Anti-basal ganglia antibodies in acute and persistent Sydenham's chorea

Back to the future: encephalitis lethargica as an autoimmune disorder?

More than 100 years after its emergence, the exact pathophysiological mechanisms underlying encephalitis lethargica (EL) are still elusive and awaiting convincing and complete elucidation. This article summarizes arguments proposed over time to support or refute the hypothesis of EL as an autoimmune neuropsychiatric disorder triggered by an infectious process. It also provides a critical evaluation of modern cases labeled as EL and a comprehensive differential diagnosis of autoimmune neurological conditions that could mimic EL. The evidence supporting the autoimmune nature of historical EL is sparse and not entirely convincing. It is possible that autoimmune mechanisms were involved in the pathogenesis of this disease as an idiosyncratic response to a yet unidentified infectious agent in genetically predisposed individuals. Although there has been an increase in the incidence of presumed autoimmune encephalomyelitis since the peak of EL pandemics, most evidence does not support an underlying autoimmune mechanism. There are significant differences between historical and recent EL cases in terms of clinical symptomatology, epidemiology, and neuropathological features, suggesting that they are different entities with only superficial similarity. The term "encephalitis lethargica," still frequently used in the medical literature, should not be used for cases occurring at present in the sporadic form. Historical EL should be kept apart from recent EL, as they differ in important aspects.

Infection and speech: Disfluency and other speech symptoms in Pediatric Acute-onset Neuropsychiatric Syndrome

INTRODUCTION

In the early 20^th century a link between infection and speech disfluency was discussed. Recent reports indicate that PANS (Pediatric Acute-onset Neuropsychiatric Syndrome), and PANDAS (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections) may be associated with a high incidence of speech disfluency. The present study specifically investigates disfluency and other speech symptoms following onset of PANS and PANDAS. Prevalence of previously reported speech related symptoms vocal tics, selective mutism and "baby talk" is included. The present study also aims to explore possible changes in articulation and intelligibility, distress due to speech impairment, and effect of PANS or PANDAS medication on speech symptoms.

METHODS

A questionnaire was distributed to caregivers of children with diagnosed or suspected PANS or PANDAS. In total 55 individuals in Sweden were included.

RESULTS

Onset of speech disfluency in association with PANS or PANDAS was reported by 54.5% of the caregivers. Most frequent disfluency symptoms were higher speech rate, superfluous verbal behavior, verbal blocks and associated motor symptoms. Previous findings of vocal tics, baby talk and mutistic behavior are supported. The present study also exposed previously unreported symptoms such as impaired articulation, reduced intelligibility, reduced speech production and language impairment. Eleven caregivers reported that medical treatment had a positive effect on speech fluency.

CONCLUSIONS

A connection between PANS and PANDAS and speech disfluency is supported, and a possible link between infection and disfluency is reactualized. Reported disfluency shares several characteristics with stuttering and cluttering, but the caregivers did not consistently associate it with stuttering. The present study also sheds new light on how symptoms of "baby talk", selective mutism and vocal tics might be viewed in this population. In all, the results indicate a substantial impact on speech fluency, speech and language in affected children, reducing quality of life.

Pediatric Autoimmune Neuropsychiatric Disorders Associated With Group A Streptococci: Etiopathology and Diagnostic Challenges

Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) have attracted a lot of interest and discussion since it was originally characterized in 1998. The role of streptococcal infection in children with abrupt-onset obsessive-compulsive disorder (OCD) and new-onset tics, the natural history of this entity, and the role of symptomatic and disease-modifying therapies, such as antibiotics, immunotherapy, and psychoactive drugs, are still unresolved issues. Alternative therapies for acute-onset OCD have been developed based on this postulated pathophysiology, including antibiotics and immunomodulatory therapy. The literature on PANDAS therapy is varied but there is no clinical consensus on the treatment of choice.

While there is no convincing evidence for the autoimmune rationale for PANDAS, given the increased attention to this entity and the apparent growth in usage of this diagnostic category, it is critical to address concerns about the condition's diagnosis, treatment, and pathogenesis.

We conducted a multi-language literature search on Medline, Cochrane, Embase, and Google Scholar for a period spanning until October 2021. The following search strings and Medical Subject Heading (MeSH) terms were used: “PANDAS,” “Group A Streptococcus,” “OCD,” and “tics.” We explored the literature on PANDAS in terms of its epidemiology, pathophysiology, the role of group A streptococcal infection, associated complications, and prophylactic and treatment modalities.

We examined current working definitions of PANDAS, analyzed differential diagnoses, and published pieces of evidence for therapies associated with this entity, with a view to proposing a therapeutic strategy for children with acute symptoms that meet PANDAS criteria, in this review article.

Therapeutic aspects of Sydenham's Chorea: an update

Sydenham’s Chorea (SC) is a hyperkinetic movement disorder associated with neuropsychiatric manifestations. It is believed to be caused by the autoimmune response following a group A beta-hemolytic streptococcal (GABHS) pharyngitis, and it is one of the major diagnostic criteria for Acute Rheumatic Fever (ARF) diagnosis. Despite having been known and studied for centuries, there are still no standardized therapies or official guidelines for SC treatment, so that it is necessarily left to physicians’ clinical experience. Antibiotic treatment, symptomatic therapies, and immunomodulatory treatment are the three pillars upon which SC patients’ management is currently based, but they still lack a solid scientific basis. The aim of this writing is precisely to review the state of the art of SC’s treatment, with an overview of the advances made in the last 5 years. However, since the therapeutic uncertainties are a mere reflection of the severe gap of knowledge that concerns SC’s pathogenesis and manifestations, the importance of high-quality research studies based on homogenized methodologies, instruments, and measured outcomes will also be stressed. (www.actabiomedica.it)

