Post-streptococcal autoimmune disorders of the central nervous system

PURPOSE OF REVIEW: Autoimmune disease has long been intertwined with investigations of infectious causes. Antibodies that are formed against an infectious agent can, through the process of molecular mimicry, also recognize healthy cells. When this occurs, the immune system erroneously destroys the healthy cells causing autoimmune disease in addition to appropriately destroying the offending infectious agent and attenuating the infectious process. The first infectious agent shown to cause a post-infectious autoimmune disorder in the central nervous system was Streptococcus pyogenes in Sydenham's chorea. The present review summarizes the most recent published findings of central nervous system diseases that have evidence of a post-streptococcal autoimmune etiology. RECENT FINDINGS: Sydenham's chorea and other central nervous system illnesses that are hypothesized to have a post-streptococcal autoimmune etiology appear to arise from targeted dysfunction of the basal ganglia. PANDAS (pediatric autoimmune disorders associated with streptococcal infections) is the acronym applied to a subgroup of children with obsessive-compulsive disorder or tic disorders occurring in association with streptococcal infections. In addition, there are recent reports of dystonia, chorea encephalopathy, and dystonic choreoathetosis occurring as sequelae of streptococcal infection. Investigators have begun to isolate and describe antistreptococcal-antineuronal antibodies as well as possible genetic markers in patients who are susceptible to these illnesses. SUMMARY: Clinical and research findings in both immunology and neuropsychiatry have established the existence of post-streptococcal neuropsychiatric disorders and are beginning to shed light on possible pathobiologic processes.     

Pediatric movement disorders: an update

PURPOSE OF REVIEW: Pediatric movement disorders the represent a broad range of disorders, the majority of which are intermittent and hyperkinetic. The goal of this review is to discuss recent findings in several under-recognized conditions (motor stereotypy disorder, restless legs syndrome, and infantile masturbation) as well as the area of autoimmune movement disorders [Sydenham's chorea and PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection)]. RECENT FINDINGS: Advances to be discussed include clarification of symptoms, diagnostic clues, epidemiology, pathogenesis, and treatment. SUMMARY: Significant progress has been made in the study of several paroxysmal movement disorders. Motor stereotypies can occur in typical children and persist over time. Infantile masturbation is often misdiagnosed for seizures or dystonia. Restless leg syndrome is a relatively common problem in children and established criteria are available. Advances have been made in the hallmark autoimmune disorder Sydenham's chorea, but PANDAS remains controversial.     

On defining Sydenham's chorea: where do we draw the line?

Sydenham's chorea (SC) is a major manifestation of rheumatic fever characterized by an array of neuropsychiatric symptoms that vary in severity, timing, and character. Some of the same symptoms are seen in Tourette's syndrome and childhood-onset obsessive-compulsive disorder. Genetic vulnerability appears to play a role in all three conditions. The term PANDAS (pediatric autoimmune neuropsychiatric disorder associated with streptococcus) has been introduced to describe a putative subset of obsessive-compulsive disorder and Tourette's syndrome that bears some resemblance to Sydenham's chorea. This article discusses whether PANDAS should be subsumed under Sydenham's chorea, thus expanding the diagnostic boundaries of Sydenham's chorea to include primarily neuropsychiatric presentations now classified as cases of obsessive-compulsive disorder or Tourette's syndrome. We conclude that PANDAS is a useful construct, but that it would be premature to view it as a subset of Sydenham's chorea-whether defined narrowly or broadly.     

