Impact of gastrointestinal and urological symptoms in children with myotonic dystrophy type 1.

Gastrointestinal and urological symptoms are frequently reported by people with myotonic dystrophy type 1 (DM1) but have remained understudied. In a cross-sectional study, frequency, nature, treatment and impact of gastrointestinal and urological symptoms in children with DM1 aged 5-18 years were assessed. We included 58 children (30 males, 28 females) with a mean age of 13 years; 74.1 % reported at least one gastrointestinal symptom. Abdominal pain was the most frequently reported symptom (51.7 %), followed by dysphagia (41.8 %), diarrhoea (36.2 %), encopresis (36.0 %), constipation (32.7 %), bloating and flatulence (both 25.9 %). The most frequently reported urological symptoms were difficulty with toilet training (59.3 %), urinary incontinence (22.0 %), enuresis nocturna (10.3 %) and voiding (23.5 % hesitancy, 4.8 % intermittency and 13.8 % dysuria). The majority considered urological and gastrointestinal symptoms to have a negative influence on their daily life; 22.4 % of parents reported severe influence on daily family life (shame, social restrictions, school absence and concerns for their children's future). Considering the high prevalence of urological and gastrointestinal symptoms in children with DM1 and their influence on daily life it is key to correctly recognize, diagnose and treat these symptoms. We recommend screening for gastrointestinal and urological symptoms in the standard of care for children with DM1.

Recognising symptoms of congenital myasthenic syndromes in children: A guide for paediatricians.

AIM: Congenital myasthenic syndromes (CMS) are a rare and diverse group of treatable neuromuscular transmission disorders. Diagnosis is often substantially delayed. This study aimed to identify common symptoms of CMS in children and their manifestation to aid diagnosis and early intervention. METHODS: We performed a retrospective cohort study, including 18 children (median age 13 years, range 9 years 5 months-18 years 0 month) with CMS. Data on CMS symptoms and their manifestation were extracted from patients' charts and supplemented with parental telephone interviews. Descriptive analyses were used to identify common symptoms. RESULTS: A median diagnostic delay of 4 years and 7 months (interquartile range: 51 months) was observed. Proximal muscle weakness (100%), ptosis (89%), clumsy gait (82%), difficulty eating solid foods (78%) and recurrent respiratory tract infections (72%) were most common in these patients. Symptoms mostly co-occurred and frequently had a fluctuating character, aggravated by infections or fatigue. CONCLUSION: Early referral to diagnose CMS is crucial to enable timely initiation of treatment. Heightened attention to a combination of symptoms related to muscle weakness, rather than individual symptoms, should support paediatricians in flagging these neuromuscular disorders. Medical history taking should be tailored to parents' perceptions, asking questions about recognisable symptoms of muscle weakness.

Natural History and Developmental Trajectories of Individuals With Disease-Causing Variants in STXBP1.

BACKGROUND AND OBJECTIVES: Pathogenic variants in STXBP1 are among the major genetic causes of neurodevelopmental disorders. Despite the increasing number of individuals diagnosed without a history of epilepsy, little is known about the natural history and developmental trajectories in this subgroup and endpoints for future therapeutic studies are limited to seizure control. METHODS: We performed a cross-sectional retrospective study using standardized questionnaires for clinicians and caregivers of individuals with STXBP1-related disorders capturing medical histories, genetic findings, and developmental outcomes. Motor and language function were assessed using Gross Motor Function Classification System (GMFCS) scores and a speech impairment score and were compared within and across clinically defined subgroups. RESULTS: We collected data of 71 individuals with STXBP1-related disorders, including 44 previously unreported individuals. Median age at inclusion was 5.3 years (interquartile range 3.5-9.3) with the oldest individual aged 43.8 years. Epilepsy was absent in 18/71 (25%) of individuals. The range of developmental outcomes was broad, including 2 individuals presenting with close to age-appropriate motor development. Twenty-nine of 61 individuals (48%) were able to walk unassisted, and 24/69 (35%) were able to speak single words. Individuals without epilepsy presented with a similar onset and spectrum of phenotypic features but had lower GMFCS scores (median 3 vs 4, p < 0.01) than individuals with epilepsy. Individuals with epileptic spasms were less likely to walk unassisted than individuals with other seizure types (6% vs 58%, p < 0.01). Individuals with early epilepsy onset had higher speech impairment scores (p = 0.02) than individuals with later epilepsy onset. DISCUSSION: We expand the spectrum of STXBP1-related disorders and provide clinical features and developmental trajectories in individuals with and without a history of epilepsy. Individuals with epilepsy, in particular epileptic spasms, and neonatal or early-onset presented with less favorable motor and language functional outcomes compared with individuals without epilepsy. These findings identify children at risk for severe disease and can serve as comparator for future interventional studies in STXBP1-related disorders.

