Distributed source localization of interictal spikes in benign childhood epilepsy with centrotemporal spikes: A standardized low-resolution brain electromagnetic tomography (sLORETA) study

Standardized hierarchical adaptive Lp regression for noise robust focal epilepsy source reconstructions

OBJECTIVE

To investigate the ability of standardization to reduce source localization errors and measurement noise uncertainties for hierarchical Bayesian algorithms with L1- and L2-norms as priors in electroencephalography and magnetoencephalography of focal epilepsy.

METHODS

Description of the standardization methodology relying on the Hierarchical Bayesian framework, referred to as the Standardized Hierarchical Adaptive Lp-norm Regularization (SHALpR). The performance was tested using real data from two focal epilepsy patients. Simulated data that resembled the available real data was constructed for further localization and noise robustness investigation.

RESULTS

The proposed algorithms were compared to their non-standardized counterparts, Standardized low-resolution brain electromagnetic tomography, Standardized Shrinking LORETA-FOCUSS, and Dynamic statistical parametric maps. Based on the simulations, the standardized Hierarchical adaptive algorithm using L2-norm was noise robust for 10 dB signal-to-noise ratio (SNR), whereas the L1-norm prior worked robustly also with 5 dB SNR. The accuracy of the standardized L1-normed methodology to localize focal activity was under 1 cm for both patients.

CONCLUSIONS

Numerical results of the proposed methodology display improved localization and noise robustness. The proposed methodology also outperformed the compared methods when dealing with real data.

SIGNIFICANCE

The proposed standardized methodology, especially when employing the L1-norm, could serve as a valuable assessment tool in surgical decision-making.

Comparative analysis of background EEG activity in juvenile myoclonic epilepsy during valproic acid treatment: a standardized, low-resolution, brain electromagnetic tomography (sLORETA) study

Background

By definition, the background EEG is normal in juvenile myoclonic epilepsy (JME) patients and not accompanied by other developmental and cognitive problems. However, some recent studies using quantitative EEG (qEEG) reported abnormal changes in the background activity. QEEG investigation in patients undergoing anticonvulsant treatment might be a useful approach to explore the electrophysiology and anticonvulsant effects in JME.

Methods

We investigated background EEG activity changes in patients undergoing valproic acid (VPA) treatment using qEEG analysis in a distributed source model. In 17 children with JME, non-parametric statistical analysis using standardized low-resolution brain electromagnetic tomography was performed to compare the current density distribution of four frequency bands (delta, theta, alpha, and beta) between untreated and treated conditions.

Results

VPA reduced background EEG activity in the low-frequency (delta-theta) bands across the frontal, parieto-occipital, and limbic lobes (threshold log-F-ratio = ±1.414, p < 0.05; threshold log-F-ratio= ±1.465, p < 0.01). In the delta band, comparative analysis revealed significant current density differences in the occipital, parietal, and limbic lobes. In the theta band, the analysis revealed significant differences in the frontal, occipital, and limbic lobes. The maximal difference was found in the delta band in the cuneus of the left occipital lobe (log-F-ratio = −1.840) and the theta band in the medial frontal gyrus of the left frontal lobe (log-F-ratio = −1.610).

Conclusions

This study demonstrated the anticonvulsant effects on the neural networks involved in JME. In addition, these findings suggested the focal features and the possibility of functional deficits in patients with JME.

Altered functional connectivity in newly diagnosed benign epilepsy with unilateral or bilateral centrotemporal spikes: A multi-frequency MEG study

OBJECTIVE

Rolandic epilepsy (RE) is one of the most common forms of epilepsy syndromes in children. The condition is usually accompanied with either unilateral or bilateral centrotemporal epileptic discharge. Despite the term "benign", many studies have reported that children with benign epilepsy with centrotemporal spikes (BECTS) display a range of pervasive cognitive difficulties. In addition, existing research suggests that unilateral and bilateral centrotemporal spikes may affect cognition through different mechanisms. Consequently, the present study aimed to investigate cognitive impairment and the resting-state network topology of children with benign epilepsy with unilateral centrotemporal spikes (U-BECTS) and with bilateral centrotemporal spikes (B-BECTS).

