Functional motor phenotypes: to lump or to split?

Biomarkers and Rehabilitation for Functional Neurological Disorder

Functional neurological disorder, or FND, is widely misunderstood, particularly when considering recent research indicating that the illness has numerous biological markers in addition to its psychiatric disorder associations. Nonetheless, the long-held view that FND is a mental illness without a biological basis, or even a contrived (malingered) illness, remains pervasive both in current medical care and general society. This is because FND involves intermittent disability that rapidly and involuntarily alternates with improved neurological control. This has in turn caused shaming, perceived low self-efficacy, and social isolation for the patients. Until now, biomarker reviews for FND tended not to examine the features that are shared with canonical neurological disorders. This review, in contrast, examines current research on FND biomarkers, and in particular their overlap with canonical neurological disorders, along with the encouraging outcomes for numerous physical rehabilitation trials for FND. These findings support the perspective endorsed here that FND is unquestionably a neurological disorder that is also associated with many biological markers that lie outside of the central nervous system. These results suggest that FND entails multiple biological abnormalities that are widely distributed in the body. General healthcare providers would benefit their care for their patients through their improved understanding of the illness and recourses for support and treatment that are provided in this review.

Unraveling the mechanisms of high-level gait control in functional gait disorders

Functional gait disorders (FGDs) are a disabling subset of Functional Neurological Disorders in which presenting symptoms arise from altered high-level motor control. The dual-task paradigm can be used to investigate mechanisms of high-level gait control. The study aimed to determine the objective measures of gait that best discriminate between individuals with FGDs and healthy controls and the relationship with disease severity and duration. High-level spatiotemporal gait outcomes were analyzed in 87 patients with FGDs (79.3% women, average age 41.9±14.7 years) and 48 healthy controls (60.4% women, average age 41.9±15.7 years) on single and motor, cognitive, and visual-fixation dual tasks. The area under the curve (AUC) from the receiver operator characteristic plot and the dual-task effect (DTE) were calculated for each measure. Dual-task interference on the top single-task gait characteristics was determined by two-way repeated measures ANOVA. Stride time variability and its standard deviation (SD) failed to discriminate between the two groups in single and dual-task conditions (AUC<0.80 for all). Significant group x task interactions were observed for swing time SD and stride time on the cognitive dual tasks (p<0.035 for all). Longer disease duration was associated with poor gait performance and unsteadiness in motor and cognitive DTE (p<0.003) but improvement in stride length and swing time on the visual dual tasks (p<0.041). Our preliminary findings shed light on measures of gait automaticity as a diagnostic and prognostic gait biomarker and underline the importance of early diagnosis and management in individuals with FGDs.

Pain and functional neurological disorder: a systematic review and meta-analysis

BACKGROUND

Functional neurological disorder (FND) is characterised by neurological symptoms, such as seizures and abnormal movements. Despite its significance to patients, the clinical features of chronic pain in people with FND, and of FND in people with chronic pain, have not been comprehensively studied.

METHODS

We systematically reviewed PubMed, Embase and PsycINFO for studies of chronic pain in adults with FND and FND in patients with chronic pain. We described the proportions of patients reporting pain, pain rating and timing, pain-related diagnoses and responsiveness to treatment. We performed random effects meta-analyses of the proportions of patients with FND who reported pain or were diagnosed with pain-related disorders.

RESULTS

Seven hundred and fifteen articles were screened and 64 were included in the analysis. Eight case-control studies of 3476 patients described pain symptoms in a higher proportion of patients with FND than controls with other neurological disorders. A random effects model of 30 cohorts found that an estimated 55% (95% CI 46% to 64%) of 4272 patients with FND reported pain. Random effects models estimated diagnoses of complex regional pain syndrome in 22% (95% CI 6% to 39%) of patients, irritable bowel syndrome in 16% (95% CI 9% to 24%) and fibromyalgia in 10% (95% CI 8% to 13%). Five studies of FND diagnoses among 361 patients with chronic pain were identified. Most interventions for FND did not ameliorate pain, even when other symptoms improved.

CONCLUSIONS

Pain symptoms and pain-related diagnoses are common in FND. Classification systems and treatments should routinely consider pain as a comorbidity in patients with FND.

Perspectives on the diagnosis and management of functional cognitive disorder: An international Delphi study

BACKGROUND

Current proposed criteria for functional cognitive disorder (FCD) have not been externally validated. We sought to analyse the current perspectives of cognitive specialists in the diagnosis and management of FCD in comparison with neurodegenerative conditions.

METHODS

International experts in cognitive disorders were invited to assess seven illustrative clinical vignettes containing history and bedside characteristics alone. Participants assigned a probable diagnosis and selected the appropriate investigation and treatment. Qualitative, quantitative and inter-rater agreement analyses were undertaken.

