Eastern Association of Electroencephalographers, 56th Annual Meeting: ‘Ski Meeting, 2002’ (original) (raw)
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Epilepsia, 2012
Purpose: Educational difficulties or even severe cognitive deterioration is seen in many childhood epilepsy syndromes. Many of those cognitive deficits are related directly to the brain disorder underlying the epilepsy syndrome. However, in other types of epilepsy, the epileptic seizures and/or epileptiform activity can be the dominant factor. This is especially unknown for the more ''subtle'' short nonconvulsive seizure types. For this reason, we analyzed a new cohort of children. Methods: A cross-sectional study of 188 children with epilepsy. Electroencephalography (EEG)-video recordings and cognitive testing were performed simultaneously. The results of children with short nonconvulsive seizures during a 2-h testing session were compared with all children with epilepsy without seizures during the 2-h cognitive testing session and with controls without epilepsy. In a second analysis the cognitive effects of frequency of epileptiform EEG discharges were analyzed. Key Findings: The cognitive effects of short nonconvulsive seizures were large, ranging from 0.5 to 1 standard deviation and concerned global cognitive function, speed of central information processing, and memory function. In children without seizures during cognitive testing, the occurrence of frequent epileptiform discharges showed more subtle effects. These effects were independent from the occurrence of short nonconvulsive seizures. Significance: We concluded that although the effect is less pronounced in number of areas involved and magnitude, the type of association between frequent epileptiform activity (>1% of the time) and cognitive function in children with epilepsy is comparable to the association between short nonconvulsive seizures and cognitive function.
Electrocorticographic factors associated with temporal lobe epileptogenicity
Pathophysiology, 2000
Continuous subdural electrocorticographic (ECoG) monitoring was performed to test the hypothesis that human temporal lobe epileptogenicity, during long-term monitoring following antiepileptic drug (AED) withdrawal, regardless of the specific AED regimen, is dependent upon ECoG ictal onset and interhemispheric spread of epileptic activity. In 121 patients, ECoG parameters were analyzed for association with seizure frequency, a clinical measure of epileptogenicity. Significantly associated with increased seizure frequency were: ictal medial temporal lobe onset, absence of ictal frontal lobe desynchronization and short interhemispheric propagation time (IHPT). Seizure frequency during long-term ECoG monitoring was not predictive of post-operative seizure outcome. It is concluded that, following AED withdrawal, regardless of the specific AED regimen, increased seizure frequency is associated with medial temporal lobe ictal onset, short IHPT and absence of frontal lobe desynchronization. The results confirm the hypothesis that human temporal lobe epileptogenicity, after withdrawal, is dependent upon ECoG ictal onset and interhemispheric spread of epileptic activity. Future development of procedures which promote ECoG factors associated with increased seizure frequency following AED withdrawal might decrease duration of invasive long-term monitoring and improve efficiency for the pre-surgical selection of temporal lobectomy candidates. Intervention producing ictal frontal lobe desynchronization and increased IHPT might inhibit temporal lobe epileptogenicity and should be evaluated for therapeutic efficacy outside of the long-term monitoring context.
Human brain mapping, 2015
Benign epilepsy with centrotemporal spikes (BECTS) is often associated with neural circuit dysfunction, particularly during the transient active state characterized by interictal epileptiform discharges (IEDs). Little is known, however, about the functional neural circuit abnormalities in BECTS without IEDs, or if such abnormalities could be used to differentiate BECTS patients without IEDs from healthy controls (HCs) for early diagnosis. To this end, we conducted resting-state functional magnetic resonance imaging (RS-fMRI) and simultaneous Electroencephalogram (EEG) in children with BECTS (n = 43) and age-matched HC (n = 28). The simultaneous EEG recordings distinguished BECTS with IEDs (n = 20) from without IEDs (n = 23). Intrinsic brain activity was measured in all three groups using the amplitude of low frequency fluctuation at rest. Compared to HC, BECTS patients with IEDs exhibited an intrinsic activity abnormality in the thalamus, suggesting that thalamic dysfunction could c...
