Attention networks in children with idiopathic generalized epilepsy

Interhemispheric Integration after Callosotomy: A Meta-Analysis of Poffenberger and Redundant-Target Paradigms

The central role of the corpus callosum in integrating perception and cognition across the cerebral hemispheres makes it highly desirable for clinical and basic research to have a repertoire of experimental paradigms assessing callosal functioning. Here, the objective was to assess the validity of two such paradigms (Poffenberger, redundant-target paradigms) by conducting single-step meta-analyses on individual case data of callosotomy patients. Studies were identified by systematic literature search (source: Pubmed and WebOfKnowledge, date: 07.03.2022) and all studies were included that reported callosotomy case data for either paradigm. Twenty-two studies (38 unique cases) provided 116 observations of the crossed-uncrossed difference (CUD) for the Poffenberger paradigm, while ten studies (22 cases, 103 observations) provided bilateral redundancy gain (bRG) measures. Using linear-mixed models with "individual" and "experiment" as random-effects variable, the mean CUD was estimated at 60.6 ms (CI95%: 45.3; 75.9) for commissurotomy, 43.5 ms (26.7; 60.2) for complete callosotomy, and 8.8 ms (1.1; 16.6) for partial anterior-medial callosotomy patients. The estimates of commissurotomy/callosotomy patients differed significantly from patients with partial callosotomy and healthy controls. The mean bRGmin (minimum unilateral reference) was estimated at 42.8 ms (27.1;58.4) for patients with complete and 30.8 ms (16.8; 44.7) for patients with partial callosotomy, both differing significantly from controls. One limitation was that different formulas for bRG were used, making it necessary to split the sample and reducing test power of some analyses. Nevertheless, the present findings suggest that both paradigms assess interhemispheric callosal integration, confirming their construct validity, but likely test distinct callosal functions.

A Potential Multimodal Test for Clinical Assessment of Visual Attention in Neurological Disorders

Attention is an important aspect of human brain function and often affected in neurological disorders. Objective assessment of attention may assist in patient care, both for diagnostics and prognostication. We present a compact test using a combination of a choice reaction time task, eye-tracking and EEG for assessment of visual attention in the clinic. The system quantifies reaction time, parameters of eye movements (i.e. saccade metrics and fixations) and event related potentials (ERPs) in a single and fast (15 min) experimental design. We present pilot data from controls, patients with mild traumatic brain injury and epilepsy, to illustrate its potential use in assessing attention in neurological patients. Reaction times and eye metrics such as fixation duration, saccade duration and latency show significant differences (p < .05) between neurological patients and controls. Late ERP components (200-800 ms) can be detected in the central line channels for all subjects, but no significant group differences could be found in the peak latencies and mean amplitudes. Our system has potential to assess key features of visual attention in the clinic. Pilot data show significant differences in reaction times and eye metrics between controls and patients, illustrating its promising use for diagnostics and prognostication.

Neurophysiological signatures reflect differences in visual attention during absence seizures

OBJECTIVE

Absences affect visual attention and eye movements variably. Here, we explore whether the dissimilarity of these symptoms during absences is reflected in differences in electroencephalographic (EEG) features, functional connectivity, and activation of the frontal eye field.

METHODS

Pediatric patients with absences performed a computerized choice reaction time task, with simultaneous recording of EEG and eye-tracking. We quantified visual attention and eye movements with reaction times, response correctness, and EEG features. Finally, we studied brain networks involved in the generation and propagation of seizures.

RESULTS

Ten pediatric patients had absences during the measurement. Five patients had preserved eye movements (preserved group) and five patients showed disrupted eye movements (unpreserved group) during seizures. Source reconstruction showed a stronger involvement of the right frontal eye field during absences in the unpreserved group than in the preserved group (dipole fraction 1.02% and 0.34%, respectively, p < 0.05). Graph analysis revealed different connection fractions of specific channels.

CONCLUSIONS

The impairment of visual attention varies among patients with absences and is associated with differences in EEG features, network activation, and involvement of the right frontal eye field.

SIGNIFICANCE

Assessing the visual attention of patients with absences can be usefully employed in clinical practice for tailored advice to the individual patient.