Hypertrophic neuropathy: a possible cause of pain in children with Noonan syndrome and related disorders.

This study is aimed at describing the findings of high-resolution nerve ultrasound in children with Noonan syndrome (NS) and related disorders experiencing pain in their legs. This retrospective cohort study was conducted in the NS expert center of the Radboud University Medical Center in the Netherlands. Patients were eligible if they were younger than 18 years, clinically and genetically diagnosed with NS or a NS related disorder, and experienced pain in their legs. Anamneses and physical examination were performed in all children. In addition, high-resolution nerve ultrasound was used to assess nerve hypertrophy and, if needed, complemented spinal magnetic resonance imaging was performed. Over a period of 6 months, four children, three with NS and one child with NS with multiple lentigines, who experienced pain of their legs were eligible for inclusion. Muscle weakness was found in two of them. High-resolution nerve ultrasound showed (localized) hypertrophic neuropathy in all patients. One child underwent additional spinal magnetic resonance imaging, which showed profound thickening of the nerve roots and plexus.  Conclusion: In the four children included with a NS and related disorders, pain was concomitant with nerve hypertrophy, which suggests an association between these two findings. The use of high-resolution nerve ultrasound and spinal magnetic resonance imaging might result in better understanding of the nature of this pain and the possible association to nerve hypertrophy in patients with NS and related disorders. What is Known: • Children with Noonan syndrome and related disorders may report pain in their legs, which is often interpreted as growing pain. • Some adults with Noonan syndrome and related disorders have hypertrophic neuropathy as a possible cause of neuropathic pain. What is New: • This is the first study using high-resolution nerve ultrasound in children with Noonan syndrome and related disorders experiencing pain in their legs. • Hypertrophic neuropathy was diagnosed as possible cause of pain in four children with Noonan syndrome and related disorders.

Cognitive phenotype of childhood myotonic dystrophy type 1: A multicenter pooled analysis.

INTRODUCTION/AIMS: There is clear evidence for brain involvement in childhood myotonic dystrophy type 1 (DM1) from imaging studies and the prevalence of intellectual impairment and neurodevelopmental disorders. The cognitive profile of children with DM1 however is poorly understood. The aim of this study was to assess the cognitive profile of children with DM1. METHODS: Neuropsychological examination reports of 45 children aged 2-17 y were analyzed. All cognitive subtests used in this cohort were pooled in 10 cognitive domains. For every patient a composite z-score was calculated for every assessed domain. Composite scores were classified as average (z > -1), mild cognitive impairment (-1 ≥ z > -2), or major cognitive impairment (z ≤ -2). RESULTS: The nature and extent of neuropsychological examinations differed between centers and patients. The domains with the highest frequency of major cognitive impairment were social cognition (4/9 children tested; 44%), attention (13/32; 41%), and fine motor skills (3/10; 30%). Combining mild and major cognitive impairment, working memory (20/28; 71%), attention (21/32; 66%), and visuospatial functions (16/28; 57%) were the most frequently affected domains. Long-term memory was least affected, with mild impairment only in 5/29 (17%). DISCUSSION: Children with DM1 may have specific cognitive deficits, most frequently affecting working memory, attention, and visuospatial functions, in addition to the previously described global intellectual impairments. We recommend including a standardized neuropsychological examination in the standards of care for DM1 children. Early recognition of cognitive deficits and behavioral disorders in children with DM1 can improve their management.

