The clinical features, underlying immunology, and treatment of autoantibody-mediated movement disorders

Deep brain stimulation (DBS) in movement disorders management: exploring therapeutic efficacy, neurobiological mechanisms, and clinical implications

Introduction

Deep brain stimulation (DBS) has emerged as a promising therapeutic approach, offering targeted neuromodulation for movement disorders refractory to medical management or stereotactic surgery. However, assessing its benefits against potential risks is essential. This meta-analysis aims to evaluate the efficacy and safety of DBS in movement disorders, shedding light on its role as an alternative therapeutic option.

Methods

A comprehensive search of databases after systemic review yielded studies published in English from 2000 to the present. Data selection, screening, extraction, and risk of bias assessment were performed meticulously. Statistical analysis was conducted using RevMan 2.0, with significant heterogeneity addressed through appropriate methods.

Results

Our meta-analysis included 40 studies assessing the Unified Parkinson's Disease Rating Scale Part III, revealing a significant improvement in motor symptoms (mean difference [MD]: -18.05, 95% confidence interval [CI] [-20.17, -15.93], P < 0.00001). Hoehn and Yahr Stage analysis demonstrated a reduction in disease severity (MD: -0.58, 95% CI [-1.05, -0.12], P = 0.01). Tremor severity (MD: -8.22, 95% CI [-12.30, -4.15], P < 0.0001), overall tremor (MD: -2.68, 95% CI [-4.59, -0.77], P = 0.006), gait velocity (MD: 0.13, 95% CI [0.08, 0.18], P < 0.00001), and Yale Global Tic Severity Scale score (MD: -9.75, 95% CI [-14.55, -4.96], P < 0.0001) also showed significant improvements with DBS.

Conclusion

DBS demonstrates efficacy in improving motor symptoms, disease severity, tremor, gait, and tic severity in movement disorders. However, further research is needed to elucidate long-term efficacy and safety outcomes.

Clinical Reasoning: Juvenile-Onset Dopa-Responsive Dystonia-Until It Isn't

Dopa-responsive dystonia (DRD) encompasses a broad spectrum of phenotypically diverse conditions, offering unique diagnostic challenges. We describe the case of a 24-year-old woman with dystonic gait and jerky position-sensitive limb tremor that initially responded exquisitely well to low-dose levodopa, suggesting DRD. Two years later, she developed parkinsonian features, ultimately leading to a diagnostic reclassification. Despite extensive investigations, the underlying etiology remained elusive until 10 years after symptom onset. We discuss this DRD mimic and briefly review the disorders from which it must be distinguished.

Anti-carbamylated protein antibodies drive AEC II toward a profibrotic phenotype by interacting with carbamylated TLR5

OBJECTIVES

This study looked at the role of anti-carbamylated protein (anti-CarP) antibodies in contributing to lung fibrosis in CTD-associated interstitial lung disease (ILD) in an autoantigen-dependent manner.

METHODS

ELISA was used to test serum samples, including 89 from the CTD-ILD group and 170 from the non-CTD-ILD group, for anti-CarP levels. Male C57BL/6 mice were used for the pulmonary fibrosis model and anti-CarP treatment in vivo (n = 5) and patient serum-derived or commercialized anti-CarP was used for cell treatment. We identified the carbamylated membrane protein via immunofluorescence (IF) and co-immunoprecipitation followed by mass spectrometry (MS) analysis. Quantitative RT-PCR, IF and western blot were performed to explore the antigen-dependent role of anti-CarP. A native electrophoretic mobility shift assay and MS analysis were used to verify direct interaction and carbamylation sites.

RESULTS

A significantly higher serum anti-CarP level was observed in CTD with ILD than without ILD. In vivo, intrapulmonary delivery of anti-CarP induces epithelial-mesenchymal transition (EMT) and microfibrotic foci. Carbamylation was enriched in type II alveolar epithelial cells (AEC II). A novel carbamylated membrane receptor, specifically recognized by anti-CarP, was identified as toll-like receptor 5 (TLR5). We found anti-CarP induces the nuclear translocation of NF-κB and downstream events, including EMT and expression of inflammatory cytokines in AEC II, which were reversed by TLR5 blocking or TLR5 knockdown. Moreover, up to 12 lysine carbamylation sites were found in TLR5 ectodomain, allowing the interaction of anti-CarP with carbamylated TLR5.

