A cross-sectional investigation of cognition and epileptiform discharges in juvenile absence epilepsy

OBJECTIVES

Despite the prevalence of cognitive symptoms in the idiopathic generalized epilepsies (IGEs), cognitive dysfunction in juvenile absence epilepsy (JAE), a common yet understudied IGE subtype, remains poorly understood. This descriptive study provides a novel, comprehensive characterization of cognitive functioning in a JAE sample and examines the relationship between cognition and 24-h epileptiform discharge load.

METHOD

Forty-four individuals diagnosed with JAE underwent cognitive assessment using Woodcock Johnson III Test of Cognitive Abilities with concurrent 24-h ambulatory EEG monitoring. Generalized epileptiform discharges of any length, and prolonged generalized discharges ≥3 s were quantified across wakefulness and sleep. The relationship between standardized cognitive scores and epileptiform discharges was assessed through regression models.

RESULTS

Cognitive performances in overall intellectual ability, acquired comprehension-knowledge, processing speed, long-term memory storage and retrieval, and executive processes were 0.63-1.07 standard deviation (SD) units lower in the JAE group compared to the population reference mean, adjusted for educational attainment. Prolonged discharges (≥3 s) were recorded in 20 patients (47.6%) from 42 available electroencephalography (EEG) studies and were largely unreported. Duration and number of prolonged discharges were associated with reduced processing speed and long-term memory storage and retrieval.

SIGNIFICANCE

Cognitive dysfunction is seen in patients with JAE across various cognitive abilities, including those representing more stable processes like general intellect. During 24-h EEG, prolonged epileptiform discharges are common yet underreported in JAE despite treatment, and they show moderate effects on cognitive abilities. If epileptiform burden is a modifiable predictor of cognitive dysfunction, therapeutic interventions should consider quantitative 24-h EEG with routine neuropsychological screening. The growing recognition of the spectrum of neuropsychological comorbidities of IGE highlights the value of multidisciplinary approaches to explore the causes and consequences of cognitive deficits in epilepsy.

Cost Analysis of Orthoptist-Led Neurofibromatosis Type 1 Screening Clinics

Purpose

To conduct a costing study comparing orthoptist-led with consultant-led clinics screening for optic pathway gliomas (OPGs) in children with neurofibromatosis Type 1 (NF1) attending the Royal Children's Hospital (RCH), Melbourne.

Methods

Patients with NF1 examined in the orthoptist-led NF1 screening clinic and/or consultant-led clinics during the study period were identified. The workflow management software Q-Flow 6® provided data documenting patient's time spent with the orthoptist, nurse, and ophthalmologist. Time points were converted into minutes and multiplied by the cost-per-minute for each profession. A bottom-up micro-costing approach was used to estimate appointment level costs. Bootstrap simulations with 1000 replications were used to estimate 95% confidence intervals (CIs) for the difference in mean appointment time and cost between clinics.

Results

Data for 130 consultant-led clinic appointments and 234 orthoptist-led clinic appointments were extracted for analysis. The mean time per appointment for the consultant-led clinic was 45.11 minutes, and the mean time per appointment for the orthoptist-led clinic was 25.85 minutes. The mean cost per appointment for the consultant-led clinic was A $84.15 (GBP £39.60) compared to the orthoptist-led clinic at A $20.40 (GBP £9.60). This represents a mean reduction of 19.25 minutes per appointment (95% CI, -24.85 to -13.66) and a mean reduction of A $63.75 (GBP £30.00) per appointment (95% CI, (A $-75.40 to $-52.10 [GBP £ -35.48 to £ -24.52]).

Conclusion

An orthoptist-led clinic screening for OPGs in patients with NF1 can be a more cost-efficient model of care for ophthalmic screening in this patient group.

A randomized controlled trial of remote microphone listening devices to treat auditory deficits in children with neurofibromatosis type 1

Background

A high proportion of patients with neurofibromatosis type 1 (NF1) present with functional hearing deficiency as a result of neural abnormality in the late auditory brainstem.

Methods

In this randomized, two-period crossover study, we investigated the hypothesis that remote-microphone listening devices can ameliorate hearing and communication deficits in affected school-aged children (7–17 years). Speech perception ability in background noise was evaluated in device-active and inactive conditions using the CNC-word test. Participants were then randomized to one of two treatment sequences: (1) inactive device for two weeks (placebo), followed by active device use for two weeks, or (2) active device for 2 weeks, followed by inactive device for 2 weeks. Listening and communication ratings (LIFE-R Questionnaire) were obtained at baseline and at the end of each treatment phase.

