Neuroimaging in Functional Movement Disorders

Functional Movement Disorder as a Prodromal Symptom of Parkinson's Disease-Clinical and Pathophysiological Insights

Functional movement disorder (FMD) is a common manifestation of functional neurological disorder. FMD can occur alongside other neurological conditions, but especially in patients with established Parkinson's disease (PD). An interesting observation emerging across cohort studies and case series is that FMD can precede the diagnosis of PD, suggesting that FMD may itself be a prodromal symptom of neurodegeneration. Such a notion would have significant clinical implications for the assessment and management of people with FMD, particularly with respect to decisions around the use of auxiliary investigations, counselling, and follow-up. In this Viewpoint we review the evidence concerning the temporal relationship between FMD and PD. We discuss the potential explanations and mechanisms for FMD as a prodromal symptom of PD, and highlight clinical considerations and important outstanding questions in the field. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Living with functional movement disorders: a tale of three battles. An interpretative phenomenological analysis

OBJECTIVES

Functional movement disorders (FMD) have poor prognosis and high physical and psychological co-morbidity. Their pathogenesis remains unclear, clinicians often find them difficult to treat, and lack of agreement between healthcare providers and patients is common. This study aimed to explore the experiences of living with FMD to improve understanding of its impact and patients' needs.

METHODS

Ten participants across the UK were recruited online through a charity's social media platforms. Semi structured interviews were conducted via video calls and were audio recorded and verbatim transcripts were analysed using interpretative phenomenological analysis.

RESULTS

Three superordinate themes were generated from the data, representing the three battles fought by the participants: (1) intrapersonal: the tug of war with the secret agent within- the power struggle with symptoms; (2) interpersonal: navigating stigma and self-preservation; (3) systemic: pursuing hope and treatments against helplessness and passivity.

CONCLUSIONS

Loss of control, feelings of powerlessness and oppression by symptoms is often mirrored in participants' experiences of seeking healthcare and navigating societal stigma. Active efforts to regain influence, improve quality of life and maintain hope can be jeopardised by others' dismissive attitudes and lack of knowledge. Antonovsky's model of salutogenesis is proposed as a useful framework for facilitating empowerment in FMD service provision.

Functional Movement Disorder Is Associated with Abnormal Interoceptive Brain Activity: A Task-based Functional MRI Study

Background

Aberrant interoceptive processing has been hypothesized to contribute to the pathophysiology of functional neurological disorder, although findings have been inconsistent. Here, we utilized functional magnetic resonance imaging (fMRI) to examine neural correlates of interoceptive attention - the conscious focus and awareness of bodily sensations - in functional movement disorder (FMD).

Methods

We used voxelwise analyses to compare blood oxygenation level-dependent responses between 13 adults with hyperkinetic FMD and 13 healthy controls (HCs) during a task requiring attention to different bodily sensations and to an exteroceptive stimulus. Additionally, we examined between-group differences in self-reported measures of interoception and evaluated their relationship with neural activity.

Results

Interoceptive conditions (heartbeat, stomach and 'body', indicating sensations from the body part or limb affected in FMD participants) activated a network involving the precuneus, the posterior cingulate cortex (PCC) and caudate nucleus (CN) bilaterally, and the right anterior insula (aINS) (p <0.05, corrected). Group differences in brain activity were mainly driven by processing of disease-related interoceptive signals, which in the FMD group was associated with a broader neural activation than monitoring gastric interoception, while no group differences were detected during cardiac interoception. Differences based on interoceptive focus (body vs heartbeat and stomach) between FMD subjects and HCs were found in PCC, CN, angular gyrus, thalamus, and in the mid-insula (p <0.05, corrected).

Conclusions

This is, to our knowledge, the first study showing that FMD is associated with abnormal interoceptive processing in regions involved in monitoring body state, attentional focus, and homeostatic inference.