Autoimmune and Paraneoplastic Chorea: A Review of the Literature

Autoimmune chorea syndromes represent a vast array of paraneoplastic, parainfectious and idiopathic disorders. It is increasingly apparent that familiarity with these disorders is critically important, as they may be treatable or may be part of a syndrome requiring further work-up and monitoring. These disorders are mediated by an aberrant immunologic attack with resultant neuronal dysfunction, manifesting as chorea. These conditions are typically accompanied by other neurologic or systemic manifestations. In this review we outline the clinical features, epidemiologic factors, and delineate the specific antibodies associated with each of these autoimmune mediated disorders. We highlight up to date information regarding this heterogeneous group of disorders, including a discussion of parainfectious Sydenham's chorea; paraneoplastic syndromes associated with CRMP-5 (collapsin response mediated protein-5/CV2) and ANNA-1 (antineuronal nuclear antibody / Hu) antibodies, in addition to neuronal antibody-associated disorders including anti-NMDAR, LGI1 (leucine-rich glioma inactivated-1) and CASPR2 (contactin associated protein-2). We discuss the more recently described entities of IgLON5, which has evidence of both immunologic and degenerative pathophysiology, in addition to PDE-10A antibody-associated chorea. We also outline chorea secondary to systemic diseases including Systemic Lupus Erythematosus (SLE) and Primary Antiphospholipid Syndrome (PAPS). We provide a framework for diagnosis and treatment.

Tics and Emotions

Tics can be associated with neurological disorders and are thought to be the result of dysfunctional basal ganglia pathways. In Tourette Syndrome (TS), excess dopamine in the striatum is thought to excite the thalamo-cortical circuits, producing tics. When external stressors activate the hypothalamic-pituitary-adrenal (HPA) axis, more dopamine is produced, furthering the excitation of tic-producing pathways. Emotional processing structures in the limbic are also activated during tics, providing further evidence of a possible emotional component in motor ticking behaviors. The purpose of this review is to better understand the relationship between emotional states and ticking behavior. We found support for the notion that premonitory sensory phenomena (PSP), sensory stimulation, and other environmental stressors that impact the HPA axis can influence tics through dopaminergic neurotransmission. Dopamine plays a vital role in cognition and motor control and is an important neurotransmitter in the pathophysiology of other disorders such as obsessive–compulsive disorder (OCD) and attention deficit hyperactivity disorder (ADHD), which tend to be comorbid with ticking disorders and are thought to use similar pathways. It is concluded that there is an emotional component to ticking behaviors. Emotions primarily involving anxiety, tension, stress, and frustration have been associated with exacerbated tics, with PSP contributing to these feelings.

Sydenham's chorea: from pathophysiology to therapeutics

Sydenham's chorea is an autoimmune chorea emerging after a group A beta-hemolytic streptococcal (GABHS) infection, i.e. a rheumatic chorea with or without the presence of carditis or arthritis. The disorder, defined by the presence of chorea, is also associated with cognitive and behavioral symptoms, including emotional lability, anxiety, depressive and obsessive-compulsive symptoms. The authors review the pathophysiology, clinical characteristics, and available evidence on therapeutic strategies, the latter including the secondary prevention of GABHS infections, reduction of chorea, and immune modulation. Sydenham's chorea has been regarded as a model for pediatric autoimmune neuropsychiatric disorders, however, the field is marked by conflicting results and controversies. Regarding therapeutics, there are limited high-quality interventional studies and the selection of treatment strategy often relies on the clinician's experience. A serial treatment algorithm is presented based upon the severity of clinical presentation and response to symptomatic pharmacotherapy.

Neurologic complications of rheumatic fever

Sydenham chorea, also known as St. Vitus dance, is a major clinical criterion for the diagnosis of acute rheumatic fever. Clinically, it results in a combination of movement disorders and complex neuropsychiatric symptoms. Cardiac damage due to rheumatic fever may also predispose to neurologic complications later in life. Rheumatic heart disease (RHD) is associated with heart remodeling, cardiac arrhythmias, and ischemic stroke. Furthermore, chronically damaged heart valves are predisposed to infection. Septic brain embolism, a known complication of infective endocarditis, may result in brain ischemia, hemorrhage, and spread of the infection to the brain.

Prozone phenomenon observed in indirect immunofluorescence assay by antibodies against neuronal antigens

A marked prozone effect was observed in indirect immunofluorescence with human sera and human cerebrospinal fluid in two clinical cases involving breast carcinoma with paraneoplastic neuronal antibodies, and anti- N-methyl-D-aspartic acid (NMDA) receptor antibodies. Anti-Yo antibodies and anti-NMDA antibodies were not detectable under high concentrations (1:10 serum dilution and neat CSF respectively) but showed a true effect when sufficiently diluted at 1:80 and 1:5 respectively. This paper demonstrates that prozone effects have their occurrences in indirect immunofluorescence, and clinicians and laboratory technicians should be wary of its implications during screening of autoantibody markers in neurological diseases.

Early childhood infections, antistreptococcal and basal ganglia antibodies in adult ADHD: a preliminary study

BACKGROUND

To explore the relationship between adult Attention Deficit/ Hyperactivity Disorder (ADHD), antistreptococcal titers, ABGA, and recurrent infections during early childhood.

METHOD

Childhood history of recurrent infections and a blood sample were collected in a sample of DSM-IV adult outpatients with ADHD. The anti-streptolysin O (ASO), anti-deoxyribonuclease B (anti-DNase B), and anti-basal ganglia antibodies (ABGA) titers were determined in patient plasma by enzyme-linked immunosorbent assay (ELISA). Titers positivity was evaluated following manufacturer's specifications. Absolute titers were also collected as continuous variables.

RESULTS

Fourteen out of 22 (63.6%) have had recurrent infections in childhood (i.e., seven, 31.8%, have had tonsillitis or adenoiditis and seven, 31.8%, have had any other infections). Eighteen patients (81.9%) were positive for anti-DNase B, five (22.7%) for ASO, and 4 (18.2%) were positive for both of them. Five participants (22.7%) were ABGA positive, whereas only two (9.1%) were positive for all three antibodies.