Antibasal ganglia antibodies and their relevance to movement disorders

PURPOSE OF REVIEW: Recently, autoaggressive immunological responses were included among the causative agents of basal ganglia dysfunction. Autoaggressive immune-mediated illnesses secondary to group A beta-haemolytic streptococcal infections present with motor and psychiatric symptoms, due to basal ganglia involvement. These disorders have been associated with serum antineuronal antibodies, relatively specific to human basal ganglia tissue. This review summarizes the most recent studies concerning antibasal ganglia antibodies, focusing on the associated phenotypes and the hypotheses concerning their pathogenicity. RECENT FINDINGS: The spectrum of post-streptococcal neuropsychiatric disorders associated with antibasal ganglia antibodies seems broader than previously recognized. Other than chorea, tics and obsessive-compulsive disorder, which constituted the bulk of previously described disorders associated with antibasal ganglia antibodies, post-streptococcal neuropsychiatric disturbances include a wider range of motor and behavioural abnormalities, in keeping with the multifunctional role of the basal ganglia. An encephalitis lethargica-like illness following streptococcal infection was reported, and unusual adult-onset movement disorders associated with antibasal ganglia antibodies were documented. Moreover, investigators provided preliminary evidence for a pathogenic role of autoantibodies in Sydenham's chorea, the prototypic post-streptococcal neuropsychiatric disorder. SUMMARY: Antibasal ganglia antibodies are relatively specific in identifying post-streptococcal neuropsychiatric disorders, which constitute a wider spectrum of movement disorders than previously recognized. Although their sensitivity in diagnosing Sydenham's chorea seems excellent, it is not yet possible to extrapolate this sensitivity to all the recently identified post-streptococcal neuropsychiatric disorders. The antigens targeted by these autoantibodies and their pathogenic importance are currently under investigation. Preliminary evidence suggests that antibasal ganglia antibodies may be pathogenic.     

Functional brain imaging in Sydenham's chorea and streptococcal tic disorders

Group A streptococcal infections cause a wide range of neuropsychiatric disorders, such as Sydenham's chorea, tics, obsessive-compulsive disorders, and pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS). Structural (computed tomography and magnetic resonance imaging) and functional (positron emission tomography, single-photon emission computed tomography) imaging studies in patients with Sydenham's chorea have suggested reversible striatal abnormalities. The objective of this study was to investigate the cerebral perfusion patterns of the subcortical structures by using hexamethylpropylenamine oxime single-photon emission computed tomography (HMPAO-SPECT) in seven cases of Sydenham's chorea and two cases of streptococcal tic disorder. HMPAO-SPECT studies revealed a hyperperfusion pattern in two and a hypoperfusion pattern in five of the chorea patients and in two patients with tic disorder. The results are discussed in relation to the duration and severity of the symptoms and the response to therapy. Functional imaging findings can be variable in Sydenham's chorea, and hyperperfusion of the striatum and thalamus could be an indicator of the response to therapy and the severity of symptoms. However, the number of cases so far investigated by either SPECT or positron emission tomography is still too limited to draw any firm conclusions.     

PANDAS: current status and directions for research

The recognition of the five criteria for PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections) by Swedo et al established a homogenous subgroup of children with childhood onset obsessive-compulsive disorder (OCD) and/or tic disorders. The five clinical characteristics that define the PANDAS subgroup are the presence of OCD and/or tic disorder, prepubertal age of onset, abrupt onset and relapsing-remitting symptom course, association with neurological abnormalities during exacerbations (adventitious movements or motoric hyperactivity), and a temporal association between symptom exacerbations and a Group-A beta-hemolytic streptococcal (GAS) infection. These five criteria have been used for the purpose of systematic research on the phenomenology and unique therapies for the PANDAS subgroup as well as studies of the pathophysiology of post-streptococcal OCD and tic disorders. The etiology of OCD and tics in the PANDAS subgroup is unknown, but is theorized to occur as a result of post-streptococcal autoimmunity in a manner similar to that of Sydenham's chorea. The working hypothesis for the pathophysiology begins with a GAS infection in a susceptible host that incites the production of antibodies to GAS that crossreact with the cellular components of the basal ganglia, particularly in the caudate nucleus and putamen. The obsessions, compulsions, tics, and other neuropsychiatric symptoms seen in these children are postulated to arise from an interaction of these antibodies with neurons of the basal ganglia.     

