Psychologic theories in functional neurologic disorders

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.

Functional Tic-Like Behaviors: A Common Comorbidity in Patients with Tourette Syndrome

BACKGROUND

Comorbid functional tic-like behaviors (FTB) have been described only rarely in patients with Tourette syndrome (TS).

OBJECTIVES

We present the first large sample of patients suffering from TS and FTB to raise awareness of this clinical presentation and to guide how to differentiate one from the other.

METHODS

We analyzed clinical data of 71 patients (n = 27 [38.0%] female, mean age: 21.5, range: 11-55) with TS + FTB.

RESULTS

In the majority of patients, FTB started abruptly on average 15 years after tic onset with "treatment-resistant" complex movements and ("coprophenomena-like") vocalizations preceded by timely related psychological stressors. Psychological evaluation revealed evidence for internal conflicts (79%), emotional dysregulation (56%), and maintaining factors (70%). About one third of patients had a positive history for further medically unexplained symptoms. Compared to a large TS sample (n = 1032), patients with TS + FTB were more likely to be female, and presented significantly more common with "coprophenomena-like" symptoms, atypical influential factors, atypical descriptions of premonitory sensations, and higher rates of comorbid obsessive-compulsive disorder and "self-injurious" behavior.

CONCLUSIONS

Based on our data it can be assumed that FTB is a common comorbidity in TS, similar to functional overlay in other movement disorders and epilepsy. Before classifying a patient as suffering from treatment-resistant TS, FTB should be ruled out.

Sense of agency and its disturbances: A systematic review targeting the intentional binding effect in neuropsychiatric disorders

Sense of agency (SoA) indicates a person's ability to perceive her/his own motor acts as actually being her/his and, through them, to exert control over the course of external events. Disruptions in SoA may profoundly affect the individual's functioning, as observed in several neuropsychiatric disorders. This is the first article to systematically review studies that investigated intentional binding (IB), a quantitative proxy for SoA measurement, in neurological and psychiatric patients. Eligible were studies of IB involving patients with neurological and/or psychiatric disorders. We included 15 studies involving 692 individuals. Risk of bias was low throughout studies. Abnormally increased action-outcome binding was found in schizophrenia and in patients with Parkinson's disease taking dopaminergic medications or reporting impulsive-compulsive behaviors. A decreased IB effect was observed in Tourette's disorder and functional movement disorders, whereas increased action-outcome binding was found in patients with the cortico-basal syndrome. The extent of IB deviation from healthy control values correlated with the severity of symptoms in several disorders. Inconsistent effects were found for autism spectrum disorders, anorexia nervosa, and borderline personality disorder. Findings pave the way for treatments specifically targeting SoA in neuropsychiatric disorders where IB is altered.

A meta-ethnographic synthesis of the experiences of stigma amongst people with functional neurological disorder

PURPOSE

Functional neurological disorder (FND) causes many neurological symptoms and significant disability. It is often misunderstood by medical professionals and the public meaning stigma is regularly reported. The aim of this review was to synthesise the qualitative findings in the literature to develop a more in-depth understanding of how people with FND experience stigma to inform future interventions.

METHOD

This review used a meta-ethnography approach. Five databases were searched (PsycINFO, Web of Science, CINAHL, MEDLINE, and EMBASE) in February 2021 and updated in July 2022 for qualitative papers in FND. Included papers were critically assessed using the critical appraisal skills programme (CASP) checklist. Data were analysed and synthesised utilising meta-ethnography.

RESULTS AND CONCLUSION

Sixteen papers were included in the final synthesis. Four major themes emerged: stigmatized by delegitimization; stigmatized by social exclusion and rejection; coping with stigma; and stigma and identity. The results identified negative, stigmatizing attitudes towards people experiencing FND symptoms in a variety of contexts including healthcare and other social institutions. The effects of stigma led to further exclusion for participants and appeared to trigger coping styles that led to additional difficulty. Stigma is a key part of the illness experience of FND and needs to be addressed.

Hypnosis and suggestion as interventions for functional neurological disorder: A systematic review

OBJECTIVE

Functional neurological disorder (FND) involves the presence of neurological symptoms that cannot be explained by neurological disease. FND has long been linked to hypnosis and suggestion, both of which have been used as treatments. Given ongoing interest, this review examined evidence for the efficacy of hypnosis and suggestion as treatment interventions for FND.

