scholarly journals Interictal discharges spread along local recurrent networks between tubers and surrounding cortex

2019 ◽  
Author(s):  
S Tumpa ◽  
R Thornton ◽  
M Tisdall ◽  
T Baldeweg ◽  
KJ Friston ◽  
...  
Keyword(s):  
Tuberous Sclerosis ◽  
Epilepsy Surgery ◽  
Local Network ◽  
Neural Mass Model ◽  
Model Parameters ◽  
Epileptiform Discharges ◽  
Interictal Epileptiform Discharges ◽  
Eeg Abnormalities ◽  
Neural Mass ◽  
Interictal Discharges

AbstractThe presence of interictal epileptiform discharges on electroencephalography (EEG) may indicate increased epileptic seizure risk and on invasive EEG are the signature of the irritative zone. In highly epileptogenic lesions – such as cortical tubers in tuberous sclerosis – these discharges can be recorded with intracranial stereotactic EEG as part of the evaluation for epilepsy surgery. Yet the network mechanisms that underwrite the generation and spread of these discharges remain poorly understood, limiting their current diagnostic use.Here, we investigate the dynamics of interictal epileptiform discharges using a combination of quantitative analysis of invasive EEG recordings and mesoscale neural mass modelling of cortical dynamics. We first characterise spatially organised local dynamics of discharges recorded from 36 separate tubers in 8 patients with tuberous sclerosis. We characterise these dynamics with a set of competing explanatory network models using dynamic causal modelling. Bayesian model comparison of plausible network architectures suggests that the recurrent coupling between neuronal populations within – and adjacent to – the tuber core explains the travelling wave dynamics observed in these patient recordings.Our results – based on interictal activity – unify competing theories about the pathological organisation of epileptic foci and surrounding cortex in patients with tuberous sclerosis. Coupled oscillator dynamics have previously been used to describe ictal activity, where fast travelling ictal discharges are commonly observed within the recruited seizure network. The interictal data analysed here add the insight that this functional architecture is already established in the interictal state. This links observations of interictal EEG abnormalities directly to pathological network coupling in epilepsy, with possible implications for epilepsy surgery approaches in tuberous sclerosis.Significance StatementInterictal epileptiform discharges (IEDs) are clinically important markers of an epileptic brain. Here we link local IED spread to network coupling through a combination of clinical recordings in paediatric patients with tuberous sclerosis complex, quantitative EEG analysis of interictal discharges spread, and Bayesian inference on coupled neural mass model parameters. We show that the kinds of interictal discharges seen in our patients require recurrent local network coupling extending beyond the putative seizure focus and that in fact only those recurrent coupled networks can support seizure-like and interictal dynamics when run in simulation. Our findings provide a novel integrated perspective on emergent epileptic dynamics in human patients.

Neurophysiological Analysis of the Genesis Mechanism of EEG During the Interictal and Ictal Periods Using a Multiple Neural Masses Model

2017 ◽  
Vol 28 (01) ◽  
pp. 1750027 ◽  
Author(s):  
Zhen Ma
Keyword(s):  
Matching Pursuit ◽  
Neural Mass Model ◽  
Model Parameters ◽  
Eeg Signals ◽  
Neural Signals ◽  
Mass Model ◽  
Neurophysiological Mechanism ◽  
Norm Minimization ◽  
Neural Mass ◽  
Inhibitory Strength

Electroencephalography (EEG) is an important method to investigate the neurophysiological mechanism underlying epileptogenesis to identify new therapies for the treatment of epilepsy. The neurophysiologically based neural mass model (NMM) can build a bridge between signal processing and neurophysiology, which can be used as a platform to explore the neurophysiological mechanism of epileptogenesis. Most EEG signals cannot be regarded as the outputs of a single NMM with identical model parameters. The outputs of NMM are simple because the diversity of neural signals in the same NMM is ignored. To improve the simulation of EEG signals, a multiple NMM is proposed, the output of which is the linear combination of the outputs of all NMMs. The NMM number is not fixed and is minimized under the premise of guaranteeing the fitting effect. Orthogonal matching pursuit is used to solve a constrained [Formula: see text] norm minimization problem for NMM number and the strength of every NMM. The results showed that the NMM number was significantly lower during the ictal period than during the interictal period, and the strength of major NMMs increased. This indicates that neural masses fuse into fewer larger neural masses with greater strength. The distribution of excitatory and inhibitory strength during the ictal and interictal periods was similar, whereas the excitation/inhibition ratio was higher during the ictal period than during the interictal period.

