Single-cell genotyping and transcriptomic proling in focal cortical dysplasia

Focal cortical dysplasia type II (FCDII) is a cortical malformation causing refractory epilepsy. FCDII arises from developmental somatic mutations in mTOR pathway genes, leading to focal cortical dyslamination and abnormal cytomegalic cells. Which cell types carry pathogenic mutations and how they affect cell-type-specific transcriptional programs remains unknown. To address this question, here we combined single-nucleus genotyping and transcriptomics in morphologically-identified cells using surgical cortical samples from genetically-characterized FCDII patients. Mutations were predominantly detected in glutamatergic neurons and astrocytes and only a small fraction of mutated cells exhibited cytomegalic features, revealing incomplete penetrance of FCDII-causing mutations. Moreover, we identified cell-type-specific transcriptional dysregulations in both mutated and non-mutated FCDII cells, including synapse and neurodevelopment-related pathways, that may account for epilepsy, and dysregulation of mitochondrial metabolism pathways in cytomegalic cells. Together, these findings reveal cell-autonomous and non-cell-autonomous mechanisms at play in FCDII, towards the development of precision therapies for this disorder

Somatic variant analysis of resected brain tissue in epilepsy surgery patients

We studied the distribution of germline and somatic variants in epilepsy surgery patients with (suspected) malformations of cortical development (MCD) who underwent surgery between 2015 and 2020 at University Medical Center Utrecht (the Netherlands) and pooled our data with four previously published cohort studies. Tissue analysis yielded a pathogenic variant in 203 of 663 (31%) combined cases. In 126 of 379 (33%) focal cortical dysplasia (FCD) type II cases and 23 of 37 (62%) hemimegalencephaly cases, a pathogenic variant was identified, mostly involving the mTOR signaling pathway. Pathogenic variants in 10 focal epilepsy genes were found in 48 of 178 (27%) FCDI/mild MCD/mMCD with oligodendroglial hyperplasia and epilepsy cases; 36 of these (75%) were SLC35A2 variants. Six of 69 (9%) patients without a histopathological lesion had a pathogenic variant in SLC35A2 (n = 5) or DEPDC5 (n = 1). A germline variant in blood DNA was confirmed in all cases with a pathogenic variant in tissue, with a variant allele frequency (VAF) of ~50%. In seven of 114 patients (6%) with a somatic variant in tissue, mosaicism in blood was detected. More than half of pathogenic somatic variants had a VAF < 5%. Further analysis of the correlation between genetic variants and surgical outcomes will improve patient counseling and may guide postoperative treatment decisions

Outcome of Epilepsy Surgery in MRI-Negative Patients Without Histopathologic Abnormalities in the Resected Tissue

BACKGROUND AND OBJECTIVE: Patients with presumed nonlesional focal epilepsy-based on either MRI or histopathologic findings-have a lower success rate of epilepsy surgery compared with lesional patients. In this study, we aimed to characterize a large group of patients with focal epilepsy who underwent epilepsy surgery despite a normal MRI and had no lesion on histopathology. Determinants of their postoperative seizure outcomes were further studied. METHODS: We designed an observational multicenter cohort study of MRI-negative and histopathology-negative patients who were derived from the European Epilepsy Brain Bank and underwent epilepsy surgery between 2000 and 2012 in 34 epilepsy surgery centers within Europe. We collected data on clinical characteristics, presurgical assessment, including genetic testing, surgery characteristics, postoperative outcome, and treatment regimen. RESULTS: Of the 217 included patients, 40% were seizure-free (Engel I) 2 years after surgery and one-third of patients remained seizure-free after 5 years. Temporal lobe surgery (adjusted odds ratio [AOR]: 2.62; 95% CI 1.19-5.76), shorter epilepsy duration (AOR for duration: 0.94; 95% CI 0.89-0.99), and completely normal histopathologic findings-versus nonspecific reactive gliosis-(AOR: 4.69; 95% CI 1.79-11.27) were significantly associated with favorable seizure outcome at 2 years after surgery. Of patients who underwent invasive monitoring, only 35% reached seizure freedom at 2 years. Patients with parietal lobe resections had lowest seizure freedom rates (12.5%). Among temporal lobe surgery patients, there was a trend toward favorable outcome if hippocampectomy was part of the resection strategy (OR: 2.94; 95% CI 0.98-8.80). Genetic testing was only sporadically performed. DISCUSSION: This study shows that seizure freedom can be reached in 40% of nonlesional patients with both normal MRI and histopathology findings. In particular, nonlesional temporal lobe epilepsy should be regarded as a relatively favorable group, with almost half of patients achieving seizure freedom at 2 years after surgery-even more if the hippocampus is resected-compared with only 1 in 5 nonlesional patients who underwent extratemporal surgery. Patients with an electroclinically identified focus, who are nonlesional, will be a promising group for advanced molecular-genetic analysis of brain tissue specimens to identify new brain somatic epilepsy genes or epilepsy-associated molecular pathways

