Neuropsychological Findings in Idiopathic Occipital Lobe Epilepsies

Brain functional network changes in patients with juvenile myoclonic epilepsy: a study based on graph theory and Granger causality analysis

Many resting-state functional magnetic resonance imaging (rs-fMRI) studies have shown that the brain networks are disrupted in adolescent patients with juvenile myoclonic epilepsy (JME). However, previous studies have mainly focused on investigating brain connectivity disruptions from the perspective of static functional connections, overlooking the dynamic causal characteristics between brain network connections. In our study involving 37 JME patients and 35 Healthy Controls (HC), we utilized rs-fMRI to construct whole-brain functional connectivity network. By applying graph theory, we delved into the altered topological structures of the brain functional connectivity network in JME patients and identified abnormal regions as key regions of interest (ROIs). A novel aspect of our research was the application of a combined approach using the sliding window technique and Granger causality analysis (GCA). This method allowed us to delve into the dynamic causal relationships between these ROIs and uncover the intricate patterns of dynamic effective connectivity (DEC) that pervade various brain functional networks. Graph theory analysis revealed significant deviations in JME patients, characterized by abnormal increases or decreases in metrics such as nodal betweenness centrality, degree centrality, and efficiency. These findings underscore the presence of widespread disruptions in the topological features of the brain. Further, clustering analysis of the time series data from abnormal brain regions distinguished two distinct states indicative of DEC patterns: a state of strong connectivity at a lower frequency (State 1) and a state of weak connectivity at a higher frequency (State 2). Notably, both states were associated with connectivity abnormalities across different ROIs, suggesting the disruption of local properties within the brain functional connectivity network and the existence of widespread multi-functional brain functional networks damage in JME patients. Our findings elucidate significant disruptions in the local properties of whole-brain functional connectivity network in patients with JME, revealing causal impairments across multiple functional networks. These findings collectively suggest that JME is a generalized epilepsy with localized abnormalities. Such insights highlight the intricate network dysfunctions characteristic of JME, thereby enriching our understanding of its pathophysiological features.

Alterations in spatiotemporal characteristics of dynamic networks in juvenile myoclonic epilepsy

BACKGROUND

Juvenile myoclonic epilepsy (JME) is characterized by altered patterns of brain functional connectivity (FC). However, the nature and extent of alterations in the spatiotemporal characteristics of dynamic FC in JME patients remain elusive. Dynamic networks effectively encapsulate temporal variations in brain imaging data, offering insights into brain network abnormalities and contributing to our understanding of the seizure mechanisms and origins.

METHODS

Resting-state functional magnetic resonance imaging (rs-fMRI) data were procured from 37 JME patients and 37 healthy counterparts. Forty-seven network nodes were identified by group-independent component analysis (ICA) to construct the dynamic network. Ultimately, patients' and controls' spatiotemporal characteristics, encompassing temporal clustering and variability, were contrasted at the whole-brain, large-scale network, and regional levels.

RESULTS

Our findings reveal a marked reduction in temporal clustering and an elevation in temporal variability in JME patients at the whole-brain echelon. Perturbations were notably pronounced in the default mode network (DMN) and visual network (VN) at the large-scale level. Nodes exhibiting anomalous were predominantly situated within the DMN and VN. Additionally, there was a significant correlation between the severity of JME symptoms and the temporal clustering of the VN.

CONCLUSIONS

Our findings suggest that excessive temporal changes in brain FC may affect the temporal structure of dynamic brain networks, leading to disturbances in brain function in patients with JME. The DMN and VN play an important role in the dynamics of brain networks in patients, and their abnormal spatiotemporal properties may underlie abnormal brain function in patients with JME in the early stages of the disease.

Multilayer brain network modeling and dynamic analysis of juvenile myoclonic epilepsy

Objective: It is indisputable that the functional connectivity of the brain network in juvenile myoclonic epilepsy (JME) patients is abnormal. As a mathematical extension of the traditional network model, the multilayer network can fully capture the fluctuations of brain imaging data with time, and capture subtle abnormal dynamic changes. This study assumed that the dynamic structure of JME patients is abnormal and used the multilayer network framework to analyze the change brain community structure in JME patients from the perspective of dynamic analysis.