Tourette's syndrome: clinical features, pathophysiology, and therapeutic approaches

Tourette's syndrome (TS) is a disorder characterized by simple and complex motor tics, vocal tics, and frequently obsessive-compulsive symptoms. Its onset occurs before the age of 21. Typically, TS shows a waxing and waning course, but a chronification of the tics, even during later life, is often observed. TS mainly occurs in boys, and shows genetic heritability with differing penetrance. The pathological mechanism is still unclear Neuroanatomical and neuroimaging studies, as well as effective treatment using antipsychotics, suggest that a disturbance of the dopaminergic system in the basal ganglia plays an important role in the pathogenesis of TS. Several possibly causative mechanisms of the disturbed dopaminergic neurotransmission are discussed, with the main emphasis on the-infection-triggered-inflammatory immune process. Extrapyramidal movement disorders are known to occur as a symptom of poststreptococcal disease, such as in Sydenham's chorea. Cases of childhood TS are proposed to be caused by such a poststreptococcal mechanism, being part of a spectrum of childhood neurobehavioral disorders termed pediatric autoimmune neuropsychiatric disorder associated with streptococcal infection (PANDAS). The overlap between TS and PANDAS is discussed, and a critical view of the PANDAS concept is presented. The therapeutic implications of the different pathological mechanisms are described, taking into consideration not only the acute or chronic natures of different infections, but also an autoimmune process. Moreover, therapeutic strategies using typical and atypical antipsychotics, and also experimental therapies such as repetitive transcranial magnetic stimulation and deep brain stimulation, are critically discussed.     

Post-streptococcal autoimmune disorders of the central nervous system

Group A Streptococcus can induce autoimmune disease in humans with particular involvement of the heart, joints, and brain. The spectrum of post-streptococcal disease of the central nervous system (CNS) has been widened recently and includes movement disorders (chorea, tics, dystonia, and Parkinsonism), psychiatric disorders (particularly emotional disorders), and associated sleep disorders. Neuroimaging and pathological studies indicate that the most vulnerable brain region is the basal ganglia. The immunopathogenesis of the disease is incompletely defined, and although there is some support for autoantibody-mediated disease, several conflicting studies cast doubt on the autoantibody hypothesis. It has been speculated that post-streptococcal autoimmunity has a role in common neuropsychiatric disease but the evidence is conflicting and routine screening of patients with Tourette syndrome and obsessive-compulsive disorder for post-streptococcal autoimmune abnormalities is not be recommended at present. However, post-streptococcal disorders of the CNS remain a useful model of neuropsychiatric disease, which may improve our understanding of abnormal movements and behaviours in children.     

Obsessive compulsive disorder: is there an association with childhood streptococcal infections and altered immune function?

During the last few years, an increased interest in the possibility of immune mediated pathophysiology of obsessive compulsive disorder (OCD) and related disorders has been seen. In the late 1980s, the National Institute of Mental Health reported an increase of obsessive compulsive symptoms in patients with Sydenham chorea (SC). Subsequently, a precipitating streptococcal infection in children with sudden onset of OCD symptoms but no chorea led to the coining of PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococcus).This association has furthered interest in studying immune parameters in non-PANDAS OCD as well. This article will review the neuropsychiatric findings in OCD and Tourette syndrome (TS) with emphasis placed on PANDAS, and its association with SC, and a review of the existing studies that have assessed immunologic measures in patients with OCD and TS.     

Soluble adhesion molecules in Gilles de la Tourette's syndrome

To investigate the immune-mediated response in TS, and its relationship with streptococcal infection, we measured serum levels of soluble intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin in patients with TS, compared to healthy and diseased controls. Soluble VCAM-1 and sE-selectin were significantly elevated in children and adults with TS, and sVCAM-1 was higher among anti-basal ganglia antibodies (ABGA)-positive adults with TS. No correlation of adhesion molecule levels to clinical severity or anti-streptococcal antibodies was observed. Children with Sydenham's chorea and paediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) showed an increased level of sICAM-1, but not sVCAM-1 and sE-selectin. These results provide initial evidence for a role of adhesion molecules and systemic inflammation in TS, and support the hypothesis of an ongoing immune-mediated process in this condition.     

