, 2 GABAbR, 3 GAD-Ab, 2 LGi1, 1 CASPR2), 40.4% AEpAb-, and 38.6% NAE. AE (AEpAb+ and AEpAb-) was significantly associated with antibody prevalence in epilepsy (APE) score ≥ 4 (80%), encephalitic phase (71.4%), psychiatric involvement (64.7%), cognitive impairment (50%), and status epilepticus (41.2%). Within the group of 29 patients without encephalitic phase and with chronic epilepsy (NEPp), 34.5% were defined as AEp. 10.4% were AEpAb+ (2 GAD, 1 CASPR2) and 24.1% were AEpAb-. NEP AEp was associated with non-cerebral autoimmune disorders, short epileptic disease duration, and cognitive impairment.

Conclusions: Autoimmune cause (AEp) should be assessed in patient suffering from recurrent seizures of unknown cause. Acute encephalitis is clearly the main AEp phenotype. AEp was also defined in more than one-third of chronic epilepsy patients (NEP) of unknown cause. Then, AEp may be combined with other autoimmune comorbidities, a shorter evolution of recurrent seizures, and cognitive impairment.
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http://dx.doi.org/10.1007/s00415-021-10457-1DOI Listing
February 2021

Stereoelectroencephalographic language mapping of the basal temporal cortex predicts postoperative naming outcome.

J Neurosurg 2021 Feb 26:1-11. Epub 2021 Feb 26.

Departments of1Neurology and.

Objective: In drug-resistant temporal lobe epilepsy (TLE) patients, the authors evaluated early and late outcomes for decline in visual object naming after dominant temporal lobe resection (TLR) according to the resection status of the basal temporal language area (BTLA) identified by cortical stimulation during stereoelectroencephalography (SEEG).

Methods: Twenty patients who underwent SEEG for drug-resistant TLE met the inclusion criteria. During language mapping, a site was considered positive when stimulation of two contiguous contacts elicited at least one naming impairment during two remote sessions. After TLR ipsilateral to their BTLA, patients were classified as BTLA+ when at least one positive language site was resected and as BTLA- when all positive language sites were preserved. Outcomes in naming and verbal fluency tests were assessed using pre- and postoperative (means of 7 and 25 months after surgery) scores at the group level and reliable change indices (RCIs) for clinically meaningful changes at the individual level.

Results: BTLA+ patients (n = 7) had significantly worse naming scores than BTLA- patients (n = 13) within 1 year after surgery but not at the long-term evaluation. No difference in verbal fluency tests was observed. When RCIs were used, 5 of 18 patients (28%) had naming decline within 1 year postoperatively (corresponding to 57% of BTLA+ and 9% of BTLA- patients). A significant correlation was found between BTLA resection and naming decline.

Conclusions: BTLA resection is associated with a specific and early naming decline. Even if this decline is transient, naming scores in BTLA+ patients tend to remain lower compared to their baseline. SEEG mapping helps to predict postoperative language outcome after dominant TLR.
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http://dx.doi.org/10.3171/2020.8.JNS202431DOI Listing
February 2021

Anticipatory anxiety of epileptic seizures: An overlooked dimension linked to trauma history.

Seizure 2021 Feb 18;85:64-69. Epub 2020 Dec 18.

Université de Lorraine, CNRS, CRAN, UMR 7039, Nancy, France; CHRU de Nancy, Département de Neurologie, Nancy, France; Pôle Hospitalo-Universitaire de Psychiatrie d'Adultes du Grand Nancy, Centre Psychothérapique de Nancy, Laxou, France. Electronic address:

Objective: Fear of having a seizure called anticipatory anxiety of epileptic seizure (AAS), constitutes a daily life burden but has been rarely studied. Our aim was to assess the prevalence and the determining factors of AAS in patients with drug-resistant focal epilepsy, a dimension that has not been thoroughly investigated before.

Methods: We conducted an observational, prospective study enrolling patients with drug-resistant focal epilepsy. The psychiatric assessment aimed to evaluate psychiatric comorbidities, trauma history, and quality of life using hetero-evaluation and self-assessment tools. Dimensions of anxiety specifically related to epilepsy (peri-and-inter-ictal) were explored as exhaustively as possible.

Results: AAS was found in 53 % of the 87 patients. We compared the two groups of patients: with or without AAS. Patients with AAS had a significantly shorter duration of epilepsy (p = 0.04). There was no difference between groups with respect to psychiatric disorders, except for cannabis dependence, more frequent in patients with AAS (p = 0.02). Compared to patients without AAS, those with AAS presented more subjective ictal anxiety (p = 0.0003) and postictal anxiety (p = 0.02), were more likely to avoid outdoor social situations due to seizure fear (p = 0.001), and had a poorer quality of life (QOLIE emotional well-being; p = 0.03). Additionally, they had experienced more traumatic events in their lifetime (p = 0.005) and reported more frequently a feeling of being unsafe during their seizures (p = 0.00002).

Significance: AAS is a specific dimension of anxiety, possibly linked to trauma history. AAS is strongly linked to subjective ictal anxiety but not to the objective severity of seizures or frequency.
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http://dx.doi.org/10.1016/j.seizure.2020.12.006DOI Listing
February 2021

Expanding the clinical spectrum of STIP1 homology and U-box containing protein 1-associated ataxia.

J Neurol 2021 Jan 8. Epub 2021 Jan 8.

Service de Génétique Médicale, Hôpitaux de Brabois, CHRU de Nancy, Rue du Morvan, 54500, Vandoeuvre-lès-Nancy, France.

Background: STUB1 has been first associated with autosomal recessive (SCAR16, MIM# 615768) and later with dominant forms of ataxia (SCA48, MIM# 618093). Pathogenic variations in STUB1 are now considered a frequent cause of cerebellar ataxia.

Objective: We aimed to improve the clinical, radiological, and molecular delineation of SCAR16 and SCA48.

Methods: Retrospective collection of patients with SCAR16 or SCA48 diagnosed in three French genetic centers (Montpellier, Strasbourg and Nancy).

