Publications by authors named "Chipaux M"

Objective: Management of ketogenic diet (KD) in case of prolonged anesthesia in children.

Methods: We conducted a retrospective study in the pediatric neurosurgery department of Rothschild Hospital Foundation in France. All the children who underwent long term anesthesia (>4h) in case of neurosurgery for drug resistant pediatric epilepsy surgery between September 2020 and January 2024 were included, excluding patients with suspected metabolic disorder or without blood sample.

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Lesional focal epilepsy (LFE) is a common and severe seizure disorder caused by epileptogenic lesions, including malformations of cortical development (MCD) and low-grade epilepsy-associated tumors (LEAT). Understanding the genetic etiology of these lesions can inform medical and surgical treatment. We conducted a somatic variant enrichment mega-analysis in brain tissue from 1386 individuals who underwent epilepsy surgery, including 599 previously unpublished individuals with ultra-deep ( > 1600x) targeted panel sequencing.

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Article Synopsis
  • * A pathogenic variant was found in 31% of the total cases analyzed, with higher rates in specific conditions like focal cortical dysplasia type II (33%) and hemimegalencephaly (62%), particularly involving the mTOR signaling pathway.
  • * The identification of germline and somatic variants, especially in focal epilepsy genes, provides insights for future analyses on genetic factors related to surgical outcomes, which could enhance patient counseling and treatment plans.
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Diamond is increasingly popular because of its unique material properties. Diamond defects called nitrogen vacancy (NV) centers allow for measurements with unprecedented sensitivity. However, to achieve ideal sensing performance, NV centers need to be within nanometers from the surface and are thus strongly dependent on the local surface chemistry.

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Article Synopsis
  • The study focuses on hypothalamic hamartomas (HHs), rare brain lesions linked to difficult-to-treat epilepsy, and explores their genetic causes in a new cohort of 9 HH patients.
  • Researchers found harmful genetic variants in known HH-related genes in 7 out of 9 cases, also discovering a new two-hit mutation involving a gene related to brain development.
  • The results highlight the significance of somatic mutations in Shh and cilia signaling pathways and point to the importance of genetic testing on brain tissue for understanding epilepsy disorders.
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Cortical malformations such as focal cortical dysplasia type II (FCDII) are associated with pediatric drug-resistant epilepsy that necessitates neurosurgery. FCDII results from somatic mosaicism due to post-zygotic mutations in genes of the PI3K-AKT-mTOR pathway, which produce a subset of dysmorphic cells clustered within healthy brain tissue. Here we show a correlation between epileptiform activity in acute cortical slices obtained from human surgical FCDII brain tissues and the density of dysmorphic neurons.

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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.

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Brain-restricted somatic variants in genes of the mechanistic target of rapamycin signalling pathway cause focal epilepsies associated with focal cortical dysplasia type II. We hypothesized that somatic variants could be identified from trace tissue adherent to explanted stereoelectroencephalography electrodes used in the presurgical epilepsy workup to localize the epileptogenic zone. We investigated three paediatric patients with drug-resistant focal epilepsy subjected to neurosurgery.

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Article Synopsis
  • This study introduces a new method for Electron Paramagnetic Resonance (EPR) spectroscopy using Nitrogen-Vacancy centers in diamond instead of traditional bulky equipment.
  • By monitoring the relaxation time (T1) of these centers, researchers successfully detected interactions with a specific compound while encoding EPR spectra through a localized magnetic field gradient.
  • The new technique significantly speeds up data collection, completing full spectra in just 3 seconds compared to the 12 minutes per data point required for individual centers, and shows high sensitivity with minimal sample volume needed.
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Background And Objectives: The gene, located at chromosome Xp11.23, encodes for a uridine diphosphate-galactose transporter. We describe clinical, genetic, neuroimaging, EEG, and histopathologic findings and assess possible predictors of postoperative seizure and cognitive outcome in 47 patients with refractory epilepsy and brain somatic gene variants.

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Diamond magnetometry makes use of fluorescent defects in diamonds to convert magnetic resonance signals into fluorescence. Because optical photons can be detected much more sensitively, this technique currently holds several sensitivity world records for room temperature magnetic measurements. It is orders of magnitude more sensitive than conventional magnetic resonance imaging (MRI) for detecting magnetic resonances.

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Diamond magnetometry can provide new insights on the production of free radicals inside live cells due to its high sensitivity and spatial resolution. However, the measurements often lack intracellular context for the recorded signal. In this paper, the possible use of single-particle tracking and trajectory analysis of fluorescent nanodiamonds (FNDs) to bridge that gap is explored.