RESULTS

Eighteen diagnostic terminologies were assigned by 45 cognitive experts from 12 countries with a median of 13 years of experience, across the seven scenarios. Accurate discrimination between FCD and neurodegeneration was observed, independently of background and years of experience: 100% of the neurodegenerative vignettes were correctly classified and 75%-88% of the FCD diagnoses were attributed to non-neurodegenerative causes. There was <50% agreement in the terminology used for FCD, in comparison with 87%-92% agreement for neurodegenerative syndromes. Blood tests and neuropsychological evaluation were the leading diagnostic modalities for FCD. Diagnostic communication, psychotherapy and psychiatry referral were the main suggested management strategies in FCD.

CONCLUSIONS

Our study demonstrates the feasibility of distinguishing between FCD and neurodegeneration based on relevant patient characteristics and history details. These characteristics need further validation and operationalisation. Heterogeneous labelling and framing pose clinical and research challenges reflecting a lack of agreement in the field. Careful consideration of FCD diagnosis is advised, particularly in the presence of comorbidities. This study informs future research on diagnostic tools and evidence-based interventions.

How Does Postural Control in Patients with Functional Motor Disorders Adapt to Multitasking-Based Immersive Virtual Reality?

BACKGROUND

Motor symptoms in functional motor disorders (FMDs) refer to involuntary, but learned, altered movement patterns associated with aberrant self-focus, sense of agency, and belief/expectations. These conditions commonly lead to impaired posture control, raising the likelihood of falls and disability. Utilizing visual and cognitive tasks to manipulate attentional focus, virtual reality (VR) integrated with posturography is a promising tool for exploring postural control disorders.

OBJECTIVES

To investigate whether postural control can be adapted by manipulating attentional focus in a 3D immersive VR environment.

METHODS

We compared postural parameters in 17 FMDs patients and 19 age-matched healthy controls over a single session under four increasingly more complex and attention-demanding conditions: simple fixation task (1) in the real room and (2) in 3D VR room-like condition; complex fixation task in a 3D VR city-like condition (3) avoiding distractors and (4) counting them. Dual-task effect (DTE) measured the relative change in performance induced by the different attention-demanding conditions on postural parameters.

RESULTS

Patients reduced sway area and mediolateral center of pressure displacement velocity DTE compared to controls (all, P < 0.049), but only under condition 4. They also showed a significant reduction in the sway area DTE under condition 4 compared to condition 3 (P = 0.025).

CONCLUSIONS

This study provides novel preliminary evidence for the value of a 3D immersive VR environment combined with different attention-demanding conditions in adapting postural control in patients with FMDs. As supported by quantitative and objective posturographic measures, our findings may inform interventions to explore FMDs pathophysiology.

Epidemiologic Disparities and Challenges in Non-parkinsonian Tremor Disorders Research: A Scoping Review Emphasizing the Indian Context

Non-parkinsonian tremors represent a heterogeneous spectrum of movement disorders where knowledge gaps persist regarding epidemiology, pathophysiology, and clinical burden. This scoping review aimed to systematically consolidate literature on these disorders in India across the domains of prevalence, biological mechanisms, psychiatric comorbidity, disability impact, and quality of life. A systematic search was undertaken across databases to identify studies on non-parkinsonian tremors in India. Extracted data were synthesized descriptively under themes spanning reported prevalence estimates and variability, proposed biological processes, psychiatric symptom rates, stigma perceptions, and quality-of-life deficits. Methodological appraisal was undertaken. Twenty-nine studies reported prevalence estimates displaying wide variability from 0.09% to 22% for essential tremor, partly attributable to definitional inconsistencies. Proposed pathologic processes centered on cerebellar dysfunction, neurotransmitter disturbances, and genetic risks. Nine studies revealed variable anxiety (6.8%-90%) and depression (3.4%-60%) rates among essential tremor patients, while two indicated perceived stigma. Five studies unanimously concurred significant quality of life impairment in essential tremors. Evidence of dystonic tremor, functional tremor, and other tremors was limited. This review exposed critical knowledge gaps and methodological limitations, while systematically evaluating the Indian literature on non-parkinsonian tremors concerning epidemiology, mechanisms, and clinical burden. Large-scale collaborative research applying standardized diagnostic criteria is imperative to determine contemporary prevalence statistics and comprehensively characterize the multifaceted disability footprint to inform patient-centric models optimizing diagnosis and holistic care.

Clinical neurophysiology of functional motor disorders: IFCN Handbook Chapter

Functional Motor Disorders are common and disabling. Clinical diagnosis has moved from one of exclusion of other causes for symptoms to one where positive clinical features on history and examination are used to make a "rule in" diagnosis wherever possible. Clinical neurophysiological assessments have developed increasing importance in assisting with this positive diagnosis, not being used simply to demonstrate normal sensory-motor pathways, but instead to demonstrate specific abnormalities that help to positively diagnose these disorders. Here we provide a practical review of these techniques, their application, interpretation and pitfalls. We also highlight particular areas where such tests are currently lacking in sensitivity and specificity, for example in people with functional dystonia and functional tic-like movements.