The ability of executive functions to predict deterioration in social abstraction in adolescents with idiopathic generalized epilepsy

Background

Epilepsy is a prevalent disease worldwide. Executive functions and social cognition are essential in daily living functioning, academic performance, and social adjustment. This study attempts to investigate the executive functions and ability to abstract social concepts in adolescents who have idiopathic generalized epilepsy and assess if the deterioration in executive functions can predict deterioration in the ability to abstract social concepts. Sixty adolescents with idiopathic generalized epilepsy aged between 12 and 19 collected from the neurology outpatient clinic at Sohag University Hospital in Upper Egypt were compared with 60 age- and sex-matched healthy adolescents regarding performance on executive function tests and ability to abstract social concepts tests. We used the Tower test to assess planning, the design fluency test to assess cognitive flexibility, the verbal fluency test to assess verbal fluency, and the Stroop test (overlapping between colour and word test) to assess inhibition and ability to abstract the social concepts test, which is composed of verbal part and performance part.

Results

Adolescents who have idiopathic generalized epilepsy have worse executive function impairment in all executive functions than control adolescents. Adolescents with idiopathic epilepsy have significantly more impairment in the ability to abstract social concepts (verbal and performance) compared to control adolescents. There is a significant correlation between executive functions and the ability to abstract social concepts (verbal and performance) in epileptic and control adolescents. Impairment in some executive functions can predict impairment in the ability to abstract social concepts (verbal and performance) in epileptic and control adolescents. Executive function impairment is correlated with the duration of illness, frequency of seizures per year, time since last epileptic fit, and presence of interictal epileptic discharge in EEG in the patient group.

Conclusions

Executive functions and the ability to abstract social concepts are significantly impaired in adolescents who have idiopathic generalized epilepsy. Impairment in executive functions can predict impairment in the ability to abstract social concepts. There is a need to screen executive functions and social abilities of adolescents with epilepsy and programmes to enhance these abilities.

Attentional networks in neurodegenerative diseases: anatomical and functional evidence from the Attention Network Test

INTRODUCTION

Understanding alterations to brain anatomy and cognitive function associated with neurodegenerative diseases remains a challenge for neuroscience today. In experimental neuroscience, several computerised tests have been developed to contribute to our understanding of neural networks involved in cognition. The Attention Network Test (ANT) enables us to measure the activity of 3 attentional networks (alertness, orienting, and executive function).

OBJECTIVES

The main aim of this review is to describe all the anatomical and functional alterations found in diverse neurological diseases using the ANT.

MATERIAL AND METHODS

We collected studies published since 2010 in the PubMed database that employed the ANT in different neurological diseases. Thirty-two articles were obtained, addressing multiple sclerosis, epilepsy, and Parkinson's disease, among other disorders.

CONCLUSIONS

Some of the anatomical structures proposed in the 3 attentional networks model were confirmed. The most relevant structures in the alertness network are the prefrontal cortex, parietal region, thalamus, and cerebellum. The thalamus is also relevant in the orienting network, together with posterior parietal regions. The executive network does not depend exclusively on the prefrontal cortex and anterior cingulate cortex, but also involves such subcortical structures as the basal ganglia and cerebellum and their projections towards the entire cortex.

Cognitive profile, psychopathological symptoms, and quality of life in newly diagnosed pediatric epilepsy: A six-month, naturalistic follow-up study

Long-term studies indicated changes in aspects of cognition, psychopathology, and quality of life (QOL) in children and adolescents followed up after the diagnosis of epilepsy. However, evidence is limited regarding what happens during the first few months after epilepsy is diagnosed because at this phase is possible to adjust and/or change an AED regimen or add other treatment interventions, if needed. This is a naturalistic, six months follow-up study that evaluated changes in overall cognitive profiles, levels of psychopathological symptoms, and quality of life (QOL) in newly diagnosed, uncomplicated pediatric epilepsy. In total, 61 (35 [57.4%] males) children and adolescents aged 7-18 years were assessed at the time of diagnosis and the initiation of antiepileptic drug (AED) treatment and six months afterward. The Revised Wechsler Intelligence Scale for Children, the Revised Child Anxiety and Depression Scale (RCADS), Nisonger Child Behavior Rating Form for typically developing children and adolescents (NCBRF), KIDSCREEN-10 Quality of Life Measure, and Adverse Event Profile (AEP) were used. The RCADS and NCBRF scores significantly increased over time, while the KIDSCREEN-10 scores significantly decreased. The most significant increases were observed in scores measuring social phobia and depressive symptoms and inattentiveness. Verbal cognitive abilities and full-scale intelligence scores changed slightly, while more changes were found in aspects of non-verbal cognitive abilities. This study showed that six months after epilepsy diagnosis and AED initiation, there were marked increases in anxiety levels, depressive symptoms, and behavioral problems, with deteriorations in QOL, while cognitive changes were relatively minimal. Therefore, monitoring levels of psychopathological symptoms and QOL in newly diagnosed epilepsy is highly recommended.

