scholarly journals Spontaneous EEG-Functional MRI in Mesial Temporal Lobe Epilepsy: Implications for the Neural Correlates of Consciousness

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Zheng Wang ◽  
Loretta Norton ◽  
R. Matthew Hutchison ◽  
John R. Ives ◽  
Seyed M. Mirsattari
Keyword(s):  
Temporal Lobe ◽  
Animal Studies ◽  
Brain Activity ◽  
Epileptic Seizures ◽  
Mesial Temporal Lobe Epilepsy ◽  
Unified Framework ◽  
Epileptiform Discharges ◽  
Interictal Epileptiform Discharges ◽  
Mesial Temporal Lobe ◽  
Hemodynamic Processes

The combination of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) has been shown to have great potential for providing a greater understanding of normal and diseased states in both human and animal studies. Simultaneous EEG-fMRI is particularly well suited for the study of epilepsy in that it may reveal the neurobiology of ictal and interictal epileptiform discharges and noninvasively localize epileptogenic foci. Spontaneous, coherent fluctuations of neuronal activity and the coupled hemodynamic responses have also been shown to provide diagnostic markers of disease, extending our understanding of intrinsically structured ongoing brain activity. Following a short summary of the hardware and software development of simultaneous EEG-fMRI, this paper reviews a unified framework of integrating neuronal and hemodynamic processes during epileptic seizures and discusses the role and impact of spontaneous activity in the mesial temporal lobe epilepsies with particular emphasis on the neural and physiological correlates of consciousness.

Analysis of Reoperation in Mesial Temporal Lobe Epilepsy With Hippocampal Sclerosis

Neurosurgery ◽  
2011 ◽  
Vol 68 (1) ◽  
pp. 89-97 ◽  
Author(s):  
Reinhard. Schulz ◽  
Matthias. Hoppe ◽  
Frank. Boesebeck ◽  
Csilla. Gyimesi ◽  
Heinz W. Pannek ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Hippocampal Sclerosis ◽  
Mesial Temporal Lobe Epilepsy ◽  
Incomplete Resection ◽  
T2 Relaxometry ◽  
Epileptiform Discharges ◽  
Interictal Epileptiform Discharges ◽  
Mesial Temporal Lobe

Abstract BACKGROUND: Most patients do well after epilepsy surgery for mesial temporal lobe sclerosis, and in only 8 to 12% of all operations, the outcome is classified as not improved. OBJECTIVE: To analyze the outcome of reoperation in cases of incomplete resection of mesial temporal lobe structures in patients with mesial temporal lobe sclerosis in temporal lobe epilepsy. METHODS: We analyzed 22 consecutive patients who underwent reoperation for mesial temporal lobe sclerosis (follow-up, 23-112 months; mean, 43.18 months) by evaluating noninvasive electroencephalographic/video monitoring before the first and second surgeries (semiology, interictal epileptiform discharges, ictal electroencephalography with special attention to the secondary contralateral evolution of the electroencephalographic seizure pattern after the initial regionalization), and magnetic resonance imaging (resection indices after the first and second surgeries on the amygdala, hippocampus, lateral temporal lobe). In 18 of 22 patients T2 relaxometry of the contralateral hippocampus was performed. RESULTS: Nine of 22 patients became seizure free; another 4 patients had a decrease in seizures and eventually became seizure free (range, 16-51 months; mean, 30.3). Recurrence of seizures is associated with (1) ictal electroencephalography with later evolution of an independent pattern over the contralateral temporal lobe (0 of 5 patients seizure free vs 5 of 7 patients non–seizure free; P = .046) and (2) a smaller amount of lateral temporal lobe resection in the second surgery (1.06 ± 0.59 cm vs 2.18 ± 1.37 cm; P = .019). No significant correlation with outcome was found for lateralization of interictal epileptiform discharges, change in semiology, other resection indices, T2 relaxometry, onset and duration of epilepsy, duration of follow-up, and side of surgery. CONCLUSION: Patients have a less favorable outcome with a reoperation if they show ictal scalp electroencephalography with secondary contralateral propagation and if only a small second resection of the lateral temporal lobe is performed.

scholarly journals Periodic epileptiform discharges in mesial temporal lobe epilepsy with hippocampal sclerosis

Seizure ◽  
2013 ◽  
Vol 22 (9) ◽  
pp. 735-742 ◽  
Author(s):  
Daniel San-Juan ◽  
Adriana Patricia M. Mayorga ◽  
Juan de Dios Del Castillo Calcáneo ◽  
Maricarmen Fernández González-Aragón ◽  
Mario Alonso-Vanegas ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Hippocampal Sclerosis ◽  
Mesial Temporal Lobe Epilepsy ◽  
Epileptiform Discharges ◽  
Mesial Temporal Lobe

scholarly journals Alterations in regional homogeneity of resting-state brain activity in mesial temporal lobe epilepsy