Not a general, symptom-unspecific, transdiagnostic marker for functional symptoms: sensorimotor processing of head control is intact in chronic pain

Introduction

Functional disorders are prevalent in all medical fields and pose a tremendous public health problem, with pain being one of the most common functional symptoms. Understanding the underlying, potentially unifying mechanism in functional (pain) disorders is instrumental in facilitating timely diagnosis, stigma reduction, and adequate treatment options. Neuroscientific models of perception suggest that functional symptoms arise due to dysregulated sensorimotor processing in the central nervous system, with brain-based predictions dominating the eventual percept. Experimental evidence for this transdiagnostic mechanism has been established in various functional symptoms. The goal of the current study was to investigate whether erroneous sensorimotor processing is an underlying transdiagnostic mechanism in chronic (functional) pain.

Method

A total of 13 patients with chronic (functional) pain [three patients with chronic (functional) pain disorder, F45.40, ICD-10; 10 patients with chronic pain disorder with somatic and psychological factors, F45.41, ICD-10]; and 15 healthy controls performed large combined eye-head gaze shifts toward visual targets, naturally and with increased head moment of inertia. We simultaneously measured participants' eye and head movements to assess head oscillations at the end of the gaze shift, which are an established indicator of (transdiagnostic) sensorimotor processing deficits of head control.

Results

Using a Bayesian analysis protocol, we found that patients with chronic (functional) pain and control participants stabilized their heads equally well (Bayes Factor 01 = 3.7, Bayes Factor exclusion = 5.23; corresponding to substantial evidence) during all sessions of the experiment.

Conclusion

Our results suggest that patients with chronic (functional) pain do not show measurable symptom-unspecific sensorimotor processing deficits. We discuss outcome parameter choice, organ system specificity, and selection of patient diagnoses as possible reasons for this result and recommend future avenues for research.

Neuropsychiatric phenotypes in functional movement disorder

OBJECTIVE

Functional movement disorder (FMD), the motor-dominant subtype of functional neurological disorder, is a complex neuropsychiatric condition. Patients with FMD also manifest non-motor symptoms. Given that patients with FMD are diagnosed based on motor phenotype, the contribution of non-motor features to the neuropsychiatric syndrome is not well characterized. The objective of this hypothesis-generating study was to explore potential novel, neuropsychiatric FMD phenotypes by combining movement disorder presentations with non-motor comorbidities including somatic symptoms, psychiatric diagnoses, and psychological traits.

METHODS

This retrospective chart review evaluated 158 consecutive patients with a diagnosis of FMD who underwent deep phenotyping across neurological and psychiatric domains. Demographic, clinical, and self-report features were analyzed. A data-driven approach using cluster analysis was performed to detect patterns when combining the movement disorder presentation with somatic symptoms, psychiatric diagnoses, and psychological factors. These new neuropsychiatric FMD phenotypes were then tested using logistic regression models.

RESULTS

Distinct neuropsychiatric FMD phenotypes emerged when stratifying by episodic vs. constant motor symptoms. Episodic FMD was associated with hyperkinetic movements, hyperarousal, anxiety, and history of trauma. In contrast, constant FMD was associated with weakness, gait disorders, fixed dystonia, activity avoidance, and low self-agency. Pain, fatigue, somatic preoccupation, and health anxiety were common across all phenotypes.

CONCLUSION

This study found patterns spanning the neurological-psychiatric interface that indicate that FMD is part of a broader neuropsychiatric syndrome. Adopting a transdisciplinary view of illness reveals readily identifiable clinical factors that are relevant for the development and maintenance of FMD.

Functional tics: Expanding the phenotypes of functional movement disorders?

BACKGROUND AND PURPOSE

Until the outbreak reported during the COVID-19 pandemic, functional tics were considered to be a relatively rare clinical phenotype, as opposed to other functional movement disorders such as functional tremor and dystonia. To better characterize this phenotype, we compared the demographic and clinical characteristics of patients who developed functional tics during the pandemic and those of patients with other functional movement disorders.

METHODS

Data from 110 patients were collected at the same neuropsychiatry centre: 66 consecutive patients who developed functional tics without other functional motor symptoms or neurodevelopmental tics and 44 patients with a mix of functional dystonia, tremor, gait, and myoclonus.

RESULTS

Both groups were characterized by female sex preponderance (70%-80%) and (sub)acute onset of functional symptoms (~80%). However, patients with functional tics had a significantly earlier age at onset of functional symptoms (21 vs. 39 years). Exposure to relevant social media content was reported by almost half of the patients with functional tics, but by none of the patients with other functional movement disorders. Comorbidity profiles were similar, with relatively high rates of anxiety/affective symptoms and other functional neurological symptoms (nonepileptic attacks).