Neuropsychiatric comorbidities in genetic/idiopathic generalized epilepsies and their effects on psychosocial outcomes

INTRODUCTION

Idiopathic/genetic generalized epilepsy (GGE) accounts for 15-20% of all epilepsy cases. Neuropsychiatric comorbidities and disorders, such as attention-deficit hyperactivity disorder (ADHD), academic failure, and poor social competence, are present at a higher rate in patients with epilepsy compared with the general population. In this study, we aimed to determine the frequency of neuropsychiatric comorbidities in GGE subgroups, and to reveal the risk factors in the patient group with neuropsychiatric comorbidities.

MATERIAL AND METHOD

This hospital-based, cross-sectional study follows the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. Patients with seizure-controlled GGE were invited to a semi-structured interview at the hospital. Variables [photosensitivity, valproic acid (VPA) resistance, timing of the neuropsychiatric comorbidities Attention deficit and hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), and low academic performance), seizure control, and timing of the antiepileptic treatment] were statistically analyzed and evaluated in terms of their association with GGE subgroups [Generalized tonic-clonic seizures alone (EGTGS), juvenile myoclonic epilepsy (JME), and juvenile absence epilepsy (JAE)], RESULTS: Total 101 patients with GGE were included in the study and the mean age was 13.94 ± 1.66 years. A total of 12.9% (n = 13) of the patients had EGTGS, 49.5% (n = 50) had JME, and 37.6% (n = 38) had JAE. VPA resistance, photosensitivity, and the presence of neuropsychiatric symptoms before the starting of epilepsy were found to be risk factors in the GGE group with neuropsychiatric comorbidities compared with the group without neuropsychiatric comorbidities (p < 0.001). The subgroups of GGE did not show any relationship with psychiatric disorders, including ADHD, ODD, and low academic performance (neuropsychiatric comorbidities) (p > 0.005). No correlation was found between seizure control and decline in neuropsychiatric symptoms (p > 0.05).

CONCLUSION

In this study, the onset of psychiatric symptoms prior to the onset of epilepsy, photosensitivity, and VPA resistance were the most important factors affecting neuropsychiatric comorbidities. The JME, JAE, and EGTCS subgroups, early initiation of antiepileptic treatment, and seizure control were found to have no effect on poor psychosocial outcome and neuropsychiatric comorbidities.

Absence epilepsy: Characteristics, pathophysiology, attention impairments, and the related risk of accidents. A narrative review

OBJECTIVE

Absence epilepsy (AE) is related to both cognitive and physical impairments. In this narrative review, we critically discuss the pathophysiology of AE and the impairment of attention in children and adolescents with AE. In particular, we contextualize the attentive dysfunctions of AE with the associated risks, such as accidental injuries.

DATA SOURCE

An extensive literature search on attention deficits and the rate of accidental injuries in AE was run. The search was conducted on Scopus, Pubmed, and the online libraries of the University of Twente and Maastricht University. Relevant references of the included articles were added. Retrospective and prospective studies, case reports, meta-analysis, and narrative reviews were included. Only studies written in English were considered. Date of last search is February 2020. The keywords used were "absence epilepsy" AND "attention"/"awareness", "absence epilepsy" AND "accidental injuries"/"accident*"/"injuries".

RESULTS

Ten retrospective and two prospective studies on cognition and AE were fully screened. Seventeen papers explicitly referring to attention in AE were reviewed. Just one paper was found to specifically focus on accidental injuries and AE, while twelve studies generally referring to epilepsy syndromes - among which AE - and related accidents were included.

