Evidence for spreading seizure as a cause of theta-alpha activity electrographic pattern in stereo-EEG seizure recordings

Intracranial electroencephalography is a standard tool in clinical evaluation of patients with focal epilepsy. Various early electrographic seizure patterns differing in frequency, amplitude, and waveform of the oscillations are observed. The pattern most common in the areas of seizure propagation is the so-called theta-alpha activity (TAA), whose defining features are oscillations in the θ − α range and gradually increasing amplitude. A deeper understanding of the mechanism underlying the generation of the TAA pattern is however lacking. In this work we evaluate the hypothesis that the TAA patterns are caused by seizures spreading across the cortex. To do so, we perform simulations of seizure dynamics on detailed patient-derived cortical surfaces using the spreading seizure model as well as reference models with one or two homogeneous sources. We then detect the occurrences of the TAA patterns both in the simulated stereo-electroencephalographic signals and in the signals of recorded epileptic seizures from a cohort of fifty patients, and we compare the features of the groups of detected TAA patterns to assess the plausibility of the different models. Our results show that spreading seizure hypothesis is qualitatively consistent with the evidence available in the seizure recordings, and it can explain the features of the detected TAA groups best among the examined models.

Download Full-text

Evidence for spreading seizure as a cause of theta-alpha activity electrographic pattern in stereo-EEG seizure recordings

10.1101/2020.07.22.215442 ◽

2020 ◽

Author(s):

Viktor Sip ◽

Julia Scholly ◽

Maxime Guye ◽

Fabrice Bartolomei ◽

Viktor Jirsa

Keyword(s):

Focal Epilepsy ◽

Epileptic Seizures ◽

Alpha Activity ◽

Electrographic Seizure ◽

Reference Models ◽

Standard Tool ◽

Electroencephalographic Signals ◽

Seizure Model ◽

Intracranial Electroencephalography ◽

Do So

AbstractIntracranial electroencephalography is a standard tool in clinical evaluation of patients with focal epilepsy. Various early electrographic seizure patterns differing in frequency, amplitude, and waveform of the oscillations are observed. The pattern most common in the areas of seizure propagation is the so-called theta-alpha activity (TAA), whose defining features are oscillations in the θ – α range and gradually increasing amplitude. A deeper understanding of the mechanism underlying the generation of the TAA pattern is however lacking. In this work we evaluate the hypothesis that the TAA patterns are caused by seizures spreading across the cortex. To do so, we perform simulations of seizure dynamics on detailed patient-derived cortical surfaces using the spreading seizure model as well as reference models with one or two homogeneous sources. We then detect the occurrences of the TAA patterns both in the simulated stereo-electroencephalographic signals and in the signals of recorded epileptic seizures from a cohort of fifty patients, and we compare the features of the groups of detected TAA patterns to assess the plausibility of the different models. Our results show that spreading seizure hypothesis is qualitatively consistent with the evidence available in the seizure recordings, and it can explain the features of the detected TAA groups best among the examined models.

Download Full-text

Epilepsy, Forgetting, and Convalescence in Ondaatje’s Warlight

Rupkatha Journal on Interdisciplinary Studies in Humanities ◽

10.21659/rupkatha.v13n2.10 ◽

2021 ◽

Vol 13 (2) ◽

Author(s):

Jan Gresil S. Kahambing ◽

Keyword(s):

Medical Humanities ◽

Short Circuit ◽

Epileptic Seizures ◽

Close Reading ◽

The Novel ◽

Health Humanities ◽

Do So

Michael Ondaatje’s Warlight (2018), his latest novel to-date, contains nostalgic elements of strangeness and cartography. In this paper, I short-circuit such themes with health under medical humanities, which heeds a Nietzschean counsel of close reading in literature. To do so, I explore the case of Rachel’s illness, namely her epileptic seizures, as an instance that drives her impetus for active forgetting and eventual convalescence. A close hermeneutical reading of the novel can reveal that both of Nietzsche’s ideas on active forgetting and convalescence provide traction in terms of what this paper constructs as Rachel’s pathography or narration of illness. Shifting the focus from the main narrator, Nathaniel, I argue that it is not the novel’s reliance on memory but the subplot events of Nathaniel’s sister and her epilepsy that form a substantial case of medical or health humanities.