Results

Each participant demonstrated functional hearing benefits with remote-microphone use. All showed a speech perception in noise increase when the device was activated with a mean phoneme-score difference of 16.4% (p < 0.001) and reported improved listening/communication abilities in the school classroom (mean difference: 23.4%; p = 0.017).

Discussion

Conventional hearing aids are typically ineffective as a treatment for auditory neural dysfunction, making sounds louder, but not clearer for affected individuals. In this study, we demonstrate that remote-microphone technologies are acceptable/tolerable in pediatric patients with NF1 and can ameliorate their hearing deficits.

Conclusion

Remote-microphone listening systems offer a viable treatment option for children with auditory deficits associated with NF1.

Delineating the autistic phenotype in children with neurofibromatosis type 1

Background

Existing research has demonstrated elevated autistic behaviours in children with neurofibromatosis type 1 (NF1), but the autistic phenotype and its relationship to other neurodevelopmental manifestations of NF1 remains unclear. To address this gap, we performed detailed characterisation of autistic behaviours in children with NF1 and investigated their association with other common NF1 child characteristics.

Methods

Participants were drawn from a larger cross-sectional study examining autism in children with NF1. The population analysed in this study scored above threshold on the Social Responsiveness Scale-Second Edition (T-score ≥ 60; 51% larger cohort) and completed the Autism Diagnostic Interview-Revised (ADI-R) and/or the Autism Diagnostic Observation Schedule-Second Edition (ADOS-2). All participants underwent evaluation of their intellectual function, and behavioural data were collected via parent questionnaires.

Results

The study cohort comprised 68 children (3–15 years). Sixty-three per cent met the ADOS-2 ‘autism spectrum’ cut-off, and 34% exceeded the more stringent threshold for ‘autistic disorder’ on the ADI-R. Social communication symptoms were common and wide-ranging, while restricted and repetitive behaviours (RRBs) were most commonly characterised by ‘insistence on sameness’ (IS) behaviours such as circumscribed interests and difficulties with minor changes. Autistic behaviours were weakly correlated with hyperactive/impulsive attention deficit hyperactivity disorder (ADHD) symptoms but not with inattentive ADHD or other behavioural characteristics. Language and verbal IQ were weakly related to social communication behaviours but not to RRBs.

Limitations

Lack of genetic validation of NF1, no clinical diagnosis of autism, and a retrospective assessment of autistic behaviours in early childhood.

Conclusions

Findings provide strong support for elevated autistic behaviours in children with NF1. While these behaviours were relatively independent of other NF1 comorbidities, the importance of taking broader child characteristics into consideration when interpreting data from autism-specific measures in this population is highlighted. Social communication deficits appear similar to those observed in idiopathic autism and are coupled with a unique RRB profile comprising prominent IS behaviours. This autistic phenotype and its relationship to common NF1 comorbidities such as anxiety and executive dysfunction will be important to examine in future research. Current findings have important implications for the early identification of autism in NF1 and clinical management.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13229-021-00481-3.

Auditory Dysfunction Among Individuals With Neurofibromatosis Type 1

IMPORTANCE

Neurofibromatosis type 1 (NF1) affects hearing through disruption of central auditory processing. The mechanisms, functional severity, and management implications are unclear.

OBJECTIVE

To investigate auditory neural dysfunction and its perceptual consequences in individuals with NF1.

DESIGN, SETTING, AND PARTICIPANTS

This case-control study included children and adults with NF1 and control participants matched on age, sex, and hearing level. Patients were recruited through specialist neurofibromatosis and neurogenetic outpatient clinics between April and September 2019. An evaluation of auditory neural activity, monaural/binaural processing, and functional hearing was conducted. Diffusion-weighted magnetic resonance imaging (MRI) data were collected from a subset of participants (10 children with NF1 and 10 matched control participants) and evaluated using a fixel-based analysis of apparent fiber density.

MAIN OUTCOMES AND MEASURES

Type and severity of auditory dysfunction evaluated via laboratory testing and questionnaire data.