METHODS

This study recruited 14 children with U-BECTS and 14 with B-BECTS. Thereafter, cognition was assessed in 28 children with BECTS and 14 healthy controls, using the fourth edition of the Wechsler Intelligence Scale (WISC-IV). Additionally, the functional network of the brain was constructed through magnetoencephalography (MEG) to record the resting-state brain magnetic signals of the brain and by computing virtual sensor waveforms at the source level. Moreover, graph theory (GT) analysis was used to assess the properties of the brain network.

RESULTS

Children in the B-BECTS group had an earlier onset of epilepsy compared to those in the U-BECTS category. In addition, both the B-BECTS and U-BECTS groups had lower Full Scale Intelligence Quotient (FSIQ), Verbal Comprehension Index (VCI), and Working Memory Index (WMI) scores, compared to the healthy controls although only children in the B-BECTS category had lower Perceptual Reasoning Index (PRI) scores. The results also showed that both BECTS groups had increased frontal cortex connectivity in specific frequency bands. Notably, children with B-BECTS showed a more disorderly and randomized network in the 1-4-Hz and 80-250-Hz frequency bands. Moreover, GT analysis showed that children with B-BECTS had lower clustering coefficient and characteristic path length in the 80-250-Hz frequency bands and higher connection strength in the 4-8-Hz frequency bands. On the other hand, the U-BECTS group had a higher clustering coefficient in the 8-12-Hz frequency bands, compared to the healthy controls. Correlation analysis revealed that there were negative correlations between network parameters, clinical characteristics, and neuropsychological data in the U-BECTS category.

CONCLUSION

The findings revealed that children with BECTS display a diffuse early cognitive deficit. In addition, resting-state suboptimal network topology may be the mechanism of cognitive impairment in children with BECTS. The study also showed that and children with B-BECTS may be at a higher risk of cognitive impairment.

Executive functioning in children with self-limited epilepsy with centrotemporal spikes: a systematic review and meta-analysis

Self-limited epilepsy with centrotemporal spikes (ECTS) is one of the most frequent focal epilepsies amongst children. Because remission usually occurs before 16 years old and patients present infrequent clinical manifestation, ECTS was considered benign for a long time. Despite the reports on cognitive deficits associated with ECTS in the last years, knowledge about the condition's specific executive function domains (inhibitory control, working memory, cognitive flexibility, verbal fluency, and higher-order executive functions) is still lacking. The following systematic review was conducted according to PRISMA guidelines. The PubMed and Scopus databases and gray literature were searched according to the following eligibility criteria: (1) original articles published in peer-review journals; (2) studies that present assessment of children with ECTS; and (3) studies with an available assessment of the executive function of the participants. A total of 43 studies (1179 patients and 1086 healthy controls) met the inclusion criteria. Data from 19 studies were extracted, and meta-analysis methods were used to compare results in the three main executive function domains and verbal fluency. The study quality was measured through the Newcastle-Ottawa Scale (NOS) and the evidence quality with the GRADEpro tool. Results and conclusions: The present systematic review is the first to gather information about executive functioning in children with ECTS. According to the meta-analyses, children with ECTS show weaker performances when compared with a control group in inhibitory control, cognitive flexibility, and verbal fluency. However, because the quality of evidence was classified as very low, caution is needed when interpreting the strength of the results.

Oral language in children with benign childhood epilepsy with centrotemporal spikes

PURPOSE

Benign childhood epilepsy with centrotemporal spikes is one of the most common childhood disorders. Despite the benignity usually attributed to this epileptic syndrome, several studies have demonstrated that these children have cognitive disabilities. Among these disturbances, language disorders have been the less studied in depth. We aimed to obtain accurate information about the language skills of children with this epileptic syndrome and to explore the correlation between demographic and clinical factors associated with epilepsy and the language skills.

METHODS

We assessed 30 children with this epileptic syndrome, followed in three hospitals in Lisbon, and 60 controls, aged between 6 and 12 years, attending the same schools and matched by age, gender, and parents' socioprofessional level. All the included children did not present cognitive impairment (reasoning ability, verbal memory), sensory, or motor limitations. The evaluation tests covered all language areas.

RESULTS

Overall, children with this epileptic syndrome had lower skills in the majority of the language areas, when compared with their peers. These children showed greater difficulties in semantics and syntax domains. The atypical evolution of the seizures and a longer duration of epilepsy were the clinical variables that most influence the language skills of our samples.

CONCLUSION

The early assessment of these capacities and the possible need for therapeutic intervention should be emphasized, in order to minimize the impact on their academic performance and quality of life.