Methods: First, functional magnetic resonance imaging (fMRI) data were obtained from 35 JME patients and 34 healthy control subjects. In addition, the communities of the two groups were explored with the help of a multilayer network model and a multilayer community detection algorithm. Finally, differences were described by metrics that are specific to the multilayer network.

Results: Compared with healthy controls, JME patients had a significantly lower modularity degree of the brain network. Furthermore, from the level of the functional network, the integration of the default mode network (DMN) and visual network (VN) in JME patients showed a significantly higher trend, and the flexibility of the attention network (AN) also increased significantly. At the node level, the integration of seven nodes of the DMN was significantly increased, the integration of five nodes of the VN was significantly increased, and the flexibility of three nodes of the AN was significantly increased. Moreover, through division of the core-peripheral system, we found that the left insula and left cuneus were core regions specific to the JME group, while most of the peripheral systems specific to the JME group were distributed in the prefrontal cortex and hippocampus. Finally, we found that the flexibility of the opercular part of the inferior frontal gyrus was significantly correlated with the severity of JME symptoms.

Conclusion: Our findings indicate that the dynamic community structure of JME patients is indeed abnormal. These results provide a new perspective for the study of dynamic changes in communities in JME patients.

The Brain Alteration of Seafarer Revealed by Activated Functional Connectivity Mode in fMRI Data Analysis

As a special occupational group, the working and living environments faced by seafarers are greatly different from those of land. It is easy to affect the psychological and physiological activities of seafarers, which inevitably lead to changes in the brain functional activities of seafarers. Therefore, it is of great significance to study the neural activity rules of seafarers' brain. In view of this, this paper studied the seafarers' brain alteration at the activated voxel level based on functional magnetic resonance imaging technology by comparing the differences in functional connectivities (FCs) between seafarers and non-seafarers. Firstly, the activated voxels of each group were obtained by independence component analysis, and then the distribution of these voxels in the brain and the common activated voxels between the two groups were statistically analyzed. Next, the FCs between the common activated voxels of the two groups were calculated and obtained the FCs that had significant differences between them through two-sample T-test. Finally, all FCs and FCs with significant differences (DFCs) between the common activated voxels were used as the features for the support vector machine to classify seafarers and non-seafarers. The results showed that DFCs between the activated voxels had better recognition ability for seafarers, especially for Precuneus_L and Precuneus_R, which may play an important role in the classification prediction of seafarers and non-seafarers, so that provided a new perspective for studying the specificity of neurological activities of seafarers.

Panayiotopoulos syndrome and Gastaut syndrome are distinct entities in terms of neuropsychological findings

BACKGROUND

Although the courses of self-limited focal epilepsies of childhood are considered as benign, a handful of studies suggested that these children may suffer from cognitive problems. Implementing tailor-made educational strategies would aid these children to reach their full potentials. Therefore, it is crucial to understand and differentiate the complete neuropsychological and behavioral profiles of these rather common syndromes. We aimed to examine the distinct cognitive and behavioral profiles of the Panayiotopoulos syndrome (PS) and the Gastaut syndrome (GS), comparatively.

METHOD

Twenty patients with PS, 20 patients with GS, and 20 healthy controls have been recruited. The testing protocol included Wechsler Intelligence Scale for Children-Revised, Conner's Continuous Performance Test, Verbal Fluency Test, Stroop Color and Word Test, Color Trails Test, Tower of London Test, Symbol Digit Modalities Test, California Verbal Learning Test-Children's Version, Rey Complex Figure Test, Benton Face Recognition Test, Benton Judgment of Line Orientation, Peabody Picture Vocabulary Test, Reading and Writing Test, Child Behavior Checklist, Conner's Parent Rating Scale-48, and Behavior Rating Inventory of Executive Function. Demographical, clinical, electrophysiological data, and imaging findings have also been evaluated.