Pediatric acute flaccid myelitis: Evaluation of diagnostic criteria and differentiation from other causes of acute flaccid paralysis.

BACKGROUND: Acute flaccid paralysis (AFP) is characterized by rapidly progressive limb weakness with low muscle tone. It has a broad differential diagnosis, which includes acute flaccid myelitis (AFM), a rare polio-like condition that mainly affects young children. Differentiation between AFM and other causes of AFP may be difficult, particularly at onset of disease. Here, we evaluate the diagnostic criteria for AFM and compare AFM to other causes of acute weakness in children, aiming to identify differentiating clinical and diagnostic features. METHODS: The diagnostic criteria for AFM were applied to a cohort of children with acute onset of limb weakness. An initial classification based on positive diagnostic criteria was compared to the final classification, based on application of features suggestive for an alternative diagnosis and discussion with expert neurologists. Cases classified as definite, probable, or possible AFM or uncertain, were compared to cases with an alternative diagnosis. RESULTS: Of 141 patients, seven out of nine patients initially classified as definite AFM, retained this label after further classification. For probable AFM, this was 3/11, for possible AFM 3/14 and for uncertain 11/43. Patients initially classified as probable or possible AFM were most commonly diagnosed with transverse myelitis (16/25). If the initial classification was uncertain, Guillain-Barré syndrome was the most common diagnosis (31/43). Clinical and diagnostic features not included in the diagnostic criteria, were often used for the final classification. CONCLUSION: The current diagnostic criteria for AFM usually perform well, but additional features are sometimes required to distinguish AFM from other conditions.

Structural mapping of GABRB3 variants reveals genotype-phenotype correlations.

PURPOSE: Pathogenic variants in GABRB3 have been associated with a spectrum of phenotypes from severe developmental disorders and epileptic encephalopathies to milder epilepsy syndromes and mild intellectual disability (ID). In this study, we analyzed a large cohort of individuals with GABRB3 variants to deepen the phenotypic understanding and investigate genotype-phenotype correlations. METHODS: Through an international collaboration, we analyzed electro-clinical data of unpublished individuals with variants in GABRB3, and we reviewed previously published cases. All missense variants were mapped onto the 3-dimensional structure of the GABRB3 subunit, and clinical phenotypes associated with the different key structural domains were investigated. RESULTS: We characterized 71 individuals with GABRB3 variants, including 22 novel subjects, expressing a wide spectrum of phenotypes. Interestingly, phenotypes correlated with structural locations of the variants. Generalized epilepsy, with a median age at onset of 12 months, and mild-to-moderate ID were associated with variants in the extracellular domain. Focal epilepsy with earlier onset (median: age 4 months) and severe ID were associated with variants in both the pore-lining helical transmembrane domain and the extracellular domain. CONCLUSION: These genotype-phenotype correlations will aid the genetic counseling and treatment of individuals affected by GABRB3-related disorders. Future studies may reveal whether functional differences underlie the phenotypic differences.

Genotype-phenotype correlations in SCN8A-related disorders reveal prognostic and therapeutic implications.