Outcome of Epilepsy Surgery in MRI-Negative Patients Without Histopathologic Abnormalities in the Resected Tissue

Background and Objective Patients with presumed nonlesional focal epilepsy - based on either MRI or histopathologic findings - have a lower success rate of epilepsy surgery compared with lesional patients. In this study, we aimed to characterize a large group of patients with focal epilepsy who underwent epilepsy surgery despite a normal MRI and had no lesion on histopathology. Determinants of their postoperative seizure outcomes were further studied. Methods We designed an observational multicenter cohort study of MRI-negative and histopathology-negative patients who were derived from the European Epilepsy Brain Bank and underwent epilepsy surgery between 2000 and 2012 in 34 epilepsy surgery centers within Europe. We collected data on clinical characteristics, presurgical assessment, including genetic testing, surgery characteristics, postoperative outcome, and treatment regimen. Results Of the 217 included patients, 40% were seizure-free (Engel I) 2 years after surgery and one-third of patients remained seizure-free after 5 years. Temporal lobe surgery (adjusted odds ratio [AOR]: 2.62; 95% CI 1.19-5.76), shorter epilepsy duration (AOR for duration: 0.94; 95% CI 0.89-0.99), and completely normal histopathologic findings - versus nonspecific reactive gliosis - (AOR: 4.69; 95% CI 1.79-11.27) were significantly associated with favorable seizure outcome at 2 years after surgery. Of patients who underwent invasive monitoring, only 35% reached seizure freedom at 2 years. Patients with parietal lobe resections had lowest seizure freedom rates (12.5%). Among temporal lobe surgery patients, there was a trend toward favorable outcome if hippocampectomy was part of the resection strategy (OR: 2.94; 95% CI 0.98-8.80). Genetic testing was only sporadically performed. Discussion This study shows that seizure freedom can be reached in 40% of nonlesional patients with both normal MRI and histopathology findings. In particular, nonlesional temporal lobe epilepsy should be regarded as a relatively favorable group, with almost half of patients achieving seizure freedom at 2 years after surgery - even more if the hippocampus is resected - compared with only 1 in 5 nonlesional patients who underwent extratemporal surgery. Patients with an electroclinically identified focus, who are nonlesional, will be a promising group for advanced molecular-genetic analysis of brain tissue specimens to identify new brain somatic epilepsy genes or epilepsy-associated molecular pathways

Propriétés fonctionnelles des réseaux et des neurones corticaux chez l'homme et l'animal atteints d'épilepsie-absence : études électrophysiologiques in vivo