CONCLUSIONS

patients with ADHD might be more prone to infections during childhood and subclinical streptococcal infections during adulthood. Moreover, they seem to have an increased risk for basal ganglia autoimmunity in adulthood. Both infections and the ensuing acquired autoimmunity could influence the neurodevelopmental process, by contributing, at least in part, to the ADHD pathogenesis.

Increased vulnerability to impulsive behavior after streptococcal antigen exposure and antibiotic treatment in rats

RATIONALE

The inflammation induced by Group A Streptococcus (GAS) infection has been viewed as a vulnerability factor in mental disorders characterized by inhibitory control deficits, such as attention-deficit/hyperactivity disorder or obsessive-compulsive disorder. Antibiotic treatment reduces GAS symptoms; however, its effects on impulsivity have not been fully assessed.

OBJECTIVES

We investigated whether GAS exposure during early adolescence might be a vulnerability factor for adult impulsivity, if antibiotic treatment acts as a protective factor, and whether these differences are accompanied by changes in the inflammatory cytokine frontostriatal regions.

METHODS

Male Wistar rats were exposed to the GAS antigen or to vehicle plus adjuvants at postnatal day (PND) 35 (with two boosts), and they received either ampicillin (supplemented in the drinking water) or water alone from PND35 to PND70. Adult impulsivity was assessed using two different models, the 5-choice serial reaction time task (5-CSRT task) and the delay discounting task (DDT). The levels of interleukin-6 (IL-6) and IL-17 were measured in the prefrontal cortex (PFc), and the tumor necrosis factor α levels (TNFα) were measured in the PFc and nucleus accumbens (NAcc).

RESULTS

GAS exposure and ampicillin treatment increased the waiting impulsivity by a higher number of premature responses when the animals were challenged by a long intertrial interval during the 5-CSRT task. The GAS exposure revealed higher impulsive choices at the highest delay (40 s) when tested by DDT, while coadministration with ampicillin prevented the impulsive choice. GAS exposure and ampicillin reduced the IL-6 and IL-17 levels in the PFc, and ampicillin treatment increased the TNFα levels in the NAcc. A regression analysis revealed a significant contribution of GAS exposure and TNFα levels to the observed effects.

CONCLUSIONS

GAS exposure and ampicillin treatment induced an inhibitory control deficit in a different manner depending on the form of impulsivity measured here, with inflammatory long-term changes in the PFc and NAcc that might increase the vulnerability to impulsivity-related neuropsychiatric disorders.

Preliminary data on prednisone effectiveness in children with Sydenham chorea

The objective of the study is to evaluate the efficacy of corticosteroids in Sydenham chorea. This is a retrospective observational study. Clinical information of children with Sydenham chorea were collected. Outcome of Sydenham chorea was evaluated in consideration of presence or absence of corticosteroid therapy. Thirty patients were enrolled. A total of 15 were treated with prednisone, 15 received symptomatic drugs or no treatment. Patients who were treated with prednisone showed faster improvement (4 vs 16 days; p = 0.002) and shorter median time of remission (30 vs 135 days; p < 0.001).Conclusion: Our study showed that corticosteroid therapy is an effective treatment of Sydenham chorea.What is Known:• Steroid treatment in Sydenham chorea is widely used but it is not standardized.• Few manuscript report a beneficial use of steroids in Sydenham chorea if compared with no treatment.What is New:• Steroid treatment seems to be effective in both clinical remission and clinical improvement of symptoms among patients with Sydenham chorea.• Steroid treatment seems to be superior to conventional treatment.

Neuropsychiatric consequences of childhood group A streptococcal infection: A systematic review of preclinical models

In recent years, clinical studies have shown strong epidemiological evidence of an increased risk of developing neuropsychiatric disorders after childhood exposure to streptococcal infection, including the Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infection (PANDAS). New preclinical studies on group A streptococcus (GAS) exposure investigate how to disentangle the influences of immune activation to induce long-term neurobehavioral effects associated with neuropsychiatric disorders such as obsessive-compulsive disorder, schizophrenia or autism. The present systematic review collects neurobehavioral evidence regarding the use of GAS exposure in animal models to study the vulnerability to different neuropsychiatric disorders, improving our understanding of its possible causes and consequences, and compares its contribution with other preclinical models of immune activation in a variety of paradigms. Specifically, we reviewed the effects of postnatal GAS exposure, in comparison with post- and prenatal exposure to Lipopolysaccharide (LPS) and Polyinosinic:polycytidylic acid (Poly I:C), on the long-term effects concerning psychomotor, cognition and socioemotional outcomes in rodents. GAS exposure in animal models has revealed different behavioral alterations such as reduced locomotion and motor coordination, a deficit in sensorimotor gating, learning, working memory, altered social behavior, and increased anxiety and stereotyped behavior. Most of the results found are in accordance with other immune activation models -LPS and Poly I:C-, with some discrepancies. The systematic review of the literature supports the preclinical model of GAS exposure as a valid model for studying the neurobehavioral consequences of streptococcal infections. Future studies on streptococcal infection could contribute increasing our knowledge on preventive actions or treatments for neuropsychiatric disorders.

Diagnosis in PANDAS: An Update

Background:

The last twenty years have seen major advancements in unraveling the etiology and the identification of biological markers of Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococci (PANDAS). However, this body of evidence has not yet been translated into a clinical setting.

Objective:

We will review the most important studies to date on PANDAS, emphasizing those whose advances could improve the diagnosis of these disorders. We also suggest the need for updated diagnosis criteria integrating the recent findings from the hereby included studies.

Methods:

Consulting the PubMed database, a literature review of the last twenty-one years (between 1998 and 2019) was carried out using the terms “PANDAS” and “pediatric autoimmune neuropsychiatric disorders” in combination with “diagnosis” and “markers”. The search resulted in 175 hits from which we selected clinical cases, original investigations, and clinical reviews.