Epilepsia ◽  
2013 ◽  
Vol 54 (4) ◽  
pp. 658-666 ◽  
Author(s):  
Hongwu Zeng ◽  
Ricardo Pizarro ◽  
Veena A. Nair ◽  
Christian La ◽  
Vivek Prabhakaran
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Resting State ◽  
Brain Activity ◽  
Mesial Temporal Lobe Epilepsy ◽  
Regional Homogeneity ◽  
Mesial Temporal Lobe

scholarly journals Menstrual cycle worsening of epileptic seizures in women with symptomatic focal epilepsy

2005 ◽  
Vol 63 (3b) ◽  
pp. 751-756 ◽  
Author(s):  
Ana Carolina Belini Bazán ◽  
Maria Augusta Montenegro ◽  
Fernando Cendes ◽  
Li Li Min ◽  
Carlos A.M. Guerreiro
Keyword(s):  
Menstrual Cycle ◽  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Seizure Frequency ◽  
Focal Epilepsy ◽  
Epileptic Seizures ◽  
Mesial Temporal Lobe Epilepsy ◽  
Menstrual Cycles ◽  
Medical Appointment ◽  
Mesial Temporal Lobe

INTRODUCTION: Hormonal fluctuation is responsible for worsening of epileptic seizures during the menstrual cycle. OBJETIVE: To identify irregularities in the menstrual cycles of women with mesial temporal lobe epilepsy (MTLE) and extratemporal focal epilepsy (ETFE) and correlate the frequency of seizures during the menstrual cycles. METHOD: We evaluated prospectively women in the menacme with MTLE and ETFE. Calendars were provided for these patients, and they were asked to mark their seizure frequency according to the menses. Calendars were reviewed in each routine medical appointment. RESULTS: Thirty-nine patients with MTLE and 14 with ETFE were evaluated. We registered 211 cycles in the patients with MTLE and 49 in those with ETFE. Irregular menstrual cycles were found in 28 (28/39, 71.7%) patients with MTLE and 6 (6/14, 42.8%) with ETFE (p=0.052). Premenstrual seizure worsening was observed in 46 (21.8%) patients with MTLE and 9 (18.3%) with ETFE (p=0.596). Menstrual worsening was observed in 47 (22.2%) patients with MTLE and 15 (30.6%) with ETFE (p=0. 217). Ovulatory worsening was observed in 36 (17%) patients with MTLE and 13 (26.5%) with ETFE (p=0,126). Catamenial worsening was observed in 58 (27.4%) of the patients with MTLE and in 17 (34.7%) of the patients with ETFE (p=0.315). CONCLUSION: There was no difference between the group of patients with MTLE and ETFE regarding the frequency of irregular cycles and seizure worsening during the premenstrual, menstrual, catamenial or ovulatory periods.

scholarly journals Analysis of Interictal Epileptiform Discharges in Mesial Temporal Lobe Epilepsy Using Quantitative EEG and Neuroimaging

2020 ◽  
Vol 11 ◽  
Author(s):  
Elaine Keiko Fujisao ◽  
Karen Fernanda Alves ◽  
Thais O. P. Rezende ◽  
Luiz Eduardo Betting
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Gray Matter ◽  
Quantitative Eeg ◽  
Mesial Temporal Lobe Epilepsy ◽  
Source Analysis ◽  
Epileptiform Discharges ◽  
Eeg Source Imaging ◽  
Mesial Temporal Lobe ◽  
Gray Matter Volumes

Objective: Investigate areas of correlation between gray matter volumes by MRI and interictal EEG source maps in subtypes of mesial temporal lobe epilepsy (MTLE).Method: 71 patients and 36 controls underwent 3T MRI and and routine EEG was performed. Voxel-based morphometry (VBM) was used for gray matter analysis and analysis of interictal discharge sources for quantitative EEG. Voxel-wise correlation analysis was conducted between the gray matter and EEG source maps in MTLE subtypes.Results: The claustrum was the main structure involved in the individual source analysis. Twelve patients had bilateral HA, VBM showed bilateral hippocampal. Twenty-one patients had right HA, VBM showed right hippocampal and thalamic atrophy and negatively correlated involving the right inferior frontal gyrus and insula. Twenty-two patients had left HA, VBM showed left hippocampal atrophy and negatively correlated involving the left temporal lobe and insula. Sixteen patients had MTLE without HA, VBM showed middle cingulate gyrus atrophy and were negatively correlated involving extra-temporal regions, the main one located in postcentral gyrus.Conclusions: Negative correlations between gray matter volumes and EEG source imaging. Neuroanatomical generators of interictal discharges are heterogeneous and vary according to MTLE subtype.Significance: These findings suggest different pathophysiological mechanisms among patients with different subtypes of MTLE.

scholarly journals Electroencephalography in Mesial Temporal Lobe Epilepsy: A Review

2012 ◽  
Vol 2012 ◽  
pp. 1-17 ◽  
Author(s):  
Manouchehr Javidan
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Mesial Temporal Lobe Epilepsy ◽  
General Information ◽  
Seizure Freedom ◽  
Temporal Region ◽  
Epileptiform Discharges ◽  
Mesial Temporal Lobe ◽  
Magnetic Resonance Imaging Mri ◽  
Sensitivity Specificity

