ORCID Profile
0000-0003-3014-1966
Current Organisations
Paris VI Jussieu
,
Ecole centrale de Paris
,
INSERM U1106
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Publications
Postictal electroencephalographic (EEG) suppression: A stereo-EEG study of 100 focal to bilateral tonic-clonic seizures
Publisher: Wiley
Date: 22-11-2019
DOI: 10.1111/EPI.14601
Abstract: We aimed to describe intracerebral aspects of postictal generalized electroencephalography suppression (PGES) following focal to bilateral tonic-clonic ("secondarily generalized tonic-clonic") seizures (GTCS) recorded using stereoelectroencephalographic (SEEG), and to correlate these with electroclinical features. Three independent observers scored semiologic and SEEG features. Patient and epilepsy characteristics were collected. Descriptive statistics and multivariate analysis were performed. The operational definition of PGES on SEEG used strict criteria (absence of visible signal at 20 μV/mm litude, in all readable channels). Postictal regional suppression (RS) was identified if only a subset of implanted electrodes showed absence of signal. We evaluated 100 seizures in 52 patients. Interobserver agreement was good (κ 0.72 for clinical features and 0.73 for EEG features). PGES was present in 27 of 100 and RS without PGES present in 42 of 100 seizures. Region of RS included epileptogenic zone in 43 of 51 (86%). No effect of s ling (multilobar or bilateral exploration) was seen. Oral tonicity (mouth opening and/or tonic vocalization during the tonic phase of GTCS) was associated with the presence of PGES (P = 0.029 negative predictive value [NPV] 0.91). Bilateral upper limb extension during the tonic phase correlated with PGES (P = 0.041 NPV 0.85). Association of both oral tonicity and bilateral upper limb extension had a high NPV of 0.96. SEEG recordings confirm true absence of signal during postictal EEG suppression. PGES is unlikely when both upper limb extension and oral tonicity are absent. We hypothesize that bilateral tonic seizure discharge at bulbar level brainstem regions is associated with the production of oral signs and may relate to mechanisms of PGES.
Cycles in epilepsy
Publisher: Springer Science and Business Media LLC
Date: 15-03-2021
DOI: 10.1038/S41582-021-00464-1
Abstract: Epilepsy is among the most dynamic disorders in neurology. A canonical view holds that seizures, the characteristic sign of epilepsy, occur at random, but, for centuries, humans have looked for patterns of temporal organization in seizure occurrence. Observations that seizures are cyclical date back to antiquity, but recent technological advances have, for the first time, enabled cycles of seizure occurrence to be quantitatively characterized with direct brain recordings. Chronic recordings of brain activity in humans and in animals have yielded converging evidence for the existence of cycles of epileptic brain activity that operate over erse timescales: daily (circadian), multi-day (multidien) and yearly (circannual). Here, we review this evidence, synthesizing data from historical observational studies, modern implanted devices, electronic seizure diaries and laboratory-based animal neurophysiology. We discuss advances in our understanding of the mechanistic underpinnings of these cycles and highlight the knowledge gaps that remain. The potential clinical applications of a knowledge of cycles in epilepsy, including seizure forecasting and chronotherapy, are discussed in the context of the emerging concept of seizure risk. In essence, this Review addresses the broad question of why seizures occur when they occur.
Author response: A taxonomy of seizure dynamotypes
Publisher: eLife Sciences Publications, Ltd
Date: 29-05-2020
A taxonomy of seizure dynamotypes
Publisher: Cold Spring Harbor Laboratory
Date: 09-02-2020
DOI: 10.1101/2020.02.08.940072
Abstract: Seizures are a disruption of normal brain activity present across a vast range of species, diseases, and conditions. Here we introduce an organizing principle that leads to the first objective Taxonomy of Seizure Dynamics (TSD) based on bifurcation theory, and applied it to the analysis of EEG data. The “dynamotype” of a seizure is the part of its dynamic composition that defines its observable characteristics, including how it starts, evolves and terminates. Analyzing over 2000 focal-onset seizures recorded from 7 epilepsy centers on five continents, we find evidence of all 16 dynamotypes predicted in TSD. We demonstrate that patients’ dynamotypes evolve during their lifetime and display complex but systematic variations including hierarchy (certain dynamotypes are more common), non-bijectivity (a patient may display multiple dynamotypes) and pairing preference (multiple dynamotypes may occur during one seizure). TSD not only provides a way to stratify patients in complement to present practical classifications but also guides biophysically based mechanistic approaches and provides a language to describe the most critical features of seizure dynamics. Taxonomy of Seizure Dynamics (TSD) provides a rigorous method for classifying and quantifying seizures and a principled framework for understanding seizure initiation and propagation.