Understanding Functional Neurological Disorder: Recent Insights and Diagnostic Challenges

Functional neurological disorder (FND), formerly called conversion disorder, is a condition characterized by neurological symptoms that lack an identifiable organic purpose. These signs, which can consist of motor, sensory, or cognitive disturbances, are not deliberately produced and often vary in severity. Its diagnosis is predicated on clinical evaluation and the exclusion of other medical or psychiatric situations. Its treatment typically involves a multidisciplinary technique addressing each of the neurological symptoms and underlying psychological factors via a mixture of medical management, psychotherapy, and supportive interventions. Recent advances in neuroimaging and a deeper exploration of its epidemiology, pathophysiology, and clinical presentation have shed new light on this disorder. This paper synthesizes the current knowledge on FND, focusing on its epidemiology and underlying mechanisms, neuroimaging insights, and the differentiation of FND from feigning or malingering. This review highlights the phenotypic heterogeneity of FND and the diagnostic challenges it presents. It also discusses the significant role of neuroimaging in unraveling the complex neural underpinnings of FND and its potential in predicting treatment response. This paper underscores the importance of a nuanced understanding of FND in informing clinical practice and guiding future research. With advancements in neuroimaging techniques and growing recognition of the disorder's multifaceted nature, the paper suggests a promising trajectory toward more effective, personalized treatment strategies and a better overall understanding of the disorder.

From Software to Hardware: A Case Series of Functional Neurological Symptoms and Cerebrovascular Disease

OBJECTIVE

Neuroimaging studies have identified alterations in both brain structure and functional connectivity in patients with functional neurological disorder (FND). For many patients, FND emerges from physical precipitating events. Nevertheless, there are a limited number of case series in the literature that describe the clinical presentation and neuroimaging correlates of FND following cerebrovascular disease.

METHODS

The authors collected data from two clinics in the United Kingdom on 14 cases of acute, improving, or delayed functional neurological symptoms following cerebrovascular events.

RESULTS

Most patients had functional neurological symptoms that were localized to cerebrovascular lesions, and the lesions mapped onto regions known to be part of functional networks disrupted in FND, including the thalamus, anterior cingulate gyrus, insula, and temporoparietal junction.

CONCLUSIONS

The findings demonstrate that structural lesions can lead to FND symptoms, possibly explained through changes in relevant mechanistic functional networks.

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.

[18F]FDG PET in conditions associated with hyperkinetic movement disorders and ataxia: a systematic review

PURPOSE

To give a comprehensive literature overview of alterations in regional cerebral glucose metabolism, measured using [18F]FDG PET, in conditions associated with hyperkinetic movement disorders and ataxia. In addition, correlations between glucose metabolism and clinical variables as well as the effect of treatment on glucose metabolism are discussed.

METHODS

A systematic literature search was performed according to PRISMA guidelines. Studies concerning tremors, tics, dystonia, ataxia, chorea, myoclonus, functional movement disorders, or mixed movement disorders due to autoimmune or metabolic aetiologies were eligible for inclusion. A PubMed search was performed up to November 2021.

RESULTS

Of 1240 studies retrieved in the original search, 104 articles were included. Most articles concerned patients with chorea (n = 27), followed by ataxia (n = 25), dystonia (n = 20), tremor (n = 8), metabolic disease (n = 7), myoclonus (n = 6), tics (n = 6), and autoimmune disorders (n = 5). No papers on functional movement disorders were included. Altered glucose metabolism was detected in various brain regions in all movement disorders, with dystonia-related hypermetabolism of the lentiform nuclei and both hyper- and hypometabolism of the cerebellum; pronounced cerebellar hypometabolism in ataxia; and striatal hypometabolism in chorea (dominated by Huntington disease). Correlations between clinical characteristics and glucose metabolism were often described. [18F]FDG PET-showed normalization of metabolic alterations after treatment in tremors, ataxia, and chorea.

CONCLUSION

In all conditions with hyperkinetic movement disorders, hypo- or hypermetabolism was found in multiple, partly overlapping brain regions, and clinical characteristics often correlated with glucose metabolism. For some movement disorders, [18F]FDG PET metabolic changes reflected the effect of treatment.