We report detailed functional analyses and genotype-phenotype correlations in 392 individuals carrying disease-causing variants in SCN8A, encoding the voltage-gated Na+ channel Nav1.6, with the aim of describing clinical phenotypes related to functional effects. Six different clinical subgroups were identified: Group 1, benign familial infantile epilepsy (n = 15, normal cognition, treatable seizures); Group 2, intermediate epilepsy (n = 33, mild intellectual disability, partially pharmaco-responsive); Group 3, developmental and epileptic encephalopathy (n = 177, severe intellectual disability, majority pharmaco-resistant); Group 4, generalized epilepsy (n = 20, mild to moderate intellectual disability, frequently with absence seizures); Group 5, unclassifiable epilepsy (n = 127); and Group 6, neurodevelopmental disorder without epilepsy (n = 20, mild to moderate intellectual disability). Those in Groups 1-3 presented with focal or multifocal seizures (median age of onset: 4 months) and focal epileptiform discharges, whereas the onset of seizures in patients with generalized epilepsy was later (median: 42 months) with generalized epileptiform discharges. We performed functional studies expressing missense variants in ND7/23 neuroblastoma cells and primary neuronal cultures using recombinant tetrodotoxin-insensitive human Nav1.6 channels and whole-cell patch-clamping. Two variants causing developmental and epileptic encephalopathy showed a strong gain-of-function (hyperpolarizing shift of steady-state activation, strongly increased neuronal firing rate) and one variant causing benign familial infantile epilepsy or intermediate epilepsy showed a mild gain-of-function (defective fast inactivation, less increased firing). In contrast, all three variants causing generalized epilepsy induced a loss-of-function (reduced current amplitudes, depolarizing shift of steady-state activation, reduced neuronal firing). Functional effects were known for 170 individuals. All 136 individuals carrying a functionally tested gain-of-function variant had either focal (n = 97, Groups 1-3) or unclassifiable (n = 39) epilepsy, whereas 34 individuals with a loss-of-function variant had either generalized (n = 14), no (n = 11) or unclassifiable (n = 6) epilepsy; only three had developmental and epileptic encephalopathy. Computational modelling in the gain-of-function group revealed a significant correlation between the severity of the electrophysiological and clinical phenotypes. Gain-of-function variant carriers responded significantly better to sodium channel blockers than to other anti-seizure medications, and the same applied for all individuals in Groups 1-3. In conclusion, our data reveal clear genotype-phenotype correlations between age at seizure onset, type of epilepsy and gain- or loss-of-function effects of SCN8A variants. Generalized epilepsy with absence seizures is the main epilepsy phenotype of loss-of-function variant carriers and the extent of the electrophysiological dysfunction of the gain-of-function variants is a main determinant of the severity of the clinical phenotype in focal epilepsies. Our pharmacological data indicate that sodium channel blockers present a treatment option in SCN8A-related focal epilepsy with onset in the first year of life.

Early infantile epileptic encephalopathy due to biallelic pathogenic variants in PIGQ: Report of seven new subjects and review of the literature.

We investigated seven children from six families to expand the phenotypic spectrum associated with an early infantile epileptic encephalopathy caused by biallelic pathogenic variants in the phosphatidylinositol glycan anchor biosynthesis class Q (PIGQ) gene. The affected children were all identified by clinical or research exome sequencing. Clinical data, including EEGs and MRIs, was comprehensively reviewed and flow cytometry and transfection experiments were performed to investigate PIGQ function. Pathogenic biallelic PIGQ variants were associated with increased mortality. Epileptic seizures, axial hypotonia, developmental delay and multiple congenital anomalies were consistently observed. Seizure onset occurred between 2.5 months and 7 months of age and varied from treatable seizures to recurrent episodes of status epilepticus. Gastrointestinal issues were common and severe, two affected individuals had midgut volvulus requiring surgical correction. Cardiac anomalies including arrythmias were observed. Flow cytometry using granulocytes and fibroblasts from affected individuals showed reduced expression of glycosylphosphatidylinositol (GPI)-anchored proteins. Transfection of wildtype PIGQ cDNA into patient fibroblasts rescued this phenotype. We expand the phenotypic spectrum of PIGQ-related disease and provide the first functional evidence in human cells of defective GPI-anchoring due to pathogenic variants in PIGQ.

Epilepsy phenotype in individuals with chromosomal duplication encompassing FGF12.