Results: Here, we report four SCAR16 and nine SCA48 patients from two SCAR16 and five SCA48 unrelated French families. All presented with slowly progressive cerebellar ataxia. Additional findings included cognitive decline, dystonia, parkinsonism and swallowing difficulties. The age at onset was highly variable, ranging from 14 to 76 years. Brain MRI showed marked cerebellar atrophy in all patients. Phenotypic findings associated with STUB1 pathogenic variations cover a broad spectrum, ranging from isolated slowly progressive ataxia to severe encephalopathy, and include extrapyramidal features. We described five new pathogenic variations, two previously reported pathogenic variations, and two rare variants of unknown significance in association with STUB1-related disorders. We also report the first pathogenic variation associated with both dominant and recessive forms of inheritance (SCAR16 and SCA48).

Conclusion: Even though differences are observed between the recessive and dominant forms, it appears that a continuum exists between these two entities. While adding new symptoms associated with STUB1 pathogenic variations, we insist on the difficulty of genetic counselling in STUB1-related pathologies. Finally, we underscore the usefulness of DAT-scan as an additional clue for diagnosis.
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http://dx.doi.org/10.1007/s00415-020-10348-xDOI Listing
January 2021

Short-term risk of relapse after a first unprovoked seizure in an adult population.

Neurophysiol Clin 2020 Apr 14;50(2):87-92. Epub 2020 Feb 14.

Neurological department, university hospital of Nancy, 54035 Nancy, France; CRAN, UMR 7039, CNRS, Lorraine university, 54500 Vandoeuvre-lès-Nancy, France. Electronic address:

Objective: To evaluate the incidence of short-term recurrence (<1 month) after a first unprovoked seizure (FUS) and the associated risk factors.

Methods: This is a prospective monocentric one-year observational study on all consecutive adult patients admitted to the Emergency Department (ED) and diagnosed as FUS. Patients underwent neurological consultation at one and three months after the FUS. Demographic information, clinical examination and seizure features, seizure recurrence at 1 and 3 months, electroencephalogram (EEG), brain imaging, precipitating factors, seizure type, and prescribed antiepileptic drugs (AED) were prospectively collected.

Results: Among 140 patients diagnosed as FUS, 109 patients attended the neurological consultation at 1 month. FUS diagnosis was confirmed in 80/109 cases. Nine patients (11.2%) had seizure recurrence before the consultation at 1 month. Identified specific risk factors of short-term recurrence were focal seizure (P=0.015) and abnormal EEG in the first 48hours (P=0.048). In the group of patients followed for three months (38 patients), the risk of seizure relapse was 15.7%.

Conclusion: Most patients with FUS diagnosed in the ED did not present seizure recurrence within the first month, especially if no specific risk factors were present (focal seizure, abnormal EEG within first 48hours). The systematic use of prophylactic AED (benzodiazepines) is not recommended in the ED in the clinical setting of FUS. A specialized consultation within a one-month period is safe and adequate for FUS follow-up.
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http://dx.doi.org/10.1016/j.neucli.2020.01.004DOI Listing
April 2020

GAD65-Ab encephalitis and subtle focal status epilepticus.

Epileptic Disord 2019 Oct;21(5):437-442

Department of Neurology, University Hospital of Nancy, University of Lorraine, Faculty of Medicine, CRAN CNRS UMR 7039, Nancy, France.

Aims: To delineate common epilepsy features associated with the presence of glutamic acid decarboxylase autoantibodies (GAD65-Ab).

Methods: Three consecutive cases of GAD65-Ab encephalitis patients, followed in our neurological department, were investigated with regards to clinical semiology and EEG.

Results: These patients presented new-onset subtle ictal clinical features. Patients 1 and 2 described prolonged and transitory feelings of "déjà vu - déjà vécu" and a "dreamy state". Patient 3 was admitted for subsequent transient aphasia events followed by paroxysmal behavioural disturbances. Epileptic origin of the symptoms was confirmed using either a standard EEG (observation of temporal status epilepticus in one case) or a prolonged EEG (focal epileptiform activity during an asymptomatic period for two patients). All patients suffered from clinical focal status epilepticus. Patients 1 and 2 presented with temporo-mesial seizures in agreement with the definition for limbic encephalitis, whereas Patient 3 presented with neocortical (lateral temporal and frontal lobe) seizures arguing for a non-limbic encephalitis. A high level of GAD65-Ab was found in cerebral spinal fluid, confirming a diagnosis of epilepsy associated with GAD65-Ab encephalitis.

Conclusion: Encephalitis seems to be a frequent neurological syndrome associated with GAD65-Ab disorders. Epilepsy may be more frequent and severe than currently suggested, as ictal semiology may be subtle for these outpatients in whom standard EEG is commonly falsely reassuring. Subtle focal status epilepticus is a particular semiology of the GAD65-Ab encephalitis spectrum.
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http://dx.doi.org/10.1684/epd.2019.1094DOI Listing
October 2019

Interictal psychiatric comorbidities of drug-resistant focal epilepsy: Prevalence and influence of the localization of the epilepsy.

Epilepsy Behav 2019 05 11;94:288-296. Epub 2018 Nov 11.

