Transient cortico-cortical disconnection during psychogenic nonepileptic seizures (PNES)

Recent advances in understanding the neurobiology of pediatric functional neurological disorder

INTRODUCTION

Functional neurological disorder (FND) is a neuropsychiatric disorder that manifests in a broad array of functional motor, sensory, or cognitive symptoms, which arise from complex interactions between brain, mind, body, and context. Children with FND make up 10%-20% of presentations to neurology services in children's hospitals and up to 20% of adolescents admitted to hospital for the management of intractable seizures.

AREAS COVERED

The current review focuses on the neurobiology of pediatric FND. The authors present an overview of the small but growing body of research pertaining to the biological, emotion-processing, cognitive, mental health, physical health, and social system levels.

EXPERT OPINION

Emerging research suggests that pediatric FND is underpinned by aberrant changes within and between neuron-glial (brain) networks, with a variety of factors - on multiple system levels - contributing to brain network changes. In pediatric practice, adverse childhood experiences (ACEs) are commonly reported, and activation or dysregulation of stress-system components is a frequent finding. Our growing understanding of the neurobiology of pediatric FND has yielded important flow-on effects for assessing and diagnosing FND, for developing targeted treatment interventions, and for improving the treatment outcomes of children and adolescents with FND.

Neurometabolic alterations in children and adolescents with functional neurological disorder

OBJECTIVES

In vivo magnetic resonance spectroscopy (MRS) was used to investigate neurometabolic homeostasis in children with functional neurological disorder (FND) in three regions of interest: supplementary motor area (SMA), anterior default mode network (aDMN), and posterior default mode network (dDMN). Metabolites assessed included N-acetyl aspartate (NAA), a marker of neuron function; myo-inositol (mI), a glial-cell marker; choline (Cho), a membrane marker; glutamate plus glutamine (Glx), a marker of excitatory neurotransmission; γ-aminobutyric acid (GABA), a marker of inhibitor neurotransmission; and creatine (Cr), an energy marker. The relationship between excitatory (glutamate and glutamine) and inhibitory (GABA) neurotransmitter (E/I) balance was also examined.

METHODS

MRS data were acquired for 32 children with mixed FND (25 girls, 7 boys, aged 10.00 to 16.08 years) and 41 healthy controls of similar age using both short echo point-resolved spectroscopy (PRESS) and Mescher-Garwood point-resolved spectroscopy (MEGAPRESS) sequences in the three regions of interest.

RESULTS

In the SMA, children with FND had lower NAA/Cr, mI/Cr (trend level), and GABA/Cr ratios. In the aDMN, no group differences in metabolite ratios were found. In the pDMN, children with FND had lower NAA/Cr and mI/Cr (trend level) ratios. While no group differences in E/I balance were found (FND vs. controls), E/I balance in the aDMN was lower in children with functional seizures-a subgroup within the FND group. Pearson correlations found that increased arousal (indexed by higher heart rate) was associated with lower mI/Cr in the SMA and pDMN.

CONCLUSIONS

Our findings of multiple differences in neurometabolites in children with FND suggest dysfunction on multiple levels of the biological system: the neuron (lower NAA), the glial cell (lower mI), and inhibitory neurotransmission (lower GABA), as well as dysfunction in energy regulation in the subgroup with functional seizures.

Content or context? A study protocol for a three-arm parallel randomised controlled trial of Re-PROGRAM, a brief internet-based intervention for patients with functional seizures

INTRODUCTION

Functional seizures (FS) mimic epilepsy but are not caused by epileptic electrical activity in the brain and are believed to have a psychological origin. There is a well-documented gap between the needs of patients with FS and available therapeutic resources. While there is potential for reducing seizure burden in patients via psychosocial intervention, there is no evidence-based care pathway or consistent availability of treatment and no effective pharmacological treatment. The objective of this study is to investigate the clinical efficacy and tolerability of a novel internet-based intervention in reducing seizure frequency.