CONCLUSIONS

Overall, we found anti-CarP drives aberrant AEC II activation by interacting with carbamylated TLR5 to promote ILD progression.

Autoimmune Movement Disorders Complicating Treatment with Immune Checkpoint Inhibitors

BACKGROUND

Immune checkpoint inhibitors (ICI) may trigger autoimmune neurological conditions, including movement disorders (MD).

OBJECTIVES

The aim of this study was to characterize MDs occurring as immune-related adverse events (irAEs) of ICIs.

METHODS

A systematic literature review of case reports/series of MDs as irAEs of ICIs was performed.

RESULTS

Of 5682 eligible papers, 26 articles with 28 patients were included. MDs occur as a rare complication of cancer immunotherapy with heterogeneous clinical presentations and in most cases in association with other irAEs. Inflammatory basal ganglia T2/fluid attenuated inversion recovery abnormalities are rarely observed, but brain imaging is frequently unrevealing. Cerebrospinal fluid findings are frequently suggestive of inflammation. Half of cases are associated with a wide range of autoantibodies. Steroids and ICI withdrawal usually lead to improvement, even though some patients experienced relapses or a severe clinical course.

CONCLUSION

MDs are a rare complication of ICIs that should be promptly recognized to offer patients a correct diagnosis and treatment.

Paraneoplastic Cerebellar Degeneration Associated with Breast Cancer: A Case Report and a Narrative Review

Paraneoplastic neurological syndromes (PNSs) are an uncommon complication of cancer, affecting nearby 1/10,000 subjects with a tumour. PNSs can involve all the central and peripheral nervous systems, the muscular system, and the neuromuscular junction, causing extremely variable symptomatology. The diagnosis of the paraneoplastic disease usually precedes the clinical manifestations of cancer, making an immediate recognition of the pathology crucial to obtain a better prognosis. PNSs are autoimmune diseases caused by the expression of common antigens by the tumour and the nervous system. Specific antibodies can help clinicians diagnose them, but unfortunately, they are not always detectable. Immunosuppressive therapy and the treatment of cancer are the cornerstones of therapy for PNSs. This paper reports a case of PNSs associated with breast tumours and focuses on the most common paraneoplastic neurological syndromes. We report a case of a young female with a clinical syndrome of the occurrence of rigidity in the right lower limb with postural instability with walking supported and diplopia, with a final diagnosis of paraneoplastic cerebellar degeneration and seronegative rigid human syndrome associated with infiltrating ductal carcinoma of the breast.

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.

Movement disorders associated with pediatric encephalitis

New onset movement disorders are a common clinical problem in pediatric neurology and can be infectious, inflammatory, metabolic, or functional in origin. Encephalitis is one of the more important causes of new onset movement disorders, and movement disorders are a common feature (~25%) of all encephalitis. However, all encephalitides are not the same, and movement disorders are a key diagnostic feature that can help the clinician identify the etiology of the encephalitis, and therefore appropriate treatment is required. Movement disorders are a characteristic feature of autoimmune encephalitis such as anti-NMDAR encephalitis, herpes simplex virus encephalitis-induced autoimmune encephalitis, and basal ganglia encephalitis. Other rarer autoantibody-associated encephalitis syndromes with movement disorder associations include encephalitis associated with glycine receptor, DPPX, and neurexin-3 alpha autoantibodies. In addition, movement disorders can accompany acute disseminated encephalomyelitis with and without myelin oligodendrocyte glycoprotein antibodies. Extremely important infectious encephalitides that have characteristic movement disorder associations include Japanese encephalitis, dengue fever, West Nile virus, subacute sclerosing panencephalitis (SSPE), and SARS-CoV-2 (COVID-19). This chapter discusses how specific movement disorder phenomenology can aid clinician diagnostic suspicion, such as stereotypy, perseveration, and catatonia in anti-NMDAR encephalitis, dystonia-Parkinsonism in basal ganglia encephalitis, and myoclonus in SSPE. In addition, the chapter discusses how the age of the patients can influence the movement disorder phenomenology, such as in anti-NMDAR encephalitis where chorea is typical in young children, even though catatonia and akinesia is more common in adolescents and adults.