Results:

This review offers a compilation of the most important studies performed to date regarding the clinical presentation and potential biological markers of PANDAS. Moreover, we suggest the refinement of some aspects in the current diagnosis criteria, such as focusing on specific symptoms and the inclusion of neuroimaging and peripheral markers.

Conclusion:

The identification of specific biological markers in PANDAS is crucial for its diagnosis and opportune treatment. Future research will determine whether PANDAS require separated diagnostic and therapeutic measures or if it should be included in recently proposed categories such as Pediatric Acute Neuropsychiatric Syndrome (PANS) or Childhood Acute Neuropsychiatric Syndrome (CANS).

Pediatric Acute-onset Neuropsychiatric Syndrome and Mycoplasma Pneumoniae Infection: A Case Report Analysis with a Metabolomics Approach

Pediatric Acute-onset Neuropsychiatric Syndrome (PANS) is a clinical condition characterized by a sudden and dramatic obsessive-compulsive disorder with a suggested post-infectious immune-mediated etiology. This condition is accompanied by an extensive series of relatively serious neuropsychiatric symptoms. The diagnosis of PANS is made by "exclusion", as the individual PANS symptoms overlap with a multiplicity of psychiatric disorders with the onset in childhood. A number of researchers accumulated evidence to support the hypothesis that PANS was closely associated with a number of infections. In the last decade, metabolomics played an essential role in improving the knowledge of complex biological systems and identifying potential new biomarkers as indicators of pathological progressions or pharmacologic responses to therapy. The metabolome is considered the most predictive phenotype, capable of recognizing epigenetic differences, reflecting more closely the clinical reality at any given moment and thus providing extremely dynamic data. In the present work, the most recent hypothesis and suggested mechanisms of this condition are reviewed and the case of a 10 - year-old girl with PANS is described, before and after clarithromycin treatment. The main results of this case report are discussed from a metabolomics point of view. The alteration of several metabolic pathways concerning the microbial activity highlights the possible role of the microbiome in the development of PANS. Furthermore, different metabolic perturbations at the level of protein biosynthesis, energy and amino acid metabolisms are observed and discussed. Based on our observations, it is believed that metabolomics is a promising technology to unravel the mysteries of PANS in the near future.

You can dance if you want to: A case of Sydenham's chorea

Isolated motor disturbances in the paediatric population are uncommon presentations to the emergency department. Choreiform movements have a broad differential diagnosis and may present insidiously with progressive worsening of asymmetric clumsiness, hypotonia and dysarthria. The incidence of Sydenham's chorea (SC) caused by acute rheumatic fever (ARF) is very rare in developed countries. We report a previously healthy, vaccinated 9-year old male who presented to our ED with intermittent and progressive right sided clumsiness for four weeks. Physical examination findings showed dysdiadokinesis and dysmetric movements of the right side, which varied in intensity and were less pronounced on serial re-examination during the same ED visit. Basic bloodwork, MRI and MRA/V showed no abnormalities, and the patient was discharged home with urgent neurology follow-up. He re-presented to our ED four days later with worsening gait and inability to hold a pencil at school. He was subsequently diagnosed with chorea by the neurology team. The cause of chorea was later determined to be SC, and the patient's throat swab came back positive for group A-beta hemolytic strep (GAS) infection. We explore current literature regarding the various presentations of ARF, differential considerations in acute chorea, and diagnostic studies needed to determine the etiology of acute chorea. With the low incidence of chorea in developed nations, this diagnosis can be easily overlooked. We highlight the importance of this diagnosis, as well as primary and secondary treatment in ARF.

Psychotic symptoms in youth with Pediatric Acute-onset Neuropsychiatric Syndrome (PANS) may reflect syndrome severity and heterogeneity

OBJECTIVE

In the clinical syndrome Pediatric Acute-onset Neuropsychiatric Syndrome (PANS), obsessive compulsive disorder (OCD) and/or food refusal symptoms have an abrupt-onset (over 48 h) coupled with at least two other specified neuropsychiatric symptoms. We aimed to characterize in detail for the first time, psychotic symptoms experienced by children with PANS as well as the impact of psychotic symptoms on disease severity and course of illness. We inform about the diagnosis of the clinical description: PANS and hope to improve evaluation, treatment, diagnostic validity and future investigation.

METHODS

Retrospective review of 143 consecutive PANS clinic patient charts meeting inclusion criteria. The Caregiver Burden Inventory, Global Impairment Score, and Children's Global Assessment Scale were used to assess impairment.

RESULTS

Visual and auditory hallucinations were each experienced by 36%, of which most (83%) were transient and complex (non-threatening voices or figures). 6.3% and 5.5% of patients experienced delusions and thought disorganization respectively. Those with psychotic symptoms showed statistically significant differences in disease impairment and caregiver burden. There were no differences in time to treatment access or length of illness.

CONCLUSIONS

Over 1/3 of children with PANS experienced transient hallucinations. They were more impaired than those without psychotic symptoms, but showed no differences in disease progression. This difference may point toward heterogeneity in PANS. When evaluating children with acute psychotic symptoms, clinicians should screen for abrupt-onset of a symptom cluster including OCD and/or food refusal, with neuropsychiatric symptoms (enuresis, handwriting changes, tics, hyperactivity, sleep disorder) before initiating treatment.

PANDAS/PANS in childhood: Controversies and evidence

Since first defined in 1998, paediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) and its later, broader iteration, paediatric acute-onset neuropsychiatric syndrome (PANS), have garnered significant attention and controversy. The role of streptococcal infection in children with explosive onset obsessive-compulsive disorder and new onset tics, the natural history of this entity, and the role of symptomatic and disease-modifying therapies, including antibiotics, immunotherapy, and psychoactive drugs, are all issues that have yet to be definitively addressed. While definitive proof of the autoimmune hypothesis of PANDAS is lacking, given the heightened attention to this entity and apparent rise in use of this diagnostic category, addressing questions around diagnosis, treatment, and etiology is imperative. In this paper, we review current working definitions of PANDAS/PANS, discuss published evidence for interventions related to this entity, and propose a clinical approach to children presenting with acute symptoms satisfying criteria for PANDAS/PANS.