Movement disorders in autoimmune diseases

Movement disorders have been known to be associated with a variety of autoimmune diseases, including Sydenham's chorea, pediatric autoimmune neuropsychiatric disorders associated with streptococcus, systemic lupus erythematosus, antiphospholipid syndrome, gluten sensitivity, paraneoplastic and autoimmune encephalopathies. Tremors, dystonia, chorea, ballism, myoclonus, parkinsonism, and ataxia may be the initial and even the only presentation of these autoimmune diseases. Although antibodies directed against various cellular components of the central nervous system have been implicated, the pathogenic mechanisms of these autoimmune movement disorders have not yet been fully elucidated. Clinical recognition of these autoimmune movement disorders is critically important as many improve with immunotherapy or dietary modifications, particularly when diagnosed early. We discuss here the clinical features, pathogenic mechanisms, and treatments of movement disorders associated with autoimmune diseases, based on our own experience and on a systematic review of the literature.     

Tourette's syndrome: a cross sectional study to examine the PANDAS hypothesis

BACKGROUND: The classical neurological disorder after group A beta haemolytic streptococcal infection is Sydenham's chorea. Recently a tic disorder occurring after group A streptococcal infection has been described and termed PANDAS (paediatric autoimmune neuropsychiatric disorders associated with streptococcal infection). It is proposed that antibodies induced after group A streptococcal infection react with basal ganglia neurones in Sydenham's chorea and PANDAS. Anti-basal ganglia antibodies (ABGA) are present in most cases of acute Sydenham's chorea, but rarely in controls. OBJECTIVE: To investigate the hypothesis that Tourette's syndrome may be associated with group A streptococcal infection and ABGA. METHODS: 100 patients with Tourette's syndrome (DSM-IV-TR) were enrolled in a cross sectional study. Children with neurological disease (n = 50) and recent uncomplicated streptococcal infection (n = 40), adults with neurological disease (n = 50), and healthy adults (n = 50) were studied as controls. Recent group A streptococcal infection was defined using antistreptolysin O titre (ASOT). ABGA were detected using western immunoblotting and indirect immunofluorescence. RESULTS: ASOT was raised in 64% of children with Tourette's syndrome compared with 15% of paediatric neurological disease controls (p < 0.0001), and in 68% of adults with Tourette's syndrome compared with 12% of adult neurological controls and 8% of adult healthy controls (p < 0.05). Western immunoblotting showed positive binding in 20% of children and 27% of adults with Tourette's syndrome, compared with 2-4% of control groups (p < 0.05). The most common basal ganglia binding was to a 60 kDa antigen, similar to the proposed antigen in Sydenham's chorea. Indirect immunofluorescence revealed autoantibody binding to basal ganglia neurones. Serological evidence of recent group A streptococcal infection, assessed by a raised ASOT, was detected in 91% (21/23) of Tourette's syndrome patients with positive ABGA compared with 57% (44/77) with negative ABGA (p < 0.01). CONCLUSIONS: The results support a role of group A streptococcal infection and basal ganglia autoimmunity in a subgroup of patients with Tourette's syndrome and suggest a pathogenic similarity between Sydenham's chorea and some patients with Tourette's syndrome.     