Intragenic mutations in FGF12 are associated with intractable seizures, developmental regression, intellectual disability, ataxia, hypotonia, and feeding difficulties. FGF12 duplications are rarely reported, but it was suggested that those might have a similar gain-of-function effect and lead to a more or less comparable phenotype. A favorable response to the sodium blocker phenytoin was reported in several cases, both in patients with an intragenic mutation and in patients with a duplication of FGF12. We report three individuals from two families with FGF12 duplications. The duplications are flanked and probably mediated by two long interspersed nuclear elements (LINEs). The duplication cases show phenotypic overlap with the cases with intragenic mutations. Though the onset of epilepsy might be later, after the onset of seizures both groups show developmental stagnation and regression in several cases. This illustrates and further confirms that chromosomal FGF12 duplications and intragenic gain-of-function mutations yield overlapping phenotypes.

Ketogenic diet for the treatment of pediatric epilepsy: review and meta-analysis.

The ketogenic diet (KD), containing high levels of fat and low levels of carbohydrates, has been used to treat refractory epilepsy since the 1920s. In the past few decades, there has been more interest in less restrictive KDs such as the modified Atkins diet (MAD). PURPOSE: Our aim was to review all evidence regarding the efficacy and tolerability of the KD and MAD from randomized controlled trials (RCTs) in children and adolescents with refractory epilepsy. METHODS: We reviewed the current literature using Cochrane, EMBASE, and MEDLINE (using PubMed). We implemented predefined criteria regarding dataextraction and study quality. RESULTS: We identified five RCTs that generated seven publications and recruited 472 children and adolescents with refractory epilepsy (≤ 18 years). The primary outcome (seizure frequency reduction (SFR) ≥ 50%) was attained in 35-56.1% of the participants in the intervention group, compared with 6-18.2% in the control group. Our meta-analysis underlined the significant efficacy of the KD compared with the control group: RR = 5.1 (95% CI 3.18-8.21, p < 0.001). Additionally, only two studies mentioned possible biomarkers to objectively evaluate the efficacy. Secondary outcomes, such as seizure severity and quality of life, were studied in three trials, leading to indecisive generalization of these findings. Gastro-intestinal adverse effects were the most prevalent, and no severe adverse effects were reported. CONCLUSION: Despite the heterogeneity between all studies, the beneficial results underline that dietary interventions should be considered for children and adolescents with refractory epilepsy who are not eligible for epilepsy surgery. Future studies should be multi-center and long-term, and evaluate potential biomarkers and adverse effects.

Failure of ketogenic diet therapy in GLUT1 deficiency syndrome.

PURPOSE: Epilepsy in GLUT1 deficiency syndrome is generally drug-resistant; ketogenic diet (KD) therapy is the mainstay of therapy, as production of ketones provides the brain with an alternative energy source, bypassing the defect in GLUT1. Failure of KD therapy and risk factors for failure have been sparsely published. METHODS: We performed a retrospective study of GLUT1DS patients with refractory epilepsy failing on KD therapy, to identify their clinical characteristics. RESULTS: Failure of the ketogenic diet was due to KD inefficacy (poor effect despite adequate ketosis), as well as intolerance and an inability to attain ketosis. Our cohort of seven patients in whom KD therapy failed stood out for their advanced age at seizure onset, i.e. almost 4 years vs 8 months in large series, female sex, as well as their advanced age at diagnosis and initiation of KD therapy. EEG recordings during KD therapy can aid in the assessment of effectiveness of the KD therapy. CONCLUSIONS: GLUT1DS is generally described as a treatable disorder and existing case series do not provide details of treatment failure. In select patients with GLUT1DS, KD therapy fails, rendering GLUT1DS an essentially untreatable disorder. Failure of the ketogenic diet was due to KD inefficacy (poor effect despite adequate ketosis), as well as intolerance and an inability to attain ketosis. Failure to reduce seizure frequency with deterioration of the EEG findings should lead to consideration of cessation of KD therapy.

