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.

Illness-Promoting Psychological Processes in Children and Adolescents with Functional Neurological Disorder.

Previous studies suggest that subjective distress in children with functional neurological disorder (FND) is associated with stress-system dysregulation and modulates aberrant changes in neural networks. The current study documents illness-promoting psychological processes in 76 children with FND (60 girls and 16 boys, aged 10.00-17.08 years) admitted to the Mind-Body Program. The children completed a comprehensive family assessment and self-report measures, and they worked with the clinical team to identify psychological processes during their inpatient admission. A total of 47 healthy controls (35 girls and 12 boys, aged 8.58-17.92 years) also completed self-report measures, but were not assessed for illness-promoting psychological processes. Children with FND (vs. controls) reported higher levels of subjective distress (total DASS score, t(104.24) = 12.18; p ˂ 0.001) and more adverse childhood experiences across their lifespans (total ELSQ score, t(88.57) = 9.38; p ˂ 0.001). Illness-promoting psychological processes were identified in all children with FND. Most common were the following: chronic worries about schoolwork, friendships, or parental wellbeing (n = 64; 84.2%); attention to symptoms (n = 61; 80.3%); feeling sad (n = 58; 76.3%); experiencing a low sense of control (helplessness) in relation to symptoms (n = 44; 57.9%); pushing difficult thoughts out of mind (n = 44; 57.9%); self-critical rumination (n = 42; 55.3%); negative/catastrophic-symptom expectations (n = 40; 52.6%); avoidance of activities (n = 38; 50%); intrusive thoughts/feelings/memories associated with adverse events (n = 38, 50%); and pushing difficult feelings out of mind (n = 37; 48.7%). In children with FND-disabled enough to be admitted for inpatient treatment-illness-promoting psychological processes are part of the clinical presentation. They contribute to the child's ongoing sense of subjective distress, and if not addressed can maintain the illness process. A range of clinical interventions used to address illness-promoting psychological processes are discussed, along with illustrative vignettes.

Evidence-Based Mind-Body Interventions for Children and Adolescents with Functional Neurological Disorder.

LEARNING OBJECTIVES: • Develop and implement treatment plans for children and adolescents with functional neurological disorder (FND)• Outline a plan to increase awareness and standardize the care for patients with FND using evidence-based interventions. ABSTRACT: Functional neurological disorder (FND) in children and adolescents involves the biological embedding of lived experience in the body and brain. This embedding culminates in stress-system activation or dysregulation and in aberrant changes in neural network function. In pediatric neurology clinics, FND represents up to one-fifth of patients. Current research shows good outcomes with prompt diagnosis and treatment using a biopsychosocial, stepped-care approach. At present, however-and worldwide-FND services are scarce, the result of long-standing stigma and ingrained belief that patients with FND do not suffer from a real ("organic") disorder and that they therefore do not require, or even deserve, treatment. Since 1994, the Mind-Body Program for children and adolescents with FND at The Children's Hospital at Westmead in Sydney, Australia-run by a consultation-liaison team-has delivered inpatient care to hundreds of patients with FND and outpatient care to hundreds of others. For less-disabled patients, the program enables community-based clinicians to implement biopsychosocial interventions locally by providing a positive diagnosis (by a neurologist or pediatrician), a biopsychosocial assessment and formulation (by clinicians from the consultation-liaison team), a physical therapy assessment, and clinical support (from the consultation-liaison team and the physiotherapist). In this Perspective we describe the elements of a biopsychosocial mind-body program intervention capable of providing, as needed, effective treatment to children and adolescents with FND. Our aim is to communicate to clinicians and institutions around the world what is needed to establish effective community treatment programs, as well as hospital inpatient and outpatient interventions, in their own health care settings.

Developmental Pathway Choices of Young People Presenting to a Gender Service with Gender Distress: A Prospective Follow-Up Study.