CONCLUSIONS

Patients who developed functional tics during the pandemic represent a phenotypic variant of the wider group of patients with functional movement disorders, associated with younger age at onset and influenced by pandemic-related factors, including increased exposure to specific social media content. Diagnostic protocols and treatment interventions should be tailored to address the specific features of this newly defined phenotype.

Moving Beyond Movement: Diagnosing Functional Movement Disorder

Functional movement disorder (FMD) is a complex neuropsychiatric syndrome, encompassing abnormal movements and weakness, and is a common cause of potentially disabling neurological symptoms. It is vital to recognize that FMD is a syndrome, with nonmotor manifestations negatively affecting a patient's quality of life. This review highlights a diagnostic algorithm, where a history suggestive of FMD is combined with the presence of positive signs on examination and appropriate investigations to make the diagnosis. Positive signs indicate internal inconsistency such as variability and distractibility, and clinical findings that are incongruent with other known neurological disease. Importantly, the clinical assessment acts as the first opportunity to allow patients to understand FMD as the cause for their symptoms. Accurate and early diagnosis of FMD is necessary given that it is a treatable and potentially reversible cause of disability, with significant risk of iatrogenic harm associated with misdiagnosis.

Pathophysiology and Treatment of Functional Paralysis: Insight from Transcranial Magnetic Stimulation

Functional paralysis (FP) or limb weakness is a common presentation of functional movement disorders (FMD), accounting for 18.1% of the clinical manifestations of FMD. The pathophysiology of FP is not known, but imaging studies have identified changes in structural and functional connectivity in multiple brain networks. It has been proposed that noninvasive brain stimulation techniques may be used to understand the pathophysiology of FP and may represent a possible therapeutic option. In this paper, we reviewed transcranial magnetic stimulation studies on functional paralysis, focusing on their pathophysiological and therapeutical implications. Overall, there is general agreement on the integrity of corticospinal pathways in FP, while conflicting results have been found about the net excitability of the primary motor cortex and its excitatory/inhibitory circuitry in resting conditions. The possible involvement of spinal cord circuits remains an under-investigated area. Repetitive transcranial magnetic stimulation appears to have a potential role as a safe and viable option for the treatment of functional paralysis, but more studies are needed to investigate optimal stimulation parameters and clarify its role in the context of other therapeutical options.

Higher Health Service Costs Associated With Delayed Diagnosis of Functional Neurological Disorder

OBJECTIVE

Functional neurological disorder (FND) is frequently encountered in clinical practice but commonly misdiagnosed, which might lead to higher direct costs for the health care system. The investigators analyzed the direct costs associated with the diagnosis of FND compared with costs associated with other neurological conditions and explored possible cost trends related to the clinical and demographic features of FND.

METHODS

Consecutive patients attending a general neurology clinic were recruited and underwent a structured assessment aimed to collect information pertaining to their demographic and clinical characteristics, as well as data regarding their prior diagnostic processes (e.g., the number of consulted specialists, number and type of investigations, emergency department visits, etc.). The costs were hence calculated and compared between the study groups.

RESULTS

A total of 155 consecutive patients were recruited; of these, 18.6% had FND, 55.84% had one or more other neurological disorder (OND), and 27.10% presented with comorbid FND and OND. The total prediagnostic costs (in euros [€]) were higher in the FND group compared with the OND group (median=€289, interquartile range [IQR] €385 vs. median=€98, IQR €216; Mann-Whitney U=879.5, p=0.04). There was a higher diagnostic delay in the FND group compared with the OND group (median=48 months, IQR 60 months vs. median=12 months, IQR 6 months; Mann-Whitney U=162.00, p<0.01). Diagnostic delay significantly correlated with the total costs in the entire study sample (Spearman's ρ=0.25, p=0.003) but more strongly in the FND group (Spearman's ρ=0.81, p<0.001). In the FND group, higher numbers of investigations and costs were associated with the presence of a physiological or psychological trigger and multiple symptoms.

CONCLUSIONS

Delayed diagnosis of FND significantly affects health care system costs, and raising awareness about FND to improve the diagnostic process and outcomes is necessary.

Data-driven clustering of combined Functional Motor Disorders based on the Italian registry

Introduction

Functional Motor Disorders (FMDs) represent nosological entities with no clear phenotypic characterization, especially in patients with multiple (combined FMDs) motor manifestations. A data-driven approach using cluster analysis of clinical data has been proposed as an analytic method to obtain non-hierarchical unbiased classifications. The study aimed to identify clinical subtypes of combined FMDs using a data-driven approach to overcome possible limits related to “a priori” classifications and clinical overlapping.

Methods

Data were obtained by the Italian Registry of Functional Motor Disorders. Patients identified with multiple or “combined” FMDs by standardized clinical assessments were selected to be analyzed. Non-hierarchical cluster analysis was performed based on FMDs phenomenology. Multivariate analysis was then performed after adjustment for principal confounding variables.