The psychiatric symptoms of rheumatic fever

OBJECTIVE: This study examined the frequency and age at onset of psychiatric disorders among children with rheumatic fever, Sydenham's chorea, or both and a comparison group. METHOD: Twenty children with rheumatic fever, 22 with Sydenham's chorea, and 20 comparison children were assessed by means of a semistructured interview and rating scales for tic disorders and obsessive-compulsive disorder. RESULTS: Obsessive-compulsive symptoms were more frequent in both the Sydenham's chorea and rheumatic fever groups than in the comparison group. The Sydenham's chorea group had a higher frequency of major depressive disorder, tic disorders, and attention deficit hyperactivity disorder (ADHD) than both the comparison and rheumatic fever groups. ADHD symptoms were associated with a higher risk of developing Sydenham's chorea. CONCLUSIONS: Both the rheumatic fever and Sydenham's chorea groups were associated with a higher risk of developing neuropsychiatric disorders than the comparison group. ADHD appears to be a risk factor for Sydenham's chorea in children with rheumatic fever.     

Chorea: non-genetic causes

PURPOSE OF REVIEW: The aim of this article is to review the literature on the non-genetic causes of chorea. The differential diagnosis of the large number of causes of sporadic chorea is often a challenging task. Interest has also been growing in the possibility that the mechanism responsible for Sydenham's chorea plays a role in the pathogeneis of other neuropsychiatric disorders. RECENT FINDINGS: Stroke is the main cause of sporadic chorea. Sydenham's chorea shares clinical features with tic disorders, such as obsessive-compulsive disorder and attention deficit hyperactivity disorder. However, there are unequivocal differences between Sydenham's chorea and Tourette's syndrome. There is initial evidence suggesting the beneficial effect of immunosuppression in Sydenham's chorea. Other autoimmune causes of chorea include systemic lupus erythematosus as well as paraneoplastic syndromes. The growing list of drugs associated with chorea include lamotrigine, methadone and lithium. Among infectious agents, HIV is the leading reported cause of chorea. SUMMARY: Patients with sporadic chorea require a thorough work up because numerous causes can lead to this condition. It remains unconfirmed whether the pathogenic mechanisms of Sydenham's chorea are responsible for other conditions such as isolated obsessive-compulsive disorder or Tourette's syndrome. Drugs and infectious agents, especially HIV, are often implicated in the causes of chorea.     

Acute postinfectious movement and psychiatric disorders in children and adolescents

The authors report 4 children and adolescents who had the acute onset of a movement and psychiatric disorder after a febrile illness. The differential diagnosis includes poststreptococcal syndromes (Sydenham chorea, pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection [PANDAS], acute disseminated encephalomyelitis) and other postinfectious conditions. Their cases illustrate difficulties in making an accurate diagnosis and determining proper therapy and they recommend a standard diagnostic approach. More research is needed to clarify the nature, causes, and appropriate treatment of these types of disorders.     

Obsessive-compulsive disorder and immunology: a review

Interest in the possibility of an immune-mediated pathophysiology of obsessive-compulsive disorder and related disorders has increased. In the late 1980s, the National Institute of Mental Health reported an increase in obsessive-compulsive symptoms (OCS) in patients with Sydenham chorea (SC). Subsequently, a precipitating streptococcal infection in children with sudden onset of OCS but no chorea led to the coining of PANDAS (Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection). This association has furthered interest in biological measures for immune and genetic susceptibility in non-PANDAS obsessive-compulsive disorder patients (OCD). Furthermore, some studies are trying to demonstrate alterations of immune parameters in OCD patients, with few positive results. In this narrative review, our objective was to describe the immunologic findings in OCD, PANDAS, and their association with SC.     

Infection-triggered anorexia nervosa in children: clinical description of four cases