Permittivity Coupling across Brain Regions Determines Seizure Recruitment in Partial Epilepsy
Publisher: Society for Neuroscience
Date: 05-11-2014
DOI: 10.1523/JNEUROSCI.1570-14.2014
Abstract: Brain regions generating seizures in patients with refractory partial epilepsy are referred to as the epileptogenic zone (EZ). During a seizure, paroxysmal activity is not restricted to the EZ, but may recruit other brain regions and propagate activity through large brain networks, which comprise brain regions that are not necessarily epileptogenic. The identification of the EZ is crucial for candidates for neurosurgery and requires unambiguous criteria that evaluate the degree of epileptogenicity of brain regions. To obtain such criteria and investigate the mechanisms of seizure recruitment and propagation, we develop a mathematical framework of coupled neural populations, which can interact via signaling through a slow permittivity variable. The permittivity variable captures effects evolving on slow timescales, including extracellular ionic concentrations and energy metabolism, with time delays of up to seconds as observed clinically. Our analyses provide a set of indices quantifying the degree of epileptogenicity and predict conditions, under which seizures propagate to nonepileptogenic brain regions, explaining the responses to intracerebral electric stimulation in epileptogenic and nonepileptogenic areas. In conjunction, our results provide guidance in the presurgical evaluation of epileptogenicity based on electrographic signatures in intracerebral electroencephalograms.
A taxonomy of seizure dynamotypes
Publisher: eLife Sciences Publications, Ltd
Date: 21-07-2020
DOI: 10.7554/ELIFE.55632
Abstract: Seizures are a disruption of normal brain activity present across a vast range of species and conditions. We introduce an organizing principle that leads to the first objective Taxonomy of Seizure Dynamics (TSD) based on bifurcation theory. The ‘dynamotype’ of a seizure is the dynamic composition that defines its observable characteristics, including how it starts, evolves and ends. Analyzing over 2000 focal-onset seizures from multiple centers, we find evidence of all 16 dynamotypes predicted in TSD. We demonstrate that patients’ dynamotypes evolve during their lifetime and display complex but systematic variations including hierarchy (certain types are more common), non-bijectivity (a patient may display multiple types) and pairing preference (multiple types may occur during one seizure). TSD provides a way to stratify patients in complement to present clinical classifications, a language to describe the most critical features of seizure dynamics, and a framework to guide future research focused on dynamical properties.
Postictal stereo‐EEG changes following bilateral tonic‐clonic seizures
Publisher: Wiley
Date: 02-07-2019
DOI: 10.1111/EPI.16252
Impaired consciousness during temporal lobe seizures is related to increased long-distance cortical–subcortical synchronization
Publisher: Oxford University Press (OUP)
Date: 04-05-2009
DOI: 10.1093/BRAIN/AWP086
Abstract: Loss of consciousness (LOC) is a dramatic clinical manifestation of temporal lobe seizures. Its underlying mechanism could involve altered coordinated neuronal activity between the brain regions that support conscious information processing. The consciousness access hypothesis assumes the existence of a global workspace in which information becomes available via synchronized activity within neuronal modules, often widely distributed throughout the brain. Re-entry loops and, in particular, thalamo-cortical communication would be crucial to functionally bind different modules together. In the present investigation, we used intracranial recordings of cortical and subcortical structures in 12 patients, with intractable temporal lobe epilepsy (TLE), as part of their presurgical evaluation to investigate the relationship between states of consciousness and neuronal activity within the brain. The synchronization of electroencephalography signals between distant regions was estimated as a function of time by using non-linear regression analysis. We report that LOC occurring during temporal lobe seizures is characterized by increased long-distance synchronization between structures that are critical in processing awareness, including thalamus (Th) and parietal cortices. The degree of LOC was found to correlate with the amount of synchronization in thalamo-cortical systems. We suggest that excessive synchronization overloads the structures involved in consciousness processing, preventing them from treating incoming information, thus resulting in LOC.
Related Organisations
Related Funding Activities
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