Epilepsy surgery in tuberous sclerosis: a review

2012 ◽  
Vol 32 (3) ◽  
pp. E5 ◽  
Author(s):  
Linton T. Evans ◽  
Richard Morse ◽  
David W. Roberts
Keyword(s):  
Tuberous Sclerosis ◽  
Epilepsy Surgery ◽  
Preoperative Evaluation ◽  
Occipital Lobe ◽  
Illustrative Case ◽  
Success Rates ◽  
Noninvasive Methods ◽  
Initial Manifestation ◽  
Epileptiform Discharges ◽  
Intractable Seizures

Seizures are the initial manifestation of tuberous sclerosis complex (TSC) in 90% of individuals. The prevalence of epilepsy in TSC is 80%–90% with a large proportion refractory to antiepileptic drugs. A review of the literature of epilepsy surgery in TSC demonstrates impressive success rates for seizure-free outcomes. These studies describe a number of novel noninvasive methods for seizure localization including PET, SPECT, and magnetoencephalography. Additionally, there is a subset of patients with TSC with bilateral, multifocal, or generalized epileptiform discharges that would have previously been excluded from resection. New developments in neuroimaging and invasive monitoring with intracranial electrodes are useful methods in identifying an epileptogenic tuber in these individuals with refractory epilepsy. The authors offer a survey of the literature and description of these methods. Additionally they present an illustrative case of ictal SPECT and intracranial electroencephalography used in the preoperative evaluation of a 10-year-old girl with intractable seizures and TSC. This patient ultimately underwent resection of an epileptogenic region within the occipital lobe.

How Long Should Routine EEG Be Recorded to Get Relevant Information?

2017 ◽  
Vol 49 (5) ◽  
pp. 335-341
Author(s):  
Hannah Doudoux ◽  
Kristina Skaare ◽  
Thomas Geay ◽  
Philippe Kahane ◽  
Jean L. Bosson ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
Relevant Information ◽  
The Other ◽  
Neurologic Manifestation ◽  
Epileptiform Discharges ◽  
Interictal Epileptiform Discharges ◽  
Eeg Abnormalities ◽  
Eeg Recordings ◽  
Time Required ◽  
Over Time

Objective. The optimal duration of routine EEG (rEEG) has not been determined on a clinical basis. This study aims to determine the time required to obtain relevant information during rEEG with respect to the clinical request. Method. All rEEGs performed over 3 months in unselected patients older than 14 years in an academic hospital were analyzed retrospectively. The latency required to obtain relevant information was determined for each rEEG by 2 independent readers blinded to the clinical data. EEG final diagnoses and latencies were analyzed with respect to the main clinical requests: subacute cognitive impairment, spells, transient focal neurologic manifestation or patients referred by epileptologists. Results. From 430 rEEGs performed in the targeted period, 364 were analyzed: 92% of the pathological rEEGs were provided within the first 10 minutes of recording. Slowing background activity was diagnosed from the beginning, whereas interictal epileptiform discharges were recorded over time. Moreover, the time elapsed to demonstrate a pattern differed significantly in the clinical groups: in patients with subacute cognitive impairment, EEG abnormalities appeared within the first 10 minutes, whereas in the other groups, data could be provided over time. Conclusion. Patients with subacute cognitive impairment differed from those in the other groups significantly in the elapsed time required to obtain relevant information during rEEG, suggesting that 10-minute EEG recordings could be sufficient, arguing in favor of individualized rEEG. However, this conclusion does not apply to intensive care unit patients.