This prospective case-cohort study examines the developmental pathway choices of 79 young people (13.25-23.75 years old; 33 biological males and 46 biological females) referred to a tertiary care hospital's Department of Psychological Medicine (December 2013-November 2018, at ages 8.42-15.92 years) for diagnostic assessment for gender dysphoria (GD) and for potential gender-affirming medical interventions. All of the young people had attended a screening medical assessment (including puberty staging) by paediatricians. The Psychological Medicine assessment (individual and family) yielded a formal DSM-5 diagnosis of GD in 66 of the young people. Of the 13 not meeting DSM-5 criteria, two obtained a GD diagnosis at a later time. This yielded 68 young people (68/79; 86.1%) with formal diagnoses of GD who were potentially eligible for gender-affirming medical interventions and 11 young people (11/79; 13.9%) who were not. Follow-up took place between November 2022 and January 2023. Within the GD subgroup (n = 68) (with two lost to follow-up), six had desisted (desistance rate of 9.1%; 6/66), and 60 had persisted on a GD (transgender) pathway (persistence rate of 90.9%; 60/66). Within the cohort as a whole (with two lost to follow-up), the overall persistence rate was 77.9% (60/77), and overall desistance rate for gender-related distress was 22.1% (17/77). Ongoing mental health concerns were reported by 44/50 (88.0%), and educational/occupational outcomes varied widely. The study highlights the importance of careful screening, comprehensive biopsychosocial (including family) assessment, and holistic therapeutic support. Even in highly screened samples of children and adolescents seeking a GD diagnosis and gender-affirming medical care, outcome pathways follow a diverse range of possibilities.

COVID-19 Vaccination in Young People with Functional Neurological Disorder: A Case-Control Study.

BACKGROUND: The emergence of acute-onset functional neurological symptoms, the focus of this study, is one of three stress responses related to immunisation. This case-control study documents the experience of 61 young people with past or current functional neurological disorder (FND) in relation to the COVID-19 vaccination program in Australia. METHODS: Information about the young person's/parent's choice and response pertaining to COVID-19 vaccination was collected as part of routine clinical care or FND research program follow-up. RESULTS: 61 young people treated for FND (47 females, mean age = 16.22 years) and 46 healthy controls (34 females, mean age = 16.37 years) were included in the study. Vaccination rates were high: 58/61 (95.1%) in the FND group and 45/46 (97.8%) in the control group. In the FND group, 2 young people (2/61, 3.3%) presented with new-onset FND following COVID-19 vaccination; two young people with resolved FND reported an FND relapse (2/36, 5.56%); and two young people with unresolved FND (2/20, 10.0%) reported an FND exacerbation. In the control group no FND symptoms were reported. CONCLUSIONS: Acute-onset FND symptoms following COVID-19 vaccination are uncommon in the general population. In young people prone to FND, COVID-19 vaccination can sometimes trigger new-onset FND, FND relapse, or FND exacerbation.

The Role of Physiotherapy in the Management of Functional Neurological Disorder in Children and Adolescents.

Children and adolescents with functional neurological (conversion) disorder (FND) present with symptoms of impaired motor and sensory function. FND involves complex interactions between the brain, mind, body, and lived experience of the child. The gold standard for treatment is therefore a holistic, biopsychosocial approach with multimodal interventions delivered by a multidisciplinary team. In this narrative review we examine the role of physiotherapy in managing FND in children. We searched Embase, Medline, PsycINFO, and PubMed (back to 2000) for relevant physiotherapy articles and also manually searched their reference lists. Two review articles and ten observational studies were identified. Data were extracted concerning the type of study, therapies involved, outcome measures, and comorbid mental health outcomes. FND symptoms resolved in 85% to 95% of the patients, and about two-thirds returned to full-time school after completing the multidisciplinary intervention. Ongoing mental health concerns at follow-up were associated with poorer functional outcomes. Key themes included the following: use of psychological interventions embedded in the physiotherapy intervention; integration of play, music, and dance; role of physical exercise in modulating physiological, neural, and endocrine systems; need for FND-specific outcome measures; ethical issues pertaining to randomized trials; and need to develop alternate study methodologies for assessing combined treatments. Clinical vignettes were included to highlight a range of physiotherapy interventions. In conclusion, the emerging literature suggests that physiotherapy for children with FND is a useful intervention for improving motor dysfunction and for addressing other concurrent issues such as physical deconditioning, neuroprotection, chronic pain, disturbed sleep, anxiety and depression, and resilience building.

Changing the culture of care for children and adolescents with functional neurological disorder.