Movement disorders in autoimmune encephalitis: an update

Autoimmune encephalitis (AE) is a form of encephalitis resulting from an immune response targeting central nervous system antigens, which is characterized by cognitive impairment, neuropsychiatric symptoms, seizures, movement disorders (MDs), and other encephalopathy symptoms. MDs frequently manifest throughout the progression of the disease, with recurrent involuntary movements leading to discomfort and, in some cases, necessitating admission to the intensive care unit. Prompt identification and management of MDs can aid in the diagnosis and prognosis of AE. This review synthesizes current knowledge on the characteristics, underlying mechanisms, and treatment options for MDs in the context of AE.

Clinical Features and Neuroimaging Findings of Neuropil Antibody-Positive Idiopathic Sporadic Ataxia of Unknown Etiology

Idiopathic sporadic ataxia (ISA) is the clinical term for nonfamilial ataxia with adult-onset and a slowly progressive course. However, immune-mediated cerebellar ataxia cannot be completely excluded from ISA. The current study investigated the neuropil antibodies against cell-surface antigens and clarified the clinical features and neuroimaging findings of patients with these antibodies. Using tissue-based immunofluorescence assays (TBAs), we examined antibodies against the cerebellum in serum samples from 67 patients who met the ISA diagnostic criteria, including 30 patients with multiple system atrophy with predominant cerebellar features (MSA-C) and 20 patients with hereditary ataxia (HA), and 18 healthy control subjects. According to the TBA results, we divided subjects into three groups: subjects positive for neuropil antibodies, subjects positive for intracellular antibodies only, and subjects negative for antibodies. We compared clinical features and neuroimaging findings in ISA patients among these three groups. The prevalence of neuropil antibodies in ISA (17.9%) was significantly higher than that in MSA-C (3.3%), HA (0%), or healthy subjects (0%). The neuropil antibody-positive ISA patients showed pure cerebellar ataxia more frequently than the other ISA patients. Two neuropil antibody-positive patients showed significant improvement of cerebellar ataxia after immunotherapy. We detected neuropil antibodies in 17.9% of ISA patients. Characteristic clinical features of neuropil antibody-positive ISA patients were pure cerebellar ataxia. Some cases of neuropil antibody-positive ISA responded to immunotherapy.

Autoimmune encephalitis: recent clinical and biological advances

In 2015, we wrote a review in The Journal of Neurology summarizing the field of autoantibody-associated neurological diseases. Now, in 2023, we present an update of the subject which reflects the rapid expansion and refinement of associated clinical phenotypes, further autoantibody discoveries, and a more detailed understanding of immunological and neurobiological pathophysiological pathways which mediate these diseases. Increasing awareness around distinctive aspects of their clinical phenotypes has been a key driver in providing clinicians with a better understanding as to how these diseases are best recognized. In clinical practice, this recognition supports the administration of often effective immunotherapies, making these diseases 'not to miss' conditions. In parallel, there is a need to accurately assess patient responses to these drugs, another area of growing interest. Feeding into clinical care are the basic biological underpinnings of the diseases, which offer clear pathways to improved therapies toward enhanced patient outcomes. In this update, we aim to integrate the clinical diagnostic pathway with advances in patient management and biology to provide a cohesive view on how to care for these patients in 2023, and the future.