CONCLUSION

Absence epilepsy and attention deficits show some patterns of pathophysiological association. This relation may account for dysfunctions in everyday activities in the pediatric population. Particular metrics, such as the risk related to biking in children with AE, should be used in future studies to address the problem in a novel way and to impact clinical indications.

Attentional networks in neurodegenerative diseases: anatomical and functional evidence from the Attention Network Test

INTRODUCTION

Understanding alterations to brain anatomy and cognitive function associated with neurodegenerative diseases remains a challenge for neuroscience today. In experimental neuroscience, several computerised tests have been developed to contribute to our understanding of neural networks involved in cognition. The Attention Network Test (ANT) enables us to measure the activity of 3 attentional networks (alertness, orienting, and executive function).

OBJECTIVES

The main aim of this review is to describe all the anatomical and functional alterations found in diverse neurological diseases using the ANT.

MATERIAL AND METHODS

We collected studies published since 2010 in the PubMed database that employed the ANT in different neurological diseases. Thirty-two articles were obtained, addressing multiple sclerosis, epilepsy, and Parkinson's disease, among other disorders.

CONCLUSIONS

Some of the anatomical structures proposed in the 3 attentional networks model were confirmed. The most relevant structures in the alertness network are the prefrontal cortex, parietal region, thalamus, and cerebellum. The thalamus is also relevant in the orienting network, together with posterior parietal regions. The executive network does not depend exclusively on the prefrontal cortex and anterior cingulate cortex, but also involves such subcortical structures as the basal ganglia and cerebellum and their projections towards the entire cortex.

The Impact of Idiopathic Generalized Epilepsy on Executive Functions

Background: Idiopathic generalized epilepsy is defined as seizures with a possible hereditary predisposition without an underlying cause or structural pathology. Assessment of executive dysfunction in idiopathic generalized epilepsies based on standard Indian battery is not available in the literature.

Aims and Objectives: To assess specific executive functions affected in patients with idiopathic epilepsy and their association with various variables.

Materials and Methods: Type of observational cross-sectional study, where clinical profile of all idiopathic epilepsy patients attending the neurology OPD was studied and their executive higher mental functions were assessed using the NIMHANS battery.

Results: A total of 75 idiopathic generalized epilepsy patients were included in the study. Executive functions that were commonly found abnormal in our study were word fluency (P ≤ .001), category fluency (P < .001), verbal n-back (P < .001), Tower of London (p < 0.01), and Stroop test (P < 0.01). Executive functions showed a significant correlation with age at symptom onset, duration of epilepsy, and in those with uncontrolled seizures.

Conclusion: Patients of idiopathic generalized epilepsy according to the present study were found to have significant executive dysfunction in multiple domains. This necessitates the screening for executive dysfunctions, which if detected should prompt the clinician to initiate cognitive retraining.

Juvenile myoclonic epilepsy shows increased posterior theta, and reduced sensorimotor beta resting connectivity

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We investigated whole brain source space connectivity in JME using across standard MEG frequency bands.

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Connectivity was increased in posterior theta and alpha bands in JME, and decreased in sensorimotor beta band.

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Our findings highlight altered interactions between posterior networks of arousal and attention and the motor system in JME.

Background

Widespread structural and functional brain network changes have been shown in Juvenile Myoclonic Epilepsy (JME) despite normal clinical neuroimaging. We sought to better define these changes using magnetoencephalography (MEG) and source space connectivity analysis for optimal neurophysiological and anatomical localisation.

Methods

We consecutively recruited 26 patients with JME who underwent resting state MEG recording, along with 26 age-and-sex matched controls. Whole brain connectivity was determined through correlation of Automated Anatomical Labelling (AAL) atlas source space MEG timeseries in conventional frequency bands of interest delta (1−4 Hz), theta (4−8 Hz), alpha (8−13 Hz), beta (13−30 Hz) and gamma (40−60 Hz). We used a Linearly Constrained Minimum Variance (LCMV) beamformer to extract voxel wise time series of ‘virtual sensors’ for the desired frequency bands, followed by connectivity analysis using correlation between frequency- and node-specific power fluctuations, for the voxel maxima in each AAL atlas label, correcting for noise, potentially spurious connections and multiple comparisons.