Download Full-text

Classification of seizures and epilepsy

Oxford Textbook of Neurological Surgery ◽

10.1093/med/9780198746706.003.0081 ◽

2019 ◽

pp. 935-944

Author(s):

Andrew McEvoy ◽

Tim Wehner ◽

Victoria Wykes

Keyword(s):

Focal Epilepsy ◽

Focal Cortical Dysplasia ◽

Hippocampal Sclerosis ◽

Epileptic Seizures ◽

Recurrence Risk ◽

Medical Emergency ◽

Unprovoked Seizure ◽

Generalized Seizures ◽

The Brain

Epileptic seizures are transient neurologic alterations due to abnormal excessive or synchronous neuronal cerebral activity. They may cause subjective symptoms (aura), and objective autonomic, behavioural, or cognitive alterations in any combination. Focal seizures are initially generated in one circumscribed area in the brain, whereas generalized seizures involve bihemispheric neuronal networks from the seizure onset. Epilepsy is a brain disease defined by the occurrence of two unprovoked seizures more than 24 h apart or one unprovoked seizure with underlying pathological or genetic factors resulting in a similar recurrence risk. Focal epilepsy syndromes are best classified by aetiology or anatomical area of origin. A seizure that does not self-terminate results in status epilepticus, and constitutes a medical emergency that requires immediate treatment. Focal cortical dysplasia and hippocampal sclerosis are the commonest aetiologies of epilepsy amenable to surgical treatment and are reviewed here. The limbic pathway may be involved in seizure propagation, and the anatomy is described.

Download Full-text

Investigation of Cerebral O-(2-[18F]Fluoroethyl)-L-Tyrosine Uptake in Rat Epilepsy Models

Molecular Imaging and Biology ◽

10.1007/s11307-020-01503-x ◽

2020 ◽

Vol 22 (5) ◽

pp. 1255-1265

Author(s):

Carina Stegmayr ◽

Rainer Surges ◽

Chang-Hoon Choi ◽

Nicole Burda ◽

Gabriele Stoffels ◽

...

Keyword(s):

Brain Tumor ◽

Focal Epilepsy ◽

Epileptic Seizures ◽

Brain Regions ◽

Epileptic Activity ◽

Fet Pet ◽

Tumor Diagnostics ◽

Potential Marker ◽

Epilepsy Models ◽

Class Iv

Abstract Purpose A recent study reported on high, longer lasting and finally reversible cerebral uptake of O-(2-[18F]fluoroethyl)-L-tyrosine ([18F]FET) induced by epileptic activity. Therefore, we examined cerebral [18F]FET uptake in two chemically induced rat epilepsy models and in patients with focal epilepsy to further investigate whether this phenomenon represents a major pitfall in brain tumor diagnostics and whether [18F]FET may be a potential marker to localize epileptic foci. Procedures Five rats underwent kainic acid titration to exhibit 3 to 3.5 h of class IV–V motor seizures (status epilepticus, SE). Rats underwent 4× [18F]FET PET and 4× MRI on the following 25 days. Six rats underwent kindling with pentylenetetrazol (PTZ) 3 to 8×/week over 10 weeks, and hence, seizures increased from class I to class IV. [18F]FET PET and MRI were performed regularly on days with and without seizures. Four rats served as healthy controls. Additionally, five patients with focal epilepsy underwent [18F]FET PET within 12 days after the last documented seizure. Results No abnormalities in [18F]FET PET or MRI were detected in the kindling model. The SE model showed significantly decreased [18F]FET uptake 3 days after SE in all examined brain regions, and especially in the amygdala region, which normalized within 2 weeks. Corresponding signal alterations in T2-weighted MRI were noted in the amygdala and hippocampus, which recovered 24 days post-SE. No abnormality of cerebral [18F]FET uptake was noted in the epilepsy patients. Conclusions There was no evidence for increased cerebral [18F]FET uptake after epileptic seizures neither in the rat models nor in patients. The SE model even showed decreased [18F]FET uptake throughout the brain. We conclude that epileptic seizures per se do not cause a longer lasting increased [18F]FET accumulation and are unlikely to be a major cause of pitfall for brain tumor diagnostics.