Pôle Hospitalo-Universitaire de Psychiatrie d'Adultes du Grand Nancy, Centre Psychothérapique de Nancy, F-54521 Laxou, France; Centre Hospitalier Universitaire de Nancy, Département de Neurologie, Nancy FR 54000, France. Electronic address:

Psychiatric comorbidities are 2 to 3 times more frequent in patients with epilepsy than in the general population. This study aimed to prospectively assess the following: (i) the prevalence of specific and nonspecific interictal psychiatric comorbidities in a population of patients with drug-resistant focal epilepsy and (ii) the influence of epilepsy lateralization and localization on these psychiatric comorbidities. In this prospective monocentric study, we collected demographic data, characteristics of the epilepsy, interictal psychiatric comorbidities, mood, anxiety, and alexithymia dimensions. We used criteria from Diagnostic and Statistical Manual of Mental Disorders IV ( DSM IV) (Mini International Mental Interview (MINI)), diagnosis criteria for specific comorbidities, and validated mood and anxiety scales (general and specific for epilepsy). Among the 87 enrolled patients (39 males, 48 females), 52.9% had at least one psychiatric comorbidity. The most common comorbidity was anxiety disorder (28.7% according to the MINI, and 38.4% screening by the Generalized Anxiety Disorder 7 (GAD 7)). Mood disorders were the second most frequent psychiatric comorbidity: 21.8% of our patients had interictal dysphoric disorders (IDDs), 16.1% presented major depressive disorders according to the MINI, and 17.2% screening by the Neurological Disorders Depression Inventory for Epilepsy (NDDIE). Patients with temporal lobe epilepsy had a higher prevalence of psychiatric comorbidities than patients with extratemporal lobe epilepsy (p = 0.002), which is probably related to a higher rate of anxiety disorders in this subgroup (p = 0.012). Prevalence of psychiatric disorders prior to epilepsy in patients was higher in right- than in left-sided epilepsy (p = 0.042). No difference was found according to limbic involvement at seizure onset. Overall, this article highlighted a very high proportion of anxiety disorders in these patients with drug-resistant focal epilepsy and the necessity to systematically detect them and thus lead to a specific treatment.
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http://dx.doi.org/10.1016/j.yebeh.2018.06.046DOI Listing
May 2019

A multi-channel approach for cortical stimulation artefact suppression in depth EEG signals using time-frequency and spatial filtering.

IEEE Trans Biomed Eng 2018 Nov 12. Epub 2018 Nov 12.

Objective: The stereo electroencephalogram (SEEG) recordings are the sate of the art tool used in pre-surgical evaluation of drug-unresponsive epileptic patients. Coupled with SEEG, electrical cortical stimulation (CS) offer a complementary tool to investigate the lesioned/healthy brain regions and to identify the epileptic zones with precision. However, the propagation of this stimulation inside the brain masks the cerebral activity recorded by nearby multi-contact SEEG electrodes. The objective of this paper is to propose a novel filtering approach for suppressing the CS artifact in SEEG signals using time, frequency as well as spatial information.

Methods: The method combines spatial filtering with tunable-Q wavelet transform (TQWT). SEEG signals are spatially filtered to isolate the CS artifacts within a few number of sources/components. The artifacted components are then decomposed into oscillatory background and sharp varying transient signals using tunable-Q wavelet transform (TQWT). The CS artifact is assumed to lie in the transient part of the signal. Using prior known time-frequency information of the CS artifacts, we selectively mask the wavelet coefficients of the transient signal and extract out any remaining significant electrophysiological activity.

Results: We have applied our proposed method of CS artifact suppression on simulated and real SEEG signals with convincing performance. The experimental results indicate the effectiveness of the proposed approach.

Conclusion: The proposed method suppresses CS artifacts without affecting the background SEEG signal.

Significance: The proposed method can be applied for suppressing both low and high frequency CS artifacts and outperforms current methods from the literature.
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http://dx.doi.org/10.1109/TBME.2018.2881051DOI Listing
November 2018

A detailed anatomical and mathematical model of the hippocampal formation for the generation of sharp-wave ripples and theta-nested gamma oscillations.

J Comput Neurosci 2018 12 31;45(3):207-221. Epub 2018 Oct 31.

Centre de Recherche en Automatique de Nancy, CRAN-CNRS UMR 7039 University of Lorraine, Vandoeuvre les Nancy, France.

The mechanisms underlying the broad variety of oscillatory rhythms measured in the hippocampus during the sleep-wake cycle are not yet fully understood. In this article, we propose a computational model of the hippocampal formation based on a realistic topology and synaptic connectivity, and we analyze the effect of different changes on the network, namely the variation of synaptic conductances, the variations of the CAN channel conductance and the variation of inputs. By using a detailed simulation of intracerebral recordings, we show that this is able to reproduce both the theta-nested gamma oscillations that are seen in awake brains and the sharp-wave ripple complexes measured during slow-wave sleep. The results of our simulations support the idea that the functional connectivity of the hippocampus, modulated by the sleep-wake variations in Acetylcholine concentration, is a key factor in controlling its rhythms.
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http://dx.doi.org/10.1007/s10827-018-0704-xDOI Listing
December 2018

Recommendations for the use of electroencephalography and evoked potentials in comatose patients.

Neurophysiol Clin 2018 Jun 18;48(3):143-169. Epub 2018 May 18.

Service de neurophysiologie clinique, CHRU de Lille, 59037 Lille cedex, France; Université de Lille, Inserm U 1171, Troubles cognitifs dégénératifs et vasculaires, centre d'excellence des maladies neurodégénératives de Lille (LiCEND), 59000 Lille cedex, France. Electronic address:

Predicting the outcome of a comatose or poorly responsive patient is a major issue for intensive care unit teams, in order to give the most accurate information to the family and to choose the best therapeutic option. However, determining the level of cortical activity in patients with disorders of consciousness is a real challenge. Reliable criteria are required to help clinicians in the decision-making process, especially in the acute phase of coma. In this paper, we propose recommendations for recording and interpreting electroencephalography and evoked potentials in comatose patients based on the literature and the clinical experience of a group of neurophysiologists trained in the management of comatose patients. We propose methodological guidelines and discuss prognostic value of each test as well as the limitations concerning recording and interpretation. Recommendations for the strategy and timing of neurophysiological assessments are also proposed according to various clinical situations.
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http://dx.doi.org/10.1016/j.neucli.2018.05.038DOI Listing
June 2018

[Diagnosis and management of de novo epilepsy].

Authors:
Tyvaert Louise

Presse Med 2018 Mar 8;47(3):227-233. Epub 2018 Mar 8.