Anti-Basal Ganglia Antibodies and Streptococcal Infection in ADHD

OBJECTIVE

Group A Streptococcus has been associated with ADHD, tic disorders (TD), and obsessive-compulsive disorder (OCD) through anti-basal ganglia antibodies (ABGA).

METHOD

We investigated the association between ABGA and streptococcal exposure with behavioral, motor, and cognitive measures in 38 children with ADHD not comorbid to OCD or TD (nc-ADHD) and in 38 healthy children. An additional group of 15 children with TD and/or OCD was examined.

RESULTS

ABGA titers were present in 3% of nc-ADHD patients and controls but in 27% of TD and/or OCD patients. Evidence of streptococcal exposure was similar between ADHD patients and controls living in the same urban area. Behavioral, motor, and cognitive measures were not associated with anti-streptococcal antibodies.

CONCLUSION

ABGA do not distinguish nc-ADHD from controls. The differences in the frequency of streptococcal exposure in previous studies are determined by the dynamic nature of the infection rather than the behavioral phenotype of ADHD.

Inherited and Acquired Choreas

Chorea is a symptom of a broad array of genetic, structural, and metabolic disorders. While chorea can result from systemic illness and damage to diverse brain structures, injury to the basal ganglia, especially the putamen or globus pallidus, appears to be a uniting features of these diverse neuropathologies. The timing of onset, rate of progression, and the associated neurological or systemic symptoms can often narrow the differential diagnosis to a few disorders. Recognizing the correct etiology for childhood chorea is critical, as numerous disorders in this category are potentially curable, or are remediable, with early treatment.

Autoimmune Movement Disorders in Children

Over the last decade, there have been significant advances in the identification, characterization, and treatment of autoimmune neurologic disorders in children. Many of these diseases include a typical movement disorder that can be a powerful aid to diagnosis. Frequently, movement disorders in autoimmune conditions are the sole or among a few presenting symptoms, allowing for earlier diagnosis of an underlying malignancy or systemic autoimmune disease. Given that early detection and treatment with immunotherapy may confer improved outcomes, recognizing these patterns of abnormal movements is essential for child neurologists. The purpose of this review is to summarize the clinical characteristics, diagnosis, and treatment of movement disorders that occur in pediatric autoimmune disorders.

Autoimmune and paraneoplastic movement disorders: An update

Movement disorders (MDs) are common in patients with autoimmune disorders affecting the central and peripheral nervous system. They may be observed in autoimmune disorders triggered by an infectious agent, such as streptococcus in Sydenham's chorea, or in basal ganglia encephalitis with antibodies against the dopamine-D2 receptors. In these patients chorea or dystonia are usually the most prominent hyperkinetic MDs. MDs are also observed in patients with diffuse or limbic encephalitis with antibodies directed against neuronal cell-surface antigens. Anti-NMDA receptor encephalitis is one of the most common and may present with a variety of MDs, including: chorea, stereotypies, dystonia and myorhythmia. The recognition of other abnormal motor phenomena such as "faciobrachial dystonic seizures" and neuromyotonia, observed in patients with LGI1 and Caspr-2 antibodies, is important because they may herald the onset of overt limbic encephalitis. Autoimmunity directed against the intracellular enzyme glutamic acid decarboxylase usually presents with MDs, most commonly stiff-person syndrome or cerebellar ataxia. Chorea may be observed in rheumatologic disorders such as systemic lupus erythematosus or antiphospholipid syndrome. Disorders with uncertain autoimmune mechanisms such as Hashimoto's encephalitis and idiopathic opsoclonus-myoclonus syndrome commonly present with tremor, myoclonus and ataxia. A rapid diagnosis of an autoimmune disorder, which typically presents with subacute onset, is critical as early therapeutic intervention improves long-term prognosis and may be life-saving. Treatment usually involves some form of immunotherapy and symptomatic therapy of the abnormal movements with dopamine depleters, dopamine receptor antagonists, or GABAergic drugs. Detection and removal of an underlying tumor is essential for optimal outcome.

Toward Pervasive Gait Analysis With Wearable Sensors: A Systematic Review

After decades of evolution, measuring instruments for quantitative gait analysis have become an important clinical tool for assessing pathologies manifested by gait abnormalities. However, such instruments tend to be expensive and require expert operation and maintenance besides their high cost, thus limiting them to only a small number of specialized centers. Consequently, gait analysis in most clinics today still relies on observation-based assessment. Recent advances in wearable sensors, especially inertial body sensors, have opened up a promising future for gait analysis. Not only can these sensors be more easily adopted in clinical diagnosis and treatment procedures than their current counterparts, but they can also monitor gait continuously outside clinics - hence providing seamless patient analysis from clinics to free-living environments. The purpose of this paper is to provide a systematic review of current techniques for quantitative gait analysis and to propose key metrics for evaluating both existing and emerging methods for qualifying the gait features extracted from wearable sensors. It aims to highlight key advances in this rapidly evolving research field and outline potential future directions for both research and clinical applications.