Why functional neurological disorder is not feigning or malingering

Functional neurological disorder (FND) is one of the commonest reasons that people seek help from a neurologist and is for many people a lifelong cause of disability and impaired quality of life. Although the evidence base regarding FND pathophysiology, treatment and service development has grown substantially in recent years, a persistent ambivalence remains amongst health professionals and others as to the veracity of symptom reporting in those with FND and whether the symptoms are not, in the end, just the same as feigned symptoms or malingering. Here, we provide our perspective on the range of evidence available, which in our view provides a clear separation between FND and feigning and malingering. We hope this will provide a further important step forward in the clinical and academic approach to people with FND, leading to improved attitudes, knowledge, treatments, care pathways and outcomes.

Classification of Functional Movement Disorders with Resting-State Functional Magnetic Resonance Imaging

Introduction: Functional movement disorder (FMD) is a type of functional neurological disorder characterized by abnormal movements that patients do not perceive as self-generated. Prior imaging studies show a complex pattern of altered activity, linking regions of the brain involved in emotional responses, motor control, and agency. This study aimed to better characterize these relationships by building a classifier using a support vector machine to accurately distinguish between 61 FMD patients and 59 healthy controls using features derived from resting-state functional magnetic resonance imaging. Materials and Methods: First, we selected 66 seed regions based on prior related studies, then we calculated the full correlation matrix between them before performing recursive feature elimination to winnow the feature set to the most predictive features and building the classifier. Results: We identified 29 features of interest that were highly predictive of the FMD condition, classifying patients and controls with 80% accuracy. Several key features included regions in the right sensorimotor cortex, left dorsolateral prefrontal cortex, left cerebellum, and left posterior insula. Conclusions: The features selected by the model highlight the importance of the interconnected relationship between areas associated with emotion, reward, and sensorimotor integration, potentially mediating communication between regions associated with motor function, attention, and executive function. Exploratory machine learning was able to identify this distinctive abnormal pattern, suggesting that alterations in functional linkages between these regions may be a consistent feature of the condition in many FMD patients. Clinical-Trials.gov ID: NCT00500994 Impact statement Our research presents novel results that further elucidate the pathophysiology of functional movement disorder (FMD) with a machine learning model that classifies FMD and healthy controls correctly 80% of the time. Herein, we demonstrate how known differences in resting-state functional magnetic resonance imaging connectivity in FMD patients can be leveraged to better understand the complex pattern of neural changes in these patients. Knowing that there are measurable predictable differences in brain activity in patients with FMD may help both clinicians and patients conceptualize and better understand the illness at the point of diagnosis and during treatment. Our methods demonstrate how an effective combination of machine learning and qualitative approaches to analyzing functional brain connectivity can enhance our understanding of abnormal patterns of brain activity in FMD patients.

The importance of screening for functional neurological disorders in patients with persistent post-concussion symptoms

BACKGROUND

Functional neurological disorder (FND) may commonly co-occur with persistent symptoms following a psychological trauma or physical injury such as concussion.

OBJECTIVE

To explore the occurrence of FND in a population with persistent post-concussion symptoms (PPCS) and the associations between FND and depression as well as anxiety in participants with PPCS.

METHODS

Sixty-three individuals with PPCS presenting to a specialized brain injury clinic completed the following questionnaires: screening for somatoform disorder conversion disorder subscale (SOM-CD), Rivermead post-concussion symptom questionnaire (RPQ), patient health questionnaire-9 (PHQ-9), and generalized anxiety disorder questionnaire- 7 (GAD-7). Both multiple linear regression and logistic regression were conducted to evaluate the relationship between questionnaires and adjust for covariates.

RESULTS

We found that total RPQ score (βˆ= 0.27; 95% CI = [0.16, 0.38]), GAD-7 score (βˆ= 0.71; 95% CI = [0.50, 0.92]) and PHQ-9 score (βˆ= 0.54; 95% CI = [0.32, 0.76]) were positively associated with SOM-CD score individually, after consideration of other covariates. Participants meeting the criteria for severe FND symptoms were 4.87 times more likely to have high PPCS symptom burden (95% CI = [1.57, 22.84]), 8.95 times more likely to have severe anxiety (95% CI = [3.31, 35.03]) and 4.11 times more likely to have severe depression symptom burden (95% CI = [1.77, 11.53]).