Results

We found increased connectivity in the theta band in posterior brain regions, surviving statistical correction for multiple comparisons (corrected p < 0.05), and decreased connectivity in the beta band in sensorimotor cortex, between right pre- and post- central gyrus (p < 0.05) in JME compared to controls.

Conclusions

Altered resting-state MEG connectivity in JME comprised increased connectivity in posterior theta – the frequency band associated with long range connections affecting attention and arousal - and decreased beta-band sensorimotor connectivity. These findings likely relate to altered regulation of the sensorimotor network and seizure prone states in JME.

Cortical excitability and seizure control influence attention performance in patients with idiopathic generalized epilepsies (IGEs)

We recently found that higher cortical excitability is associated with poorer attention performance in healthy adults. While patients with idiopathic generalized epilepsies (IGEs), previously termed genetic generalized epilepsies, are known to demonstrate increased cortical excitability and cognitive deficits, a relationship between these variables in IGEs has not been investigated. Therefore, we aimed to characterize the effects of cortical excitability and seizure control on cognitive performance in IGEs. We studied 30 patients with IGEs (16 patients with controlled IGEs (cIGEs) and 14 patients with treatment-resistant IGEs (trIGEs)) and 24 healthy controls (HCs). Transcranial magnetic stimulation (TMS) was used to measure cortical excitability, including long-interval intracortical inhibition (LICI). Attention was assessed with the Digit Span Forwards, Digit Span Backwards, Trails A, and Flanker tasks. Executive functioning was assessed using Trails B, Stroop Color and Word, and the Wisconsin Card Sorting Task. Two-way multivariate analyses of variance (MANOVAs) were conducted to assess the influences of seizure control (HCs vs. cIGEs vs. trIGEs) and cortical excitability (inhibitory vs. excitatory) on composite measures of attention and executive functions. Attention performance was significantly affected by cortical excitability and seizure control. Participants with primarily excitatory LICI responses, indicating higher cortical excitability, performed worse than inhibitory responders on composite attention (Wilks' lambda = 0.748, F(4, 44) = 3.72, p = 0.011). While participants with cIGEs and trIGEs did not significantly differ in attention performance, participants with trIGEs performed worse on the Digit Forwards (False Discovery Rate (FDR)p < 0.001), Digit Backwards (FDRp = 0.015), and Flanker (FDRp = 0.0075) tasks compared with HCs. These results provide support for the relationship between cortical excitability and attention dysfunction in IGEs. Further investigation is needed to determine whether there is a causal relationship between these variables and whether intracortical gamma-aminobutyric acid (GABA)_B networks may be targeted to improve attention deficits in clinical populations with decreased LICI. Findings also suggest that additional research directly comparing cognition in patients with cIGEs and trIGEs is warranted.

Altered functional connectivity among default, attention, and control networks in idiopathic generalized epilepsy

Numerous resting-state fMRI studies have demonstrated altered functional connectivity within canonical intrinsic connectivity networks (ICNs) in patients with idiopathic generalized epilepsy (IGE). It is possible that the widespread ICN abnormalities on electroencephalography in IGE derive from abnormal functional interactions between ICNs. To test this possibility, we explored the functional connectivity between the subnetworks of the default mode network (DMN), attention network (ATN), and frontoparietal control network (FPN) using independent component analysis of resting-state fMRI data collected from 27 patients with IGE characterized by generalized tonic-clonic seizures (GTCS) and 29 matched healthy controls. It was observed that the left FPN exhibited increased connectivity with the anterior DMN and ventral ATN, while the right FPN exhibited increased connectivity with the anterior and posterior DMNs in the patients with IGE-GTCS. Furthermore, the functional connectivity between the anterior DMN and ventral ATN was negative in healthy controls but positive in the patients with IGE-GTCS. In addition, the anterior DMN exhibited increased intranetwork functional connectivity in the right frontal pole in IGE-GTCS. These findings suggest that IGE-GTCS is likely associated with a disrupted brain organization probably derived from abnormal functional interactions among ICNs. Furthermore, the alterations in the functional architecture of the ICNs may be related to deficits in mentation and attention in IGE-GTCS, providing informative evidence for the understanding of the pathophysiology of IGE-GTCS.