Paraneoplastic Stiff Person Syndrome With Anti-amphiphysin Antibodies Presenting With Pruritus as the Initial Manifestation: An Unusual Case

Stiff person syndrome (SPS), also known as Stiff-man syndrome/Moersch-Woltman syndrome, is a rare disorder of the central nervous system, first described in 1956, characterized by rigidity and stimulus-triggered painful muscle spasms of predominantly axial and proximal limb muscles. There are many variants of SPS; these include the classical SPS, stiff leg syndrome, and paraneoplastic variant. The paraneoplastic variant of SPS is more common in patients with breast cancer with anti-amphiphysin antibodies, followed by colon carcinoma, lung carcinomas, thymoma, and Hodgkin's lymphoma. A possible autoimmune origin for the disease has been proposed, including antibodies against glutamic acid decarboxylase and amphiphysin. We thus describe a case of anti-amphiphysin antibody-positive SPS, which initially manifested with generalized pruritus. After extensive investigations and removing her underlying tumor, she reported complete recovery of her symptoms.

A novel diagnostic approach for patients with adult-onset dystonia

Adult-onset dystonia can be acquired, inherited or idiopathic. The dystonia is usually focal or segmental and for a limited number of cases causal treatment is available. In recent years, rapid developments in neuroimmunology have led to increased knowledge on autoantibody-related dystonias. At the same time, genetic diagnostics in sequencing technology have evolved and revealed several new genes associated with adult-onset dystonia. Furthermore, new phenotype-genotype correlations have been elucidated. Consequently, clinicians face the dilemma of which additional investigations should be performed and whether to perform genetic testing or not. To ensure early diagnosis and to prevent unnecessary investigations, integration of new diagnostic strategies is needed.We designed a new five-step diagnostic approach for adult-onset dystonia. The first four steps are based on a broad literature search and expert opinion, the fifth step, on when to perform genetic testing, is based on a detailed systematic literature review up to 1 December 2021.The basic principle of the algorithm is that genetic testing is unlikely to lead to changes in management in three groups: (1) patients with an acquired form of adult-onset dystonia; (2) patients with neurodegenerative disorders, presenting with a combined movement disorder including dystonic symptoms and (3) patients with adult-onset isolated focal or segmental dystonia. Throughout the approach, focus lies on early identification of treatable forms of dystonia, either acquired or genetic.This novel diagnostic approach for adult-onset dystonia can help clinicians to decide when to perform additional tests, including genetic testing and facilitates early aetiological diagnosis, to enable timely treatment.

Association between clinical factors and orofacial dyskinesias in anti-N-methyl-D-aspartate receptor encephalitis

BACKGROUND AND PURPOSE

We aimed to determine whether demographic information, clinical characteristics, laboratory tests, and imaging features are associated with orofacial dyskinesias (OFLD) in patients with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis.

METHODS

In this retrospective study, patients who were diagnosed with anti-NMDAR encephalitis were enrolled. All patients' factors, including demographic information, clinical characteristics, laboratory tests, and imaging features, were obtained at the time of hospitalization. The neurological function was assessed using the modified Rankin scale (mRS). Univariate and multivariate logistic regressions were used to examine the associations between clinical factors and OFLD.

RESULTS

In total, 119 patients (median age: 28.0 [19.0-41.0] years; 67 females) were recruited. Of 119 patients, 44 (37.0%) had OFLD. OFLD was associated with increased mRS at admission, serum sodium, lumbar puncture pressure, female biologic sex, fever, psychiatric symptoms, seizures, impaired consciousness, autonomic dysfunction, and central hypoventilation in univariate logistic regression, respectively. Multivariate regression analysis revealed that female biologic sex (odds ratios [OR], 4.73; 95% confidence interval [CI], 1.27-17.64; p = .021), increased mRS at admission (OR, 2.09; 95% CI, 1.18-3.71; p = .011), psychiatric symptoms (OR, 7.27; 95% CI, 1.20-43.91; p = .031), and seizures (OR, 5.11; 95% CI, 1.22-21.43; p = .026) were associated with OFLD, after adjusting for confounding factors.

CONCLUSIONS

Our analysis suggests that the following clinical factors are associated with OFLD: female biologic sex, increased mRS at admission, psychiatric symptoms, and seizures.