CONCLUSION

The findings of this study indicate an association between FND and post-concussion symptoms as well as an association between FND and symptoms of depression and anxiety in patients with PPCS. Patients with PPCS should be screened for FND to provide a more targeted treatment approach that includes somatic-focused interventions.

Dysfunctional Networks in Functional Dystonia

Functional dystonia, the second most common functional movement disorder, is characterized by acute or subacute onset of fixed limb, truncal, or facial posturing, incongruent with the action-induced, position-sensitive, and task-specific manifestations of dystonia. We review neurophysiological and neuroimaging data as the basis for a dysfunctional networks in functional dystonia. Reduced intracortical and spinal inhibition contributes to abnormal muscle activation, which may be perpetuated by abnormal sensorimotor processing, impaired selection of movements, and hypoactive sense of agency in the setting of normal movement preparation but abnormal connectivity between the limbic and motor networks. Phenotypic variability may be related to as-yet undefined interactions between abnormal top-down motor regulation and overactivation of areas implicated in self-awareness, self-monitoring, and active motor inhibition such as the cingulate and insular cortices. While there remain many gaps in knowledge, further combined neurophysiological and neuroimaging assessments stand to inform the neurobiological subtypes of functional dystonia and the potential therapeutic applications.

Understanding, Recognizing, and Managing Functional Speech Disorders: Current Thinking Illustrated With a Case Series

PURPOSE

Functional speech disorders (FSDs), a subtype of functional neurological disorders, are distinguishable from neurogenic motor speech disorders based on their clinical features, clinical course, and response to treatment. However, their differential diagnosis and management can be challenging. FSDs are not well understood, but growing evidence suggests a biopsychosocial basis distinct from structural lesions that cause neurogenic motor speech disorders.

METHOD AND RESULTS

Following an overview of FSDs, four patients are described to illustrate the range of clinical manifestations, biopsychosocial contexts, and responses to treatment of FSDs. The path to differential diagnosis is discussed, with particular attention to positive features that led to the FSD diagnosis. Approaches to education, counseling, and management are discussed.

CONCLUSIONS

This case series demonstrates that FSDs can present with a variety of manifestations including dysfluencies, articulation errors, dysphonia, rate and prosodic abnormalities, and combinations of disruptions in speech subsystems. FSDs may present in the context of known recent or remote physical or psychosocial trauma or, as in many cases, in the absence of an identifiable triggering event. FSDs are recognizable by positive clinical features and should not be considered a diagnosis of exclusion. With appropriate identification, counseling, and treatment, FSDs may resolve, sometimes rapidly; in some cases, treatment may be prolonged or ineffective.

ASTASIA-ABASIA, PSYCHOGENIC OR ORGANIC? IT &#769;S NOT EASY

Astasia-abasia was described by Paul Blocq as a psychogenic condition; later, several brain injuries have been described for its explanation too.

Diagnosis and Initial Treatment of Functional Movement Disorders in Children

Functional movement disorders (FMD) are complex neurobehavioral disorders that can be a significant source of disability for both children and their caregivers. While FMD in the adult population is better characterized, the aim of this paper is to review the pertinent clinical and historical features, diagnostic criteria, and multi-disciplinary management of FMD in the pediatric population. We highlight recent trends in pediatric FMD, including the increase in functional tic-like behaviors that has been observed during the COVID-19 pandemic.

Functional neurological disorder: Extending the diagnosis to other disorders, and proposing an alternate disease term—Attentionally-modifiable disorder

BACKGROUND: The term “functional neurological disorder,” or “FND,” applies to disorders whose occurrence of neurological symptoms fluctuate with the patient’s attention to them. However, many other disorders that are not called “FND” nonetheless can also follow this pattern. Consequently, guidelines are unclear for diagnosing “FND.” OBJECTIVE: To review the neurological conditions that follow this pattern, but which have not so far been termed “FND,” to understand their overlap with conditions that have been termed “FND,” and to discuss the rationale for why FND has not been diagnosed for them. METHOD: A systematic review of the PubMed literature registry using the terms “fluctuation,” “inconsistency,” or “attention” did not yield much in the way of these candidate disorders. Consequently, this review instead relied on the author’s personal library of peer-reviewed studies of disorders that have resembled FND but which were not termed this way, due to his longstanding interest in this problem. Consequently, this approach was not systematic and was subjective regarding disease inclusion. RESULTS: This review identified numerous, diverse conditions that generally involve fluctuating neurological symptoms that can vary with the person’s attention to them, but which have not been called “FND.” The literature was unclear for reasons for not referring to “FND” in these instances. CONCLUSION: Most likely because of historical biases, the use of the term “FND” has been unnecessarily restricted. Because at its core FND is an attentionally-influenced disorder that can respond well to behavioral treatments, the field of neurological rehabilitation could benefit by extending the range of conditions that could be considered as “FND” and referred for similar behavioral treatments. Because the term “FND” has been viewed unfavorably by some patients and clinical practitioners and whose treatment is not implied, the alternative term attentionally-modifiable disorder is proposed.