CHRU de Nancy, service de neurologie, 29, avenue du Maréchal-de-Lattre-de-Tassigny, 54035 Nancy, France. Electronic address:

The diagnosis of de novo epilepsy is complex. An accurate diagnostic approach has to be followed based on specific key steps. Epileptic seizure or non-epileptic malaise: risk of diagnosis error around 20%. Facing a first unprovoked seizure, the practitioner has to know the risk factors specifically linked to an increase risk of seizure recurrence. In presence of these factors, an antiepileptic drug would be indicated. The first antiepileptic drug has to be highly selected according to the epilepsy type and causes but also to the patient characteristics (sex, age, comorbidities, associated drugs, profession, and way of life…) An exhaustive patient Education needs to support the first antiepileptic drug prescription: (sleep and nutritional advices, benefit of observance, antiepileptic drugs features and side effects, follow-up, prognosis…) A regular follow-up is essential to control the observance, tolerability and efficacy of the antiepileptic drug, and to control also the good acceptance of the disease. A systematic research of common comorbidities may be also performed. Electroencephalogram and antiepileptic drugs levels are unnecessary in the classical follow up of known epileptic patients (except specific cases).
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http://dx.doi.org/10.1016/j.lpm.2017.11.015DOI Listing
March 2018

Indications and limits of stereoelectroencephalography (SEEG).

Neurophysiol Clin 2018 Feb 17;48(1):15-24. Epub 2018 Jan 17.

Paediatric Neurosurgery, Rothschild Foundation Hospital, 25-29, rue Manin, 75019 Paris, France.

Epilepsy surgery is now an accepted treatment to achieve seizure control in carefully selected patients, both children and adults, suffering from drug-resistant focal epilepsy. Although surgical strategies can often be defined on the basis of non-invasive diagnostic procedures, and despite the recent advances in this field, an increasing number of more complex cases requires invasive EEG (iEEG) to provide precise information on the localization of the epileptogenic zone (EZ), its relationships with eloquent cortex (EC), and the feasibility of a tailored surgical resection. Stereoelectroencephalography (SEEG) is one of the iEEG techniques currently used in the presurgical work-up, and it is well-distinguished from other invasive techniques, such as subdural grids and strips. SEEG depth electrodes enable exploration of deeply located structures and lesions, and of buried cortex, which are not easily assessable by subdural or other iEEG methods. Simultaneous recording of SEEG signals from deep and superficial brain structures allows, when the position of each electrode is precisely determined, delineation of a three-dimensional, spatial and temporal organization of epileptic activities. In the following chapter we discuss some specific indications (temporal or extra-temporal, lesional or non-lesional epilepsies) as well as the limits of the SEEG technique, with respect to some epileptological issues during presurgical evaluation.
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http://dx.doi.org/10.1016/j.neucli.2017.11.006DOI Listing
February 2018

French guidelines on stereoelectroencephalography (SEEG).

Neurophysiol Clin 2018 Feb 23;48(1):5-13. Epub 2017 Dec 23.

Unité des explorations fonctionnelles neurologiques, CHU de Rennes, 2, rue Henri-le-Guilloux, 35033 Rennes cedex 9, France; EA 4712 « Comportement et Noyaux Gris Centraux », faculté de médecine, université de Rennes 1, avenue Léon-Bernard, 35043 Rennes, France.

Stereoelectroencephalography (SEEG) was designed and developed in the 1960s in France by J. Talairach and J. Bancaud. It is an invasive method of exploration for drug-resistant focal epilepsies, offering the advantage of a tridimensional and temporally precise study of the epileptic discharge. It allows anatomo-electrical correlations and tailored surgeries. Whereas this method has been used for decades by experts in a limited number of European centers, the last ten years have seen increasing worldwide spread of its use. Moreover in current practice, SEEG is not only a diagnostic tool but also offers a therapeutic option, i.e., thermocoagulation. In order to propose formal guidelines for best clinical practice in SEEG, a working party was formed, composed of experts from every French centre with a large SEEG experience (those performing more than 10 SEEG per year over at least a 5 year period). This group formulated recommendations, which were graded by all participants according to established methodology. The first part of this article summarizes these within the following topics: indications and limits of SEEG; planning and management of SEEG; surgical technique; electrophysiological technical procedures; interpretation of SEEG recordings; and SEEG-guided radio frequency thermocoagulation. In the second part, those different aspects are discussed in more detail by subgroups of experts, based on existing literature and their own experience. The aim of this work is to present a consensual French approach to SEEG, which could be used as a basic document for centers using this method, particularly those who are beginning SEEG practice. These guidelines are supported by the French Clinical Neurophysiology Society and the French chapter of the International League Against Epilepsy.
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http://dx.doi.org/10.1016/j.neucli.2017.11.005DOI Listing
February 2018

sEEG is a Safe Procedure for a Comprehensive Anatomic Exploration of the Insula: A Retrospective Study of 108 Procedures Representing 254 Transopercular Insular Electrodes.

Oper Neurosurg (Hagerstown) 2018 01;14(1):1-8

Neurosurgery Department, University Hospital of Nancy, Nancy, France.

Background: The exploration of the insula in pre-surgical evaluation of epilepsy is considered to be associated with a high vascular risk resulting in an incomplete exploration of the insular cortex.

Objective: To report a retrospective observational study of insular exploration using stereoelectroencephalography (sEEG) with transopercular and parasagittal oblique intracerebral electrodes from January 2008 to January 2016. The first purpose of this study was to evaluate the surgical risks of insular cortex sEEG exploration. The second purpose was to define the ability of placing intracerebral contacts in the whole insular cortex.

Methods: Ninety-nine patients underwent 108 magnetic resonance imaging (MRI)-guided stereotactic implantations of intracerebral electrodes in the context of preoperative assessment of drug-resistant epilepsy, including at least 1 electrode placed in the insular cortex. On postoperative computed tomography images co-registered with MRI, followed by MRI segmentation and application of a transformation matrix, intracerebral contact coordinates of the insular electrodes' contacts were anatomically localized in the Talairach space. Finally, dispersion and clustering analysis was performed.