De Novo Mutations Affecting the Catalytic Cα Subunit of PP2A, PPP2CA, Cause Syndromic Intellectual Disability Resembling Other PP2A-Related Neurodevelopmental Disorders.

Type 2A protein phosphatases (PP2As) are highly expressed in the brain and regulate neuronal signaling by catalyzing phospho-Ser/Thr dephosphorylations in diverse substrates. PP2A holoenzymes comprise catalytic C-, scaffolding A-, and regulatory B-type subunits, which determine substrate specificity and physiological function. Interestingly, de novo mutations in genes encoding A- and B-type subunits have recently been implicated in intellectual disability (ID) and developmental delay (DD). We now report 16 individuals with mild to profound ID and DD and a de novo mutation in PPP2CA, encoding the catalytic Cα subunit. Other frequently observed features were severe language delay (71%), hypotonia (69%), epilepsy (63%), and brain abnormalities such as ventriculomegaly and a small corpus callosum (67%). Behavioral problems, including autism spectrum disorders, were reported in 47% of individuals, and three individuals had a congenital heart defect. PPP2CA de novo mutations included a partial gene deletion, a frameshift, three nonsense mutations, a single amino acid duplication, a recurrent mutation, and eight non-recurrent missense mutations. Functional studies showed complete PP2A dysfunction in four individuals with seemingly milder ID, hinting at haploinsufficiency. Ten other individuals showed mutation-specific biochemical distortions, including poor expression, altered binding to the A subunit and specific B-type subunits, and impaired phosphatase activity and C-terminal methylation. Four were suspected to have a dominant-negative mechanism, which correlated with severe ID. Two missense variants affecting the same residue largely behaved as wild-type in our functional assays. Overall, we found that pathogenic PPP2CA variants impair PP2A-B56(δ) functionality, suggesting that PP2A-related neurodevelopmental disorders constitute functionally converging ID syndromes.

Diagnostic exome sequencing in 100 consecutive patients with both epilepsy and intellectual disability.

OBJECTIVE: Epilepsy is highly prevalent among patients with intellectual disability (ID), and seizure control is often difficult. Identification of the underlying etiology in this patient group is important for daily clinical care. We assessed the diagnostic yield of whole exome sequencing (WES). In addition, we evaluated which clinical characteristics influence the likelihood of identifying a genetic cause and we assessed the potential impact of the genetic diagnosis on (antiepileptic) treatment strategy. METHODS: One hundred patients with both unexplained epilepsy and (borderline) ID (intelligence quotient ≤ 85) were included. All patients were evaluated by a clinical geneticist, a (pediatric) neurologist, and/or a specialist ID physician. WES analysis was performed in two steps. In step 1, analysis was restricted to the latest versions of ID and/or epilepsy gene panels. In step 2, exome analysis was extended to all genes (so-called full exome analysis). The results were classified according to the American College of Medical Genetics and Genomics guidelines. RESULTS: In 58 patients, the diagnostic WES analysis reported one or more variant(s). In 25 of the 100 patients, these were classified as (likely) pathogenic, in 24 patients as variants of uncertain significance, and in the remaining patients the variant was most likely not related to the phenotype. In 10 of 25 patients (40%) with a (likely) pathogenic variant, the genetic diagnosis might have an impact on the treatment strategy in the future. SIGNIFICANCE: This study illustrates the clinical diagnostic relevance of WES for patients with both epilepsy and ID. It also demonstrates that implementing WES diagnostics might have impact on the (antiepileptic) treatment strategy in this population. Confirmation of variants of uncertain significance in (candidate) genes may further increase the yield.

Can epilepsy be treated by antibiotics?