Functional MRI connectivity of the primary motor cortex in functional dystonia patients

BACKGROUND

Functional movement disorders include a wide spectrum of clinically documented movement disorders without an apparent organic substrate.

OBJECTIVE

To explore the functional connectivity (FC) of the primary motor (M1) cortex in functional dystonia (FD) patients relative to healthy controls, with a focus on different clinical phenotypes.

METHODS

Forty FD patients (12 fixed [FixFD]; 28 mobile [MobFD]) and 43 healthy controls (14 young FixFD-age-matched [yHC]; 29 old MobFD-age-matched [oHC]) underwent resting state fMRI. A seed-based FC analysis was performed using bilateral M1 as regions of interest.

RESULTS

Compared to controls, FD patients showed reduced FC between left M1 and left dorsal anterior cingulate cortex, and between right M1 and left M1, premotor/supplementary motor area (SMA), dorsal posterior cingulate cortex (PCC), and bilateral precuneus. Relative to yHC, FixFD patients showed reduced FC between M1 and precuneus bilaterally. Compared to oHC, MobFD patients revealed reduced FC between right M1 and left M1, premotor/SMA, dorsal-PCC, bilateral primary sensory cortices and parieto-occipital areas, and increased FC of right M1 with right associative visual cortex and bilateral ventral-PCC. FixFD patients, relative to MobFD, showed lower FC between the right M1 and right associative visual area, and bilateral precuneus and ventral-PCC.

CONCLUSIONS

This study suggests an altered brain FC of the motor circuit with areas involved in emotional processes and sense of agency in FD. FixFD patients showed FC abnormalities mainly in areas related to sense of agency, while MobFD in regions involved in sensorimotor functions (reduced FC) and emotional processing (increased FC).

Subjective versus objective measures of distress, arousal and symptom burden in patients with functional seizures and other functional neurological symptom disorder presentations: A systematic review

Symptoms and functioning can be measured subjectively using self-report measures or objectively, based on physiological changes. This raises the question whether subjective and objective measures are closely correlated and - if not - whether one is more accurate or meaningful than the other, especially in patients with Functional Seizures (FS) or other Functional Neurological Symptom Disorders (FND), where subjective and objective observations may be thought particularly likely to deviate. This systematic review explores these questions focussing on measures of distress, arousal and symptom burden. Eighteen studies (12 FS, 6 other FND) capturing 396 FND patients were included. Eleven reported no correlation between subjective and objective measures. Only four studies reported significant correlations (r's = -0.74-0.59, p's < 0.05). The small number of studies and diverse methodologies do not provide conclusive answers to the questions posed. Given that subjective and objective measures capture different aspects of current state or function, a combination of measurement approaches is likely to provide optimal information about patients' health state. In view of the attentional and perceptual alterations implicated in FND, the difference between objective and subjective measures may represent an interesting observation in its own right.

A dimensional approach to functional movement disorders: Heresy or opportunity

Functional movement disorders (FMD) are a common and disabling neuropsychiatric condition, part of the spectrum of functional neurological/conversion disorder. FMD represent one of the most enigmatic disorders in the history of medicine. However, in the twenty years after the first report of distinctive abnormal brain activity associated with functional motor symptoms, there have been tremendous advances in the pathophysiologic understanding of these disorders. FMD can be characterized as a disorder of aberrant neurocircuitry interacting with environmental and genetic factors. These developments suggest that research on FMD could be better served by an integrative, neuroscience-based approach focused on functional domains and their neurobiological substrates. This approach has been developed in 'Research Domain Criteria' (RDoC) project, which promotes a dimensional approach to psychiatric disorders. Here, we use the RDoC conceptualization to review recent neuroscience research on FMD, focusing on the domains most relevant to these disorders. We discuss how the adoption of a similar integrative framework may facilitate the identification of the mechanisms underlying FMD and could also have potential clinical applicability.