Results: There was no morbidity, in particular hemorrhagic complications, or mortality related to insular electrodes. Statistical comparison of intracerebral contact positions demonstrated that whole insula exploration is possible on the left and right sides. In addition, the clustering analysis showed the homogeneous distribution of the electrodes within the insular cortex.

Conclusion: In the presurgical evaluation of drug-resistant epilepsy, the insular cortex can be explored safely and comprehensively using transopercular sEEG electrodes. Parasagittal oblique trajectories may also be associated to achieve an optimal exploration.
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http://dx.doi.org/10.1093/ons/opx106DOI Listing
January 2018

[Epilepsy diagnosis: diagnostic criteria, syndromic and etiologic evaluation].

Authors:
Louise Tyvaert

Rev Prat 2017 03;67(3):264-271

Département de neurologie, CHRU Nancy, Nancy, France

The initial assessment of a patient with possible new-onset epilepsy is an important issue, epilepsy diagnosis leading to major consequences. Considering the new definition, epilepsy can be diagnosed after a single epileptic seizure reducing the morbidity associated with the seizure recurrence. This definition supposed a meticulous diagnostic approach to eliminate differential diagnosis and seizure occurring during an acute symptomatic event. A prompt and accurate diagnostic assessment of the epileptic syndrome and of the etiology is also essential to guide the therapeutic strategy and to provide information about the global outcome. This diagnostic evaluation should be performed or supervised by a specialist and severe cases need to be referred in a specialized epilepsy center.
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March 2017

Whole-Brain High-Resolution Structural Connectome: Inter-Subject Validation and Application to the Anatomical Segmentation of the Striatum.

Brain Topogr 2017 May 7;30(3):291-302. Epub 2017 Feb 7.

Department of Neurology, Nancy University Hospital, Nancy, France.

The present study describes extraction of high-resolution structural connectome (HRSC) in 99 healthy subjects, acquired and made available by the Human Connectome Project. Single subject connectomes were then registered to the common surface space to allow assessment of inter-individual reproducibility of this novel technique using a leave-one-out approach. The anatomic relevance of the surface-based connectome was examined via a clustering algorithm, which identified anatomic subdivisions within the striatum. The connectivity of these striatal subdivisions were then mapped on the cortical and other subcortical surfaces. Findings demonstrate that HRSC analysis is robust across individuals and accurately models the actual underlying brain networks related to the striatum. This suggests that this method has the potential to model and characterize the healthy whole-brain structural network at high anatomic resolution.
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http://dx.doi.org/10.1007/s10548-017-0548-0DOI Listing
May 2017

Assessing human brain impedance using simultaneous surface and intracerebral recordings.

Neuroscience 2017 02 22;343:411-422. Epub 2016 Dec 22.

Université de Lorraine, CRAN, UMR 7039, 2 av. de la Forêt de Haye, 54500 Vandoeuvre-lés-Nancy, France; CNRS, CRAN, UMR 7039, France.

Most of the literature on the brain impedance proposes a frequency-independent resistive model. Recently, this conclusion was tackled by a series of papers (Bédard et al., 2006; Bédard and Destexhe, 2009; Gomes et al., 2016), based on microscopic sale modeling and measurements. Our paper aims to investigate the impedance issue using simultaneous in vivo depth and surface signals recorded during intracerebral electrical stimulation of epileptic patients, involving a priori different tissues with different impedances. Our results confirm the conclusions from Logothethis et al. (2007): there is no evidence of frequency dependence of the brain tissue impedance (more precisely, there is no difference, in terms of frequency filtering, between the brain and the skull bone), at least at a macroscopic scale. In order to conciliate findings from both microscopic and macroscopic scales, we recall different neural/synaptic current generators' models from the literature and we propose an original computational model, based on fractional dynamics.
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http://dx.doi.org/10.1016/j.neuroscience.2016.12.013DOI Listing
February 2017

A functional magnetic resonance imaging investigation of theory of mind impairments in patients with temporal lobe epilepsy.

Neuropsychologia 2016 Dec 12;93(Pt A):271-279. Epub 2016 Nov 12.

Epilepsy Unit, Department of Clinical Neurophysiology, Lille University Medical Center, Lille, France; Vascular and Degenerative Cognitive Disorders Research Unit (INSERM U-1171), University of Lille 2, Lille, France.

Although patients with mesial temporal lobe epilepsy (mTLE) are known to have theory of mind (ToM) impairments, the latter's neural functional bases have yet to be explored. We used functional magnetic resonance imaging (fMRI) to gain insights into the neural dysfunction associated with ToM impairments in patients with mTLE. Twenty-five patients (12 and 13 with right and left mTLE, respectively) and 25 healthy controls performed the "animated shapes" task during fMRI. This complex ToM task requires both explicit reasoning about mental states and implicit processing of information on biological motion and action. The animated shapes evoke both ToM and non-ToM interaction perception, and the corresponding neural activation patterns were compared. Behavioral performance (i.e. categorization of the interactions) was also recorded. Relative to healthy controls, both patients with right and left mTLE were impaired in categorizing ToM interactions. The fMRI results showed that both patients with right and left mTLE had less intense neural activation (relative to controls) in regions involved in the implicit component of ToM processes (i.e. the fusiform gyrus in patients with right mTLE and the supplementary motor area in patients with left mTLE). In patients with right mTLE, we also observed more intense activation (relative to controls) in regions involved in the explicit component of ToM processes (i.e. the dorsal medial prefrontal cortex); age at onset of epilepsy also mediated activation in regions involved in the explicit component (i.e. the ventral medial prefrontal cortex and the temporoparietal junction). Patients with left mTLE displayed greater activation of the contralateral mesial regions (relative to controls); we speculate that this may correspond to the deployment of a compensatory mechanism. This study provides insights into the disturbances of the implicit/explicit ToM neural network in patients with mTLE. These impairments in the ToM neural network depend on clinical characteristics, such as the laterality (right or left mTLE) and the age at onset of epilepsy.
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http://dx.doi.org/10.1016/j.neuropsychologia.2016.11.007DOI Listing
December 2016

Ictal changes in parasympathetic tone: Prediction of postictal oxygen desaturation.