Spike frequency is dependent on epilepsy duration and seizure frequency in temporal lobe epilepsy
Epileptic disorders : international epilepsy journal with videotape, 2005
We wanted to investigate factors that are associated with frequency of interictal epileptiform discharges by investigating 303 patients with temporal lobe epilepsy (TLE). We included all patients who consecutively underwent the adult presurgical evaluation program at our center and who had intractable, medial TLE with complex partial seizures due to unilateral medial temporal lobe lesions. The interictal EEG samples were automatically recorded and stored on computer. The location and frequency of interictal epileptiform discharges were assessed by visual analysis of interictal EEG samples of 2-minute duration every hour. There were 303 patients (aged 16-63) who met the inclusion criteria. The median interictal epileptiform discharge frequency was 15 IED/h, the median seizure frequency was 4 seizures/month. According to univariate analyses, we found that age at monitoring, epilepsy duration, and higher seizure frequency were associated with higher interictal epileptiform discharge fr...
Changes in interictal spike features precede the onset of temporal lobe epilepsy
Annals of Neurology, 2012
Objective: One cornerstone event during epileptogenesis is the occurrence of the first spontaneous seizure (SZ1). It is therefore important to identify biomarkers of the network alterations leading to SZ1. In experimental models of temporal lobe epilepsy (TLE), interictal-like activity (ILA) precedes SZ1 by several days. The goal of this study was to determine whether ILA dynamics bore electrophysiological features signaling the impeding transition to SZ1. Methods: Experimental TLE was triggered by pilocarpine-or kainic acid-induced status epilepticus (SE). Continuous electroencephalographic recordings were performed 7 days before and up to 40 days after SE. The amplitude and duration of the spike and wave components of interictal spikes were analyzed. Results: Two types of interictal spikes were distinguished: type 1, with a spike followed by a long-lasting wave, and type 2, with a spike without wave. The number, amplitude, and duration of type 1 spikes started to decrease, whereas the number of type 2 spikes increased, several days before SZ1, reaching their minimum/maximum values just before SZ1. Interpretation: The change in ILA pattern could constitute a predictive biomarker of SZ1. The mechanisms underlying these dynamic modifications and their functional impact are discussed in the context of the construction of an epileptogenic network.
Interictal spikes and epileptic seizures: their relationship and underlying rhythmicity
Brain, 2016
We report on a quantitative analysis of electrocorticography data from a study that acquired continuous ambulatory recordings in humans over extended periods of time. The objectives were to examine patterns of seizures and spontaneous interictal spikes, their relationship to each other, and the nature of periodic variation. The recorded data were originally acquired for the purpose of seizure prediction, and were subsequently analysed in further detail. A detection algorithm identified potential seizure activity and a template matched filter was used to locate spikes. Seizure events were confirmed manually and classified as either clinically correlated, electroencephalographically identical but not clinically correlated, or subclinical. We found that spike rate was significantly altered prior to seizure in 9 out of 15 subjects. Increased pre-ictal spike rate was linked to improved predictability; however, spike rate was also shown to decrease before seizure (in 6 out of the 9 subjects). The probability distribution of spikes and seizures were notably similar, i.e. at times of high seizure likelihood the probability of epileptic spiking also increased. Both spikes and seizures showed clear evidence of circadian regulation and, for some subjects, there were also longer term patterns visible over weeks to months. Patterns of spike and seizure occurrence were highly subject-specific. The pre-ictal decrease in spike rate is not consistent with spikes promoting seizures. However, the fact that spikes and seizures demonstrate similar probability distributions suggests they are not wholly independent processes. It is possible spikes actively inhibit seizures, or that a decreased spike rate is a secondary symptom of the brain approaching seizure. If spike rate is modulated by common regulatory factors as seizures then spikes may be useful biomarkers of cortical excitability.
Cognitive and Behavioral Co-Morbidities of Epilepsy
2012
Cognitive impairment and behavioral disturbances are devastating co-morbidities of epilepsy. In some patients these co-morbidities may be of greater consequence than the epilepsy itself. There is increasing recognition that cognitive and behavioral co-morbidities can be both chronic, primarily due to the underlying etiology of the epilepsy, and in dynamic evolution because of recurrent seizures or interictal spikes. With both chronic and dynamic effects, the type and severity of the impairment is related to the maturational stage of the brain at the time epilepsy appears. A number of morphological changes can occur with epilepsy including cell loss, synaptic reorganization and changes in neurogenesis. Seizures can also result in physiological alterations in excitatory and inhibitory currents, alterations in temporal coding of information and impaired single cell firing patterns. In parallel with these morphological and physiological changes, rats subjected to seizures show considerable cognitive and behavioral deficits. Likewise, interictal spikes can result in cognitive impairment, and in the developing animal, impaired neurogenesis and cell loss. Epilepsy is a disorder that affects neuronal networks, and the cognitive and behavioral deficits related to epilepsy are due to the pathological interactions between many brain components. Recent studies have suggested that pathological alterations in oscillatory patterns have an important role in the cognitive and behavioral co-morbidities of epilepsy.
