Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology, Jan 23, 2014
Direct electrical cortical stimulation (CS) is widely used to map eloquent cortex. It can be appl... more Direct electrical cortical stimulation (CS) is widely used to map eloquent cortex. It can be applied extraoperatively in patients undergoing intracranial EEG recordings using chronically implanted electrodes (subdural, depth or a combination), or it can be used intraoperatively. Seizures can be induced by CS but there is controversy regarding the utility of CS induced seizures in defining the epileptogenic zone and hence practice varies considerably between centres. Some centres use seizures induced by direct CS routinely to aid in defining the epileptogenic zone. In contrast, others do not rely on such information and explicitly avoid stimulating seizures during cortical mapping. Intra- and extraoperative techniques have been used to stimulate seizures with varying results, which may in part reflect these methodological differences. We here aim to review current views, definitions and studies on seizures induced by direct electrical CS. In addition we discuss mechanisms and methodo...
Nuclear factor (erythroid-derived 2) factor 2 (Nrf2) is a crucial transcription factor mediating ... more Nuclear factor (erythroid-derived 2) factor 2 (Nrf2) is a crucial transcription factor mediating protection against oxidants. Nrf2 is negatively regulated by cytoplasmic Kelch-like ECH associated protein 1 (Keap1) thereby providing inducible antioxidant defence. Antioxidant properties of Nrf2 are thought to be mainly exerted by stimulating transcription of antioxidant proteins, whereas its effects on ROS production within the cell are uncertain. Live cell imaging and qPCR in brain hippocampal glio-neuronal cultures and explants slice cultures with graded expression of Nrf2, i.e. Nrf2-knockout (Nrf2-KO), wild-type (WT), and Keap1-knockdown (Keap1-KD). We here show that ROS production in Nrf2-KO cells and tissues is increased compared to their WT counterparts. Mitochondrial ROS production is regulated by the Keap1-Nrf2 pathway by controlling mitochondrial bioenergetics. Surprisingly, Keap1-KD cells and tissues also showed higher rates of ROS production when compared to WT, although wi...
This study aimed to determine clinical features of adult patients with gelastic seizures recorded... more This study aimed to determine clinical features of adult patients with gelastic seizures recorded on video -electroencephalography (EEG) over a 5-year period. We screened video-EEG telemetry reports for the occurrence of the term "gelastic" seizures, and assessed the semiology, EEG features, and duration of those seizures. Gelastic seizures were identified in 19 (0.8%) of 2,446 admissions. The presumed epileptogenic zone was in the hypothalamus in one third of the cases, temporal lobe epilepsy was diagnosed in another third, and the remainder of the cases presenting with gelastic seizures were classified as frontal, parietal lobe epilepsy or remained undetermined or were multifocal. Gelastic seizures were embedded in a semiology, with part of the seizure showing features of automotor seizures. A small proportion of patients underwent epilepsy surgery. Outcome of epilepsy surgery was related to the underlying pathology; two patients with hippocampal sclerosis had good outco...
To investigate the utility of EEG source imaging to lateralize ictal patterns in frontal lobe epi... more To investigate the utility of EEG source imaging to lateralize ictal patterns in frontal lobe epilepsy, which were nonlateralized by standard EEG analysis. Prospective analysis of 17 seizures in 8 patients with unilateral frontal lobe epilepsy MRI lesions and nonlateralizing ictal scalp EEG. We applied four EEG source imaging techniques (phase maps, symmetric dipoles, low-resolution brain electromagnetic tomography analysis, and classical low-resolution brain electromagnetic tomography analysis recursively applied) to the averaged seizure pattern. We tested (1) the ability of these techniques to lateralize seizure patterns, (2) the agreement of the lateralization result with MRI lesion side and subdural EEG recordings, individually for each method and for concordance of all. We found lateralizing results in 5 of 17 seizures when analyzing phase maps, 8 of 17 when analyzing dipoles, and 5 of 17 in both classical low-resolution brain electromagnetic tomography analysis recursively applied and low-resolution brain electromagnetic tomography analysis. No discordance with the MRI lesion side was seen when analyzing phase maps, whereas dipole analysis was discordant to the MRI lesion in two seizures, classical low-resolution brain electromagnetic tomography analysis recursively applied in one, and low-resolution brain electromagnetic tomography analysis in two. Agreement between all imaging methods was found in three seizures (three patients), all in line with the side of the MRI lesion. Advanced EEG review methods and source localization provide useful lateralizing information in difficult frontal lobe epilepsy seizure patterns.