Neurology 2015 Oct 4;85(14):1233-9. Epub 2015 Sep 4.

From the Epilepsy Unit (W.S., A.-C.T., P.D., L.T.), INSERM CIC-IT 1403 (R.L., J.D.J.), Department of Nuclear Medicine and Molecular Imaging (F.S.), Lille University Medical Center; INSERM U1171 (W.S., P.D., L.T., F.S.), University of Lille, France; and the Department of Clinical Neuroscience (P.R.), Lausanne, Switzerland.

Objective: To measure changes in parasympathetic tone before, during, and after temporal seizures, and to determine whether changes in high-frequency heart rate variability are correlated with postictal oxygen desaturation.

Methods: We recorded the electrocardiogram and peripheral oxygen saturation during 55 temporal lobe seizures and calculated a high-frequency variability index (HFVI) as a marker of parasympathetic tone for periods of 20 minutes (centered on seizure onset). We then compared HFVI values in seizures with and without postictal hypoxemia, and looked for correlations between HFVI changes and the risk of sudden unexpected death in epilepsy (SUDEP) (as assessed with the SUDEP-7 Inventory).

Results: Parasympathetic tone decreased rapidly at the onset of temporal lobe seizures, reached its minimum value at the end of the seizure, and then gradually returned to its preictal value. Changes in parasympathetic tone were more intense and longer-lasting in older patients with a longer duration of epilepsy. The HFVI was significantly lower during seizures with hypoxemia, and remained significantly lower 5 minutes after the end of the seizure. The change in the HFVI slope over the first 30 seconds of the seizure was predictive of postictal oxygen desaturation. Postictal autonomic changes were correlated with the SUDEP-7 scores.

Conclusion: Our results showed that ictal autonomic dysfunction is correlated with postictal hypoxemia. A prolonged impairment of parasympathetic tone might expose a patient to a greater risk of postictal sudden unexpected death. The real-time measurement of parasympathetic tone in patients with epilepsy may be of value to medical staff as an early warning system.
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http://dx.doi.org/10.1212/WNL.0000000000001994DOI Listing
October 2015

Characterization and prediction of the recognition of emotional faces and emotional bursts in temporal lobe epilepsy.

J Clin Exp Neuropsychol 2015 ;37(9):931-45

a Epilepsy Unit, Department of Clinical Neurophysiology , Lille University Medical Center , Lille , France.

Introduction: The present study sought to characterize and predict the recognition of emotional stimuli (presented in a visual or auditory modality) by patients with temporal lobe epilepsy (TLE).

Method: Fifty TLE patients and 50 matched controls performed two emotion recognition tasks (emotional faces and emotional bursts). Neutral stimuli were also presented, and emotional biases were monitored by analyzing errors. Demographic, cognitive, psychobehavioral and (in TLE patients only) clinical and quality of life data were also recorded.

Results: Compared with controls, TLE patients were impaired in the recognition of fear expressions in both visual and auditory modality tasks. However, impairments in the two channels were not always concomitant on the individual level. In the visual modality, recognition of disgust and neutral expressions was significantly worse in TLE patients. In the auditory modality, nonsignificant trends toward poor recognition of disgust and neutral expressions were observed. Negative biases were noted in TLE patients; expressions of fear (faces and bursts) were more frequently misinterpreted as disgust, and neutral facial expressions were more frequently misinterpreted as sadness. Impairments in the recognition of facial fear were less pronounced in left TLE patients who (according to structural magnetic resonance imaging, MRI) did not have any brain lesions. In TLE patients, low levels of social support (a quality of life parameter) were associated with worse recognition of facial disgust, and higher levels of apathy were associated with better recognition of neutral faces.

Conclusions: TLE patients are impaired in some aspects of emotion recognition with both visual and auditory stimuli, although the differential impact of TLE on these modalities requires further research. These emotional impairments are related to quality of life and psychobehavioral parameters.
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http://dx.doi.org/10.1080/13803395.2015.1068280DOI Listing
June 2016

Use of emergency departments by known epileptic patients: An underestimated problem?

Epilepsy Res 2015 Jul 9;113:1-4. Epub 2015 Mar 9.

Department of Clinical Neurophysiology, EA 1046, University of Lille Nord de France, Lille, France. Electronic address:

Background And Purpose: Seizure is a frequent reason of admission in emergency department (ED) but little is known about the proportion and the characteristics of known epileptic patients (KEPs) who used emergency services.

Methods: Over a 12-month period, we prospectively recruited adults admitted for seizure to a tertiary hospital ED. For KEPs, clinical epilepsy features and characteristics of the admission were collected.

Results: Of the 60,578 ED admissions, 990 were related to seizure; 580 of these admissions concerned 448 different KEPs (257 males; median age: 44); 339 were residents in the health district. Epilepsy was structural/metabolic in 268 (59.8%) patients, genetic in 44 (9.8%) and unknown/undetermined in 136 (30.3%); 218 (48.7%) patients were under a single antiepileptic drug and 135 (30.1%) were followed by an epileptologist. Of the 580 KEP admissions, 440 (75.8%) concerned patients who had called the emergency medical assistance number, 252 (43.4%) with a discharge diagnosis of usual seizure and 43 (7.4%) of a status epilepticus. Half the KEPs were discharged without hospitalization. We estimated that 9.0% of KEPs residing in the district had used the ED during the period.

Conclusion: Proportion of KEPs using ED is high. Most of the admissions concerned usual seizures suggesting that staff training and educational programmes for patients and for their relatives need to be improved. The organization of the prehospital and of the emergency medical services should also be adjusted to this specific need. Further research should be conducted to optimize the seizure care pathway for KEPs.
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http://dx.doi.org/10.1016/j.eplepsyres.2015.02.017DOI Listing
July 2015

[Drug Shortage May Have Serious Outcome: the French Exemple of Phenytoine].