As members of a multidisciplinary team of professionals who treat children and adolescents with functional neurological (conversion) disorder (FND), we highlight the pressing need to develop an FND-informed culture of care that takes into account recent advances in our understanding of this group of patients. Stories of clinical encounters in health care settings from around the world-told by children and adolescents with FND, their parents, and health professionals-portray an outdated culture of care characterized by iatrogenic stigma, erosion of empathy and compassion within the clinician-patient relationship, and a lack of understanding of FND and its complex neurobiology. After a brief exploration of the outdated culture, we share our counterstories: how we and our colleagues have worked, and continue to work, to create an FND-informed culture in the health systems where we practice. We discuss the therapeutic use of child-friendly language. We also discuss a range of structural, educational, and process interventions that can be used to promote FND-informed beliefs and attitudes, FND-informed clinician-patient encounters, and FND-informed referral processes, treatment pathways, and therapeutic interventions.

Psychologically Informed Physical Therapy for Children and Adolescents With Functional Neurological Symptoms: The Wellness Approach.

Children with functional neurological disorder (FND) present with motor and sensory neurological symptoms that impair health and physical functioning and that create an ongoing clinical burden for caregivers and hospitals worldwide. Treatment programs for these children involve a multidisciplinary approach with physical therapy as a fundamental component. However, standard musculoskeletal approaches to physical therapy are ineffective or may even exacerbate symptoms because they are unresponsive to the biopsychosocial context in which FND emerges: FND typically occurs in the context of stress, either physical or emotional; symptoms are amplified by attention; and presentations are complicated by psychological factors. Informed, in part, by published guidelines for physical therapy with adult FND patients, this article examines common challenges that arise when working with children: overcoming previous negative encounters in the medical system; avoiding amplification of symptoms by drawing attention to them; and managing comorbid pain, falls, faints, nonepileptic seizures, dizziness, fatigue, and breathlessness, plus psychological symptoms such as anticipatory anxiety and panic attacks. What emerges is a psychologically informed therapeutic approach to physical therapy for children with functional neurological symptoms. This approach prioritizes interpersonal processes and physical therapy techniques that establish a therapeutic relationship and create a safe space for physical therapy, that use indirect physical therapy approaches redirecting the focus of attention away from symptoms and emphasizing the completion of tasks and activities engaging the sick body part indirectly, that tailor the intervention to address the needs and presentation of each particular child, and that integrate psychological interventions to manage common challenges.

Blood CRP levels are elevated in children and adolescents with functional neurological symptom disorder.

There is accumulating evidence that patients with functional neurological symptom disorder (FND) show activation of multiple components of the stress system-the hypothalamic-pituitary-adrenal axis, autonomic nervous system, and brain regions involved in arousal- and emotion-processing. This study aims to examine whether the immune-inflammatory component of the stress system is also activated. C-reactive protein (CRP) blood titre levels were measured in 79 children and adolescents with FND. CRP values ≥ 2 mg/L suggest low-grade inflammation. CRP values > 10 mg/L suggest a disease process. Sixty-six percent of subjects (n = 52) had CRP titres ≥ 2 mg/L. The upward shift in the distribution of CRP levels suggested low-grade inflammation (median CRP concentration was 4.60 mg/L, with 75th and 90th percentiles of 6.1 and 10.3 mg/L, respectively). Elevated CRP titres were not explained by sex, pubertal status, BMI, or medical factors. Confounder analyses suggested that history of maltreatment (χ2 = 2.802, df = 1, p = 0.094, φ = 0.190; ß = 2.823, p = 0.04) and a diagnosis of anxiety (χ2 = 2.731, df = 1, p = 0.098, φ = 0.187; ß = 4.520, p = 0.061) contributed to elevated CRP levels. Future research will need to identify the origins and locations of immune cell activation and the pathways and systems contributing to their activation and modulation. Because functional activity in neurons and glial cells-the brain's innate effector immune cells-is tightly coupled, our finding of elevated CRP titres suggests activation of the immune-inflammatory component of the brain's stress system. A more direct examination of inflammation-related molecules in the brain will help clarify the role of immune-inflammatory processes in FND.

"Motoring in idle": The default mode and somatomotor networks are overactive in children and adolescents with functional neurological symptoms.