The neuroimaging evidence of brain abnormalities in functional movement disorders

Neuroimaging has been pivotal in identifying and reframing our understanding of functional movement disorders (FMDs). If accessible, it compensates for the limitations of the clinical exam and is especially useful where there is overlap of functional symptoms with classical presentations of disease. Imaging in FMDs has increasingly identified structural and functional abnormalities that implicate hypoactivation of the cortical and subcortical motor pathways and increased modulation by the limbic system. Neurobiological theories suggest an impaired sense of agency, faulty top-down regulation of motor movement and abnormal emotional processing in these individuals. This framework challenges our traditional understanding of FMDs as distinct from the deceptive term of 'organic' diseases and proposes that these conditions not be considered as mutually exclusive. This review summarizes the literature to date and explores the role of imaging in the diagnosis of FMDs and in detecting its underlying molecular network.

Acute non-traumatic tetraparesis - Differential diagnosis

INTRODUCTION

Potentially life-threatening disorders may present in the emergency department with acute tetraparesis, and their recognition is crucial for an appropriate management and timely treatment. Our review aims to systematize the differential diagnosis of acute non-traumatic tetraparesis.

RESULTS

Causes of tetraparesis can be classified based on the site of defect: upper motor neuron (UMN), peripheral nerve, neuromuscular junction or muscle. History of present illness should include the distribution of weakness (symmetric/asymmetric or distal/proximal/diffuse) and associated clinical features (pain, sensory findings, dysautonomia, and cranial nerve abnormalities such as diplopia and dysphagia). Neurological examination, particularly tendon reflexes, helps further in the localization of nerve lesions and distinction between UMN and lower motor neuron. Ancillary studies include blood and cerebral spinal fluid analysis, neuroaxis imaging, electromyography, muscle magnetic resonance and muscle biopsy.

CONCLUSIONS

Acute tetraparesis is still a debilitating and potentially serious neurological condition. Despite all the supplementary ancillary tests, the neurological examination is the key to achieve a correct diagnosis. The identification of life-threatening neurologic disorders is pivotal, since failing to identify patients at risk of complications, such as acute respiratory failure, may have catastrophic results.

Structural neuroimaging of somatoform disorders: A systematic review

Although there has been an increment in neuroimaging research in somatoform disorders (SD), to date little is known about the neural correlates of these diseases. Therefore, in this systematic, review we aimed at summarizing the existing evidence of structural brain alterations in SD as per DSM-IV and DSM-5 criteria. Three electronic databases (Scopus, PubMed and Web of Science) were searched. Only case-control studies using structural neuroimaging were included. Forty-five out of 369 articles fulfilled inclusion criteria and were reviewed. Compared to controls, subjects with SD showed morphological alterations encompassing motor, limbic and somatosensory circuits. Although far from being conclusive, the results suggested that SD are characterized by selective alterations of large-scale brain networks implicated in cognitive control, emotion regulation and processing, stress and somatic-visceral perception. This review highlights the need for further multimodal neuroimaging studies with longitudinal designs, in larger and better-characterized samples, to elucidate the temporal and causal relationship between neuroanatomical changes and SD, which is paramount for informing tailored treatments.

Cerebrospinal fluid glutamate changes in functional movement disorders

The aim of this study was to assess cerebrospinal fluid (CSF) concentrations of specific amino acids using a high-performance liquid chromatography system in a sample of patients with functional movement disorders (FMDs) and in a sample of controls. CSF levels of glutamate were significantly lower in patients with FMD than in controls. This finding argues in favor of glutamatergic dysfunction in the pathophysiology of FMD.