Therapie 2015 Jul-Aug;70(4):377-80. Epub 2015 Apr 16.

Centre Régional de Pharmacovigilance, CHRU, Lille, France.

In 2012, in France, phenytoin sodium was used as a substitute for phenytoin base during a shortage at the dose of 100 mg for 100 mg, according to the French Health Agency recommendations. However, this substitution was problematic because the two specialties were not bioequivalent. We report here the case of a 29-year old woman who presented with severe epilepsy. The substitution of phenytoin base by phenytoin sodium induced an increase of seizure frequency leading to several hospitalizations and sick leave. Phenytoin base was finally available again in 2013 which allowed a reduction of seizure frequency. Six similar cases, including one death, were reported to the French pharmacovigilance system. Drug shortages are increasingly common and can have serious consequences. Reporting the difficulties that drug shortage causes to health authorities is important in order to improve their management and to better support patients.
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http://dx.doi.org/10.2515/therapie/2015018DOI Listing
August 2015

Arousal in response to neutral pictures is modified in temporal lobe epilepsy.

Epilepsy Behav 2015 Apr 17;45:15-20. Epub 2015 Mar 17.

EA 1046 Vascular and Degenerative Cognitive Disorders Research Unit, Lille North of France University, Lille, France; Memory Resource and Research Centre, Lille University Medical Center, Lille, France.

The objectives of the present study were to (i) better characterize visual emotional experience in patients with temporal lobe epilepsy (TLE), (ii) identify clinical risk factors that might be predictive of a change in emotional experience, and (iii) study the relationships between emotional experience and psychobehavioral/quality-of-life factors. Fifty patients with TLE and fifty matched controls evaluated the emotional content of unpleasant, pleasant, and neutral pictures with respect to their valence (unpleasant-to-pleasant) and arousal (low-to-high) levels. Demographic, cognitive, and psychobehavioral data were recorded for all participants, and clinical data and factors related to quality of life were also collected for patients with TLE. There were no significant differences between the group with TLE and the control group in terms of valence evaluations. However, arousal scores for neutral pictures were significantly higher in patients with TLE than in controls. There was also a nonsignificant trend towards lower arousal scores for pleasant pictures in patients with TLE than in controls. Although none of the recorded clinical factors were found to be related to emotional experience, the level of apathy was predictive of greater arousal experience for neutral pictures in patients with TLE. In conclusion, emotional experience appears to be modified in TLE and might be related to apathy. Changes in emotional experience should be taken into account in studies in which neutral stimuli are used to establish a baseline level when assessing emotional and cognitive processing.
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http://dx.doi.org/10.1016/j.yebeh.2015.02.005DOI Listing
April 2015

Study on the Relationships between Intrinsic Functional Connectivity of the Default Mode Network and Transient Epileptic Activity.

Front Neurol 2014 10;5:201. Epub 2014 Oct 10.

UMR 1046, University of Lille 2 , Lille , France ; Department of Clinical Neurophysiology, Lille University Medical Center , Lille , France.

Rationale: Simultaneous recording of electroencephalogram and functional MRI (EEG-fMRI) is a powerful tool for localizing epileptic networks via the detection of hemodynamic changes correlated with interictal epileptic discharges (IEDs). fMRI can be used to study the long-lasting effect of epileptic activity by assessing stationary functional connectivity during the resting-state period [especially, the connectivity of the default mode network (DMN)]. Temporal lobe epilepsy (TLE) and idiopathic generalized epilepsy (IGE) are associated with low responsiveness and disruption of DMN activity. A dynamic functional connectivity approach might enable us to determine the effect of IEDs on DMN connectivity and to better understand the correlation between DMN connectivity changes and altered consciousness.

Method: We studied dynamic changes in DMN intrinsic connectivity and their relation to IEDs. Six IGE patients (with generalized spike and slow-waves) and 6 TLE patients (with unilateral left temporal spikes) were included. Functional connectivity before, during, and after IEDs was estimated using a sliding window approach and compared with the baseline period.

Results: No dependence on window size was observed. The baseline DMN connectivity was decreased in the left hemisphere (ipsilateral to the epileptic focus) in TLEs and was less strong but remained bilateral in IGEs. We observed an overall increase in DMN intrinsic connectivity prior to the onset of IEDs in both IGEs and TLEs. After IEDs in TLEs, we found that DMN connectivity increased before it returned to baseline values. Most of the DMN regions with increased connectivity before and after IEDs were lateralized to the left hemisphere in TLE (i.e., ipsilateral to the epileptic focus).

Conclusion: RESULTS suggest that DMN connectivity may facilitate IED generation and may be affected at the time of the IED. However, these results need to be confirmed in a larger independent cohort.
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http://dx.doi.org/10.3389/fneur.2014.00201DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4193009PMC
October 2014

Intra-subject reliability of the high-resolution whole-brain structural connectome.

Neuroimage 2014 Nov 7;102 Pt 2:283-93. Epub 2014 Aug 7.

Department of Clinical Neurophysiology, Lille University Hospital, France; UMR 1046, University of Lille, France.

Recent advances in diffusion weighted image acquisition and processing allow for the construction of anatomically highly precise structural connectomes. In this study, we introduce a method to compute high-resolution whole-brain structural connectome. Our method relies on cortical and subcortical triangulated surface models, and on a large number of fiber tracts generated using a probabilistic tractography algorithm. Each surface triangle is a node of the structural connectivity graph while edges are fiber tract densities across pairs of nodes. Surface-based registration and downsampling to a common surface space are introduced for group analysis whereas connectome surface smoothing aimed at improving whole-brain network estimate reliability. Based on 10 datasets acquired from a single healthy subject, we evaluated the effects of repeated probabilistic tractography, surface smoothing, surface registration and downsampling to the common surface space. We show that, provided enough fiber tracts and surface smoothing, good to excellent intra-acquisition reliability could be achieved. Surface registration and downsampling efficiently established triangle-to-triangle correspondence across acquisitions and high inter-acquisition reliability was obtained. Computational time and disk/memory usages were monitored throughout the steps. Although further testing on large cohort of subjects is required, our method presents the potential to accurately model whole-brain structural connectivity at high-resolution.
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http://dx.doi.org/10.1016/j.neuroimage.2014.07.064DOI Listing
November 2014

Characterization and prediction of theory of mind disorders in temporal lobe epilepsy.