RESULTS

With regard to intelligence, the patients with PS scored less in all scales compared to the healthy controls. However, only the performance IQ (intelligence quotient) scores differed significantly between the patient groups, with the patients with PS scoring lower than the patients with GS. Verbal memory problems were eminent in both of the patient groups; whereas, visual memory was impaired only in the group with PS. Psychomotor speed was affected in both groups. Reading problems were prominent only in the patients with PS. Writing and arithmetic skills were defective in both patient groups. There were no noteworthy behavioral problems in comparison to healthy subjects.

CONCLUSION

Using neuropsychological profiles, this study demonstrated that the GS and the PS are two distinct entities. Cognitive dysfunction is a more prominent and widespread feature of the patients with PS; whereas, the patients with GS suffer only from milder and isolated cognitive problems.

How reading in single- and multiple-column types influence our cognitive load: an EEG study

Purpose

The impact of different screen-based typography styles on individuals’ cognitive processing of information has not been given much consideration in the literature, though such differences would imply different learning outcomes. This study aims to enrich the current understanding of the impact of reading in single- and multiple-column types on students’ cognitive processing.

Design/methodology/approach

An electroencephalogram (EEG) was used to record and analyze the brain signals of 27 students while reading from single- and multiple- column layouts.

Findings

The results showed a significant difference in students’ cognitive load when reading text from different types of columns. All students exerted less processing efforts when text was presented in two-column format, thus experiencing less cognitive load.

Originality/value

Using EEG, this study examined the neural consequences of reading in single- and multiple-column types on cognitive load during reading. The findings can be used to enrich the current instructional design practices on how different typographical formats facilitate learners’ cognitive performance.

Altered Structural and Functional Connectivity of Juvenile Myoclonic Epilepsy: An fMRI Study

The aim of this study was to investigate the structural and functional connectivity (FC) of juvenile myoclonic epilepsy (JME) using resting state functional magnetic resonance imaging (rs-fMRI). High-resolution T1-weighted magnetic resonance imaging (MRI) and rs-fMRI data were collected in 25 patients with JME and in 24 control subjects. A FC analysis was subsequently performed, with seeding at the regions that demonstrated between-group differences in gray matter volume (GMV). Then, the observed structural and FCs were associated with the clinical manifestations. The decreased GMV regions were found in the bilateral anterior cerebellum, the right orbital superior frontal gyrus, the left middle temporal gyrus, the left putamen, the right hippocampus, the bilateral caudate, and the right thalamus. The changed FCs were mainly observed in the motor-related areas and the cognitive-related areas. The significant findings of this study revealed an important role for the cerebellum in motor control and cognitive regulation in JME patients, which also have an effect on the activity of the occipital lobe. In addition, the changed FCs were related to the clinical features of JME patients. The current observations may contribute to the understanding of the pathogenesis of JME.

Extrastriate visual cortex in idiopathic occipital epilepsies: The contribution of retinotopic areas to spike generation

OBJECTIVES

To provide insight into the pathophysiology of idiopathic childhood occipital epilepsies (ICOEs), by mapping the contribution of retinotopic visual areas to the generation and sustainment of epileptic activity.

METHODS

Thirteen patients affected by ICOEs (mean age = 10.9 years) underwent a video electroencephalography-functional magnetic resonance imaging (EEG-fMRI) study. A flexible-related fMRI analysis was applied to estimate the shape of the blood oxygen level-dependent (BOLD) response in each patient. Second-level analysis was performed using the interictal EEG discharge (IED)-specific response shape for the ICOE group. The resulting fMRI t-maps were warped to the Population-Average, Landmark- and Surface-based (PALS)-B12 atlas in Caret. For localization purposes, functional results were plotted and compared against 19 retinotopic areas for each hemisphere. A correlation analysis was performed between the hemodynamic maps and electroclinical variables.