Development of Diagnosis Model for Early Lung Nodules Based on a Seven Autoantibodies Panel and Imaging Features

Background

There is increasing incidence of pulmonary nodules due to the promotion and popularization of low-dose computed tomography (LDCT) screening for potential populations with suspected lung cancer. However, a high rate of false-positive and concern of radiation-related cancer risk of repeated CT scanning remains a major obstacle to its wide application. Here, we aimed to investigate the clinical value of a non-invasive and simple test, named the seven autoantibodies (7-AABs) assay (P53, PGP9.5, SOX2, GAGE7, GUB4-5, MAGEA1, and CAGE), in distinguishing malignant pulmonary diseases from benign ones in routine clinical practice, and construct a neural network diagnostic model with the development of machine learning methods.

Method

A total of 933 patients with lung diseases and 744 with lung nodules were identified. The serum levels of the 7-AABs were tested by an enzyme-linked Immunosorbent assay (ELISA). The primary goal was to assess the sensitivity and specificity of the 7-AABs panel in the detection of lung cancer. ROC curves were used to estimate the diagnosis potential of the 7-AABs in different groups. Next, we constructed a machine learning model based on the 7-AABs and imaging features to evaluate the diagnostic efficacy in lung nodules.

Results

The serum levels of all 7-AABs in the malignant lung diseases group were significantly higher than that in the benign group. The sensitivity and specificity of the 7-AABs panel test were 60.7% and 81.5% in the whole group, and 59.7% and 81.1% in cases with early lung nodules. Comparing to the 7-AABs panel test alone, the neural network model improved the AUC from 0.748 to 0.96 in patients with pulmonary nodules.

Conclusion

The 7-AABs panel may be a promising method for early detection of lung cancer, and we constructed a new diagnostic model with better efficiency to distinguish malignant lung nodules from benign nodules which could be used in clinical practice.

Diagnosis and Clinical Features in Autoimmune-Mediated Movement Disorders

Movement disorders are common manifestations in autoimmune-mediated encephalitis. This group of diseases is suspected to be triggered by infection or neoplasm. Certain phenotypes correlate with specific autoantibody-related neurological disorders, such as orofacial-lingual dyskinesia with N-methyl-D-aspartate receptor encephalitis and faciobrachial dystonic seizures with leucine-rich glioma-inactivated protein 1 encephalitis. Early diagnosis and treatment, especially for autoantibodies targeting neuronal surface antigens, can improve prognosis. In contrast, the presence of autoantibodies against intracellular neuronal agents warrants screening for underlying malignancy. However, early clinical diagnosis is challenging because these diseases can be misdiagnosed. In this article, we review the distinctive clinical phenotypes, magnetic resonance imaging findings, and current treatment options for autoimmune-mediated encephalitis.

Stiff-person syndrome with paraneoplastic neurological syndrome: a case report and literature review

BACKGROUND

Stiff-person syndrome (SPS) manifests by progressive rigidity along with muscle spasms that affect the axial and limb muscles. First discovered in 1956, significant progress has been made in its clinical characterization, comprehension of pathogenesis, as well as effective treatment therapy.

CASE PRESENTATION

A 67-year old female patient presented with a 2-year history of progressive stiffness along with painful spasms in both legs, with her condition worsening over the previous year making it considerably difficult for her to stand and walk. Here, we report a Stiff-person syndrome patient (SPS) with lung adenocarcinoma who was positive for anti-glutamate decarboxylase (anti-GAD) antibodies. Treatment with hormones and gamma-globulin improved her symptoms. In addition, we present a literature review of SPS patients with tumors.

CONCLUSIONS

The diagnosis of autoimmune SPS was on the basis of clinical, electrophysiological, as well as immunological findings. Early SPS detection is critical to preventing long-term disability.

Clinical features and outcome of patients with autoimmune cerebellar ataxia evaluated with the Scale for the Assessment and Rating of Ataxia

BACKGROUND AND PURPOSE

This study was undertaken to assess the long-term outcome of patients with paraneoplastic and non paraneoplastic autoimmune cerebellar ataxia (ACA) using the Scale for the Assessment and Rating of Ataxia (SARA).