METHOD

A systematic search of bibliographic databases was conducted to identify group studies published over the last hundred years. No restrictions were placed on study design, language, or clinical setting. Two reviewers independently assessed papers for inclusion, extracted data, and rated study quality.

RESULTS

The search identified 35 studies, including 5 randomised controlled trials, 2 non-randomised trials, and 28 pre-post studies. Of 1584 patients receiving either intervention, 1379 (87%) showed significant improvements, including many who demonstrated resolution of their symptoms in the short-term. Given the heterogeneity of interventions and limitations in study quality overall, more formal quantitative synthesis was not possible.

CONCLUSIONS

The findings highlight longstanding and ongoing interest in using hypnosis and suggestion as interventions for FND. While the findings appear promising, limitations in the evidence base, reflecting limitations in FND research more broadly, prevent definitive recommendations. Further research seems warranted given these supportive findings.

Personality traits related to cognitive functioning in patients with functional neurological disorder

Cognitive symptoms are prevalent in patients with functional neurological disorder (FND). Several studies have suggested that personality traits such as neuroticism may play a pivotal role in the development of FND. FND has also been associated with alexithymia: patients with FND report difficulties in identifying, analyzing, and verbalizing emotions. Whether or not alexithymia and other personality traits are associated with cognitive symptomatology in patients with FND is unknown. In the current study, we explored whether the Big Five personality model factors (neuroticism, extraversion, openness, agreeableness, and conscientiousness) and alexithymia were associated with cognitive functioning in FND. Twenty-three patients with FND were assessed using a neuropsychological assessment and questionnaire assessment to explore personality traits (Neuroticism-Extraversion-Openness Five-Factor Inventory) and alexithymia (Bermond-Vorst Alexithymia Questionnaire). The results indicated that high conscientiousness was associated with lower planning scores (ρ = -0.52, p = .012) and high scores on alexithymia were associated with lower scores on verbal memory scores (ρ = -0.46, p = .032) and lower sustained attention scores (ρ = -0.45, p = .046). The results did not remain significant after controlling for multiple testing. The preliminary results of our study suggest that personality and cognitive symptomatology in patients with FND are topics that should be further explored in future studies, as cognitive symptomology can affect treatment results.

Somatic Symptom Disorder and Health Anxiety: Assessment and Management

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) Somatic Symptom Disorder (SSD) and Illness Anxiety Disorder (IAD) replaced the diagnostic entities of the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) somatoform disorders and hypochondriasis. SSD turns away from specifying the presence or absence of a medical condition for presented symptoms and instead focuses on excessive symptom-related affects, cognitions, and behaviors. People with pathological health anxiety can be diagnosed with SSD or IAD, depending on the intensity of accompanying somatic symptoms. Cognitive-behavioral therapy shows the best empirical evidence for an effective treatment of SSD and IAD.

Psychiatrists' attitudes towards functional neurological disorders: results from a national survey

Introduction

Functional neurological disorder (FND) presents motor, sensory, and cognitive symptoms characterized by clinical signs incongruent with known neurological disease. Together with other health professionals, like neurologists, psychiatrists can play an essential role in diagnosing and managing these disorders. Hence, understanding their opinion and clinical experience with FND is of utmost importance to catch potential educational needs and improve healthcare services for patients. This study aims at assessing the knowledge, opinion, and clinical approach of Italian psychiatrists to FND.

Methods

Members of the Italian Society of Psychiatry completed a 14-item web-based survey investigating their approach to FND. Results. Overall, 174 questionnaires were completed. Our main findings suggest that Italian psychiatrists have a psychogenetic conceptualization of FND. "Conversion disorders", in fact, is the term most frequently used by Italian psychiatrists to refer to FND, thus implying a psychological etiology of these disorders. Congruently with this view, psychotherapy associated with pharmacological therapy is considered the most appropriate treatment by psychiatrists, while physiotherapy is an under-recognized treatment option for FND.

Discussion

The present study highlights that a psychogenetic view of FND dominates among Italian psychiatrists. This could be due to out-of-date knowledge about the pathophysiology of this group of disorders. Promoting education about novel approaches to FND would be of crucial importance to improving care for patients suffering from this condition.