Cortical Excitability, Synaptic Plasticity, and Cognition in Benign Epilepsy With Centrotemporal Spikes: A Pilot TMS-EMG-EEG Study

PURPOSE

Children with benign epilepsy with centrotemporal spikes have rare seizures emerging from the motor cortex, which they outgrow in adolescence, and additionally may have language deficits of unclear etiology. We piloted the use of transcranial magnetic stimulation paired with EMG and EEG (TMS-EMG, TMS-EEG) to test the hypotheses that net cortical excitability decreases with age and that use-dependent plasticity predicts learning.

METHODS

We assessed language and motor learning in 14 right-handed children with benign epilepsy with centrotemporal spikes. We quantified two TMS metrics of left motor cortex excitability: the resting motor threshold (measure of neuronal membrane excitability) and amplitude of the N100-evoked potential (an EEG measure of GABAergic tone). To test plasticity, we applied 1 Hz repetitive TMS to the motor cortex to induce long-term depression-like changes in EMG- and EEG-evoked potentials.

RESULTS

Children with benign epilepsy with centrotemporal spikes tolerate TMS; no seizures were provoked. Resting motor threshold decreases with age but is elevated above maximal stimulator output for half the group. N100 amplitude decreases with age after controlling for resting motor threshold. Motor cortex plasticity correlates significantly with language learning and at a trend level with motor learning.

CONCLUSIONS

Transcranial magnetic stimulation is safe and feasible for children with benign epilepsy with centrotemporal spikes, and TMS-EEG provides more reliable outcome measures than TMS-EMG in this group because many children have unmeasurably high resting motor thresholds. Net cortical excitability decreases with age, and motor cortex plasticity predicts not only motor learning but also language learning, suggesting a mechanism by which motor cortex seizures may interact with language development.

Changes in background electroencephalographic activity in benign childhood epilepsy with centrotemporal spikes after oxcarbazepine treatment: a standardized low-resolution brain electromagnetic tomography (sLORETA) study

Background

Several neuroimaging studies have reported neurophysiological alterations in patients with benign childhood epilepsy with centrotemporal spikes (BCECTS). However, reported outcomes have been inconsistent, and the progression of these changes in the brain remains unresolved. Moreover, background electroencephalography (EEG) in cases of BCECTS has not been performed often.

Methods

We investigated background EEG activity changes after six months of oxcarbazepine treatment to better understand the neurophysiological alterations and progression that occur in BCECTS. In 18 children with BCECTS, non-parametric statistical analyses using standardized low resolution brain electromagnetic tomography (sLORETA) were performed to compare the current density distribution of four frequency bands (delta, theta, alpha, and beta) between untreated and treated conditions.

Results

Background EEG activity for the delta frequency band was significantly decreased in the fronto-temporal and limbic regions of the left hemisphere after oxcarbazepine treatment (threshold log-F-ratio = ±2.729, P < 0.01). The maximum current density difference was found in the parahippocampal gyrus of the left limbic lobe (Montreal Neurological Institute coordinate [x, y, z = 25, − 20, − 10], Brodmann area 28) (log-F-ratio = 3.081, P < 0.01).

Conclusions

Our results indicate the involvement of the fronto-temporal and limbic cortices in BCECTS, and limbic lobe involvement, including the parahippocampal gyrus, was noted. In addition to evidence of the involvement of the fronto-temporal and limbic cortices in BCECTS, this study also found that an antiepileptic drug could reduce the delta frequency activity of the background EEG in these regions.

Benign epilepsy with centrotemporal spikes - Current concepts of diagnosis and treatment

Benign epilepsy with centrotemporal spikes (BECTS) is the most common focal epilepsy of the childhood and also one of the best known. It has a proclivity to start at a particular age and remit spontaneously before adolescence. Majority of patients may avoid long-term treatment, because of the mild course and very good outcome. Only few patients may present cognitive deficits if the proper treatment is not implied. BECTS is a part of heterogeneous group of syndromes that consists of Landau-Kleffner Syndrome (LKS), Continuous Spike-and-Wave during Sleep (CSWS) and Atypical benign partial epilepsy (ABPE). These syndromes may be also a result of various trajectories that BECTS may evolve to. Disease is suggested to have genetic origins, as some patients have relatives with different types of epilepsy. The discovery of the pathogenic mechanism of the disease and implementation of targeted therapy belong to the main challenges in the treatment of these patients.