METHODS AND ANALYSIS

A 3-arm parallel randomised controlled trial will compare the efficacy of brief guided internet-based therapy to unguided internet-based therapy and to standard care. Approximately 100 participants with FS will be recruited, with diagnostic criteria based on gold standard video-electroencephalogram (v-EEG) monitoring; patients will be randomly assigned to one of the three study arms. The primary study outcome will be FS frequency at 6 weeks and at follow-up (6 and 12 months) compared with baseline. Seizure frequency will be modelled using Poisson regression. Secondary outcomes include psychosocial functioning, healthcare resource usage, anxiety, depression, somatisation and life impact. Between-group differences will be evaluated using analysis of variance. Analysis of covariance will estimate within-group changes on secondary outcomes. Cognitive and psychological factors will be used as predictors of seizure reduction in exploratory analyses. A qualitative survey using a semi-structured interview will use thematic analyses to explore participants' treatment experiences, their impressions of FS management and perceived mechanisms for change.

ETHICS AND DISSEMINATION

The study was approved by the Human Research and Ethics Committee of the Alfred Hospital Human Research Ethics Committee as part of the Australian Multisite Ethics approval system. Results of the study will be presented at national and international conferences and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ACTRN12622000262707.

Double vision

The legitimacy of an illness is often determined by our understanding of the underlying disorder. In this essay, Stoyan Popkirov considers what this means for our approach to functional neurological disorders such as dissociative seizures.

Case Report: Atonic PNES Capture in fMRI

Psychogenic Non-Epileptic Seizures (PNES) are a misunderstood and disabling pathology, characterized by a paroxysmal occurrence of clinical signs without the epileptic activity. Resting-state functional MRI (fMRI) studies in patients with PNES have shown abnormal functional connectivity of the resting-state networks, especially in the limbic and motor systems, and in the precuneus. However, the transient nature of PNES episodes prevents us from elucidating the underlying mechanisms of seizures. Here, we report the case of a patient who presented an atonic episode of PNES during a 3T fMRI session. The patient is a 23-year-old woman, suffering from post-traumatic stress disorder, with no neurological comorbidities. The preprocessing of the fMRI images involved realignment, co-registration, segmentation, normalization, denoising (PhysIO toolbox), and smoothing. The time boundary of the seizure was defined according to the patient's reports, and the seizure period was contrasted with the resting state period before the seizure. A whole-brain analysis showed significant activations (left inferior temporal gyrus, left temporo-occipital junction) and deactivations (right precuneus, right superior parietal lobule, right postcentral gyrus, bilateral lingual gyri, inferior occipital gyri, and cerebellar lobules; right insula in a sub-thresholded analysis). Activations and deactivations occurred in four cerebral networks: emotional processing, agency, self-perception, and dissociation. To our knowledge, this report is the first published case of functional MRI during PNES. These results could confirm the emotional and dissociative hypothesis of the physiopathology of PNES and highlight future targets for neuromodulation.

How to do things with words Two seminars on the naming of functional (psychogenic, non-epileptic, dissociative, conversion, …) seizures

Amongst the most important conditions in the differential diagnosis of epilepsy is the one that manifests as paroxysms of altered behaviour, awareness, sensation or sense of bodily control in ways that often resemble epileptic seizures, but without the abnormal excessive or synchronous electrical activity in the brain that defines these. Despite this importance, there remains little agreement - and frequent debate - on what to call this condition, known inter alia as psychogenic non-epileptic seizures (PNES), dissociative seizures (DS), functional seizures (FS), non-epileptic attack disorder (NEAD), pseudoseizures, conversion disorder with seizures, and by many other labels besides. This choice of terminology is not merely academic - it affects patients' response to and understanding of their diagnosis, and their ability to navigate health care systems.This paper summarises two recent discussions hosted by the American Epilepsy Society and Functional Neurological Disorders Society on the naming of this condition. These discussions are conceptualised as the initial step of an exploration of whether it might be possible to build consensus for a new diagnostic label.