Download Full-text

Bispectrum and Recurrent Neural Networks: Improved Classification of Interictal and Preictal States

Scientific Reports ◽

10.1038/s41598-019-52152-2 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Laura Gagliano ◽

Elie Bou Assi ◽

Dang K. Nguyen ◽

Mohamad Sawan

Keyword(s):

Neural Networks ◽

Multilayer Perceptron ◽

Recurrent Neural Networks ◽

Short Term Memory ◽

Focal Epilepsy ◽

Single Layer ◽

Epileptic Seizures ◽

Novel Approach ◽

Multilayer Perceptron Networks

Abstract This work proposes a novel approach for the classification of interictal and preictal brain states based on bispectrum analysis and recurrent Long Short-Term Memory (LSTM) neural networks. Two features were first extracted from bilateral intracranial electroencephalography (iEEG) recordings of dogs with naturally occurring focal epilepsy. Single-layer LSTM networks were trained to classify 5-min long feature vectors as preictal or interictal. Classification performances were compared to previous work involving multilayer perceptron networks and higher-order spectral (HOS) features on the same dataset. The proposed LSTM network proved superior to the multilayer perceptron network and achieved an average classification accuracy of 86.29% on held-out data. Results imply the possibility of forecasting epileptic seizures using recurrent neural networks, with minimal feature extraction.

Download Full-text

Potentially Pathological Alpha-Pattern as a Variant of Vigilance EEG in Drug-Resistant Epilepsy

Pediatrician (St Petersburg) ◽

10.17816/ped8448-56 ◽

2017 ◽

Vol 8 (4) ◽

pp. 48-56

Author(s):

Aleksandr A. Chukhlovin ◽

Mikhail V. Aleksandrov ◽

Sergey A. Lytaev ◽

Vugar R. Kasumov ◽

Marina E. Pavlovskaya ◽

...

Keyword(s):

Alpha Rhythm ◽

Refractory Epilepsy ◽

Functional Decline ◽

Clinical Signs ◽

Epileptic Seizures ◽

Alpha Activity ◽

Drug Resistant ◽

Scalp Eeg ◽

Russian Scientific Research Institute ◽

Drug Resistant Epilepsy

As a result of pathomorphosis affecting the mechanisms of electrical activity generation interictal EEG may show reduced epileptiform changes whereas clinically apparent epileptic seizures may be present. In these cases patterns of dominant alpha activity are sometimes recorded on the scalp. In this study variations of alpha activity in patients with refractory epilepsy are classified. A group of 50 refractory epilepsy patients aged between 20 and 55 years who were submitted to Polenov Russian Scientific Research Institute of Neurosurgery in 2014-2017 was included in this study. They underwent scalp EEG as a part of their presurgical assessment. In 12 cases patterns of potentially pathological alpha activity were observed. Three variations of alpha-patterns were described: 1) alpha-rhythm with decreased regional diversity and a marked synchronization in temporal areas; 2) alpha-rhythm with reduced epileptiform complexes integrated into the spindles, 3) decelerated non-rhythmic alpha activity distorted by the higher frequency components. Distinguished varieties of potentially pathological alpha-activity according to their order here represent gradual functional decline of normal thalamo-cortical interaction. Considering clinical manifestation of drug-resistant epilepsy with frequent seizures in these patients, reported varieties of alpha activity can not be interpreted as Landolt’s syndrome (forced normalization of EEG). Invasive electrocorticographic monitoring demonstrated that bursts of sharpened polyphasic waves coinciding with alpha-rhythm on scalp EEG are consistent with epileptic discharges on the brain cortex surface. This allows to think of these components as correlates of epileptic activity. Therefore, on a number of occasions in patients with epilepsy a dissonance between clinical signs and electroencephalographic patterns recorded during restful wakefulness may be observed, when epileptiform components are absent or reduced to nonspecific complexes.