RESULTS

A total of 44 participants (18 [41%] female individuals) with NF1 with a mean (SD) age of 16.9 (10.7) years and 44 control participants (18 [41%] female individuals) with a mean (SD) age of 17.2 (10.2) years were included in the study. Overall, 11 participants (25%) with NF1 presented with evidence of auditory neural dysfunction, including absent, delayed, or low amplitude electrophysiological responses from the auditory nerve and/or brainstem, compared with 1 participant (2%) in the control group (odds ratio [OR], 13.03; 95% CI, 1.59-106.95). Furthermore, 14 participants (32%) with NF1 showed clinically abnormal speech perception in background noise compared with 1 participant (2%) in the control group (OR, 20.07; 95% CI, 2.50-160.89). Analysis of diffusion-weighted MRI data of participants with NF1 showed significantly lower apparent fiber density within the ascending auditory brainstem pathways. The regions identified corresponded to the neural dysfunction measured using electrophysiological assessment.

CONCLUSIONS AND RELEVANCE

The findings of this case-control study could represent new neurobiological and clinical features of NF1. Auditory dysfunction severe enough to impede developmental progress in children and restrict communication in older participants is a common neurobiological feature of the disorder.

Circulating tumor DNA for malignant peripheral nerve sheath tumors in neurofibromatosis type 1

PURPOSE

The leading cause of early death in patients with neurofibromatosis type 1 (NF1) is malignant peripheral nerve sheath tumor (MPNST). The principles of management include early diagnosis, surgical clearance and close monitoring for tumor recurrence. Current methods for diagnosis, detection of residual disease and monitoring tumor burden are inadequate, as clinical and radiological features are non-specific for malignancy in patients with multiple tumors and lack the sensitivity to identify early evidence of malignant transformation or tumor recurrence. Circulating tumor DNA (ctDNA) is a promising tool in cancer management and has the potential to improve the care of patients with NF1. In the following article we summarise the current understanding of the genomic landscape of MPNST, report on the previous literature of ctDNA in MPNST and outline the potential clinical applications for ctDNA in NF1 associated MPNST. Finally, we describe our prospective cohort study protocol investigating the utility of using ctDNA as an early diagnostic tool for MPNSTs in NF1 patients.

Aberrant splicing and transcriptional activity of TPP1 result in CLN2-like disorder

RNA sequencing (RNAseq) is emerging as a complementary tool to DNA sequencing, providing utility in diagnosis for disorders such as neuronal ceroid lipofuscinosis CLN2 disease. We describe an individual with a presentation suggestive of an attenuated CLN2 phenotype, including a history of regression, recent-onset microcephaly and spasticity from age five years. Exome sequencing revealed two variants inherited in trans in TPP1, NM_000391.4:c.225A>G; p.(Gln75 = ) and NM_000391.4:c.1012C>G; p.(Gln338Glu), both classified as variants of uncertain significance. TPP1 activity was found to be significantly reduced in fibroblasts of the affected individual. RNAseq was performed to assess the impact of compound heterozygous variants in TPP1 and enabled the identification of three aberrant splicing events. The c.225A>G variant introduces a 5 nucleotide truncation of exon 3 and a loss of reading frame. The majority of CLN2 transcripts exclude either exon 8 or exons 7-8, resulting in large in-frame deletions. Isoform specific RT-PCR confirmed the aberrant splicing events are mutually exclusive, suggesting that the paternal exon 8 c.1012C>G variant results in exon skipping. This case study demonstrates how RNAseq can be used as an orthogonal test to inform the interpretation of some variants of unknown significance and its particular importance in disorders where effective disease management requires early diagnosis.

The severe epilepsy syndromes of infancy: A population-based study

OBJECTIVE

To study the epilepsy syndromes among the severe epilepsies of infancy and assess their incidence, etiologies, and outcomes.

METHODS

A population-based cohort study was undertaken of severe epilepsies with onset before age 18 months in Victoria, Australia. Two epileptologists reviewed clinical features, seizure videos, and electroencephalograms to diagnose International League Against Epilepsy epilepsy syndromes. Incidence, etiologies, and outcomes at age 2 years were determined.