Neural activity in functional movement disorders after inpatient rehabilitation

Functional movement disorders (FMD) are a common source of disability in neurology.While treatment of FMD can reduce motor severity and disability, the neural mechanisms implicated in such a response remain unclear. We aimed to investigate neural changes in patients with FMD after a one-week multidisciplinary motor retraining (MoRe) treatment program. Fourteen FMD patients completed an emotional Go/No-Go fMRI task before and after MoRe treatment. Standardized pre- and post-treatment videos were rated for motor severity by a blinded reviewer using the psychogenic movement disorder rating scale (PMDRS). PMDRS scores before and after treatment were used for whole-brain regression. PMDRS scores were significantly reduced after MoRe treatment. Worse severity prior to treatment was associated with greater primary motor cortex (M1) activation at baseline and a larger response to treatment. Globally, increased connectivity between bilateral amygdala and premotor regions was observed following treatment. Lower post-treatment PMDRS scores were associated with increased connectivity between amygdala and ventromedial prefrontal cortex, whereas higher post-treatment PMDRS scores (and poorer treatment response) were associated with increased connectivity between amygdala and M1. Motor retraining in FMD may reorganize activity and connectivity in emotion processing and motor planning networks, with shifts in amygdala connectivity from posterior to frontal/prefrontal regions.

Cortical Inhibitory Imbalance in Functional Paralysis

BACKGROUND

Functional neurological disorders are characterized by neurological symptoms that have no identifiable pathology and little is known about their underlying pathophysiology.

OBJECTIVES

To analyze motor cortex excitability and intracortical inhibitory and excitatory circuits' imbalance in patients with flaccid functional weakness.

METHODS

Twenty-one consecutive patients with acute onset of flaccid functional weakness were recruited. Single and paired-pulse transcranial magnetic stimulation (TMS) protocols were used to analyze resting motor thresholds (RMT) and intracortical inhibitory (short interval intracortical inhibition - SICI) and excitatory (intracortical facilitation - ICF) circuits' imbalance between the affected and non-affected motor cortices.

RESULTS

We observed a significant increase in RMT and SICI in the affected motor cortex (p < 0.001), but not for ICF, compared to the contralateral unaffected side.

CONCLUSION

This study extends current knowledge of functional weakness, arguing for a specific central nervous system abnormality which may be involved in the symptoms' pathophysiology.

Adult-Onset Gilles de la Tourette Syndrome: Psychogenic or Organic? The Challenge of Abnormal Neurophysiological Findings

Gilles de la Tourette syndrome (GTS) is characterized by multiple motor and vocal tics. Adult-onset cases are rare and may be due to "reactivation" of childhood tics, or secondary to psychiatric or genetic diseases, or due to central nervous system lesions of different etiologies. Late-onset psychogenic motor/vocal tics resembling GTS have been described. Neurophysiology may serve to differentiate organic from functional GTS. Altered blink reflex pre-pulse inhibition (BR-PPI), blink reflex excitability recovery (BR-ERC), and short-interval intracortical inhibition (SICI) have been described in GTS. We report a 48-years-old male, who developed numerous motor/vocal tics 2 months after sustaining non-commotional craniofacial trauma in a car accident. Both his father and brother had died earlier in car crashes. He presented with blepharospasm-like forced lid closure, forceful lip pursing, noisy suction movements, and deep moaning sounds, occurring in variable combinations, without warning symptoms or internal "urge." Tics showed low distractibility and these increased with attention. Standard magnetic resonance imaging, electroencephalography, and evoked potentials were unremarkable. Neuropsychology diagnosed moderately impaired intellect, attention, and executive functions. Psychiatric assessment revealed somatization disorder and generalized anxiety. BR-PPI was unremarkable, while BR-ERC was enhanced, even showing facilitation at short intervals. SICI was markedly reduced at 1 and 3 ms and intracortical facilitation (ICF) was enhanced at 10 ms. The patient fulfilled Fahn and Williams' diagnostic criteria for a psychogenic movement disorder. Neurophysiology, however, documented hyperexcitability of motor cortex and brainstem. We suggest that-similar to what has been reported in psychogenic dystonia-a pre-existing predisposition may have led to the functional hyperkinetic disorder in response to severe psychic stress.