Autoimmunity against a glycolytic enzyme as a possible cause for persistent symptoms in Lyme disease

Some patients with a history of Borrelia burgdorferi infection develop a chronic symptomatology characterized by cognitive deficits, fatigue, and pain, despite antibiotic treatment. The pathogenic mechanism that underlines this condition, referred to as post-treatment Lyme disease syndrome (PTLDS), is currently unknown. A debate exists about whether PTLDS is due to persistent infection or to post-infectious damages in the immune system and the nervous system. We present the case of a patient with evidence of exposure to Borrelia burgdorferi sl and a long history of debilitating fatigue, cognitive abnormalities and autonomic nervous system issues. The patient had a positive Western blot for anti-basal ganglia antibodies, and the autoantigen has been identified as γ enolase, the neuron-specific isoenzyme of the glycolytic enzyme enolase. Assuming Borrelia own surface exposed enolase as the source of this autoantibody, through a mechanism of molecular mimicry, and given the absence of sera reactivity to α enolase, a bioinformatical analysis was carried out to identify a possible cross-reactive conformational B cell epitope, shared by Borrelia enolase and γ enolase, but not by α enolase. Taken that evidence, we hypothesize that this autoantibody interferes with glycolysis in neuronal cells, as the physiological basis for chronic symptoms in at least some cases of PTLDS. Studies investigating on the anti-γ enolase and anti-Borrelia enolase antibodies in PTLDS are needed to confirm our hypotheses.

Autoantibody-Associated Movement Disorders in Children: Proven and Proposed

Movement disorders secondary to autoantibodies in children represent a rapidly expanding group of conditions. Once considered to be limited to poststreptococcal Sydenham's chorea or rare cases of childhood systemic lupus erythematosus, a variety of antibody-related movement abnormalities are now seen as part of noninfectious autoimmune encephalitis or within an expanding list of postinfectious disorders. In this article, several proposed autoantibody-mediated movement disorders in children are reviewed. In each one, there is a hypothesized antibody biomarker that is believed to be pathogenic and cause the clinical symptoms. As will be discussed, in some, such as anti-NMDA receptor encephalitis, the strength of supporting evidence is strong. In others, antibodies have been identified, but their role as the pathophysiological mechanism remains undetermined. Lastly, there are proposed disorders, such as PANDAS, that are controversial on both a clinical and autoimmune basis.

Autoimmune choreas

Chorea, a movement disorder characterised by a continuous flow of unpredictable muscle contractions, has a myriad of genetic and non-genetic causes. Although autoimmune processes are rare aetiology of chorea, they are relevant both for researchers and clinicians. The aim of this article is to provide a review of the epidemiology, clinical and laboratory features, pathogenesis and management of the most common autoimmune causes of chorea. Emphasis is given particularly to Sydenham's chorea, systemic lupus erythematosus, primary antiphospolipid antibody syndrome, paraneoplastic chorea and anti-N-methyl-d-aspartate receptor encephalitis.

Hello from the Other Side: How Autoantibodies Circumvent the Blood-Brain Barrier in Autoimmune Encephalitis

Antibodies against neuronal receptors and synaptic proteins are associated with autoimmune encephalitides (AE) that produce movement and psychiatric disorders. In order to exert their pathological effects on neural circuits, autoantibodies against central nervous system (CNS) targets must gain access to the brain and spinal cord by crossing the blood–brain barrier (BBB), a tightly regulated gateway formed by endothelial cells lining CNS blood vessels. To date, the pathogenic mechanisms that underlie autoantibody-triggered encephalitic syndromes are poorly understood, and how autoantibodies breach the barrier remains obscure for almost all AE syndromes. The relative importance of cellular versus humoral immune mechanisms for disease pathogenesis also remains largely unexplored. Here, we review the proposed triggers for various autoimmune encephalopathies and their animal models, as well as basic structural features of the BBB and how they differ among various CNS regions, a feature that likely underlies some regional aspects of autoimmune encephalitis pathogenesis. We then discuss the routes that antibodies and immune cells employ to enter the CNS and their implications for AE. Finally, we explore future therapeutic strategies that may either preserve or restore barrier function and thereby limit immune cell and autoantibody infiltration into the CNS. Recent mechanistic insights into CNS autoantibody entry indicate promising future directions for therapeutic intervention beyond current, short-lived therapies that eliminate circulating autoantibodies.

The Genetic Etiology of Tourette Syndrome: Large-Scale Collaborative Efforts on the Precipice of Discovery

Gilles de la Tourette Syndrome (TS) is a childhood-onset neurodevelopmental disorder that is characterized by multiple motor and phonic tics. It has a complex etiology with multiple genes likely interacting with environmental factors to lead to the onset of symptoms. The genetic basis of the disorder remains elusive. However, multiple resources and large-scale projects are coming together, launching a new era in the field and bringing us on the verge of discovery. The large-scale efforts outlined in this report are complementary and represent a range of different approaches to the study of disorders with complex inheritance. The Tourette Syndrome Association International Consortium for Genetics (TSAICG) has focused on large families, parent-proband trios and cases for large case-control designs such as genomewide association studies (GWAS), copy number variation (CNV) scans, and exome/genome sequencing. TIC Genetics targets rare, large effect size mutations in simplex trios, and multigenerational families. The European Multicentre Tics in Children Study (EMTICS) seeks to elucidate gene-environment interactions including the involvement of infection and immune mechanisms in TS etiology. Finally, TS-EUROTRAIN, a Marie Curie Initial Training Network, aims to act as a platform to unify large-scale projects in the field and to educate the next generation of experts. Importantly, these complementary large-scale efforts are joining forces to uncover the full range of genetic variation and environmental risk factors for TS, holding great promise for identifying definitive TS susceptibility genes and shedding light into the complex pathophysiology of this disorder.

Migraine Headache in Patients with Sydenham's Chorea

We compared the frequency of migraine among Sydenham's chorea (SC) patients, rheumatic fever (RF) patients without neurological symptoms and matched controls. Migraine was more frequent in SC patients (12/55, 21.8%) than in controls (9/110, 8.1%) and as common as in the RF group (10/55, 18.2%). Our data are in agreement with previous studies reporting higher frequency of migraine in other basal ganglia disorders, such as essential tremor and Tourette's syndrome.