RESULTS

Seventy-three of 114 (64%) infants fulfilled diagnostic criteria for epilepsy syndromes at presentation, and 16 (14%) had "variants" of epilepsy syndromes in which there was one missing or different feature, or where all classical features had not yet emerged. West syndrome (WS) and "WS-like" epilepsy (infantile spasms without hypsarrhythmia or modified hypsarrhythmia) were the most common syndromes, with a combined incidence of 32.7/100 000 live births/year. The incidence of epilepsy of infancy with migrating focal seizures (EIMFS) was 4.5/100 000 and of early infantile epileptic encephalopathy (EIEE) was 3.6/100 000. Structural etiologies were common in "WS-like" epilepsy (100%), unifocal epilepsy (83%), and WS (39%), whereas single gene disorders predominated in EIMFS, EIEE, and Dravet syndrome. Eighteen (16%) infants died before age 2 years. Development was delayed or borderline in 85 of 96 (89%) survivors, being severe-profound in 40 of 96 (42%). All infants with EIEE or EIMFS had severe-profound delay or were deceased, but only 19 of 64 (30%) infants with WS, "WS-like," or "unifocal epilepsy" had severe-profound delay, and only two of 64 (3%) were deceased.

SIGNIFICANCE

Three quarters of severe epilepsies of infancy could be assigned an epilepsy syndrome or "variant syndrome" at presentation. In this era of genomic testing and advanced brain imaging, diagnosing epilepsy syndromes at presentation remains clinically useful for guiding etiologic investigation, initial treatment, and prognostication.

Contribution of rare genetic variants to drug response in absence epilepsy

OBJECTIVE

We investigated the possible significance of rare genetic variants to response to valproic acid (VPA) and ethosuximide (ETX) in patients with absence epilepsy. Our primary hypothesis was that rare CACNA1H variants are more frequent in ETX-non-responsive patients compared to ETX-responsive. Our secondary hypothesis was that rare variants in GABA-receptor genes are more frequent in VPA-non-responsive patients compared to VPA-responsive.

METHODS

We recruited patients with absence epilepsy treated with both VPA and ETX, and performed whole exome sequencing in order to investigate the potential role of rare variants in CACNA1H, other voltage-gated calcium channel (VGCC) genes, or GABA-receptor genes in predicting response to ETX or VPA.

RESULTS

Sixty-two patients were included; 12 were ETX-responsive, 14 VPA-responsive, and 36 did not have a clear positive response to either medication. We did not find significant enrichment inCACNA1H rare variants in ETX-responsive patients (odds ratio 3.43; 0.43-27.65; p = 0.20), nor was there enrichment for other VGCC genes. No significant enrichment of GABA-receptor gene rare variants was seen for VPA-non-responsive patients versus VPA-responsive. We found enrichment of rare GABA-receptor variants in our absence cohort compared to controls (odds ratio 3.82; 1.68-8.69). There was no difference in frequency of CACNA1H rs61734410 and CACNA1I rs3747178 polymorphisms between ETX-responsive and ETX-non-responsive groups; these polymorphisms have previously been reported to predict lack of response to ETX in absence epilepsy.

SIGNIFICANCE

We conclude that if CACNA1H rare variants predict lack of response to ETX, a larger sample is necessary to test this with sufficient power. Increased GABA-receptor gene rare variant frequency in absence epilepsy patients who fail initial anti-seizure therapy suggests subtle GABA receptor dysfunction may contribute to the underlying pathophysiology.

Understanding autism spectrum disorder and social functioning in children with neurofibromatosis type 1: protocol for a cross-sectional multimodal study

INTRODUCTION

Children with the single-gene disorder neurofibromatosis type 1 (NF1) appear to be at an increased risk for autism spectrum disorder (ASD) and exhibit a unique social-cognitive phenotype compared with children with idiopathic ASD. A complete framework is required to better understand autism in NF1, from neurobiological levels through to behavioural and functional outcomes. The primary aims of this study are to establish the frequency of ASD in children with NF1, examine the social cognitive phenotype, investigate the neuropsychological processes contributing to ASD symptoms and poor social functioning in children with NF1, and to investigate novel structural and functional neurobiological markers of ASD and social dysfunction in NF1. The secondary aim of this study is to compare the neuropsychological and neurobiological features of ASD in children with NF1 to a matched group of patients with idiopathic ASD.

