fMRI brain response during sentence reading comprehension in children with benign epilepsy with centro-temporal spikes

Abnormal white matter structural network topological property in patients with temporal lobe epilepsy

BACKGROUND

Diffusion tensor imaging (DTI) studies have demonstrated white matter (WM) abnormalities in patients with temporal lobe epilepsy (TLE). However, alterations in the topological properties of the WM structural network in patients with TLE remain unclear. Graph theoretical analysis provides a new perspective for evaluating the connectivity of WM structural networks.

METHODS

DTI was used to map the structural networks of 18 patients with TLE (10 males and 8 females) and 29 (17 males and 12 females) age- and gender-matched normal controls (NC). Graph theory was used to analyze the whole-brain networks and their topological properties between the two groups. Finally, partial correlation analyses were performed on the weighted network properties and clinical characteristics, namely, duration of epilepsy, verbal intelligence quotient (IQ), and performance IQ.

RESULTS

Patients with TLE exhibited reduced global efficiency and increased characteristic path length. A total of 31 regions with nodal efficiency alterations were detected in the fractional anisotropy_ weighted network of the patients. Communication hubs, such as the middle temporal gyrus, right inferior temporal gyrus, left calcarine, and right superior parietal gyrus, were also differently distributed in the patients compared with the NC. Several node regions showed close relationships with duration of epilepsy, verbal IQ, and performance IQ.

CONCLUSIONS

Our results demonstrate the disruption of the WM structural network in TLE patients. This study may contribute to the further understanding of the pathological mechanism of TLE.

Activation Map Reveals Language Impairment in Children with Benign Epilepsy with Centrotemporal Spikes (BECTS)

Objective

Neuropsychological evidence revealed language impairment in children with benign epilepsy with centrotemporal spikes (BECTS). This study investigates language function using task-activated fMRI.

Methods

We conducted a language task fMRI study on three groups on a 3.0T MRI scanner, including a new onset drug naïve group (NODN-BECTS, n=11, age=9.6±1.6), an established epilepsy with medication-treated group (Med-BECTS, n=17, age=10.7±2.2) and a healthy control group (HC, n=18, age=10.8±1.7). We use MATLAB14 and SPM12 to pre-process and analyze the data. A one-sample t-test was used to identify task-related brain activation changes in each group, based on the general linear model (GLM). And, then two sample t-test was performed to compare different activated regions between groups. In addition, scores on the most recent Mandarin school exams were acquired to examine and contrast extra-scanner language performance.

Results

Statistical results show that some language-related brain regions (such as the left superior frontal gyrus and cerebellar vermis) were additionally activated in the NODN-BECTS group compared with the HC group. Compared with NODN-BECTS and HC groups, decreased activations were found in language-related regions in the Med-BECTS group, including the left insula, superior and middle frontal gyri, and bilateral middle occipital gyri. On the Mandarin school exams, the average score for HC was 87.3±8.2, NODN was 84.8±7.8, and Med was 78.2±13.2. There was a trend toward statistical significance between the Med and the HC (p = 0.074) as well as NODN (p = 0.092) groups. No statistically significant differences were found between the HC and the NODN-BECTS groups.

Significance

Language task fMRI reveals additional areas of activation in new onset BECTS compared to healthy controls which may be compensatory in nature. Antiseizure medications (ASMs) and/or longer duration of BECTS additionally appears to affect language-related regions and reduce their functional ability.

Text integration processes in children with Childhood Epilepsy with Centro-Temporal Spikes

Although Childhood Epilepsy with Centro-Temporal Spikes (CECTS) is considered a 'benign' form of epilepsy, word reading, listening comprehension, and reading comprehension difficulties have been reported. We examined two core skills for text comprehension, coherence monitoring and inference generation, in children with CECTS and compared performance with typically developing controls. Children with CECTS (n = 23; 9 females; mean age 9 y 0 m) and the comparison group (n = 38; 14 females; mean age 9 y 1 m) completed two tasks. For coherence monitoring they heard 24 narrative texts, 16 containing two inconsistent sentences, and responded to a yes/no question to assess identification of the inconsistency after each text; for inference making they heard 16 texts designed to elicit a target inference by integrating information in two sentences and responded to a yes/no question to assess generation of the inference. In both tasks there was a near condition, in which critical sentences were adjacent, and a far condition in which these sentences were separated by filler sentences. Accuracy to the question and the processing time for critical sentences in the text were measured. We used listening comprehension tasks to control for variation in word reading ability. Mixed effects analyses for each task revealed that children with CECTS show comparable levels of accuracy to age-matched peers in these tasks tapping two core text integration skills: detection of inconsistencies and generation of inferences. However, they take longer to process texts indicating a likely source of their listening and reading comprehension difficulties.