Autoimmunity against dopamine receptors in neuropsychiatric and movement disorders: a review of Sydenham chorea and beyond

Antineuronal autoantibodies are associated with the involuntary movement disorder Sydenham chorea (SC) and paediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) which are characterized by the acute onset of tics and/or obsessive compulsive disorder (OCD). In SC and PANDAS, autoantibodies signal human neuronal cells and activate calcium calmodulin-dependent protein kinase II (CaMKII). Animal models immunized with group A streptococcal antigens demonstrate autoantibodies against dopamine receptors and concomitantly altered behaviours. Human monoclonal antibodies (mAbs) derived from SC target and signal the dopamine D2L (long) receptor (D2R). Antibodies against D2R were elevated over normal levels in SC and acute-onset PANDAS with small choreiform movements, but were not elevated over normal levels in PANDAS-like chronic tics and OCD. The expression of human SC-derived anti-D2R autoantibody V gene in B cells and serum of transgenic mice demonstrated that the human autoantibody targets dopaminergic neurones in the basal ganglia and other types of neurones in the cortex. Here, we review current evidence supporting the hypothesis that antineuronal antibodies, specifically against dopamine receptors, follow streptococcal exposures and may target dopamine receptors and alter central dopamine pathways leading to movement and neuropsychiatric disorders.

Language Impairment in Adolescents With Sydenham Chorea

BACKGROUND

Neuropsychiatric comorbidities are frequent in Sydenham chorea. However, cognitive impairment in Sydenham chorea has not been sufficiently described. The objective of this study was to evaluate expressive and receptive language deficits in adolescents with Sydenham chorea.

METHODS

Twenty patients with Sydenham chorea were compared with 20 patients with rheumatic fever without chorea and 20 healthy controls. Participants were matched for age and gender. Participants were assessed with verbal fluency tasks (phonemic and semantic) and with verbal comprehension tasks (Token Test). Patients with Sydenham chorea were also assessed with the Universidade Federal de Minas Gerais Sydenham Chorea Rating Scale.

RESULTS

Performance in verbal fluency and in verbal comprehension tasks differed significantly (P < 0.01) among the three groups. Patients with Sydenham chorea performed significantly worse than healthy control group in phonemic and semantic verbal fluency tasks as well as in the Token Test. The group with rheumatic fever also performed worse than healthy controls in phonemic verbal fluency. Severity of motor signs in Sydenham chorea inversely correlated with performance in phonemic verbal fluency (words beginning with letter S, and total sum of words beginning with letters F, A, and S).

CONCLUSIONS

Adolescents with Sydenham chorea show difficulties in verbal fluency and in verbal comprehension. Patients with rheumatic fever also have some degree of language impairment. Future studies must investigate language impairment in difference stages of Sydenham chorea (acute, persistent, and remission) and putative biological markers.

Antibasal Ganglia Antibodies and Antistreptolysin O in Noncomorbid ADHD

OBJECTIVE

An association between streptococcal infections, ABGA positivity, and no comorbidity ADHD (nc-ADHD) has been little investigated. The aim of this study was to evaluate the streptococcal infection frequency, defined entitled serum antistreptolysin O (ASO), and frequency of serum ABGA positivity in a sample of patients with nc-ADHD.

METHOD

In all 40 participants were investigated the ASO titer and ABGA.

RESULTS

The results showed that ABGA positivity was statistically significantly higher in patients affected by ADHD than in patients of a control group, and pathological values of ASO were statistically more frequent in the ADHD group than the control group.

CONCLUSION

These data suggest that streptococcal infections and autoimmune reactions against the basal ganglia are more frequent in ADHD patients than patients in a control group.

Comparative Proteomics for the Evaluation of Protein Expression and Modifications in Neurodegenerative Diseases

Together with hypothesis-driven approaches, high-throughput differential proteomic analysis performed primarily not only in human cerebrospinal fluid and serum but also on protein content of other tissues (blood cells, muscles, peripheral nerves, etc.) has been used in the last years to investigate neurodegenerative diseases. Even if the goal for these analyses was mainly the discovery of neurodegenerative disorders biomarkers, the characterization of specific posttranslational modifications (PTMs) and the differential protein expression resulted in being very informative to better define the pathological mechanisms. In this chapter are presented and discussed the positive aspects and challenges of the outcomes of some of our investigations on neurological and neurodegenerative disease, in order to highlight the important role of protein PTMs studies in proteomics-based approaches.

Sydenham Chorea and PANDAS in South Africa: Review of Evidence and Recommendations for Management in Resource-Poor Countries

In South Africa, and worldwide, rheumatic fever represents a public health problem. Improved diagnosis and management of Sydenham chorea, a major manifestation of acute rheumatic fever is key to prevention of rheumatic heart disease. This article reviews Sydenham chorea from its original description to current opinions. Recommendations are founded on expert opinion as class 1 data is lacking. This South African perspective is relevant to resource-poor settings globally insofar as it provides diagnosis and management recommendations for primary- and secondary-level healthcare professionals who care for patients in such environments. Four basic tenets of care are recommended, namely, elimination of the streptococcal infection, symptomatic treatment, immunological treatment, and nonpharmacologic interventions. A user-friendly outcome measurement tool, viable for use in low-resource settings is presented. Introduction of this tool may lead to increased awareness of the neuropsychiatric manifestations of poststreptococcal movement disorders in Africa, where reports are limited.