Results

From a study population of n = 410 subjects with FMDs, we selected n = 188 subjects [women: 133 (70.7%); age: 47.9 ± 14.4 years; disease duration: 6.4 ± 7.7 years] presenting combined FMDs to be analyzed. Based on motor phenotype, two independent clusters were identified: Cluster C1 (n = 82; 43.6%) and Cluster C2 (n = 106; 56.4%). Cluster C1 was characterized by functional tremor plus parkinsonism as the main clinical phenotype. Cluster C2 mainly included subjects with functional weakness. Cluster C1 included older subjects suffering from anxiety who were more treated with botulinum toxin and antiepileptics. Cluster C2 included younger subjects referring to different associated symptoms, such as pain, headache, and visual disturbances, who were more treated with antidepressants.

Conclusion

Using a data-driven approach of clinical data from the Italian registry, we differentiated clinical subtypes among combined FMDs to be validated by prospective studies.

Improvement in motor symptoms, physical fatigue, and self-rated change perception in functional motor disorders: a prospective cohort study of a 12-week telemedicine program

BACKGROUND

Functional motor disorders (FMDs) are highly disabling conditions associated with long-term disability, poor quality of life, and economic burden on health and social care. While multidisciplinary 5-days rehabilitation programs have been shown to reduce motor and non-motor symptoms, long-term management and monitoring in FMDs remain an unmet need.

AIM

To compare a 12-weeks telemedicine program against a 12-weeks self-management program after a 5-days rehabilitation program for improving motor, non-motor symptoms, quality of life, and perception of change in patients with FMDs.

METHODS

The study population was 64 consecutive patients with a definite diagnosis of FMDs who underwent a 5-days in-person rehabilitation program followed by either a self-management (the first 32 patients) or a telemedicine program (the latter 32 patients). Validated measures of motor and non-motor symptoms such as fatigue and pain, quality of life, perception of change, gait, and postural control were recorded before (T0), after completion of rehabilitation (T1), and then again at 3 months (T2).

RESULTS

Improvement at 3-month follow-up assessment of motor symptoms (p < 0.001), physical fatigue (p = 0.028), and self-rated change perception (p = 0.043) was greater in the telemedicine group. No different between-groups effect was found on other dimensions of fatigue, pain, physical and mental health, and gait and postural control.

CONCLUSIONS

Long-term management and expert monitoring of patients with FMDs via telemedicine may enhance long-term outcomes in motor symptoms and physical fatigue, with a positive long-term impact on self-rated health perception of change.

Do demographic and clinical features and comorbidities affect the risk of spread to an additional body site in functional motor disorders?

The aim of this study is to assess changes in the body distribution and the semeiology of functional motor disorder (FMD) in patients who reported only one or more than one body site affected at FMD onset. Data were obtained from the Italian Registry of Functional Motor Disorders, which included patients with a diagnosis of clinically definite FMDs. The relationship between FMD features and spread to other body sites was estimated by multivariate Cox regression analysis. We identified 201 (49%) patients who reported only one body site affected at FMD onset and 209 (51%) who reported multiple body sites affected at onset. FMD spread from the initial site to another site in 43/201 (21.4%) patients over 5.7 ± 7.1 years in those with only one site affected at FMD onset; FMD spread to an another body site in 29/209 (13.8%) over 5.5 ± 6.5 years. The spread of FMD was associated with non-motor functional symptoms and psychiatric comorbidities only in the patients with one body site affected at FMD onset. Our findings provide novel insight into the natural history of FMD. The number of body sites affected at onset does not seem to have a consistent influence on the risk of spread. Furthermore, our findings suggest that psychiatric comorbidities and non-motor functional symptoms may predict the spread of FMD symptoms, at least in patients with one body site affected at onset.

Gender disparity and abuse in functional movement disorders: a multi-center case-control study

BACKGROUND

To determine gender differences in rates of sexual and physical abuse in functional movement disorders compared to controls and evaluate if the gender disparity of functional movement disorders is associated with abuse history.

METHODS

We performed a retrospective case-control study of self-reported trauma data from 696 patients (512 women) with functional movement disorders from six clinical sites compared to 141 controls (98 women) and population data. Chi-square was used to assess gender and disorder associations; logistic regression was used to model additive effects of abuse and calculate the attributable fraction of abuse to disorder prevalence.

RESULTS

Higher rates of sexual abuse were reported by women (35.3%) and men (11.5%) with functional movement disorders compared to controls (10.6% of women; 5.6% of men). History of sexual abuse increased the likelihood of functional movement disorders among women by an odds ratio of 4.57 (95% confidence interval 2.31-9.07; p < 0.0001) and physical abuse by an odds ratio of 2.80 (95% confidence interval 1.53-5.12; p = 0.0007). Population attributable fraction of childhood sexual abuse to functional movement disorders in women was 0.12 (0.05-0.19). No statistically significant associations were found in men, but our cohort of men was underpowered despite including multiple sites.