Epilepsy as a dynamical system, a most needed paradigm shift in epileptology
Epilepsy & Behavior, 2019
Márcio Flávio Dutra Moraes, Daniel de Castro Medeiros, Flávio Afonso Gonçalves Mourao, Sergio Augusto Vieira Cancado, Vinicius Rosa Cota - The idea of the epileptic brain being highly excitable and facilitated to synchronic activity has guided pharmacological treatment since the early twentieth century. Although tackling epilepsy's seizure-prone feature, by tonically modifying overall circuit excitability and/or connectivity, the last 50 years of drug development has not seen a substantial improvement in seizure suppression of refractory epilepsies. This review presents a new conceptual framework for epilepsy in which the temporal dynamics of the disease plays a more critical role in both its understanding and therapeutic strategies. The repetitive epileptiform pattern (characteristic during ictal activity) and other well-defined electrographic signatures (i.e., present during the interictal period) are discussed in terms of the sequential activation of the circuit motifs. Lessons learned from the physiological activation of neural circuitry are used to further corroborate the argument and explore the transition from proper function to a state of instability. Furthermore, the review explores how interfering in the temporally dependent abnormal connectivity between circuits maywork as a therapeutic approach. We also reviewthe use of probing stimulation to access network connectivity and evaluate its power to determine transitional states of the dynamical system as it moves towards regions of instability, especially when conventional electrographic monitoring is proven inefficient. Unorthodox cases, with little or no scalp electrographic correlate, in which ictogenic circuitry and/or seizure spread is temporally restricted to neurovegetative, cognitive, and motivational areas are shown as possible explanations for sudden death in epilepsy (SUDEP) and other psychiatric comorbidities. In short, this review presents a paradigm shift in the way that we address the disease and is aimed to encourage debate rather than narrow the rationale epilepsy is currently engaged in.
The Neuropsychological and Academic Substrate of New/Recent-Onset Epilepsies
The Journal of Pediatrics, 2013
Objective-To characterize neuropsychological and academic status in children, age 8-18 years, with new/recent-onset idiopathic generalized epilepsy (IGE) and idiopathic localization-related epilepsy (ILRE) compared with healthy controls. Study design-Participants underwent neuropsychological assessment and parents were interviewed regarding their child's academic history. Cognitive scores for children with epilepsy were age-and sex-adjusted and compared with controls across both broad-band (IGE n = 41 and ILRE n = 53) and narrow-band (childhood/juvenile absence, juvenile myoclonic, benign epilepsy with centro-temproral spikes, and focal [temporal/frontal/NOS]) syndromes. Academic histories were examined including problems antecedent to epilepsy onset and diagnosis. Results-Children with new-onset epilepsies exhibit considerable cognitive abnormality at baseline including patterns of shared abnormalities across syndromes (e.g., psychomotor slowing) as well as unique syndrome-specific cognitive effects (eg, executive function in IGE and language/verbal memory in ILRE) that are observed and sometimes exacerbated in specific IGE and ILRE syndromes. Academic difficulties are evident in approximately 50% of the children with epilepsy, affecting all syndrome groups to an equal degree. Discussion-Patterns of shared and syndrome-specific cognitive abnormalities and academic problems are present early in the course of virtually all epilepsy syndromes examined here, including syndromes classically viewed as benign. This is the base upon which the effects of recurrent seizures, treatment and psychosocial effects will be added over time.
Diagnostics
Although specific neuropsychological deficits have been recognized during the active phase of epilepsy with centrotemporal spikes (ECTS), the natural cognitive and neuropsychological history after remission has not been elucidated so far. We evaluated the natural cognitive and neuropsychological outcomes five years after disease remission and investigated possible predictors of long-term outcome among socio-demographic and electro-clinical variables. We performed an observational cross-sectional study. Electro-clinical characteristics during the active phase of epilepsy, as well as antiepileptic treatment and premorbid neurodevelopmental concerns were reviewed for 70 patients. At least five years after epilepsy remission, all patients were contacted, and 46 completed a structured questionnaire about patients’ current education and academic skills, general health, and parents’ socio-economic status. Among them, 23 patients underwent an ad hoc cognitive and neuropsychological protocol...