The neurobiology of functional neurological disorders characterised by impaired awareness

We review the neurobiology of Functional Neurological Disorders (FND), i.e., neurological disorders not explained by currently identifiable histopathological processes, in order to focus on those characterised by impaired awareness (functionally impaired awareness disorders, FIAD), and especially, on the paradigmatic case of Resignation Syndrome (RS). We thus provide an improved more integrated theory of FIAD, able to guide both research priorities and the diagnostic formulation of FIAD. We systematically address the diverse spectrum of clinical presentations of FND with impaired awareness, and offer a new framework for understanding FIAD. We find that unraveling the historical development of neurobiological theory of FIAD is of paramount importance for its current understanding. Then, we integrate contemporary clinical material in order to contextualise the neurobiology of FIAD within social, cultural, and psychological perspectives. We thus review neuro-computational insights in FND in general, to arrive at a more coherent account of FIAD. FIAD may be based on maladaptive predictive coding, shaped by stress, attention, uncertainty, and, ultimately, neurally encoded beliefs and their updates. We also critically appraise arguments in support of and against such Bayesian models. Finally, we discuss implications of our theoretical account and provide pointers towards an improved clinical diagnostic formulation of FIAD. We suggest directions for future research towards a more unified theory on which future interventions and management strategies could be based, as effective treatments and clinical trial evidence remain limited.

Functional neurological disorder and placebo and nocebo effects: shared mechanisms

Functional neurological disorder (FND) is characterized by neurological symptoms that cannot be explained by a structural neurological cause. Among the different aetiological models that have been proposed for FND, of note is the Bayesian predictive coding model, which posits that perception relies on top-down cortical predictions (priors) to infer the source of incoming sensory information. This model can also apply to non-pathological experiences, such as placebo and nocebo effects, wherein sensory information is shaped by prior expectations and learning. To date, most studies of the relationship between placebo and nocebo effects and FND have focused on the use of placebos for diagnosis and treatment of FND. Here, we propose that this relationship might go beyond diagnosis and therapy. We develop a framework in which shared cognitive, personality and neuroanatomical factors justify the consideration of a deeper link between FND and placebo and nocebo effects. This new perspective might offer guidance for clarification of the pathogenesis of FND and for the identification of potential biomarkers and therapeutic targets.

Cognitive Behavioral Therapy: Principles, Science, and Patient Selection in Neurology

Cognitive behavioral therapy (CBT) is a widely used therapeutic modality in general psychiatric practice. In this review, we consider its application to neurological disorders. We examine the basic framework of CBT-that symptoms, emotions, thoughts, and behaviors are all interrelated and that therapeutic interventions that lead to change in thoughts or behavior may have the potential to reduce symptoms or emotional distress. We also outline specific methodological issues to consider when reading or planning studies of CBT interventions, highlighting important topics pertaining to quality control, control group selection, dropouts, and generalizability. We then review the evidence base for CBT's use across a range of neurological disorders. In doing so, we highlight where there is a clear evidence base, and where it is a technique with potential. The review is targeted at a general neurology audience as introduction to the topic not as an advanced guide for expert practitioners.

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.

One-year follow-up of treatment outcomes and patient opinions of Retraining and Control Therapy (ReACT) for pediatric functional seizures

Retraining and Control Therapy (ReACT), a short-term treatment for pediatric functional seizures (FS), has been demonstrated to improve FS in children compared to supportive therapy. However, long-term maintenance of FS-reduction after ReACT is unclear. This study aims to assess seizure frequency 1 year after ReACT and determine patient and parents' opinions of ReACT. Children with functional seizures who previously completed ReACT and their parents were asked to report 30-day FS frequency 1 year after completing ReACT. They also reported if ReACT was helpful. Paired samples t-tests were used to compare FS frequency before ReACT to 1 year after and to compare FS frequency in 30 days after ReACT to 1 year after. Fourteen children (Mean_age = 15.43) and their parents participated. Seven-day FS frequency for patients at 1-year follow-up (Mean = 0.15) was significantly lower than 7-day FS frequency pre-ReACT (Mean = 5.62; p = 0.005). No differences were found when comparing FS frequency during 30 days post-ReACT (Mean = 0.29) and in 30 days before 1-year follow-up (Mean = 0.71). This study confirms long-term maintenance of FS-reduction after ReACT and supports the efficacy of targeting FS directly as opposed to mood or stress for reducing FS. Additionally, children and parents believe ReACT is beneficial.