Brain magnetic resonance imaging findings and brain volumetric differences in a large series of benign rolandic epilepsy

BACKGROUND

Several studies with a small sample size have investigated the relationship between structural and functional changes on MRI and the clinical and natural history of BRE. We aim to assess the frequency of incidental epileptogenic lesions on brain MRI in a large cohort of patients diagnosed with BRE and to assess the difference in volumetric brain measurements in BRE patients compared to healthy controls.

METHODS

The case-control study includes 214 typical BRE cases and 197 control children with non-epileptic spells. Brain MRIs were evaluated for abnormalities which were classified into normal and abnormal with or without epileptogenic lesions with categorization of epileptogenic lesions. Brain segmentation was also performed for a smaller group of BRE patients and another healthy control group. Pearson's chi-squared test and two-tailed independent samples t-test were used.

RESULTS

In patients with BRE, 7% had an epileptogenic lesion on their MRI. The frequency of epileptogenic lesion in the control group was 10.2% and not significantly different from those with BRE (p= 0.2). Significantly higher intracranial and white matter volumes were found in BRE patients compared to the healthy group while lower gray matter volume was found in BRE patients. Cortical and subcortical regions showed either higher or lower volumes with BRE. Interestingly, altered subcallosal cortex development which has a known association with depression was also found in BRE.

CONCLUSIONS

Our findings confirm the absence of any association between specific brain MRI abnormalities and BRE. However, the altered cortical and subcortical development in BRE patients suggests a microstructural-functional correlation.

Writing and Reading Skills in Children with Benign Childhood Epilepsy with Centrotemporal Spikes: Systematic Review

In this study, we present the results from a systematic literature review that aimed to gather information about the writing and reading capacities of children with benign childhood epilepsy with centrotemporal spikes. This research comprises studies published between 2005 and 2016 in PubMed, Science Direct, and PsycInfo that included the keywords “benign childhood epilepsy with centrotemporal spikes”/ “rolandic epilepsy” with “written language”/ “reading” / “writing” / “literacy”/ “learning disabilities.” The study selection criteria were: (i) conducted with children with this epileptic syndrome aged between 5:11 and 16; (ii) involving children with active epilepsy or in remission; (iii) assessing written language or learning skills involving reading and writing; and (iv) published in journals with scientific refereeing. From the articles that met all the criteria defined, we compiled and synthesized the information about written language abilities. Reading problems appear to have higher incidence in this population, mostly with regard to the speed and reading accuracy and the ability to comprehend a written text. Fewer limitations were found in writing skills, but some studies showed difficulties in words writing, punctuation/ accentuation, and spontaneous writing coherence and cohesion. We also found disparities in the results regarding the relationship between writing skills and the clinical variables associated with epilepsy. Despite the heterogeneity of this population, it was possible to synthesize and define more precisely the written language variations presented. However, more concrete information is needed about written language disorders in this population, to present valid data to support clinical and pedagogical practices.

Systematic review of executive functions in children with self-limited epilepsy with centrotemporal spikes

Self-limited Epilepsy with Centrotemporal Spikes (ECTS) is a self-limiting childhood epilepsy with an overall good prognosis. The neurocognitive profile of ECTS shows various degrees of neuropsychological impairment, with speech impairment and executive dysfunction being the most prominent. This review aimed to clarify the executive function (EF) profile of children with ECTS and the clinical variables' impact on these abilities. We conducted a systematic review of the relevant literature for articles published up to January 2021. Demographic and clinical characteristics were abstracted from the original records. EF tasks used in the studies were classified according to Diamond's model, which identified four components: working memory, inhibitory control, cognitive flexibility, and higher order EFs. Twenty-three studies were included. Among the included records, 14 studies examined working memory, 15 inhibitory control, 15 flexibility, 4 higher order EFs, and 2 general EFs. Results confirmed the presence of a specific impairment in two abilities: inhibitory control and cognitive flexibility. This review confirms the need to assess each EF both in verbal and visual-spatial tasks. The early detection of children with ECTS at risk of developing neuropsychological impairment could activate interventions and prevent worse school achievement, social functioning, and a poor quality of life. Systematic review registration: PROSPERO: CRD42021245959.