Neuropsychology 2015 May 28;29(3):485-92. Epub 2014 Jul 28.

Epilepsy Unit, Department of Clinical Neurophysiology, Lille University Medical Center.

Objective: Patients with temporal lobe epilepsy (TLE) have impaired theory of mind (ToM). However, ToM involves a variety of processes, such as understanding a person's intentions ("cognitive" ToM) and emotional states ("affective" ToM). The objectives of the present study were to characterize ToM disorders in TLE patients, identify patients at risk of ToM disorders, and study the relationships between psychobehavioral and quality of life factors and ToM disorders.

Method: Fifty TLE patients and 50 controls performed ToM tasks assessing their understanding of verbal clumsiness (faux pas), sarcastic remarks, and mentalistic actions. Demographic, cognitive, and psychobehavioral data, and (for TLE patients) clinical and quality of life factors, were recorded.

Results: Compared with controls, TLE patients showed impairments in all ToM tasks: 84% misunderstood faux pas, and around 50% misunderstood sarcasm. A long duration of epilepsy and young age at onset were risk factors for ToM impairments. In TLE patients, ToM impairments were associated with impaired empathy and anhedonia. Their affective states were less positively and more negatively valenced than in controls. Low positive affectivity was predictive of greater cognitive and affective ToM impairments for the faux pas task, and high negative affectivity was predictive of greater cognitive ToM abilities for the sarcasm task. The lack of social support was correlated with impaired ToM but was not a predictive factor.

Conclusions: Both cognitive and affective ToM processes are impaired in TLE patients. Impaired ToM has an impact on empathy abilities and is related to affective disturbances in TLE patients.
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http://dx.doi.org/10.1037/neu0000126DOI Listing
May 2015

Functional magnetic resonance imaging suggests automatization of the cortical response to inspiratory threshold loading in humans.

Respir Physiol Neurobiol 2013 Dec 27;189(3):571-80. Epub 2013 Aug 27.

Department of Experimental Medicine, Transcranial Magnetic Stimulation Laboratory McGill University Health Centre, Montréal, QC, Canada; Université Paris 6, ER10UPMC Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France; Assistance Publique - Hôpitaux de Paris, Département d'Anesthésie Réanimation, Groupe Hospitalier Pitié-Salpêtrière, Paris, France.

Inspiratory threshold loading (ITL) induces cortical activation. It is sustained over time and is resistant to distraction, suggesting automaticity. We hypothesized that ITL-induced changes in cerebral activation may differ between single-breath ITL and continuous ITL, with differences resembling those observed after cortical automatization of motor tasks. We analyzed the brain blood oxygen level dependent (BOLD) signal of 11 naive healthy volunteers during 5 min of random, single-breath ITL and 5 min of continuous ITL. Single-breath ITL increased BOLD in many areas (premotor cortices, bilateral insula, cerebellum, reticular formation of the lateral mesencephalon) and decreased BOLD in regions co-localizing with the default mode network. Continuous ITL induced signal changes in a limited number of areas (supplementary motor area). These differences are comparable to those observed before and after overlearning of motor tasks. We conclude that the respiratory-related cortical activation observed in response to ITL is likely due to automated, attention-independent mechanisms. Also, ITL activates cortical circuits right from the first breath.
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http://dx.doi.org/10.1016/j.resp.2013.08.005DOI Listing
December 2013

Epileptic discharges affect the default mode network--FMRI and intracerebral EEG evidence.

PLoS One 2013 28;8(6):e68038. Epub 2013 Jun 28.

Montreal Neurological Institute, McGill University, Montréal, Québec, Canada.

Functional neuroimaging studies of epilepsy patients often show, at the time of epileptic activity, deactivation in default mode network (DMN) regions, which is hypothesized to reflect altered consciousness. We aimed to study the metabolic and electrophysiological correlates of these changes in the DMN regions. We studied six epilepsy patients that underwent scalp EEG-fMRI and later stereotaxic intracerebral EEG (SEEG) sampling regions of DMN (posterior cingulate cortex, Pre-cuneus, inferior parietal lobule, medial prefrontal cortex and dorsolateral frontal cortex) as well as non-DMN regions. SEEG recordings were subject to frequency analyses comparing sections with interictal epileptic discharges (IED) to IED-free baselines in the IED-generating region, DMN and non-DMN regions. EEG-fMRI and SEEG were obtained at rest. During IEDs, EEG-fMRI demonstrated deactivation in various DMN nodes in 5 of 6 patients, most frequently the pre-cuneus and inferior parietal lobule, and less frequently the other DMN nodes. SEEG analyses demonstrated decrease in gamma power (50-150 Hz), and increase in the power of lower frequencies (<30 Hz) at times of IEDs, in at least one DMN node in all patients. These changes were not apparent in the non-DMN regions. We demonstrate that, at the time of IEDs, DMN regions decrease their metabolic demand and undergo an EEG change consisting of decreased gamma and increased lower frequencies. These findings, specific to DMN regions, confirm in a pathological condition a direct relationship between DMN BOLD activity and EEG activity. They indicate that epileptic activity affects the DMN, and therefore may momentarily reduce the consciousness level and cognitive reserve.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0068038PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3695970PMC
April 2014

Understanding the epileptogenicity of lesions: a correlation between intracranial EEG and EEG/fMRI.

Epilepsia 2010 Feb;51 Suppl 1:54-8

Montreal Neurological Institute and Hospital, Montréal, Québec, Canada.

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http://dx.doi.org/10.1111/j.1528-1167.2009.02447.xDOI Listing
February 2010