METHODS AND ANALYSIS

This is an international, multisite, prospective, cross-sectional cohort study of children with NF1, idiopathic ASD and typically developing (TD) controls. Participants will be 200 children with NF1 (3-15 years of age), 70 TD participants (3-15 years) and 35 children with idiopathic ASD (7-15 years). Idiopathic ASD and NF1 cases will be matched on age, sex and intelligence. All participants will complete cognitive testing and parents will rate their child's behaviour on standardised questionnaires. Neuroimaging will be completed by a subset of participants aged 7 years and older. Children with NF1 that screen at risk for ASD on the parent-rated Social Responsiveness Scale 2nd Edition will be invited back to complete the Autism Diagnostic Observation Scale 2nd Edition and Autism Diagnostic Interview-Revised to determine whether they fulfil ASD diagnostic criteria.

ETHICS AND DISSEMINATION

This study has hospital ethics approval and the results will be disseminated through peer-reviewed publications and international conferences.

Spinal Cord Hyperintensities in Neurofibromatosis Type 1: Are They the Cord Equivalent of Unidentified Bright Objects in the Brain?

BACKGROUND

Focal areas of T2 hyperintensity are seen on magnetic resonance imaging (MRI) in patients with neurofibromatosis type 1 (NF1). These lesions are commonly known as "unidentified bright objects" of the brain. We have seen similar lesions in the spinal cord of the same patient population. Our aim was to determine the prevalence and characterize the imaging features of these T2 hyperintense spinal cord lesions in children with NF1.

METHODS

A search of our hospital's medical imaging database yielded all children with NF1 and MRI of the brain and/or spine between February 2014 and April 2017. Medical imaging was reviewed for T2 hyperintense signal changes and medical records were reviewed of those children with T2 hyperintense spinal cord lesions.

RESULTS

During the study period 155 children underwent a brain MRI and 72 had a spine MRI. One hundred twenty-three (79%) showed multiple cerebral T2 hyperintense lesions and six (8%) had non-contrast enhancing spinal cord T2 hyperintensities with five children having had a follow-up scan. The one child without follow-up imaging was not further pursued. Interval scanning showed stable appearance of the spinal cord lesions in four children and signal reduction in one child. All five children with T2 hyperintense changes in the spinal cord had an MRI brain and all (100%) also exhibited cerebral T2 hyperintensities.

CONCLUSIONS

Focal areas of signal hyperintensity in the spinal cord are the corollary of the better described cerebral T2 hyperintensities in individuals with NF1.

Risk of seizures in children with tectal gliomas

The objective of this study was to determine the prevalence of seizures in children with tectal gliomas and to determine if there are common clinical, electroencephalography (EEG), or radiologic findings that predict risk of seizures in these patients. We conducted a retrospective review of all patients with tectal gliomas over a 22-year period at a single institution. Data extraction included sex, age at presentation of tectal glioma and age of presentation with seizures, magnetic resonance imaging (MRI) findings, seizure frequency and semiology, and EEG findings. We identified 79 patients, 66 of whom had adequate imaging and clinical data for further analysis. Eight patients (12.1%) had a history of seizures. Three patients had a clear symptomatic cause of seizures. Three patients were diagnosed with a tectal glioma as an incidental finding after a first seizure. One patient had a history of febrile convulsions. One patient had a generalized seizure 5 years after presenting with macrocephaly. Although the risk of seizure in children with known tectal glioma was relatively high, we did not identify specific clinical, radiologic, EEG, or MRI features that are predictive of increased risk. Thus, in children with tectal gliomas who have seizures, alternative causes for the seizures must be sought.

Nummular headache associated with focal hair heterochromia in a child

Nummular headache (NH) is a recently described headache syndrome where continuous or intermittent pain is localised to a coin-shaped region of the skull. NH can be a primary headache disorder or secondary to intracranial or extracranial pathology. We report a four-year-old boy who presented with nummular headache co-localised with a patch of discoloured hair and propose a common aetiology.

Isolated intracranial hypertension as a late manifestation of sinus venous compression secondary to a depressed skull fracture

Cerebral venous sinus compression can mimic idiopathic intracranial hypertension. The authors report the case of a 12-year-old girl who presented with diplopia and papilledema 3 weeks after a head injury. Lumbar puncture confirmed raised intracranial pressure, and neuroimaging subsequently identified a skull fracture compressing the right transverse sinus. Papilledema and diplopia resolved following surgical elevation of the bone fragment. Computer tomography or magnetic resonance venography are indicated in children presenting with isolated intracranial hypertension following head injury to exclude cerebral venous sinus compression secondary to skull fracture.