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.

Working Memory in Pediatric Epilepsy: A Systematic Review and Meta-Analysis

Working memory is a multicomponent system that is supported by overlapping specialized networks in the brain. Baddeley's working memory model includes four components: the phonological loop, visuo-spatial sketchpad, the central executive, and episodic buffer. The aim of this review was to establish the gravity and pattern of working memory deficits in pediatric epilepsy. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guided electronic searches. Sixty-five studies were included in the review. Meta-analyses revealed significant impairments across each working memory component: phonological loop (g = 0.739), visuo-spatial sketchpad (g = 0.521), and central executive (g = 0.560) in children with epilepsy compared to controls. The episodic buffer was not examined. The pattern of impairments, however, differed according to the site and side of seizure focus. This suggests that working memory components are differentially vulnerable to the location of seizure focus in the developing brain.

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.

Neural correlates of verbal working memory in children with epilepsy with centro-temporal spikes

BACKGROUND

Previous functional magnetic resonance imaging (fMRI) studies have identified brain systems underlying different components of working memory (WM) in healthy subjects. The aim of this study was to compare the functional integrity of these neural networks in children with self-limited childhood epilepsy with centro-temporal spikes (ECTS) as compared to healthy controls, using a verbal working memory task (WMT).

METHODS

Functional MRI of WM in seventeen 6-to-13 year-old children, diagnosed with ECTS, and 17 sex- and age-matched healthy controls were conducted at 3 T. To estimate BOLD responses during the maintenance of low, medium, and high WMT loads, we used a Sternberg verbal WMT. Neuropsychological testing prior to scanning and behavioral data during scanning were also acquired.

RESULTS

Behavioral performances during WMT, in particular accuracy and response time, were poorer in children with ECTS than in controls. Increased WM load was associated with increased BOLD signal in all subjects, with significant clusters detected in frontal and parietal regions, predominantly in the left hemisphere. However, under the high load condition, patients showed reduced activation in the frontal, temporal and parietal regions as compared to controls. In brain regions where WM-triggered BOLD activation differed between groups, this activation correlated with neuropsychological performances in healthy controls but not in patients with ECTS, further suggesting WM network dysfunction in the latter.

CONCLUSION

Children with ECTS differ from healthy controls in how they control WM processes during tasks with increasing difficulty level, notably for high WM load where patients demonstrate both reduced BOLD activation and behavioral performances.

The role of task-based neural activation research in understanding cognitive deficits in pediatric epilepsy

Children with epilepsy can experience significant cognitive dysfunction that can lead to academic underachievement. Traditionally believed to be primarily due to the effects of factors such as the chronicity of epilepsy, medication effects, or the location of the primary epileptogenic lesion;, recent evidence has indicated that disruption of cognition-specific distributed neural networks may play a significant role as well. Specifically, over the last decade, researchers have begun to characterize the mechanisms underlying disrupted cognitive substrates by evaluating neural network abnormalities observed during specific cognitive tasks, using task-based functional magnetic resonance imaging (fMRI). This targeted review assesses the current literature investigating the relationship between neural network abnormalities and cognitive deficits in pediatric epilepsy. The findings indicate that there are indeed neural network abnormalities associated with deficits in executive function, language, processing speed, and memory. Overall, cognitive dysfunction in pediatric epilepsy is associated with a decrease in neural network activation/deactivation as well as increased recruitment of brain regions not typically related to the specific cognitive task under investigation. The research to date has focused primarily on children with focal epilepsy syndromes with small sample sizes and differing research protocols. More extensive research in children with a wider representation of epilepsy syndromes (including generalized epilepsy syndromes) is necessary to fully understand these relationships and begin to identify underlying cognitive phenotypes that may account for the variability observed across children with epilepsy. Furthermore, more uniformity in fMRI protocols and neuropsychological tasks would be ideal to advance this literature.