CONCLUSIONS

Our study suggests that violence against women may account for some of the gender disparity in rates of functional movement disorders. Most people with functional movement disorders do not report a history of abuse, so it remains just one among many relevant risk factors to consider.

Vaccine-induced functional neurological disorders in the Covid-19 era

The large amount of information available to the public regarding vaccines against Covid-19 coupled with pandemic stress and increased somatic attention could potentially precipitate development of functional neurological disorders (FNDs) following vaccination. A growing number of reports indicate that functional symptoms may follow Covid-19 vaccination, similar to those observed with other vaccines previously. We review previously reported cases of FND following vaccination against Covid-19 and present three additional cases. While two patients presented to the Emergency Department with functional movement disorders, one patient presented with protracted limb weakness and sensory dysfunction. The superficial resemblance to Guillain-Barré syndrome, a known but uncommon complication of vaccination prompted an extensive workup. Clinicians need to convey the diagnosis of FND in clear and unequivocal terms to facilitate institution of appropriate therapy and rehabilitation, but importantly also to dispel any doubts in the minds of the public regarding the safety of the available vaccines. Given the presence of significant vaccine hesitancy in many countries, this is critical to the success of the global immunisation effort.

Triggers in functional motor disorder: a clinical feature distinct from precipitating factors

Background and objective

People with functional motor disorder (FMD) report triggers—sensory or motor-induced stimuli that exacerbate or initiate paroxysmal occurrences of their movement disorder. These are a distinct phenomenon from precipitating factors occurring at the initial onset of the disorder. We aimed to assess triggers in FMD and understand their relevance to paroxysmal variability often seen in FMD.

Methods

We enrolled consecutive outpatients with a definite diagnosis of FMD. Each patient underwent a detailed clinical evaluation also including the presence of trigger factors and video-recordings both during neurological examination and physiotherapy treatment. Patients were classified as having “triggers” (T-FMD) or “not having triggers” (NoT-FMD) as well as “paroxysmal” compared to “persistent with paroxysmal variability”.

Results

The study sample was 100 patients (82% female) with FMD; the mean age at onset was 41 years. Triggers were observed in 88% of patients and in 65 of these the FMD was pure paroxysmal. The most common triggers were movement or physical exercise, followed by emotional, visual, touch, and auditory stimuli; 39 (44%) were isolated and 49 (56%) were combined triggers. Among the T-FMD patients, FMD were paroxysmal in 74% (n = 65) and persistent with paroxysmal variability in 26% (n = 23). The T-FMD patients were younger (p = 0.016) and had a gait disorder (p = 0.035) more frequently than the NoT-FMD patients.

Discussion

Triggers are frequent in FMD and may have diverse overlapping clinical presentations. In this sample, FMD was most often paroxysmal, suggesting the value of noting triggers as clinical clues in the diagnosis and rehabilitation of FMD.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-022-11102-1.

Updates in Functional Movement Disorders: from Pathophysiology to Treatment Advances

Purpose of Review

This review discusses advances in functional movement disorders (FMD) over the past 3 years, with a focus on risk factors, diagnosis, pathophysiology, neuroimaging studies, and treatment.

Recent Findings

The past decade has brought a revived interest in functional movement disorders, with a growing number of studies exploring pathophysiological mechanisms. Here, we review recent studies demonstrating changes in attention, emotional and sensorimotor function in FMD. Through international collaborative efforts, progress has been made in defining biomarkers and outcome measures, an important prerequisite towards standardization of diagnosis and reporting of outcomes in clinical trials. Of particular interest are neuroimaging studies demonstrating functional and structural changes in motor and emotional brain circuits, deepening our understanding of FMD as a neurocircuit disorder and potentially paving the way towards new treatments. Currently available treatment modalities have shown successful outcomes via outpatient, inpatient, and virtual delivery.

Summary

The last 3 years have seen tremendous efforts to better understand, diagnose, and treat FMD. The disease model has been broadened to include a biopsychosocial formulation, and insights on the pathophysiology on FMD are informing treatment efforts. Several international multidisciplinary research collaborations are underway to define biomarkers and best outcome measures, highlighting the path towards improved standardization of future treatment trials. Additionally, the rise of telemedicine during the COVID-19 pandemic has reduced geographic barriers and paved the way for virtual therapy sessions and self-guided programs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11910-022-01192-9.

Neurological and neuropsychological adverse effects of SARS-CoV-2 vaccines - where do we stand?