BACKGROUND: Anorexia nervosa (AN) is a serious illness with no definitive treatment. Clinical and research evidence led to the hypothesis that some children with AN may have a pediatric autoimmune neuropsychiatric disorder associated with streptococcus (PANDAS), similar in pathogenesis to other hypothesized PANDAS disorders. METHODS: Four youngsters (ages, 11-15 years) with PANDAS AN were treated with an open trial of antibiotics, in addition to conventional treatment. They were evaluated for eating disorder and obsessive-compulsive symptoms, and for weight gain. Evidence of streptococcal infection came from clinical evaluation, throat cultures, and two serological tests: anti-deoxyribonuclease B (anti-DNase B) and anti-streptolysin O (ASO) titers. The "rheumatic" marker D8/17 was also measured. This B-cell alloantigen is associated, in several publications, with poststreptococcal autoimmunity: Rheumatic fever (RF), Sydenham's chorea (SC), and possibly PANDAS obsessive compulsive disorder (OCD) and tic disorders. RESULTS: There was clinical evidence of possible antecedent streptococcal infection in all four patients, two of whom had comorbid OCD, with possible infection-triggered AN. All four had the rheumatic marker: A percentage of D8/17-positive B cells of 28-38%, with a mean of 33% (12% or more is considered positive for the marker). The patients responded to conventional treatment plus antibiotics with weight restoration and decreased eating disorder and obsessive-compulsive symptoms. Three needed to gain weight and did so. CONCLUSIONS: There may be a link between infectious disease and some cases of AN, which raises the possibility of new treatment.     

Poststreptococcal acute disseminated encephalomyelitis with basal ganglia involvement and auto-reactive antibasal ganglia antibodies.

Antibasal ganglia antibodies (ABGA) are associated with Sydenham's chorea and pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections. We present 10 patients with acute disseminated encephalomyelitis (ADEM) associated with Group A beta hemolytic streptococcal infection. The clinical phenotype was novel, with 50% having a dystonic extrapyramidal movement disorder, and 70% a behavioral syndrome. None of the patients had rheumatic fever or Sydenham's chorea. Enzyme-linked immunosorbent assay, Western immunoblotting, and immunohistochemistry were used to detect ABGA. Neurological (n = 40) and streptococcal (n = 40) controls were used for comparison. Enzyme-linked immunosorbent assay results showed significantly elevated ABGA in the patients with poststreptococcal ADEM. Western immunoblotting demonstrated ABGA reactivity to three dominant protein bands of 60, 67, or 80 kDa; a finding not reproduced in controls. Fluorescent immunohistochemistry demonstrated specific binding to large striatal neurones, which was not seen in controls. Streptococcal serology was also significantly elevated in the poststreptococcal ADEM group compared with neurological controls. Magnetic resonance imaging studies showed hyperintense basal ganglia in 80% of patients with poststreptococcal ADEM, compared to 18% of patients with nonstreptococcal ADEM. These findings support a new subgroup of postinfectious autoimmune inflammatory disorders associated with Group A beta hemolytic streptococcus, abnormal basal ganglia imaging, and elevated ABGA.     

Striatal microinfusion of Tourette syndrome and PANDAS sera: failure to induce behavioral changes.

Rodent striatal microinfusions have been suggested as a model for assessing the behavioral effects induced by antineuronal antibodies. We used this approach to evaluate the proposed autoimmune etiology for Tourette syndrome (TS) and pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS). Sera were assessed from patients with TS (n = 9) preselected based on the presence of elevated enzyme-linked immunosorbent assay optical densities against putamen homogenate and sera from patients with PANDAS (n = 8), selected from a larger group assayed for antibodies against a putamen synaptosomal preparation. The effect of antibodies against the streptococcal M5 protein were also studied. A total of 44 Fischer rats received bilateral infusion of sera: 23 ventral striatum (5 PANDAS, 5 TS, 5 anti-M5 protein, and 8 control); 21 ventrolateral striatum (5 PANDAS, 5 TS, 5 anti-M5 protein, and 6 controls). Cannulas were placed bilaterally and symmetrically by stereotactic techniques. After animals were allowed to recover for 1 week, sera were microinfused for 3 days. Animal behavior was then simultaneously quantified by daily observation and monitoring using automated activity boxes for 10 days after infusion. No significant alterations in stereotypic behavior or movement were observed between the PANDAS, TS, or anti-M5 protein and control groups. Our findings are in contrast to previous reports, and suggest the need for further investigations to determine the validity of the model and of autoimmune-mediated hypotheses for pediatric movement disorders.