Functional and Structural Network Disorganizations in Typical Epilepsy With Centro-Temporal Spikes and Impact on Cognitive Neurodevelopment

Epilepsy with Centrotemporal Spikes (ECTS) is the most common form of self-limited focal epilepsy. The pathophysiological mechanisms by which ECTS induces neuropsychological impairment in 15-30% of affected children remain unclear. The objective of this study is to review the current state of knowledge concerning the brain structural and functional changes that may be involved in cognitive dysfunctions in ECTS. Structural brain imaging suggests the presence of subtle neurodevelopmental changes over the epileptogenic zone and over distant regions in ECTS. This structural remodeling likely occurs prior to the diagnosis and evolves over time, especially in patients with cognitive impairment, suggesting that the epileptogenic processes might interfere with the dynamics of the brain development and/or the normal maturation processes. Functional brain imaging demonstrates profound disorganization accentuated by interictal epileptic spikes (IES) in the epileptogenic zone and in remote networks in ECTS. Over the epileptogenic zone, the literature demonstrates changes in term of neuronal activity and synchronization, which are effective several hundred milliseconds before the IES. In the same time window, functional changes are also observed in bilateral distant networks, notably in the frontal and temporal lobes. Effective connectivity demonstrates that the epileptogenic zone constitutes the key area at the origin of IES propagation toward distant cortical regions, including frontal areas. Altogether, structural and functional network disorganizations, in terms of: (i) power spectral values, (ii) functional and effective connectivity, are likely to participate in the cognitive impairment commonly reported in children with ECTS. These results suggest a central and causal role of network disorganizations related to IES in the neuropsychological impairment described in ECTS children.

Abnormal cortical activation during an auditory word comprehension task in benign childhood epilepsy with centrotemporal spikes: A magnetoencephalographic study

OBJECTIVE

Benign childhood epilepsy with centrotemporal spikes (BECTS), also known as rolandic epilepsy, has recently been reported to be associated with variable degrees of cognitive dysfunction. Many studies reported poor language ability in children with BECTS compared with healthy control children. To elucidate the harmful effects of BECTS on language cognition, we studied the magnetoencephalographic activity elicited by an auditory language comprehension task.

METHODS

The participants (N = 20) included 10 children diagnosed with BECTS (aged 10.8 ± 2.8 years) and 10 age-matched healthy children (control) (aged 10.6 ± 1.6 years). Cognitive function was assessed using general intellectual function and language ability. In patients with BECTS, we reviewed the clinical course and electroencephalogram (EEG) findings. We recorded the cortical responses elicited by an auditory language comprehension task using magnetoencephalography (MEG). We compared those results between groups and analyzed the correlation with cognitive scores and frequency of spikes.

RESULTS

The full-scale intelligence quotient (FSIQ) by the Wechsler Intelligence Scale for Children-4th edition was significantly reduced in the group with BECTS (96.4 ± 12.3) compared with the control group (110.0 ± 7.4). In half of the group with BECTS, the auditory comprehension score fell below the age-standard level. In the group with BECTS, the cortical activation during the task showed reduced intensity in language-associated areas such as the bilateral primary auditory cortex, left superior and mid-temporal areas, and inferior frontal area compared with those in the control group. In addition, the cortical activation in the left superior temporal area was negatively correlated with spike frequency and positively correlated with FSIQ in the group with BECTS. Conversely, the right inferior frontal and mid-temporal areas had increased the activations in the group with BECTS. From the time frequency analysis, low gamma band event-related desynchronization was reduced in the group with BECTS.

CONCLUSION

Epileptic spikes negatively influenced responsiveness to the auditory language comprehension task in the language-associated cortices. These findings suggest that epileptic spikes could have a negative impact on the functional activity in rolandic areas and become a reason to change the functional development of the language network.

Frequency-specific alterations in the amplitude and synchronization of resting-state spontaneous low-frequency oscillations in benign childhood epilepsy with centrotemporal spikes

OBJECTIVES

Spontaneous low-frequency oscillations in different frequency bands have diverse physiological meanings. The amplitude of low-frequency fluctuation (ALFF) and functional connectivity (FC) in different frequency bands in Benign Childhood Epilepsy with Centrotemporal Spikes (BECTS) are unknown and worth exploring.

METHOD

Resting-state functional magnetic resonance imaging data were collected in 51 drug-naïve BECTS patients and 76 healthy controls. The ALFF was calculated for the typical (0.01 - 0.08 Hz), slow-5 (0.01-0.027 Hz), slow-4 (0.027-0.073 Hz), and slow-3 (0.073-0.198 Hz) frequency bands. The bilateral precuneus/posterior cingulate cortex (PCU/PCC) showed a common alteration of ALFF in different frequency bands, and was selected as the seed for calculating FC per voxel.