Objective: Children and adolescents with functional neurological symptom disorder (FND) present with diverse neurological symptoms not explained by a disease process. Functional neurological symptoms have been conceptualized as somatoform dissociation, a disruption of the brain's intrinsic organization and reversion to a more primitive level of function. We used EEG to investigate neural function and functional brain organization in children/adolescents with FND. Method: EEG was recorded in the resting eyes-open condition in 57 patients (aged 8.5-18 years) and 57 age- and sex-matched healthy controls. Using a topographical map, EEG power data were quantified for regions of interest that define the default mode network (DMN), salience network, and somatomotor network. Source localization was examined using low-resolution brain electromagnetic tomography (LORETA). The contributions of chronic pain and arousal as moderators of differences in EEG power were also examined. Results: Children/adolescents with FND had excessive theta and delta power in electrode clusters corresponding to the DMN-both anteriorly (dorsomedial prefrontal cortex [dmFPC]) and posteriorly (posterior cingulate cortex [PCC], precuneus, and lateral parietal cortex)-and in the premotor/supplementary motor area (SMA) region. There was a trend toward increased theta and delta power in the salience network. LORETA showed activation across all three networks in all power bands and localized neural sources to the dorsal anterior cingulate cortex/dmPFC, mid cingulate cortex, PCC/precuneus, and SMA. Pain and arousal contributed to slow wave power increases in all three networks. Conclusions: These findings suggest that children and adolescents with FND are characterized by overactivation of intrinsic resting brain networks involved in threat detection, energy regulation, and preparation for action.

Psychogenic non-epileptic seizures in children and adolescents: Part I - Diagnostic formulations.

Psychogenic non-epileptic seizures (PNES) are a nonspecific, umbrella category that is used to collect together a range of atypical neurophysiological responses to emotional distress, physiological stressors and danger. Because PNES mimic epileptic seizures, children and adolescents with PNES usually present to neurologists or to epilepsy monitoring units. After a comprehensive neurological evaluation and a diagnosis of PNES, the patient is referred to mental health services for treatment. This study documents the diagnostic formulations - the clinical formulations about the probable neurophysiological mechanisms - that were constructed for 60 consecutive children and adolescents with PNES who were referred to our Mind-Body Rehabilitation Programme for treatment. As a heuristic framework, we used a contemporary reworking of Janet's dissociation model: PNES occur in the context of a destabilized neural system and reflect a release of prewired motor programmes following a functional failure in cognitive-emotional executive control circuitry. Using this framework, we clustered the 60 patients into six different subgroups: (1) dissociative PNES (23/60; 38%), (2) dissociative PNES triggered by hyperventilation (32/60; 53%), (3) innate defence responses presenting as PNES (6/60; 10%), (4) PNES triggered by vocal cord adduction (1/60; 2%), (5) PNES triggered by activation of the valsalva manoeuvre (1/60; 1.5%) and (6) PNES triggered by reflex activation of the vagus (2/60; 3%). As described in the companion article, these diagnostic formulations were used, in turn, both to inform the explanations of PNES that we gave to families and to design clinical interventions for helping the children and adolescents gain control of their PNES.

Psychogenic non-epileptic seizures in children and adolescents: Part II - explanations to families, treatment, and group outcomes.

Psychogenic non-epileptic seizures (PNES) - time-limited disturbances of consciousness and motor-sensory control, not accompanied by ictal activity on electroencephalogram (EEG) - are best conceptualized as atypical neurophysiological responses to emotional distress, physiological stressors and danger. Patients and families find the diagnosis of PNES difficult to understand; the transition from neurology (where the diagnosis is made) to mental health services (to which patients are referred for treatment) can be a bumpy one. This study reports how diagnostic formulations constructed for 60 consecutive children and adolescents with PNES were used to inform both the explanations about PNES that were given to them and their families and the clinical interventions that were used to help patients gain control over PNES. Families were able to accept the diagnosis of PNES and engage in treatment when it was explained how emotional distress, illness and states of high arousal could activate atypical defence responses in the body and brain - with PNES being an unwanted by-product of this process. Patients and their families made good use of therapeutic interventions. A total of 75% of children/adolescents (45/60) regained normal function and attained full-time return to school. Global Assessment of Functioning scores increased from 41 to 67 ( t(54) = 10.09; p < .001). Outcomes were less favourable in children/adolescents who presented with chronic PNES and in those with a chronic, comorbid mental health disorder that failed to resolve with treatment. The study highlights that prompt diagnosis, followed by prompt multidisciplinary assessment, engagement, and treatment, achieves improved outcomes in children/adolescents with PNES.