There is mounting evidence for the role of the gut microbiota and gut-brain interactions in neurological diseases. We present six patients with drug-resistant epilepsy who attained temporary seizure freedom during antibiotic treatment. The effect on seizure frequency waned within 2 weeks after cessation of antibiotic treatment. We hypothesized that antibiotic treatments may have a short-term effect, through gut microbiota disruption, on gut-brain interactions and ultimately seizure frequency. This observed impact of antibiotics on seizure frequency hints at a possible role of the gut microbiota in epilepsy and its manifestations. This begs the question: can epilepsy be treated by antibiotics? Or perhaps in a broader sense: can alterations in the gut microbiota be used as a treatment modality in drug-resistant epilepsy? This concept and the six intriguing cases provide interesting leads for epilepsy management.

[Idiopathic intracranial hypertension and obesity]. / Idiopathische intracraniële hypertensie bij obesitas.

BACKGROUND: Idiopathic intracranial hypertension (IIH) is a neurological syndrome characterized by elevated intracranial pressure in the absence of intracerebral abnormalities or hydrocephalus. CASE DESCRIPTION: A 17-year-old girl gained more than 25 kg in weight during treatment with risperidone and subsequently developed headache, diplopia and loss of vision due to IIH. After insertion of a ventriculoperitoneal drain and discontinuation of risperidone she lost weight and her symptoms improved. Her visual functions recovered almost fully during follow-up. CONCLUSION: Patients with IIH are mainly overweight young women who present with raised intracranial pressure evidenced by headache, nausea, vomiting and vision disturbances. Prescribed medication-induced weight gain may lead to IIH. Treatment of IIH should be focused on the prevention of severe and irreversible loss of vision.

Functional and structural network impairment in childhood frontal lobe epilepsy.

In childhood frontal lobe epilepsy (FLE), cognitive impairment and educational underachievement are serious, well-known co-morbidities. The broad scale of affected cognitive domains suggests wide-spread network disturbances that not only involves, but also extends beyond the frontal lobe. In this study we have investigated whole brain connectional properties of children with FLE in relation to their cognitive impairment and compared them with healthy controls. Functional connectivity (FC) of the networks was derived from dynamic fluctuations of resting state fMRI and structural connectivity (SC) was obtained from fiber tractograms of diffusion weighted MRI. The whole brain network was characterized with graph theoretical metrics and decomposed into modules. Subsequently, the graph metrics and the connectivity within and between modules were related to cognitive performance. Functional network disturbances in FLE were related to increased clustering, increased path length, and stronger modularity compared to healthy controls, which was accompanied by stronger within- and weaker between-module functional connectivity. Although structural path length and clustering appeared normal in children with FLE, structural modularity increased with stronger cognitive impairment. It is concluded that decreased coupling between large-scale functional network modules is a hallmark for impaired cognition in childhood FLE.

Frontal lobe connectivity and cognitive impairment in pediatric frontal lobe epilepsy.

PURPOSE: Cognitive impairment is frequent in children with frontal lobe epilepsy (FLE), but its etiology is unknown. With functional magnetic resonance imaging (fMRI), we have explored the relationship between brain activation, functional connectivity, and cognitive functioning in a cohort of pediatric patients with FLE and healthy controls. METHODS: Thirty-two children aged 8-13 years with FLE of unknown cause and 41 healthy age-matched controls underwent neuropsychological assessment and structural and functional brain MRI. We investigated to which extent brain regions activated in response to a working memory task and assessed functional connectivity between distant brain regions. Data of patients were compared to controls, and patients were grouped as cognitively impaired or unimpaired. KEY FINDINGS: Children with FLE showed a global decrease in functional brain connectivity compared to healthy controls, whereas brain activation patterns in children with FLE remained relatively intact. Children with FLE complicated by cognitive impairment typically showed a decrease in frontal lobe connectivity. This decreased frontal lobe connectivity comprised both connections within the frontal lobe as well as connections from the frontal lobe to the parietal lobe, temporal lobe, cerebellum, and basal ganglia. SIGNIFICANCE: Decreased functional frontal lobe connectivity is associated with cognitive impairment in pediatric FLE. The importance of impairment of functional integrity within the frontal lobe network, as well as its connections to distant areas, provides new insights in the etiology of the broad-range cognitive impairments in children with FLE.