Electroencephalography (EEG) has an important role in the diagnosis and classification of epilepsy. It can provide information for predicting the response to antiseizure drugs and to identify the surgically remediable epilepsies. In temporal lobe epilepsy (TLE) seizures could originate in the medial or lateral neocortical temporal region, and many of these patients are refractory to medical treatment. However, majority of patients have had excellent results after surgery and this often relies on the EEG and magnetic resonance imaging (MRI) data in presurgical evaluation. If the scalp EEG data is insufficient or discordant, invasive EEG recording with placement of intracranial electrodes could identify the seizure focus prior to surgery. This paper highlights the general information regarding the use of EEG in epilepsy, EEG patterns resembling epileptiform discharges, and the interictal, ictal and postictal findings in mesial temporal lobe epilepsy using scalp and intracranial recordings prior to surgery. The utility of the automated seizure detection and computerized mathematical models for increasing yield of non-invasive localization is discussed. This paper also describes the sensitivity, specificity, and predictive value of EEG for seizure recurrence after withdrawal of medications following seizure freedom with medical and surgical therapy.

scholarly journals EEG Signal Connectivity for Characterizing Interictal Activity in Patients With Mesial Temporal Lobe Epilepsy

2021 ◽  
Vol 12 ◽  
Author(s):  
Leonardo R. da Costa ◽  
Brunno M. de Campos ◽  
Marina K. M. Alvim ◽  
Gabriela Castellano
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Betweenness Centrality ◽  
Epileptiform Activity ◽  
Mesial Temporal Lobe Epilepsy ◽  
Eeg Signal ◽  
Eeg Signals ◽  
Graph Metrics ◽  
Epileptiform Discharges ◽  
Mesial Temporal Lobe

Over the last decade, several methods for analysis of epileptiform signals in electroencephalography (EEG) have been proposed. These methods mainly use EEG signal features in either the time or the frequency domain to separate regular, interictal, and ictal brain activity. The aim of this work was to evaluate the feasibility of using functional connectivity (FC) based feature extraction methods for the analysis of epileptiform discharges in EEG signals. These signals were obtained from EEG-fMRI sessions of 10 patients with mesial temporal lobe epilepsy (MTLE) with unilateral hippocampal atrophy. The connectivity functions investigated were motif synchronization, imaginary coherence, and magnitude squared coherence in the alpha, beta, and gamma bands of the EEG. EEG signals were sectioned into 1-s epochs and classified according to (using neurologist markers): activity far from interictal epileptiform discharges (IED), activity immediately before an IED and, finally, mid-IED activity. Connectivity matrices for each epoch for each FC function were built, and graph theory was used to obtain the following metrics: strength, cluster coefficient, betweenness centrality, eigenvector centrality (both local and global), and global efficiency. The statistical distributions of these metrics were compared among the three classes, using ANOVA, for each FC function. We found significant differences in all global (p < 0.001) and local (p < 0.00002) graph metrics of the far class compared with before and mid for motif synchronization on the beta band; local betweenness centrality also pointed to a degree of lateralization on the frontotemporal structures. This analysis demonstrates the potential of FC measures, computed using motif synchronization, for the characterization of epileptiform activity of MTLE patients. This methodology may be helpful in the analysis of EEG-fMRI data applied to epileptic foci localization. Nonetheless, the methods must be tested with a larger sample and with other epileptic phenotypes.

scholarly journals Reversible MRI abnormalities in mesial temporal lobe epilepsy: a case report

2013 ◽  
Vol 7 (3) ◽  
pp. 77-84
Author(s):  
Chiara Pizzanelli ◽  
Lorenzo Caciagli ◽  
Veronica Bartolami ◽  
Filippo Sean Giorgi ◽  
Ilaria Pesaresi ◽  
...  
Keyword(s):  
Case Report ◽  
Temporal Lobe ◽  
Epileptic Seizures ◽  
Mesial Temporal Lobe Epilepsy ◽  
Epileptic Activity ◽  
Imaging Method ◽  
Antiepileptic Therapy ◽  
Apparent Diffusion ◽  
Mesial Temporal Lobe

The question regarding  the existence of abnormalities in the neuroimaging exams immediately after status epilecticus or epileptic seizures, but showing complete reversibility after a proper antiepileptic therapy, has long been debated. The first reports attempting to demonstrate their existence date back to the 1980s, and relied upon computed tomography as the imaging method of choice. After the introduction of MRI, a more appropriate characterization of these abnormalities was obtained along with the description of their most frequent features: (a) T2 signal hyperintensity in the white matter and, occasionally, (b) reduced apparent diffusion coefficient (ADC) and increased signal in DWI sequences.The MRI abnormalities induced by epileptic activity pose a broad differential diagnosis including infections, inflammatory autoimmune encephalopathies, neoplasms. It remains a diagnosis of exclusion and requires proper diagnostic iter in order to reduce the risk of misdiagnosis and unnecessary intervention.In this case report, a thorough presentation will be outlined about MRI alterations in the left mesial temporal lobe, which resulted completely reversible after a proper antiepileptic therapy.

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