Cognitive function in childhood epilepsy: importance of attention deficit hyperactivity disorder

Background and Purpose

To determine how cognitive function is related to epilepsy classification and comorbid attention deficit hyperactivity disorder (ADHD) in children with newly diagnosed epilepsy of genetic or unknown etiology.

Methods

The medical records of children aged 6-16 years with newly diagnosed epilepsy of genetic or unknown etiology were reviewed retrospectively. The Korean Education Development Institute-Wechsler Intelligence Scale for Children and the Comprehensive Attention Test were used to evaluate intelligence and attention/executive function, respectively.

Results

The data of a total of 149 children, 103 with focal seizures and 46 with generalized seizures, were reviewed. The prevalence of ADHD was 49.2% (59 out of 120 examined patients), and ADHD patients exhibited significantly worse auditory selective attention, flanker test results, and spatial working memory. Patients with generalized seizures exhibited significantly worse auditory selective and sustained attention than patients with focal seizures. In patients with generalized seizures, sustained attention, flanker test findings, and spatial working memory were found to be affected by ADHD, and auditory selective and sustained attention were significantly worse in patients with benign childhood epilepsy with centrotemporal spikes and ADHD than in their counterparts without ADHD.

Conclusions

Cognitive processes are affected by seizure type and comorbid ADHD. Proper characterization of these neuropsychiatric impairments may allow earlier intervention during the disease course.

Effects of painful stimulation and acupuncture on attention networks in healthy subjects

Pain is a subjective sensory and emotional experience, and it has been reported that many different brain regions are regulated by pain, and that pain can impact attention. Acupuncture is an important treatment component of Chinese traditional medicine, and has been used for thousands of years to treat a wide variety of conditions. Although several studies have shown that acupuncture improves consciousness, the precise impact of both acupuncture and painful stimulation on attention is unclear. Are all of the attention networks modulated, or do these stimuli act on a specific network? Is the effect of painful stimulation similar to that of acupuncture? We administered the attention network test to 30 participants (15 males) to investigate the relative efficiencies of three independent attention networks (alerting, orienting, and executive control networks) under three conditions: baseline, after painful stimulation, and after acupuncture. The degree of pain experienced was assessed on a horizontally oriented visual analogue scale. The results showed that painful stimulation and acupuncture had similar effects on the orienting and executive control networks; however, there was a significantly different effect between the three conditions on the alerting network. In conclusion, (1) painful stimulation can selectively impact attention; (2) acupuncture can also selectively impact attention; i.e., both have selective influences on the alerting and executive control networks, but not on the orienting network; (3) the effects of acupuncture and painful stimulation are not identical. The mechanisms by which painful stimulation and acupuncture influence attention warrant further research.

Attention deficit hyperactivity disorder (ADHD) in childhood epilepsy

ADHD and epilepsy common are both common childhood disorders and both can have significant negative consequences on a child's behavioural, learning, and social development. Both conditions can co-occur and population studies suggest that the prevalence of ADHD in childhood epilepsy is between 12 and 17%. The prevalence of epilepsy in ADHD is lower but it is not clear if the rate of epilepsy is higher in ADHD populations than in the general population. There is a higher occurrence of ADHD--Primarily Inattentive subtype in children with epilepsy and the reasons for this are not altogether clear but attention difficulties are very prevalent in childhood epilepsy. Seizure/epilepsy variables do not appear to be important correlates in most cases of ADHD in epilepsy although they may play a role in some cases. Individuals with both epilepsy and intellectual disability may be at higher risk for significant ADHD symptoms although screening and assessment in children with intellectual disability and epilepsy may be challenging. Children with epilepsy and ADHD are likely to be at higher risk for more negative outcomes in school and in terms of quality of life compared with children with epilepsy alone. Published studies on the treatment of ADHD in childhood epilepsy have focussed exclusively on the use of psychopharmacology and particularly methylphenidate. Although methylphenidate appears to be effective for some children with epilepsy the issue of whether it may lower seizure threshold continues to be debated. Children with epilepsy are at significant risk for ADHD and there is a need for more studies focussing on safe and efficacious interventions for symptoms of ADHD in this population.