History of abuse and psychogenic nonepileptic seizures: A systematic review

Psychogenic nonepileptic seizures resemble epileptic seizures but lack the physiological basis of epileptic seizures. We conducted a systematic review to explore whether childhood abuse is a risk factor for subsequent development of PNES. We reviewed only papers with an epilepsy control group, which employed strict criteria for diagnosis of epilepsy and well-validated tools for assessing abuse history. Odds ratios (ORs) for the different categories of childhood abuse and for childhood abuse as a whole were calculated where not previously available, and pooled ORs were calculated where suitable. In papers where OR could not be calculated data are presented as p values. Most Odds Ratios fell between 1.8 and 5.2 with relatively narrow confidence intervals. In 14 out of 18 calculations, 95% confidence intervals did not cross 1. This suggests that the chance of reporting abuse is higher in people with PNES than those with epilepsy and may be a causative factor in developing PNES. Several limitations of the data and directions for future study are discussed.

Functional Cognitive Disorders (FCD): How Is Metacognition Involved?

Functional cognitive disorders (FCD) have become a subject of increasing clinical interest in recent years, in part because of their high prevalence amongst patients attending dedicated memory clinics. Empirical understanding of FCD based on observational studies is growing, suggesting a relationship to other functional neurological disorders (FND) based on shared phenomenology. However, understanding of FCD at the theoretical level has been lacking. One suggestion has been that FCD are disorders of metacognition, most usually of metamemory. In this article, a brief overview of these constructs is presented along with existing evidence for their impairment in FCD. Previous adaptations of theoretical models of FND to accommodate FCD are reviewed. A novel application to FCD of Nelson and Narens’ monitoring and control model of metamemory is then attempted, positing an improper setting of the monitoring function, with examples of ecological relevance. Formulation of FCD in light of a metacognitive model of anosognosia is also considered. Although lacking mechanistic and neuroanatomical sophistication, this metacognitive formulation of FCD may give pointers for future hypothesis-driven research and a pragmatic basis for management strategies.

A practical review of functional neurological disorder (FND) for the general physician

We present a practical overview of functional neurological disorder (FND), its epidemiology, assessment and diagnosis, diagnostic pitfalls, treatment, aetiology and mechanism. We present an update on functional limb weakness, tremor, dystonia and other abnormal movements, dissociative seizures, functional cognitive symptoms and urinary retention, and 'scan-negative' cauda equina syndrome. The diagnosis of FND should rest on clear positive evidence, typically from a combination of physical signs on examination or the nature of seizures. In treatment of FND, clear communication of the diagnosis and the involvement of the multidisciplinary team is beneficial. We recommend that patients with FND are referred to specialists with expertise in neurological diagnosis. FND is a common presentation in emergency and acute medical settings and there are many practical elements to making a positive diagnosis and communication which are useful for all physicians to be familiar with.

The pathophysiology of functional movement disorders

Functional neurological disorder is characterized by neurological symptoms that cannot be explained by typical neurological diseases or other medical conditions. This review will critically discuss the literature on the pathophysiology of functional movement disorders (FMD), including functional neuroimaging studies, neurophysiological studies, studies on biomarkers and genetic studies. According to PRISMA guidelines for systematic reviews, we selected 39 studies. A complex scenario emerged, with the involvement of different areas of the brain in the pathophysiology of FMD. Our findings showed a hypoactivation of the contralateral primary motor cortex, a decreased activity in the parietal lobe, an aberrant activation of the amygdala, an increased temporo-parietal junction activity and a hyperactivation of insular regions in patients with FMD. Functional connectivity (FC) findings underlined aberrant connections between amygdala and motor areas, temporo-parietal junction and insula. We proposed amygdala hyperactivation as a possible biological marker for FMD and FC alterations between amygdala and other areas of the brain as consequent epiphenomena, accounting for the pathophysiological complexity of FMD. These conclusions might drive novel treatment hypotheses.

Predisposing Risk Factors for Functional Limb Weakness: A Case-Control Study

OBJECTIVE

Functional limb weakness is a common symptom of functional neurological disorder. Few controlled studies have examined possible predisposing factors to determine their specificity for this symptom.

METHODS

In this prospective case-control study, patients with functional limb weakness (<2 years duration, N=107) were compared with a control group (comprising patients with weakness attributable to neurological disease, N=46, and healthy individuals, N=39). A structured clinical interview and questionnaires assessed potential predisposing factors, including family structure and childhood abuse and neglect (Childhood Trauma Questionnaire [CTQ]), personality traits (NEO Five-Factor Inventory), medical and surgical comorbidity, and exposure to a symptom model.