Absence epilepsy is an epileptic syndrome which main symptom is a transient alteration of consciousness, with generalized spike-and-wave discharges in EEG, which arise from a dysfunction in the corticothalamic loop and are initiated from a subclass of pyramidal neurons located in the deep layers of the somatosensory cortex. I have investigated two unresolved, issues: 1/ the role of the cortical inhibition in the ictogenic processes, 2/ the neurophysiological mechanisms of sensory processing during absence seizures. By the means of EEG and intracellular recordings in vivo in an animal model: the Genetic Absence Epilepsy Rats from Strasbourg (GAERS), I have examined how the early excitation in theictogenic neurons during seizures was shortly followed by a chlore-dependent synaptic hyperpolarization, concomitant with bursting activities in local GABAergic interneurons. The GABA system has an active inhibitory effect, which constraints the firing of ictogenic neurons within a tight temporal window. In a second study, in human and GAERS, I explored how sensory information was processed during SWDs. In the epileptic child, visual stimulations resulted in occipital evoked potentials, bigger than in non-epileptic subjects. Tactile stimulation of the GAERS applied during seizures induced cortical evoked potentials, reflected in the pyramidal neurons by excitatory synaptic potentials bigger than in interictal condition. Impairment of consciousness during absences do not result from a filtering of sensory information. These researches provide new information on the functional properties of the cortical circuits expressing the electrical paroxysms during absence seizuresL'épilepsie-absence est un syndrome épileptique dont le principal symptôme est une altération transitoire de la conscience, avec décharges pointes-ondes généralisées, qui ont pour origine un dysfonctionnement dans la boucle cortico-thalamique, et naissant dans une sous-population de neurones pyramidaux localisée dans les couches profondes du cortex somatosensoriel. A l'aide d'enregistrements EEG et intracellulaires in vivo dans un modèle animal: les Genetic Absence Epilepsy Rats from Strasbourg, j'ai examiné comment l'excitation initiale des neurones ictogèniques lors des crises est suivie par une hyperpolarisation synaptique chlore-dépendante, concomitante d'une décharge en bouffées dans les interneurones GABAergiques locaux. Le système GABA exerce un effet strictement inhibiteur et contraint la décharge des neurones ictogéniques dans une fenêtre temporelle étroite. Dans une deuxième étude chez l'homme et chez le GAERS, j'ai exploré comment des informations sensorielles sont traitées au cours des DPO. Chez l'enfant épileptique, des stimulations visuelles résultent en des potentiels évoqués occipitaux, plus amples que chez les sujets non-épileptiques. Des stimulations tactiles chez le GAERS induisent lors des crises des potentiels évoqués dans l'EEG et, dans les neurones pyramidaux sous-jacents, des potentiels synaptiques excitateurs plus amples que dans la condition inter-critique. Les troubles de la conscience lors des absences ne résultent donc pas d'un filtrage des informations sensorielles. L'ensemble des recherches fournit des données nouvelles sur les propriétés fonctionnelles des circuits corticaux exprimant les paroxysmes électriques lors des crises d'absenc

Propriétés fonctionnelles des réseaux et des neurones corticaux chez l'homme et l'animal atteints d'épilepsie-absence : études électrophysiologiques in vivo

Absence epilepsy is an epileptic syndrome which main symptom is a transient alteration of consciousness, with generalized spike-and-wave discharges in EEG, which arise from a dysfunction in the corticothalamic loop and are initiated from a subclass of pyramidal neurons located in the deep layers of the somatosensory cortex. I have investigated two unresolved, issues: 1/ the role of the cortical inhibition in the ictogenic processes, 2/ the neurophysiological mechanisms of sensory processing during absence seizures. By the means of EEG and intracellular recordings in vivo in an animal model: the Genetic Absence Epilepsy Rats from Strasbourg (GAERS), I have examined how the early excitation in theictogenic neurons during seizures was shortly followed by a chlore-dependent synaptic hyperpolarization, concomitant with bursting activities in local GABAergic interneurons. The GABA system has an active inhibitory effect, which constraints the firing of ictogenic neurons within a tight temporal window. In a second study, in human and GAERS, I explored how sensory information was processed during SWDs. In the epileptic child, visual stimulations resulted in occipital evoked potentials, bigger than in non-epileptic subjects. Tactile stimulation of the GAERS applied during seizures induced cortical evoked potentials, reflected in the pyramidal neurons by excitatory synaptic potentials bigger than in interictal condition. Impairment of consciousness during absences do not result from a filtering of sensory information. These researches provide new information on the functional properties of the cortical circuits expressing the electrical paroxysms during absence seizuresL'épilepsie-absence est un syndrome épileptique dont le principal symptôme est une altération transitoire de la conscience, avec décharges pointes-ondes généralisées, qui ont pour origine un dysfonctionnement dans la boucle cortico-thalamique, et naissant dans une sous-population de neurones pyramidaux localisée dans les couches profondes du cortex somatosensoriel. A l'aide d'enregistrements EEG et intracellulaires in vivo dans un modèle animal: les Genetic Absence Epilepsy Rats from Strasbourg, j'ai examiné comment l'excitation initiale des neurones ictogèniques lors des crises est suivie par une hyperpolarisation synaptique chlore-dépendante, concomitante d'une décharge en bouffées dans les interneurones GABAergiques locaux. Le système GABA exerce un effet strictement inhibiteur et contraint la décharge des neurones ictogéniques dans une fenêtre temporelle étroite. Dans une deuxième étude chez l'homme et chez le GAERS, j'ai exploré comment des informations sensorielles sont traitées au cours des DPO. Chez l'enfant épileptique, des stimulations visuelles résultent en des potentiels évoqués occipitaux, plus amples que chez les sujets non-épileptiques. Des stimulations tactiles chez le GAERS induisent lors des crises des potentiels évoqués dans l'EEG et, dans les neurones pyramidaux sous-jacents, des potentiels synaptiques excitateurs plus amples que dans la condition inter-critique. Les troubles de la conscience lors des absences ne résultent donc pas d'un filtrage des informations sensorielles. L'ensemble des recherches fournit des données nouvelles sur les propriétés fonctionnelles des circuits corticaux exprimant les paroxysmes électriques lors des crises d'absenc