The respiratory control of carbon dioxide in children and adolescents referred for treatment of psychogenic non-epileptic seizures.

Psychogenic non-epileptic seizures (PNES) are a common problem in paediatric neurology and psychiatry that can best be understood as atypical responses to threat. Threats activate the body for action by mediating increases in arousal, respiration, and motor readiness. In previous studies, a range of cardiac, endocrine, brain-based, attention-bias, and behavioral measures have been used to demonstrate increases in arousal, vigilance, and motor readiness in patients with PNES. The current study uses respiratory measures to assess both the motor readiness of the respiratory system and the respiratory regulation of CO2. Baseline respiratory rates during clinical assessment and arterial CO2 levels during the hyperventilation component of routine video electroencephalogram were documented in 60 children and adolescents referred for treatment of PNES and in 50 controls. Patients showed elevated baseline respiratory rates [t(78) = 3.34, p = .001], with 36/52 (69%) of patients [vs. 11/28 (39%) controls] falling above the 75th percentile (χ 2 = 6.7343; df = 1; p = .009). Twenty-eight (47%) of patients [vs. 4/50 (8%) controls] showed a skewed hyperventilation-challenge profile-baseline PCO2 <36 mmHg, a trough PCO2 ≤ 20 mmHg, or a final PCO2 <36 mmHg after 15 min of recovery-signaling difficulties with CO2 regulation (χ 2 = 19.77; df = 1; p < .001). Children and adolescents with PNES present in a state of readiness-for-action characterized by high arousal coupled with activation of the respiratory motor system, increases in ventilation, and a hyperventilation-challenge profile shifted downward from homeostatic range. Breathing interventions that target arousal, decrease respiratory rate, and normalize ventilation and arterial CO2 may help patients shift brain-body state and avert PNES episodes.

Cortical arousal in children and adolescents with functional neurological symptoms during the auditory oddball task.

OBJECTIVE: Stress, pain, injury, and psychological trauma all induce arousal-mediated changes in brain network organization. The associated, high level of arousal may disrupt motor-sensory processing and result in aberrant patterns of motor function, including functional neurological symptoms. We used the auditory oddball paradigm to assess cortical arousal in children and adolescents with functional neurological symptom disorder. METHOD: Electroencephalogram (EEG) data was collected in fifty-seven children and adolescents (41 girls; 16 boys, aged 8.5-18 years) with acute functional neurological symptoms and age- sex- matched controls during a conventional auditory oddball task. The high-resolution fragmentary decomposition technique was used to analyse the amplitude of event-related potentials (ERPs) to target tones at midline sites (Fz, Cz, and Pz). RESULTS: Compared to age- and sex-matched controls, and across all three midline sites, children and adolescents with functional neurological symptoms showed increased amplitude of all ERP components (P50, N100, P200, N200, and P300) (t-value range 2.28-8.20; p value-range 0.023 to < 0.001) to the emotionally-neutral auditory stimulus. CONCLUSIONS: Our findings add to a growing literature indicating that a baseline state of high arousal may be a precondition for generating functional neurological symptoms, a finding that helps explain why a range of psychological and physiological stressors can trigger functional neurological symptoms in some patients. Interventions that target cortical arousal may be central to the treatment of paediatric patients with functional neurological symptom disorder.

Reduction of autonomic regulation in children and adolescents with conversion disorders.