scholarly journals Successful Hemispherotomy in a Patient with Encephalopathy with Continuous Spikes and Waves during Sleep Related to Neonatal Thalamic Hemorrhage: A Case Report with Intracranial Electroencephalogram Findings

2021 ◽  
Vol 11 (7) ◽  
pp. 827
Author(s):  
Shimpei Baba ◽  
Tohru Okanishi ◽  
Toshiki Nozaki ◽  
Naoki Ichikawa ◽  
Kazuki Sakakura ◽  
...  
Keyword(s):  
Case Report ◽  
Epilepsy Surgery ◽  
Parietal Lobe ◽  
Sinus Thrombosis ◽  
Absence Seizures ◽  
Epileptiform Discharges ◽  
Thalamic Hemorrhage ◽  
First Case ◽  
Eeg Abnormalities ◽  
Continuous Spikes And Waves

Neonatal thalamic hemorrhage is a strong risk factor for developing encephalopathy with continuous spikes and waves during sleep (ECSWS), even when not accompanied by widespread cortical destruction. The efficacy and indication of resective epilepsy surgery in such patients has not yet been reported. A 4-year-old boy was diagnosed with ECSWS based on strong epileptiform activation during sleep and neurocognitive deterioration. He had a history of left thalamic hemorrhage related to a straight sinus thrombosis during the newborn period. He presented with daily absence seizures that were refractory to medical treatment. At age 5, he underwent intracranial electroencephalogram (EEG) recording using depth and subdural strip electrodes placed in the left thalamus and over bilateral cortex, respectively. Interictal and ictal epileptiform discharges were observed in the thalamus, always preceded by discharges in the left or right parietal lobe. Left hemispherotomy successfully normalized the EEG of his unaffected hemisphere and extinguished his seizures. This is the first case report documenting resective epilepsy surgery in a patient with ECSWS due to neonatal thalamic injury without widespread cerebral destruction. Based on intracranial EEG findings, his injured thalamus did not directly generate the EEG abnormalities or absence seizures on its own. Patients with ipsilateral neonatal thalamic injury and even mild lateralized cortical changes may be candidates for resective or disconnective surgery for ECSWS.

scholarly journals Parameter inference on brain network models with unknown node dynamics and spatial heterogeneity

2021 ◽  
Author(s):  
Viktor Sip ◽  
Spase Petkoski ◽  
Meysam Hashemi ◽  
Viktor K Jirsa
Keyword(s):  
Synthetic Data ◽  
Brain Network ◽  
Training Data ◽  
Neural Mass Model ◽  
Brain Dynamics ◽  
Model Parameters ◽  
Special Focus ◽  
Mass Model ◽  
Whole Brain ◽  
Neural Mass

Model-based data analysis of whole-brain dynamics links the observed data to model parameters in a network of neural masses. In recent years a special focus was placed on the role of regional variance of model parameters for the emergent activity. Such analyses however depend on the properties of the employed neural mass model, which is often obtained through a series of major simplifications or analogies. Here we propose a data-driven approach where the neural mass model needs not to be specified. Building on the recent progresses in identification of dynamical systems with neural networks, we propose a method to infer from the functional data both the neural mass model representing the regional dynamics as well as the region- and subject-specific parameters, while respecting the known network structure. We demonstrate on two synthetic data sets that our method is able to recover the original model parameters, and that the trained generative model produces dynamics resembling the training data both on the regional level and on the whole-brain level. The present approach opens a novel way to the analysis of resting-state fMRI with possible applications in understanding the changes of whole-brain dynamics during aging or in neurodegenerative diseases.

scholarly journals A personalizable autonomous neural mass model of epileptic seizures