RESULTS

The patients with functional limb weakness and the control subjects were similar in gender and age. Self-reported childhood sexual abuse (15% versus 5%, p<0.01), and physical abuse (18% versus 7%, p<0.01; CTQ "moderate or above") were more common in the functional limb weakness group, although the absolute frequency was lower than anticipated. In the functional limb weakness group, there were modest differences in two personality traits, compared with the control group: higher neuroticism (p=0.02) and lower openness (p=0.01). Medical comorbidity, including appendectomy (33% versus 5%), irritable bowel syndrome (36% versus 18%), and chronic back pain (40% versus 16%), was more frequent in the functional limb weakness group. There were no differences in birth order or exposure to a symptom model.

CONCLUSIONS

Medical and surgical comorbidity and adverse childhood experience are risk factors, but not essential, for the development of functional limb weakness. However, evidence for personality traits or exposure to a symptom model is less robust.

Evaluation of LiNES: A New Measure of Trauma, Negative Affect, and Relationship Insecurity Over the Life Span in Persons With FND

OBJECTIVE

The authors evaluated potential predisposing vulnerabilities and perpetuating factors among individuals with functional neurological disorder (FND) by using the novel Lifespan Negative Experiences Scale (LiNES), which assesses retrospective self-report of interpersonal trauma, negative affect, and relationship insecurity at three developmental stages: childhood, adolescence, and adulthood.

METHODS

The LiNES, Childhood Abuse and Trauma Scale (CATS), Relationship Scales Questionnaire (RSQ), and Positive and Negative Affect Schedule (PANAS) were administered to 71 individuals with FND. The reliability and validity of LiNES were examined by correlation with the other measures. FND patients' responses on LiNES were compared with those of 170 healthy control subjects.

RESULTS

LiNES scores in the FND group were internally consistent and correlated highly with CATS, RSQ, and PANAS scores. At each developmental stage, LiNES trauma scores were higher among patients with FND, compared with control subjects. The FND subgroup, which comprised patients who also had nonepileptic attack disorder, had higher trauma scores, compared with the FND-only subgroup. Compared with control subjects, patients with FND reported greater negative affect and relationship insecurity in adulthood. Lifetime LiNES scores for interpersonal trauma and relationship insecurity predicted FND group classification with >80% accuracy.

CONCLUSIONS

This study provides further support for the links between FND and trauma, negative affect, and insecure attachment. Recognition of these factors is likely to be important for treatment and stratification of important subpopulations in research. These findings provide new insights into the association between the timing of negative experiences and their effect, with LiNES emerging as a potentially useful measure for patients presenting with FND.

Neuropsychiatry: Definitions, Concepts, and Patient Types

Neuropsychiatry is an integrative discipline defined by its history, its preferred patients, and its theoretic framework. Dealing with human behavior needs to consider the brain, but such consideration should avoid oversimplification: neurologic understanding is not essential, necessary, or desirable in all conditions encountered in clinical psychiatry. Neuropsychiatric theory is founded on discoveries in the areas of synaptic plasticity and cortical/limbic anatomy (bottom-up), but also evolutionary biology and anthropology (top-down). Going forward, we need to synthesize vital information, distinguish the essential from the trivial or tenuous, and remain open to dialogue with allied disciplines, our patients, and our students.

Interactive sequences between fathers and preterm infants in the neonatal intensive care unit

AIMS

The first purpose of the study was to examine fathers' spontaneous communicative behavior with their preterm infants in the neonatal intensive care unit, and how father's and infant's behaviors affected each other. The second purpose was to examine any possible association between the fathers' and/or infants' characteristics and the quality of fathers' behaviors with their infants.

STUDY DESIGN/SUBJECTS/OUTCOME MEASURES

Father-preterm infant dyads (n=20) were assessed at 34-36 weeks postmenstrual age, during a spontaneous face-to-face communication with the infant placed in a heated cot in the NICU, and coded according to the Parent-Preterm Infant Coding System.

RESULTS

The presence of the father's Affiliative Behavior increased the occurrences of infant Gazing at the parent's face. In turn, infant gazing increased the occurrence of paternal Affiliative Behavior. The likelihood of infant's Gazing at the father's face was also significantly elicited by infrequent occurrences of paternal Affectionate Talk, co-occurring with Gazing at infant with Positive Facial Affect (but no Touch). With regard to the predictors of quality in father-infant interactions, we found a significant positive correlation between fathers' level of depressive symptomatology and fathers' Affiliative Behavior.