The devastating characteristic of COVID-19 pandemic calls for immediate and effective solutions to tackle it. Vaccines seem to be the only promising and effective way to fight against the novel coronavirus - even against new mutated variants. Because of the rapid development and distribution of numerous COVID-19 vaccines in different platforms, meticulous evaluation of vaccines' safety is more critical than ever - especially given the fact that most of the candidates have not completed the clinical phase. Therefore, to optimize the vaccines' safety and efficacy, it is highly important to carefully report and scientifically discuss the serious adverse effects following vaccination. In this respect, we discuss different neurological and neuropsychological adverse effects of COVID-19 vaccines including demyelinating diseases, Bell's palsy (BP), cerebrovascular complications, seizures, functional neurological disorders (FNDs), and some other rare adverse events, and hypothetical mechanisms which can lead to the reported side effects. Given the fact that the incidence of such events are rare and most of them are treatable, the current review aims to shed light on how much the relationship between COVID-19 vaccines and these complications can be reliable and provide an insight for future studies with much more meticulous methodologies to discuss the possible correlational or causal relationship between these complications and COVID-19 vaccines and elucidate whether or not the neurological side effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines can count as a considerable threat to public health.

Altered Brain Activity in Depression of Parkinson's Disease: A Meta-Analysis and Validation Study

Background

The pathophysiology of depression in Parkinson's disease (PD) is not fully understood. Studies based upon functional MRI (fMRI) showed the alterations in the blood-oxygen-level-dependent (BOLD) fluctuations in multiple brain regions pertaining to depression in PD. However, large variance was observed across previous studies. Therefore, we conducted a meta-analysis to quantitatively evaluate the results in previous publications and completed an independent regions-of-interests (ROIs)-based analysis using our own data to validate the results of the meta-analysis.

Methods

We searched PubMed, Embase, and Web of Science to identify fMRI studies in PD patients with depression. Using signed differential mapping (SDM) method, we performed a voxel-based meta-analysis. Then, a validation study by using multiscale entropy (MSE) in 28 PD patients with depression and 25 PD patients without depression was conducted. The fMRI scan was completed in anti-depression-medication-off state. The ROIs of the MSE analysis were the regions identified by the meta-analysis.

Results

A total of 126 PD patients with depression and 153 PD patients without depression were included in meta-analysis. It was observed that the resting-state activities within the posterior cingulate gyrus, supplementary motor area (SMA), and cerebellum were altered in depressed patients. Then, in the validation study, these regions were used as ROIs. PD patients with depression had significantly lower MSE of the BOLD fluctuations in these regions (posterior cingulate gyrus: F = 0.856, p = 0.049; SMA: F = 0.914, p = 0.039; cerebellum: F = 0.227, p = 0.043).

Conclusion

Our study revealed that the altered BOLD activity in cingulate, SMA, and cerebellum of the brain were pertaining to depression in PD.

Incidence of amyotrophic lateral sclerosis in Sardinia, Italy: age-sex interaction and spatial-temporal variability

Objective: This study assessed amyotrophic lateral sclerosis (ALS) incidence in Sardinia, Italy, and the combined contribution of age and gender to disease risk. We also checked disease incidence for spatial-temporal variability. Methods: ALS patients from all neurological centers of the study area who had onset during 2010-2019 and fulfilled El Escorial revised diagnostic criteria were included. Incidence was calculated for the overall study area and each province separately. Additive interaction between age and sex on ALS incidence was assessed. Results: The average crude annual incidence rate was 3.6/100,000 person-years (95% CI, 3.2-4.1), 3.1/100,000 person-years (95% CI, 2.7-3.5) when age-adjusted. Incidence was greater among people aged ≥65 years and men, with the two variables undergoing significant additive interaction. Incidence increased yearly over the study period, with annual incidence correlating with the increasing yearly frequency of people aged ≥65 years, but not with the proportion of incident cases carrying genetic mutations. Stratifying by province, the rates from Oristano and South Sardinia were higher than the rate from Cagliari. ALS patients from areas at different risk were comparable for frequency of clinical/genetic features. Conclusion: ALS incidence in Sardinia was in the upper part of the European range of variability. We also provided new information about age and sex as risk factors for ALS, showing male sex as a modifier of the effect of aging on ALS incidence. Spatial-temporal variations in ALS incidence correlated to changes in the proportion of the aging population rather than to the distribution of genetic factors.

Rasagiline Withdrawal Syndrome in Parkinson’s Disease

Parkinson’s disease (PD) patients using dopamine agonists can develop withdrawal symptoms, referred to as dopamine agonist withdrawal syndrome (DAWS), under dose tapering or discontinuation of these drugs. DAWS includes a severe stereotypical cluster of psychiatric and psychological symptoms encompassing severe mood and anxiety disturbances, autonomic symptoms, as well as generalized pain and drug cravings. However, symptoms of withdrawal of dopamine replacement therapies (DRT) are not simply limited to dopamine agonists tapering, as observed in PD patients on deep brain stimulation after dopaminergic drugs withdrawal related to surgery. To date, no DRT-related withdrawal syndrome has been described in PD patients who discontinue rasagiline, an irreversible inhibitor of monoamine oxidase-B (MAO-B). Here we report three PD patients who developed a severe withdrawal syndrome after rasagiline suspension. The syndrome was mainly characterized by prominent psychiatric disorders (depression, anxiety with panic attacks, dysphoria, and agitation) associated with fatigue, generalized pain, and autonomic manifestations (closely resembling symptoms of DAWS). In our opinion, this report suggests the importance of closely monitoring PD patients undergoing rasagiline suspension for withdrawal symptoms and provides interesting points of reflection on the role of rasagiline and other MAO-B inhibitors in mood disorders.