Chorea: A Journey through History

The original descriptions of chorea date from the Middle Ages, when an epidemic of "dancing mania" swept throughout Europe. The condition was initially considered a curse sent by a saint, but was named "Saint Vitus's dance" because afflicted individuals were cured if they touched churches storing Saint Vitus's relics. Paracelsus coined the term chorea Sancti Viti and recognized different forms of chorea (imaginativa, lasciva, and naturalis). In the 17th century, Thomas Sydenham provided an accurate description of what he termed chorea minor. He also described rheumatic fever but did not associate it with chorea. It was only in 1850 that See established a relationship between chorea and rheumatic disease. A connection with cardiac involvement was soon recognized and in 1866 Roger postulated that chorea, arthritis, and heart disease had a common cause. The last quarter of the 19th century is marked by the works of Jean-Martin Charcot, Silas Weir Mitchell, William Osler, and William Richard Gowers, all of paramount importance in the refinement of the definition of chorea, its causes, and differential diagnosis. In 1841, Charles Oscar Waters gave a concise account of a syndrome, likely to be Huntington's disease (HD), later described further by George Huntington and named after him. In 1955, the Venezuelan physician Americo Negrette published a book describing communities in the State of Zulia in Venezuela, with unusual numbers of individuals with chorea. Negrette's works culminated in the creation of the Venezuela project and the subsequent discovery of seminal findings in HD. We review the historical facts and outstanding physicians that mark both HD and Sydenham's chorea's history in various sections.

Evaluation of basal ganglia and thalamic inflammation in children with pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection and tourette syndrome: a positron emission tomographic (PET) study using 11C-[R]-PK11195

We applied PET scanning with (11)C-[R]-PK11195 (PK) to evaluate neuroinflammatory changes in basal ganglia and thalamus in children with clinically diagnosed pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS) and Tourette syndrome. Seventeen children with PANDAS (mean age: 11.4 ± 2.6 years; 13 males), 12 with Tourette syndrome (mean age: 11.0 ± 3.0 years; 10 males), and 15 normal adults (mean age: 28.7 ± 7.9 years; 8 males) underwent dynamic PK PET imaging and binding potential, a measure of ligand-TSPO receptor (expressed by activated microglia) binding, was calculated for basal ganglia and thalamus. Binding potential values, suggesting underlying activated microglia-mediated neuroinflammation, were found to be increased in bilateral caudate and bilateral lentiform nucleus in the PANDAS group and in bilateral caudate nuclei only in the Tourette syndrome group, compared to control group. These differences in the pattern and extent of neuroinflammation also signify a possible difference in pathophysiological etiology between PANDAS and Tourette syndrome patients.

Antineuronal antibodies in a heterogeneous group of youth and young adults with tics and obsessive-compulsive disorder

BACKGROUND AND OBJECTIVE

Antineuronal antibodies have been implicated in tic and obsessive compulsive disorders (OCD) associated with group A streptococcal infections. We investigated antineuronal autoantibody levels as well as antibody-mediated neuronal cell signaling activity, as previously reported for Sydenham chorea and pediatric autoimmune neuropsychiatric disorder associated with streptococci (PANDAS), to determine immunological profiles for a large cohort of children with tics and/or OCD.

METHODS

Study participants (n=311; ages 4-27 years, 66% male) were selected from a larger group of individuals with self-reported neuropsychiatric symptoms (n=742) and included only those with accurate knowledge of group A streptococcal infection status, except for four individuals in whom streptococcal infection status was unknown. Healthy control samples (n=16; ages 5-14 years, 81% male), came from the National Institute of Mental Health and Yale University. In addition to serum donations, participants and/or legal guardians provided neuropsychiatric and related medical histories of symptoms that had lasted >1 year. Antineuronal immunoglobulin G (IgG) titers were measured by standard enzyme-linked immunosorbent assay (ELISA) and compared with mean titers of normal age-matched sera against lysoganglioside, tubulin, and dopamine receptors (D1R and D2R). Antibody-mediated signaling of calcium calmodulin dependent protein kinase II (CaMKII) activity in a human neuronal cell line (SK-N-SH) was tested in serum.

RESULTS

Of 311 individuals, 222 (71%) had evidence of group A streptococcal infection, which was associated with tics and/or OCD status (p=0.0087). Sera from individuals with tics and/or OCD (n=261) had evidence of elevated serum IgG antibodies against human D1R (p<0.0001) and lysoganglioside (p=0.0001), and higher serum activation of CaMKII activity (p<0.0001) in a human neuronal cell line compared with healthy controls (n=16). Furthermore, patients with tics and OCD had significantly increased activation of CaMKII activity compared with patients with only tics or only OCD (p<0.033 for each).

CONCLUSION

Our study suggested a significant correlation of streptococcal-associated tics and OCD with elevated anti-D1R and antilysoganglioside antineuronal antibodies in serum concomitant with higher activation of CaMKII in human neuronal cells. Youth and young adults with chronic tics and OCD may have underlying infectious/immunologic etiology.

Severe Sydenham's chorea (chorea paralytica) successfully treated with plasmapheresis

Sydenham’s chorea is often regarded as a relatively benign and self-limiting condition. Treatment is typically symptomatic, although occasionally immunomodulatory therapies are required in severe forms. Here we report a girl who was affected with the severe variant, chorea paralytica, who responded dramatically and rapidly to plasmapheresis, having failed other therapies.

Post-infectious autoimmune disorders: Sydenham's chorea, PANDAS and beyond

Infections, and the resulting immune response to these infections, have recently received increased recognition as pathogenic mechanisms for neuropsychiatric disorders. Sydenham's chorea (SC), a widely recognized post-streptococcal autoimmune disorder, represents a model for this proposed pathogenesis. In SC, a dysregulated immune response to a streptococcal infection is hypothesized to result in inflammation of neuronal networks, particularly the basal ganglia nuclei. The resulting dysfunction in the basal ganglia nuclei are hypothesized to lead to a constellation of adventitious movements and psychiatric symptoms, which investigations have shown are amenable to immunomodulatory therapies. PANDAS (Pediatric Autoimmune Neuropsychiatric Disorder Associated with Streptococcal infections) has been proposed as a variant of SC, and is hypothesized to share a pathogenic mechanism, despite a unique symptom profile of predominantly psychiatric symptoms. In this review, we present the clinical aspects of both disorders, the data for potential shared etiopathogenesis between them, and the evidence for the therapeutic use of immunomodulatory therapies for the symptoms of SC and PANDAS. This article is part of a Special Issue entitled SI: Neuroimmunology in Health And Disease.