CONCLUSION

Our results show the of bidirectional sequential patterns of communication between fathers and preterm infants at 35 weeks postmenstrual age, and provide important information about the quality and modalities of paternal communication and their influence on infant behavioral states. From a clinical perspective, these results suggest that father-specific interventions designed to improve and sustain fathers' positive engagement with infants in the NICU should be pursued.

Current Concepts in Diagnosis and Treatment of Functional Neurological Disorders

Importance

Functional neurological disorders (FND) are common sources of disability in medicine. Patients have often been misdiagnosed, correctly diagnosed after lengthy delays, and/or subjected to poorly delivered diagnoses that prevent diagnostic understanding and lead to inappropriate treatments, iatrogenic harm, unnecessary and costly evaluations, and poor outcomes.

Observations

Functional Neurological Symptom Disorder/Conversion Disorder was adopted by the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, replacing the term psychogenic with functional and removing the criterion of psychological stress as a prerequisite for FND. A diagnosis can now be made in an inclusionary manner by identifying neurological signs that are specific to FNDs without reliance on presence or absence of psychological stressors or suggestive historical clues. The new model highlights a wider range of past sensitizing events, such as physical trauma, medical illness, or physiological/psychophysiological events. In this model, strong ideas and expectations about these events correlate with abnormal predictions of sensory data and body-focused attention. Neurobiological abnormalities include hypoactivation of the supplementary motor area and relative disconnection with areas that select or inhibit movements and are associated with a sense of agency. Promising evidence has accumulated for the benefit of specific physical rehabilitation and psychological interventions alone or in combination, but clinical trial evidence remains limited.

Conclusions and Relevance

Functional neurological disorders are a neglected but potentially reversible source of disability. Further research is needed to determine the dose and duration of various interventions, the value of combination treatments and multidisciplinary therapy, and the therapeutic modality best suited for each patient.

A review of functional neurological symptom disorder etiology and the integrated etiological summary model

Functional neurological symptom disorder (FNSD) is characterized by neurological symptoms that are unexplained by other traditional neurological or medical conditions. Both physicians and patients have limited understanding of FNSD, which is often explained as a physical manifestation of psychological distress. Recently, diagnostic criteria have shifted from requiring a preceding stressor to relying on positive symptoms. Given this shift, we have provided a review of the etiology of FNSD. Predisposing factors include trauma or psychiatric symptoms, somatic symptoms, illness exposure, symptom monitoring and neurobiological factors. Neurobiological research has indicated that patients with FNSD have a decreased sense of agency and abnormal attentional focus on the affected area, both of which are modulated by beliefs and expectations about illness. Sick role and secondary gain may reinforce and maintain FNSD. The integrated etiological summary model combines research from various fields and other recent etiological models to represent the current understanding of FNSD etiology. It discusses a potential causal mechanism and informs future research and treatment.

Calming Cycle Theory and the Co-Regulation of Oxytocin

The biological functions of oxytocin in attachment and bonding between mother and infant in parturition and breastfeeding and between adults have been studied extensively. However, most current authors have proposed that infant attachment to the mother is learned through operant conditioning mechanisms via the infant's brain and central nervous system. We propose that oxytocin levels in the mother and infant are co-regulated by emotional connection or disconnection, and that the autonomic co-conditioning learning mechanism can be exploited to change a negative physiological and behavioral response between mother and infant into a positive one. Lack of efficacy and scalability of child development therapies that have come out of the attachment theoretical framework have prompted calls for new ideas. Here, we review calming cycle theory, which takes a new view of the emotional relationship of mother and infant, and predicts ways to positively intervene when problems arise. The theory builds upon the research and ideas of Pavlov and his followers and proposes that subcortical Pavlovian co-conditioning of the autonomic nervous systems of mother and infant is the key to maintaining emotional connection between the two and to shaping emotional behavior of the infant into adulthood. We review evidence in support of calming cycle theory from a randomized controlled trial of Family Nurture Intervention (FNI), which is designed to overcome adverse emotional, behavioral, and developmental outcomes in prematurely born infants. Finally, we discuss the role of visceral oxytocin and emotional behavior, and that the conditional mother-infant relationship may affect behavioral changes through anti-inflammatory gut-brain stem vagal signaling.