Download Full-text

Epilepsy Surgery for Refractory Focal Epilepsy based on the Analysis of High Frequency Oscillations with Intracranial Electroencephalography : A Case Report

Japanese Journal of Neurosurgery ◽

10.7887/jcns.24.32 ◽

2015 ◽

Vol 24 (1) ◽

pp. 32-39

Author(s):

Akihiko Kondo ◽

Tomoyuki Akiyama ◽

Takashi Agari ◽

Makio Oka ◽

Yoshinori Kobayashi ◽

...

Keyword(s):

Case Report ◽

Epilepsy Surgery ◽

High Frequency ◽

Focal Epilepsy ◽

High Frequency Oscillations ◽

Intracranial Electroencephalography

Download Full-text

Wilder Penfield and the vascular hypothesis of focal epilepsy

Journal of Neurosurgery ◽

10.3171/2018.8.jns181990 ◽

2019 ◽

Vol 131 (6) ◽

pp. 1947-1953 ◽

Cited By ~ 2

Author(s):

Richard Leblanc

Keyword(s):

Focal Epilepsy ◽

Cerebral Metabolism ◽

Epileptic Seizures ◽

Epileptogenic Zone ◽

Vascular Plexus ◽

Posttraumatic Epilepsy ◽

Parasympathetic Nerves ◽

Initial Support ◽

The Subject ◽

Intracranial Arteries

The vascular hypothesis held that posttraumatic epilepsy results from reflex vasoconstriction of cortical arteries around a cerebral scar. Penfield’s initial support and eventual refutation of the vascular hypothesis is the subject of this paper, which is based on a review of his clinical charts, operative and electrocorticographic reports, and brain maps held in the Montreal Neurological Institute archives. Penfield and his collaborators discovered that posttraumatic cortical scars are composed of astro-glial fibers, collagen fibrils, and a neo-vascular plexus that anastomoses with the surrounding cortical arteries. He hypothesized that the contracting scar applied traction to these arteries, which caused epileptic seizures. This was supported by his observations that cortical arteries constrict during an epileptic seizure. Penfield’s subsequent investigations led to the discovery that parasympathetic nerves innervate the intracranial arteries, that experimental vasospasm can produce cortical infarction, and that cerebral blood flow (CBF) is coupled to cerebral metabolism. In fact, Penfield found that CBF increases in the epileptogenic zone around a cortical scar, contrary to what the hypothesis had predicted. Despite this, Penfield’s investigations shed new light on the dynamics of the cerebral circulation that were not fully understood until decades later.

Download Full-text

Mental and behavioral disorders in temporal lobe epilepsy

Psihiatru ro ◽

10.26416/psih.58.3.2019.2526 ◽

2019 ◽

Vol 58 (3) (1) ◽

pp. 23-27

Author(s):

Diana Vulea ◽

Simona Butnăraşu ◽

Ciprian Băcilă

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Medical Condition ◽

Focal Epilepsy ◽

Epileptic Seizures ◽

General Medical Condition ◽

Legal Implications ◽

The Right ◽

Psychiatric Manifestations ◽

Mental And Behavioral Disorders

The evolution of temporal lobe epilepsy often implies complex psychiatric manifestations, as the elements can be part of an aura, as well as of a psychiatric pathology of its own. This paper presents the case of a patient diagnosed with focal epilepsy of the right mesial temporal lobe, who subsequently developed psychotic disorder due to a general medical condition with medico-legal implications, treatment noncompliance and difficulties in controlling epileptic seizures.

Download Full-text