Sudden Onset, Fixed Dystonia and Acute Peripheral Trauma as Diagnostic Clues for Functional Dystonia

Background

The differentiation of functional dystonia from idiopathic dystonia may be clinically challenging.

Objective

To identify clinical features suggestive of functional dystonia to guide physicians to distinguish functional dystonia from idiopathic dystonia.

Methods

Patient data were extracted from the Italian Registry of Functional Motor Disorders and the Italian Registry of Adult Dystonia. Patients with functional and idiopathic dystonia were followed up at the same clinical sites, and they were similar in age and sex.

Results

We identified 113 patients with functional dystonia and 125 with idiopathic dystonia. Sudden onset of dystonia, evidence of fixed dystonia, and acute peripheral trauma before dystonia onset were more frequent in the functional dystonia group. No study variable alone achieved satisfactory sensitivity and specificity, whereas a combination of variables yielded 85% sensitivity and 98% specificity. A diagnostic algorithm was developed to reduce the risk of misclassifying functional dystonia.

Conclusion

Our findings extend the current diagnostic approach to functional dystonia by showing that clinical information about symptom onset, fixed dystonia, and history of peripheral trauma may provide key clues in the diagnosis of functional dystonia.

Qualitative smell/taste disorders as sequelae of acute COVID-19

Background

Qualitative smell/taste disorders (such as phantosmia, parosmia, phantogeusia, and parageusia) have not yet been fully characterized in patients who had COVID-19, whereas quantitative disturbances (i.e., reduction/loss of smell/taste) have been widely investigated.

Objective

To simultaneously assess the presence of both quantitative and qualitative smell/taste dysfunctions in patients who suffered from COVID-19.

Methods

We enrolled 17 consecutive patients who suffered from COVID-19 over the last 6 months and 21 healthy controls, matched for sex and age. After a negative nasopharyngeal swab, the Sniffin’ Sticks Test and the Taste Strips were used to assess olfactory and taste function, respectively. At the same time, the presence of phantosmia, parosmia, phantogeusia, and parageusia was investigated with a standardized questionnaire.

Results

Qualitative disturbances of smell and/or taste were found in 6/17 (35.3%) patients. Phantosmia was reported in 2/17 (11.8%) patients and parosmia in 4/17 (23.5%). There were no significant differences in smell test scores between patients who reported phantosmia and/or parosmia and patients who did not. Phantogeusia was described in 3/17 (17.6%) patients, and parageusia was identified in 4/17 (23.5%) patients. All tested patients were normogeusic.

Conclusion

Around one-third of patients who recover from COVID-19 may have persistent qualitative dysfunction in smell/taste domains. Detection of phantogeusia in long-term COVID-19 patients represents a further novel finding. Further investigation is needed to better characterize the pathophysiology of phantosmia, parosmia, phantogeusia, and parageusia in patients who had COVID-19.

Functional gait disorders: Demographic and clinical correlations

OBJECTIVE

We aimed to describe the prevalence and clinical-demographical features of patients with functional gait disorders (FGDs) and to compare them to patients with functional motor disorders (FMDs) without FGDs (No-FGDs).

METHODS

In this multicenter observational study, we enrolled patients with a clinically definite diagnosis of FMDs in 25 tertiary movement disorders centers in Italy. Each subject with FMDs underwent a comprehensive clinical assessment, including screening for different subtypes of functional gait disorders. Multivariate regression models were implemented in order to estimate the adjusted odds ratio (OR; 95% confidence interval) of having FGDs in relation to sociodemographic and clinical characteristics.

RESULTS

Out of 410 FMDs, 26.6% (n = 109) of patients exhibited FGDs. The most frequent FGDs were slow gait (n = 43, 39.4%), astasia-abasia (n = 26, 23.8%), and knee buckling (n = 24, 22%). They exhibited single FGDs in 51.4% (n = 56) or complex FGDs (more than one type of FGDs) in 48.6% (n = 53) of cases. On multivariate regression analysis, the presence of FGDs was more likely associated with older age (OR 1.03, 95% CI 1.01-1.04), functional visual symptoms (OR 2.19, 95% CI 1.08-4.45), and the diagnosis of somatic symptoms disorder (OR 2.97, 95% CI 1.08-8.17). FGDs were also more likely to undergo physiotherapy (OR 1.81, 95% CI 1.08-3.03).

CONCLUSIONS

People with FMDs may present with different and overlapping types of FGDs, which may occur in older age. The association of FGDs with functional visual symptoms and somatic symptoms disorder opens up to new avenues to the understanding of the neural mechanisms of these disorders.