2021 ◽  
Author(s):  
Edmundo Lopez-Sola ◽  
Roser Sanchez-Todo ◽  
Èlia Lleal ◽  
Elif Köksal-Ersöz ◽  
Maxime Yochum ◽  
...  
Keyword(s):  
Low Voltage ◽  
Chloride Transport ◽  
Pyramidal Cells ◽  
Brain Network ◽  
Neural Mass Model ◽  
Inhibitory Input ◽  
Model Parameters ◽  
Epileptogenic Zone ◽  
Mass Model ◽  
Neural Mass

The prospect of personalized computational modeling in neurological disorders, and in particular in epilepsy, is poised to revolutionize the field. Work in the last two decades has demonstrated that neural mass models (NMM) can realistically reproduce and explain epileptic seizure transitions as recorded by electrophysiological methods (EEG, SEEG). In previous work, advances were achieved by i) increasing excitation in NMM and ii) heuristically varying network inhibitory coupling parameters or, equivalently, inhibitory synaptic gains. Based on those studies, we provide here a laminar neural mass model capable of realistically reproducing the electrical activity recorded by SEEG in the epileptogenic zone during interictal to ictal states. With the exception of the external noise input onto the pyramidal cell population, the model dynamics are autonomous --- all model parameters are static. By setting the system at a point close to bifurcation, seizure-like transitions are generated, including pre-ictal spikes, low voltage fast activity, and ictal rhythmic activity. A novel element in the model is a physiologically plausible algorithm for chloride accumulation dynamics: the gain of GABAergic post-synaptic potentials is modulated by the pathological accumulation of Cl$^-$ in pyramidal cells, due to high inhibitory input and/or dysfunctional chloride transport. In addition, in order to simulate SEEG signals to compare with real recordings performed in epileptic patients, the NMM is embedded first in a layered model of the neocortex and then in a realistic physical model. We compare modeling results with data from four epilepsy patient cases. By including key pathophysiological mechanisms, the proposed framework captures succinctly the electrophysiological phenomenology observed in ictal states, paving the way for robust personalization methods using brain network models based on NMMs.

scholarly journals D.05 SREDA-like temporal EEG seizure pattern in LGI1-antibody mediated encephalitis

2016 ◽  
Vol 43 (S2) ◽  
pp. S14-S14
Author(s):  
C Steriade ◽  
S Mirsattari ◽  
BJ Murray ◽  
R Wennberg
Keyword(s):  
Clinical Features ◽  
Temporal Lobe ◽  
Limbic Encephalitis ◽  
Cognitive Symptoms ◽  
Epileptiform Discharges ◽  
Interictal Epileptiform Discharges ◽  
Eeg Abnormalities ◽  
Eeg Data ◽  
Temporal Lobe Seizures ◽  
Eeg Recordings

Background: Leucine-rich glioma inactived-1 (LGI1) antibodies are associated with limbic encephalitis and distinctive seizure types, which are typically immunotherapy-responsive. While nonspecific EEG abnormalities are commonly seen, specific EEG characteristics are not currently understood to be useful for suspecting the clinical diagnosis. Based on initial observations in two patients, we analyzed the EEG recordings in a larger series of patients and describe a novel ictal pattern that can suggest the diagnosis of LGI1-antibody mediated encephalitis, even in the absence of common clinical features. Methods: Clinical and EEG data were collected in nine patients with LGI1 antibodies. Results: Psychiatric and cognitive symptoms were common, as were tonic seizures associated with EEG electrodecremental events (often with the so-called faciobrachial dystonic semiology). A rarity or absence of interictal epileptiform discharges contrasted with frequent subclinical temporal lobe seizures in some patients, which at times showed characteristics similar to subclinical rhythmic electrographic discharges of adults (SREDA), including sensitivity to hyperventilation. Conclusions: LGI1-antibody mediated encephalitis may be associated with tonic seizures and corresponding electrodecremental events, as well as an unusual SREDA-like pattern of frequent subclinical temporal lobe seizures, which may be triggered by hyperventilation, all in the setting of rare interictal epileptiform discharges.

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