Utilisation néonatale des prostaglandines E1 dans la prise en charge des cardiopathies congénitales en réanimation médicale pédiatrique (à propos de 62 cas)

NANCY1-SCD Medecine (545472101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Propriétés fonctionnelles des réseaux et des neurones corticaux chez l'homme et l'animal atteints d'épilepsie-absence (études électrophysiologiques in vivo)

L épilepsie-absence est un syndrome épileptique dont le principal symptôme est une altération transitoire de la conscience, avec décharges pointes-ondes généralisées, qui ont pour origine un dysfonctionnement dans la boucle cortico-thalamique, et naissant dans une sous-population de neurones pyramidaux localisée dans les couches profondes du cortex somatosensoriel. A l aide d enregistrements EEG et intracellulaires in vivo dans un modèle animal: les Genetic Absence Epilepsy Rats from Strasbourg, j ai examiné comment l excitation initiale des neurones ictogèniques lors des crises est suivie par une hyperpolarisation synaptique chlore-dépendante, concomitante d une décharge en bouffées dans les interneurones GABAergiques locaux. Le système GABA exerce un effet strictement inhibiteur et contraint la décharge des neurones ictogéniques dans une fenêtre temporelle étroite. Dans une deuxième étude chez l homme et chez le GAERS, j ai exploré comment des informations sensorielles sont traitées au cours des DPO. Chez l enfant épileptique, des stimulations visuelles résultent en des potentiels évoqués occipitaux, plus amples que chez les sujets non-épileptiques. Des stimulations tactiles chez le GAERS induisent lors des crises des potentiels évoqués dans l EEG et, dans les neurones pyramidaux sous-jacents, des potentiels synaptiques excitateurs plus amples que dans la condition inter-critique. Les troubles de la conscience lors des absences ne résultent donc pas d un filtrage des informations sensorielles. L ensemble des recherches fournit des données nouvelles sur les propriétés fonctionnelles des circuits corticaux exprimant les paroxysmes électriques lors des crises d absenceAbsence epilepsy is an epileptic syndrome which main symptom is a transient alteration of consciousness, with generalized spike-and-wave discharges in EEG, which arise from a dysfunction in the corticothalamic loop and are initiated from a subclass of pyramidal neurons located in the deep layers of the somatosensory cortex. I have investigated two unresolved, issues: 1/ the role of the cortical inhibition in the ictogenic processes, 2/ the neurophysiological mechanisms of sensory processing during absence seizures. By the means of EEG and intracellular recordings in vivo in an animal model: the Genetic Absence Epilepsy Rats from Strasbourg (GAERS), I have examined how the early excitation in theictogenic neurons during seizures was shortly followed by a chlore-dependent synaptic hyperpolarization, concomitant with bursting activities in local GABAergic interneurons. The GABA system has an active inhibitory effect, which constraints the firing of ictogenic neurons within a tight temporal window. In a second study, in human and GAERS, I explored how sensory information was processed during SWDs. In the epileptic child, visual stimulations resulted in occipital evoked potentials, bigger than in non-epileptic subjects. Tactile stimulation of the GAERS applied during seizures induced cortical evoked potentials, reflected in the pyramidal neurons by excitatory synaptic potentials bigger than in interictal condition. Impairment of consciousness during absences do not result from a filtering of sensory information. These researches provide new information on the functional properties of the cortical circuits expressing the electrical paroxysms during absence seizuresPARIS-BIUSJ-Biologie recherche (751052107) / SudocSudocFranceF

Electrophysiological technical procedures

International audienceThe reliability of the interpretation of SEEG data depends entirely on the technical quality of the acquisition recording. Digitalization of data and the development of computer technology, over the last 20 years have transformed electrophysiological procedures. Recording equipment must be able to record concomitantly clinical events and brain electrical activity. Recording is carried out during wakefulness and sleep and with use of various activation methods (hyperventilation, intermittent photic stimulation). Intracerebral electrical stimulations (with low and high frequency) and the acquisition of evoked potentials complete the SEEG exploration. This chapter will discuss the characteristics of video-EEG recording equipment, procedures for acquisition and creation of SEEG montages, technical recording and activations, procedures of intracerebral electrical stimulations and the acquisition of evoked potentials