This study sought to determine the frequency and clinical significance of nonhabitual seizures in... more This study sought to determine the frequency and clinical significance of nonhabitual seizures in 101 consecutive patients undergoing presurgical intracranial electroencephalography intracranial (icEEG) recording. We compared clinical data, recording details, and postsurgical outcome in patients with nonhabitual seizures to those without nonhabitual seizures during icEEG. In patients with nonhabitual seizures we compared icEEG recordings of nonhabitual seizures to recordings of habitual seizures. Nonhabitual seizures were recorded in 10% of patients. Those patients had a significantly higher rate of procedure-related complications compared to patients without nonhabitual seizures. Ultimate seizure outcome did not differ between the groups. Nonhabitual seizures often occurred within the first 3 days of icEEG recording and had larger seizure-onset zones compared to the patient's habitual seizures. Nonhabitual seizures have no effect on outcome of epilepsy surgery but may serve as important markers of procedure-related complications during icEEG.
Journal of neurology, neurosurgery, and psychiatry, Jan 2, 2015
To define factors that predict whether patients with pharmacoresistant focal epilepsy are offered... more To define factors that predict whether patients with pharmacoresistant focal epilepsy are offered epilepsy surgery (including invasive EEG) and the main reasons for not proceeding with these after non-invasive presurgical evaluation. We retrospectively analysed data from 612 consecutive patients with focal epilepsy admitted to a video-EEG Telemetry Unit for presurgical evaluation, and used a multivariate logistic regression model to assess the predictive value of factors for being offered potentially curative surgery. In the multivariate analysis, bilateral lesions on MRI (OR: 0.10; 95% CI 0.03 to 0.24), no lesion (OR: 0.33; 95% CI 0.22 to 0.49) or extratemporal lobe epilepsy (OR: 0.30; 95% CI 0.20 to 0.45) were the only factors that significantly reduced the probability of being offered surgery. 32% of patients who were offered epilepsy surgery decided against proceeding. There was a low chance (<10%) of being offered surgery if there were bilateral lesions on MRI and extratempo...
Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology, Jan 23, 2014
Direct electrical cortical stimulation (CS) is widely used to map eloquent cortex. It can be appl... more Direct electrical cortical stimulation (CS) is widely used to map eloquent cortex. It can be applied extraoperatively in patients undergoing intracranial EEG recordings using chronically implanted electrodes (subdural, depth or a combination), or it can be used intraoperatively. Seizures can be induced by CS but there is controversy regarding the utility of CS induced seizures in defining the epileptogenic zone and hence practice varies considerably between centres. Some centres use seizures induced by direct CS routinely to aid in defining the epileptogenic zone. In contrast, others do not rely on such information and explicitly avoid stimulating seizures during cortical mapping. Intra- and extraoperative techniques have been used to stimulate seizures with varying results, which may in part reflect these methodological differences. We here aim to review current views, definitions and studies on seizures induced by direct electrical CS. In addition we discuss mechanisms and methodo...
Nuclear factor (erythroid-derived 2) factor 2 (Nrf2) is a crucial transcription factor mediating ... more Nuclear factor (erythroid-derived 2) factor 2 (Nrf2) is a crucial transcription factor mediating protection against oxidants. Nrf2 is negatively regulated by cytoplasmic Kelch-like ECH associated protein 1 (Keap1) thereby providing inducible antioxidant defence. Antioxidant properties of Nrf2 are thought to be mainly exerted by stimulating transcription of antioxidant proteins, whereas its effects on ROS production within the cell are uncertain. Live cell imaging and qPCR in brain hippocampal glio-neuronal cultures and explants slice cultures with graded expression of Nrf2, i.e. Nrf2-knockout (Nrf2-KO), wild-type (WT), and Keap1-knockdown (Keap1-KD). We here show that ROS production in Nrf2-KO cells and tissues is increased compared to their WT counterparts. Mitochondrial ROS production is regulated by the Keap1-Nrf2 pathway by controlling mitochondrial bioenergetics. Surprisingly, Keap1-KD cells and tissues also showed higher rates of ROS production when compared to WT, although wi...