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Purpose: Corpus callosotomy is a palliative surgical procedure for patients with drug-resistant epilepsy and suffering from drop attacks, which are a source of major deterioration in quality of life and can be responsible for severe traumatic injury. The objective of this study is to identify clinical markers that would predict a better outcome in terms of drop attacks and other types of epileptic seizures.

Methods: We reviewed a retrospective series of children who underwent complete corpus callosotomy at our institution, between January 1998 and February 2019.

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Free radicals are crucial indicators for stress and appear in all kinds of pathogenic conditions, including cancer, cardiovascular diseases, and infection. However, they are difficult to detect due to their reactivity and low abundance. We use relaxometry for the detection of radicals with subcellular resolution.

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Focal seizure semiology is often inadequately studied, specifically in preschool children. Among drug-resistant epilepsies amenable to surgery, temporal lobe seizure semiology has been widely described in this age group. Nevertheless, a systematic anatomo-electroclinical study has never been performed.

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Free radicals play a vital role in all kinds of biological processes including immune responses. However, free radicals have short lifetimes and are highly reactive, making them difficult to measure using current methods. Here, we demonstrate that relaxometry measurement, or T1, inherited from the field of diamond magnetometry can be used to detect free radicals in living cells with subcellular resolution.

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Article Synopsis
  • Brain mosaic mutations contribute significantly to severe focal epilepsies linked to various cortical malformations.
  • Researchers collected cerebrospinal fluid (CSF) during surgery to identify somatic variants in cell-free DNA (cfDNA) using a specialized testing method.
  • Evidence showed that in 3 out of 12 patients with known brain mutations, these mutations could also be detected in cfDNA from CSF, indicating a new potential way to diagnose the causes of epilepsy.
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Purpose: Interictal positron emission tomography (PET) with F-FDG has largely proved its utility in presurgical evaluation of drug-resistant epilepsies (DRE) and in the surgical outcomes. Interictal hypometabolism topography is related to the neuronal networks involved in the seizure onset zone (SOZ) and spread pathways. F-FDG PET has a good prognostic value for post-surgical outcome, especially in cases with unique focal ictal semiology and a limited extent of hypometabolism.

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Objective: Report of the contribution of invasive EEG (iEEG) and epileptogenicity mappings (EM) in a pediatric cohort of patients with epilepsy associated with focal polymicrogyria (PMG) and candidates for resective surgery.

Method: Retrospective pediatric case series of patients presenting focal PMG-related refractory epilepsy undergoing an invasive exploration (iEEG) at Fondation Rothschild Hospital. We reviewed clinical data, structural MRI, and visual analysis of iEEG recordings.

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Focal cortical dysplasia (FCD) and hemimegalencephaly (HME) are related malformations with shared etiologies. We report three patients with a spectrum of cortical malformations associated with pathogenic brain-specific somatic Ras homolog enriched in brain (RHEB) variants. The somatic variant load directly correlated with the size of the malformation, with upregulated mTOR activity confirmed in dysplastic tissues.

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Focal malformations of cortical development (MCD) are linked to somatic brain mutations occurring during neurodevelopment. Mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy (MOGHE) is a newly recognized clinico-pathological entity associated with pediatric drug-resistant focal epilepsy, and amenable to neurosurgical treatment. MOGHE is histopathologically characterized by clusters of increased oligodendroglial cell densities, patchy zones of hypomyelination, and heterotopic neurons in the white matter.

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Diamond magnetometry is a quantum sensing method involving detection of magnetic resonances with nanoscale resolution. For instance, T1 relaxation measurements, inspired by equivalent concepts in magnetic resonance imaging (MRI), provide a signal that is equivalent to T1 in conventional MRI but in a nanoscale environment. We use nanodiamonds (between 40 and 120 nm) containing ensembles of specific defects called nitrogen vacancy (NV) centers.

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Purpose: Herpes simplex virus encephalitis (HSE) is the most common cause of sporadic viral encephalitis in children and is responsible for epilepsy in approximately half of patients. In addition to medical treatment, epilepsy surgery may be offered to drug-resistant patients but carries a high risk of relapse of herpetic encephalitis. We are reporting our series of patients operated on between 2000 and 2019 with the systematic administration of acyclovir (ACV).

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Hypothalamic hamartomas are aberrant masses, composed of abnormally distributed neurons and glia. Along endocrine and cognitive symptoms, they may cause epileptic seizures, including the specific gelastic and dacrystic seizures. Surgery is the treatment of drug-resistant hamartoma epilepsy, with associated positive results on endocrine, psychiatric, and cognitive symptoms.

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Fluorescent nanodiamonds are frequently used as biolabels. They have also recently been established for magnetic resonance and temperature sensing at the nanoscale level. To properly use them in cell biology, we first have to understand their intracellular fate.

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