OBJECTIVE: Conversion symptoms--functional neurological disturbances of body function--occur in association with extreme arousal, often in the context of emotional distress. The mechanisms that determine how and why such symptoms occur remain unknown. In this study, we used cardiac measures to assess arousal and cardiac autonomic regulation in children and adolescents who presented with acute conversion symptoms. METHODS: Heart rate was recorded in 57 children and adolescents (41 girls; 8.5-18 years old) with acute conversion symptoms and 57 age- and sex-matched healthy controls, during a resting condition and then during tasks involving cognitive and emotional activation. Arousal and autonomic regulation were assessed by measures of heart rate and heart rate variability. Psychological measures included attachment and emotional distress. RESULTS: Children and adolescents with conversion symptoms displayed higher autonomic arousal than did the controls, both at baseline and during task conditions (higher heart rate: baseline mean [standard deviation] = 82 [9.49] versus 74 [10.79] beats/min, p < .001; lower root mean squared successive differences-heart rate variability: 45.35 [27.97] versus 58.62 [25.69] ms(2), p = .012; and lower high-frequency heart rate variability: 6.50 [1.19] versus 7.01 [0.95] ln[ms(2)] p = .017), and decreased autonomic regulation (attenuation of heart rate increases across tasks). The baseline pattern of increased autonomic arousal was especially pronounced in children with coercive-preoccupied patterns of attachment. Autonomic measures were not correlated with measures of emotional distress. CONCLUSIONS: High autonomic arousal may be a precondition for generating conversion symptoms. Functional dysregulations of the cardiac, respiratory, and circulatory systems may mediate fainting episodes and nonepileptic seizures, and aberrant patterns of functional connectivity between motor areas and central arousal systems may be responsible for generating motor conversion symptoms.

Conversion disorder in children and adolescents: a disorder of cognitive control.

OBJECTIVE: To assess cognitive function in children and adolescents presenting with acute conversion symptoms. METHODS: Fifty-seven participants aged 8.5-18 years (41 girls and 16 boys) with conversion symptoms and 57 age- and gender-matched healthy controls completed the IntegNeuro neurocognitive battery, an estimate of intelligence, and self-report measures of subjective emotional distress. RESULTS: Participants with conversion symptoms showed poorer performance within attention, executive function, and memory domains. Poorer performance was reflected in more errors on specific tests: Switching of Attention (t(79) = 2.17, p = .03); Verbal Interference (t(72) = 2.64, p = .01); Go/No-Go (t(73) = 2.20, p = .03); Memory Recall and Verbal Learning (interference errors for memory recall; t(61) = 3.13, p < .01); and short-delay recall (t(75) = 2.05, p < .01) and long-delay recall (t(62) = 2.24, p = .03). Poorer performance was also reflected in a reduced span of working memory on the Digit Span Test for both forward recall span (t(103) = -3.64, p < .001) and backward recall span (t(100) = -3.22, p < .01). There was no difference between participants and controls on IQ estimate (t(94) = -589, p = .56), and there was no correlation between cognitive function and perceived distress. CONCLUSIONS: Children and adolescents with acute conversion symptoms have a reduced capacity to manipulate and retain information, to block interfering information, and to inhibit responses, all of which are required for effective attention, executive function, and memory.

Patterns of emotional-cognitive functioning in pediatric conversion patients: implications for the conceptualization of conversion disorders.

OBJECTIVES: To examine patterns of emotion processing in children and adolescents with conversion disorders and to determine whether those patterns are associated with particular clusters of conversion symptoms. Autobiographical narratives were used to investigate the organization of information about distressing feelings and memories. METHODS: Structured interviews about attachment relationships and autobiographical events were administered to 76 controls and 76 matched subjects aged 6 to 18 years. Age-appropriate assessments of attachment were used: the School-aged Assessment of Attachment for children and the Transition to Adulthood Attachment Interview for adolescents. Patterns of emotion processing were identified using dynamic-maturational model discourse analysis and categorized into four clusters: inhibitory, normative/balanced, coercive-preoccupied, and mixed inhibitory and coercive-preoccupied. These clusters were then cross-tabulated with the sensorimotor characteristics of children with conversion disorders. RESULTS: Emotion processing in children with conversion disorders was categorized as psychological inhibition (57%), psychological coercion-preoccupation (34%), and mixed (9%). Psychological inhibition was associated with negative conversion symptoms (discrete sensorimotor deficits, p = .003) and positive conversion symptoms (tremors and tics, p = .04). Psychological coercion-preoccupation was associated with all other disturbances of motor function: bizarre gaits and postures, whole-body floppiness, and refusals to move (p < .0001). Nonepileptic seizures occurred across both groups (56% versus 42%, p = .8). CONCLUSIONS: Contrary to the classic understanding of conversion disorder as a unified diagnostic entity with diverse symptoms, this study identified two distinct subtypes of conversion patients-those using psychological inhibition and those using psychological coercion-preoccupation-whose symptoms fell into discrete clusters. Further research is needed to determine the neural mechanisms underlying these processes.