RESULTS

The shape of the group-averaged hemodynamic response in ICOE patients showed an earlier time-to-peak and a more pronounced undershoot than the canonical hemodynamic response function (HRF). The random-effect analysis showed positive hemodynamic changes in the bilateral temporooccipital network. With regard to the retinotopic subdivision of the visual cortex, the primary visual area was consistently spared. Conversely, an extensive involvement of the occipitotemporal cortex, including the fusiform gyrus, and the occipitoparietal areas was observed. Moreover, a linear relationship was detected between the occipital spike-density and BOLD increases at the postcentral gyrus and temporooccipital cortex.

SIGNIFICANCE

Our data indicate that both the ventral and dorsal visual pathways are involved in spike generation in ICOEs, to extents that vary between patients, and reinforce the concept of benign childhood seizure susceptibility syndrome as a substrate for ICOEs. Finally, these results underscore the need for appropriate neuropsychological testing in these children, aimed at revealing selective impairments in functions subserved by both visual pathways.

Idiopathic photosensitive occipital epilepsy: clinical and electroencephalographic (EEG) features

Idiopathic photosensitive occipital lobe epilepsy is a reflex, age- and localization-related syndrome. We describe the clinical and electroencephalographic features, therapy, and outcome of 16 children/adolescents with this syndrome. The cohort included 2 sets of siblings and 7 patients with other first- or second-degree relatives with a seizure history. All patients had occipital onset seizures and 15 had secondarily generalized tonic-clonic seizures. Seizure frequency was relatively low in all patients but one. Myoclonic seizures later developed in 2 patients with juvenile myoclonic epilepsy. Eight patients achieved full seizure control with monotherapy, and 5 required a second drug; 3 patients had rare seizures and were not treated with antiepileptics. Seven patients required special education or developmental assistance. This interesting syndrome sheds light on the pathophysiology and genetic etiology of common phenomena such as photosensitivity and headache. Further large prospective studies are required to better define this unique syndrome and its implications.

Benign childhood focal epilepsies

The idiopathic focal epilepsies comprise a group of syndromes characterized by focal-onset seizures for which there is no detectable structural brain abnormality and for which there is a proposed functional mechanism for the epilepsy and electroencephalography (EEG) abnormalities. This group includes benign rolandic epilepsy (BRE), benign epilepsy with occipital paroxysms (both early onset and late-onset types), idiopathic photosensitive occipital lobe epilepsy, and some less well-defined syndromes. The limits of the early onset idiopathic occipital epilepsy syndrome are not clear, and perhaps this entity represents part of a larger syndrome group of "autonomic" age-related epilepsies. The term "idiopathic" implies absence of a structural brain lesion and a genetic propensity to seizures. The term "benign" implies that the epileptic seizures are easily treated or require no treatment, show remission without sequelae with ultimate and definitive remission before adulthood, do not have severe or exceedingly disturbing seizures, and have no associated serious intellectual or behavioral disturbances. It may be that a syndrome is benign only when it can be recognized early with reasonable certainty, thereby avoiding unnecessary investigations, overtreatment, and lifestyle restrictions. Although BRE has such characteristic clinical and EEG features to make early recognition possible, this is less constantly so in the other focal idiopathic epilepsy syndromes, where the term "benign" may be inappropriate. Mild and selective neuropsychological impairment may occur even in those with typical syndromes but it is unclear whether such selective deficits outlast the active phase of epilepsy. Sometimes the clinical course may be complicated by obvious cognitive and language impairments. In such cases, the term benign is obviously inappropriate, even when seizures are rare. In most patients with the typical focal idiopathic epilepsy syndromes, medication is not necessary.