This study aimed to determine clinical features of adult patients with gelastic seizures recorded... more This study aimed to determine clinical features of adult patients with gelastic seizures recorded on video -electroencephalography (EEG) over a 5-year period. We screened video-EEG telemetry reports for the occurrence of the term "gelastic" seizures, and assessed the semiology, EEG features, and duration of those seizures. Gelastic seizures were identified in 19 (0.8%) of 2,446 admissions. The presumed epileptogenic zone was in the hypothalamus in one third of the cases, temporal lobe epilepsy was diagnosed in another third, and the remainder of the cases presenting with gelastic seizures were classified as frontal, parietal lobe epilepsy or remained undetermined or were multifocal. Gelastic seizures were embedded in a semiology, with part of the seizure showing features of automotor seizures. A small proportion of patients underwent epilepsy surgery. Outcome of epilepsy surgery was related to the underlying pathology; two patients with hippocampal sclerosis had good outco...
To investigate the utility of EEG source imaging to lateralize ictal patterns in frontal lobe epi... more To investigate the utility of EEG source imaging to lateralize ictal patterns in frontal lobe epilepsy, which were nonlateralized by standard EEG analysis. Prospective analysis of 17 seizures in 8 patients with unilateral frontal lobe epilepsy MRI lesions and nonlateralizing ictal scalp EEG. We applied four EEG source imaging techniques (phase maps, symmetric dipoles, low-resolution brain electromagnetic tomography analysis, and classical low-resolution brain electromagnetic tomography analysis recursively applied) to the averaged seizure pattern. We tested (1) the ability of these techniques to lateralize seizure patterns, (2) the agreement of the lateralization result with MRI lesion side and subdural EEG recordings, individually for each method and for concordance of all. We found lateralizing results in 5 of 17 seizures when analyzing phase maps, 8 of 17 when analyzing dipoles, and 5 of 17 in both classical low-resolution brain electromagnetic tomography analysis recursively applied and low-resolution brain electromagnetic tomography analysis. No discordance with the MRI lesion side was seen when analyzing phase maps, whereas dipole analysis was discordant to the MRI lesion in two seizures, classical low-resolution brain electromagnetic tomography analysis recursively applied in one, and low-resolution brain electromagnetic tomography analysis in two. Agreement between all imaging methods was found in three seizures (three patients), all in line with the side of the MRI lesion. Advanced EEG review methods and source localization provide useful lateralizing information in difficult frontal lobe epilepsy seizure patterns.
This study sought to determine the frequency and clinical significance of nonhabitual seizures in... more This study sought to determine the frequency and clinical significance of nonhabitual seizures in 101 consecutive patients undergoing presurgical intracranial electroencephalography intracranial (icEEG) recording. We compared clinical data, recording details, and postsurgical outcome in patients with nonhabitual seizures to those without nonhabitual seizures during icEEG. In patients with nonhabitual seizures we compared icEEG recordings of nonhabitual seizures to recordings of habitual seizures. Nonhabitual seizures were recorded in 10% of patients. Those patients had a significantly higher rate of procedure-related complications compared to patients without nonhabitual seizures. Ultimate seizure outcome did not differ between the groups. Nonhabitual seizures often occurred within the first 3 days of icEEG recording and had larger seizure-onset zones compared to the patient&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s habitual seizures. Nonhabitual seizures have no effect on outcome of epilepsy surgery but may serve as important markers of procedure-related complications during icEEG.
Journal of neurology, neurosurgery, and psychiatry, Jan 2, 2015
To define factors that predict whether patients with pharmacoresistant focal epilepsy are offered... more To define factors that predict whether patients with pharmacoresistant focal epilepsy are offered epilepsy surgery (including invasive EEG) and the main reasons for not proceeding with these after non-invasive presurgical evaluation. We retrospectively analysed data from 612 consecutive patients with focal epilepsy admitted to a video-EEG Telemetry Unit for presurgical evaluation, and used a multivariate logistic regression model to assess the predictive value of factors for being offered potentially curative surgery. In the multivariate analysis, bilateral lesions on MRI (OR: 0.10; 95% CI 0.03 to 0.24), no lesion (OR: 0.33; 95% CI 0.22 to 0.49) or extratemporal lobe epilepsy (OR: 0.30; 95% CI 0.20 to 0.45) were the only factors that significantly reduced the probability of being offered surgery. 32% of patients who were offered epilepsy surgery decided against proceeding. There was a low chance (<10%) of being offered surgery if there were bilateral lesions on MRI and extratempo...
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