RESULTS

In the typical band, BECTS patients showed increased ALFF in the left rolandic operculum and the right pre/postcentral gyrus, and decreased ALFF in the bilateral PCU/PCC, some of which were shared by the slow-5, slow-4, and slow-3 bands. Decreased ALFF in the left angular gyrus was also found in the slow-3 band. Only the bilateral PCU/PCC showed a frequency-dependent correlation with the total seizure frequency and full-scale intelligence quotient. Regions having degenerated FC with the bilateral PCU/PCC in BECTS patients were mainly in the left prefrontal cortex and bilateral anterior cingulate cortex for the typical and slow-5 bands, and in the bilateral temporal limbic system and striatum for the slow-4 and slow-3 bands.

CONCLUSION

Alteration of the ALFF and FC differed with distinct frequency bands. Therefore, employing different frequency bands would provide more meaningful findings for BECTS patients.

Language skills in children with benign childhood epilepsy with centrotemporal spikes: A systematic review

Benign childhood epilepsy with centrotemporal spikes (BECTS) is the epileptic syndrome that most affects preschool and school-age children. Despite being usually considered a benign condition, several studies have shown that this epileptic syndrome is responsible for cognitive morbidities in children, namely at the level of attention and memory, as well as language. However, language disorders are still superficially addressed by the literature. This review aimed to compile and synthesize recent literature in this area. This systematic bibliographic research comprises studies published between 2005 and 2016 in PubMed, Science Direct, and PsycInfo computer databases that included the keywords "language", "cognition", "benign childhood epilepsy with centrotemporal spikes", "rolandic epilepsy", and "children". Studies were selected according to the following criteria: (i) published in scientific peer reviewed journals; (ii) performed with children between the ages of 3 and 16 years; and (iii) performed in children with BECTS in the active phase or after remission. Eighteen studies met these criteria. Nine studies mentioned language skill disorders in children with BECTS in the receptive and productive domains of semantics and seven studies in morphosyntax. Regarding phonological awareness, six studies have found limitations in the intrasyllabic, syllabic, and phonemic levels. These studies have also detected deficits in verbal fluency (semantic and phonemic) and in verbal memory. Because of the heterogeneity of the study samples and the use of innumerable distinct tasks in the evaluation of language skills, the results obtained still show some lack of consensus regarding the affected areas. Despite this, it was possible to synthesize and define more precisely the oral language variations presented by this population. We have concluded that the changes in semantic skills are the most frequently mentioned. The studies have also showed morphosyntactic and phonological disorders, in spite of showing some variability among them.

Structural Covariance Network of Cortical Gyrification in Benign Childhood Epilepsy with Centrotemporal Spikes

Benign childhood epilepsy with centrotemporal spikes (BECTS) is associated with cognitive and language problems. According to recent studies, disruptions in brain structure and function in children with BECTS are beyond a Rolandic focus, suggesting atypical cortical development. However, previous studies utilizing surface-based metrics (e.g., cortical gyrification) and their structural covariance networks at high resolution in children with BECTS are limited. Twenty-six children with BECTS (15 males/11 females; 10.35 ± 2.91 years) and 26 demographically matched controls (15 males/11 females; 11.35 ± 2.51 years) were included in this study and subjected to high-resolution structural brain MRI scans. The gyrification index was calculated, and structural brain networks were reconstructed based on the covariance of the cortical folding. In the BECTS group, significantly increased gyrification was observed in the bilateral Sylvain fissures and the left pars triangularis, temporal, rostral middle frontal, lateral orbitofrontal, and supramarginal areas (cluster-corrected p < 0.05). Global brain network measures were not significantly different between the groups; however, the nodal alterations were most pronounced in the insular, frontal, temporal, and occipital lobes (FDR corrected, p < 0.05). In children with BECTS, brain hubs increased in number and tended to shift to sensorimotor and temporal areas. Furthermore, we observed significantly positive relationships between the gyrification index and age (vertex p < 0.001, cluster-level correction) as well as duration of epilepsy (vertex p < 0.001, cluster-level correction). Our results suggest that BECTS may be a condition that features abnormal over-folding of the Sylvian fissures and uncoordinated development of structural wiring, disrupted nodal profiles of centrality, and shifted hub distribution, which potentially represents a neuroanatomical hallmark of BECTS in the developing brain.