Disengagement and inhibition of visual-spatial attention are differently impaired in children with rolandic epilepsy and Panayiotopoulos syndrome

We assessed voluntary orientation and reorientation of visuospatial attention in 313 healthy 6- to 22-year-old participants, 30 children suffering from benign epilepsy with centrotemporal spikes (BECTS) and 13 children with Panayiotopoulos syndrome (PS). The developmental section highlights the late development of reorienting skills. Only children with BECTS-R showed a strong tendency toward a rightward bias in attentional orientation. Additionally, a unilateral deficit of disengagement characterizes the patients with BECTS-R and comorbid ADHD. Right rolandic spikes seem to aggravate subclinical reorienting difficulties. Finally, children with PS failed to diffuse inhibition, except in the nearest area outside the attentional focus. This deficit could be attributed to the typical occipital-to-frontal spreading of the spikes in PS. By showing distinct attentional deficiencies according to the epileptic syndrome and the epileptic focus lateralization in BECTS, the results provide new evidence for alterations of attentional mechanisms by interictal epileptic activity, which probably contribute to learning difficulties.

Cognitive function of idiopathic childhood epilepsy

Most children with epilepsy are of normal intelligence. However, a significant subset will have temporary or permanent cognitive impairment. Factors that affect cognitive function are myriad and include the underlying neuropathology of the epilepsy, seizures, epileptiform discharges, psychosocial problems, age at seizure onset, duration of epilepsy, and side effects associated with antiepileptic drugs. This review article discusses cognitive function in children with idiopathic epilepsy and the effects of antiepileptic drugs on cognitive function in children.

Visuoperceptive impairment in adult patients with occipital lobe epilepsies

The aim of the study was to verify whether adult patients with occipital lobe epilepsy (OLE) are at risk for cognitive impairment compared with controls. Twenty patients with OLE and 20 controls, matched as closely as possible to the epilepsy group in terms of gender, age, education, and intelligence, were administered a battery of tests based on visuoperceptive domains. None of the participants was affected by progressive pathologies, received any medication other than antiepileptic drugs, nor had a psychiatric background. We noted a statistically significant difference between patients with OLE and controls in the following tasks: Perceptive Differences Test, and Object Denomination Test, and Famous Faces Test (P<0.05). No difference was noted between symptomatic and nonsymptomatic patients with respect to neuropsychological results (P>0.05). The linear regression analysis performed did not show any statistically significant contribution by clinical variables. Our data confirm that patients with OLE manifest subtle difficulties in processing and mental manipulation of visual spatial data.

Neuropsychological deficits in childhood epilepsy syndromes

Seizure disorders are relatively common in childhood, and the International League Against Epilepsy (ILAE) provides a hierarchical classification system to define seizure types. At the final level of classification, specific epilepsy syndromes are defined that represent a complex of signs and symptoms unique to an epilepsy condition. The present review discusses the issues related to several of these epilepsy syndromes in childhood, including those classified as generalized idiopathic epilepsies (e.g., childhood absence epilepsy, juvenile absence epilepsy, juvenile myoclonic epilepsy), focal epilepsies (benign rolandic epilepsy, occipital epilepsy, temporal lobe epilepsy, frontal lobe epilepsy) and the "epileptic encephalopathies," including Dravet's Syndrome, West Syndrome, Lennox-Gastaut Syndrome, Myoclonic Astatic Epilepsy, and Landau-Kleffner Syndrome. For each syndrome, the epidemiology, clinical manifestations, treatments, and neuropsychological findings are discussed.

Neuropsychological deficits in childhood epilepsy syndromes

Seizure disorders are relatively common in childhood, and the International League Against Epilepsy (ILAE) provides a hierarchical classification system to define seizure types. At the final level of classification, specific epilepsy syndromes are defined that represent a complex of signs and symptoms unique to an epilepsy condition. The present review discusses the issues related to several of these epilepsy syndromes in childhood, including those classified as generalized idiopathic epilepsies (e.g., childhood absence epilepsy, juvenile absence epilepsy, juvenile myoclonic epilepsy), focal epilepsies (benign rolandic epilepsy, occipital epilepsy, temporal lobe epilepsy, frontal lobe epilepsy) and the "epileptic encephalopathies," including Dravet's Syndrome, West Syndrome, Lennox-Gastaut Syndrome, Myoclonic Astatic Epilepsy, and Landau-Kleffner Syndrome. For each syndrome, the epidemiology, clinical manifestations, treatments, and neuropsychological findings are discussed.