METHODS

Patients with subacute cerebellar ataxia admitted to our institution between September 2012 and April 2020 were prospectively recruited. Serum and/or cerebrospinal fluid was tested for neural autoantibodies by indirect immunofluorescence on mouse brain, cell-based assays, and radioimmunoassay. SARA and modified Rankin Scale (mRS) score were employed to assess patients' outcome.

RESULTS

Fifty-five patients were recruited, of whom 23 (42%) met the criteria for cerebellar ataxia of autoimmune etiology. Neural autoantibodies were detected in 22 of 23 patients (Yo-immunoglobulin G [IgG], n = 6; glutamic acid decarboxylase 65-IgG, n = 3; metabotropic glutamate receptor 1-IgG, n = 2; voltage-gated calcium channel P/Q type-IgG, n = 2; Hu-IgG, n = 1; glial fibrillary acidic protein-IgG, n = 1; IgG-binding unclassified antigens, n = 7). Thirteen patients were diagnosed with paraneoplastic cerebellar syndrome (PCS) and 10 with idiopathic ACA. All patients received immunotherapy. Median SARA score was higher in the PCS group at all time points (p = 0.0002), while it decreased significantly within the ACA group (p = 0.049) after immunotherapy. Patients with good outcome (mRS ≤ 2) had less neurological disability (SARA < 15) at disease nadir (p = 0.039) and presented less frequently with paraneoplastic neurological syndrome (p = 0.0028). The univariate linear regression model revealed a good correlation between mRS and SARA score both at disease onset (p < 0.0001) and at last follow-up (p < 0.0001). SARA score < 11 identified patients with good outcome.

CONCLUSIONS

Patients with idiopathic ACA significantly improved after immunotherapy. SARA score accurately reflects patients' clinical status and may be a suitable outcome measure for patients with ACA.

Movement disorders associated with neuronal antibodies: a data-driven approach

Background

Movement disorders can be associated with anti-neuronal antibodies.

Methods

We conducted a systematic review of cases with documented anti-neuronal antibodies in serum and/or cerebrospinal fluid published in PubMed before April 1, 2020. Only patients with at least one movement disorder were included. We used random forests for variable selection and recursive partitioning and regression trees for the creation of a data-driven decision algorithm, integrated with expert’s clinical feedback.

Results

Three hundred and seventy-seven studies met eligibility criteria, totaling 844 patients and 13 antibodies: amphiphysin, GAD, GlyR, mGluR1, ANNA-2/Ri, Yo/PCA-1, Caspr2, NMDAR, LGI-1, CRMP5/CV2, ANNA-1/Hu, IgLON5, and DPPX. Stiffness/rigidity/spasm spectrum symptoms were more frequently associated with amphiphysin, GAD, and GlyR; ataxia with mGluR1, ANNA-2/Ri, Yo/PCA-1, Caspr2, and ANNA-1/Hu; dyskinesia with NMDAR and paroxysmal movement with LGI1; chorea/choreoathetosis with CRMP5/CV2, IgLON5, and NMDAR; myoclonus with GlyR and DPPX; tremors with ANNA2/Ri and anti-DPPX; and parkinsonism with IgLON5 and NMDAR. Data-driven classification analysis determined the following diagnostic predictions (with probability selection): psychiatric symptoms and dyskinesia predicted NMDAR (71% and 87%, respectively); stiffness/rigidity/spasm and ataxia, GAD (67% and 47%, respectively); ataxia and opsoclonus, ANNA-2/Ri (68%); chorea/choreoathetosis, CRMP5/CV2 (41%). These symptoms remained the top predictors in random forests analysis. The integration with an expert opinion analysis refined the precision of the approach. Breast and lung tumors were the most common tumors. On neuroimaging, cerebellar involvement was associated with GAD and Yo/PCA-1; temporal involvement with Caspr2, LGI-1, ANNA-1/Hu.

Conclusion

Selected movement disorders are associated with specific anti-neuronal antibodies. The combination of data-driven and expert opinion approach to the diagnosis may assist early management efforts.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-021-10934-7.

Parkinsonism in viral, paraneoplastic, and autoimmune diseases

Secondary parkinsonism, namely parkinsonism due to causes other than idiopathic neurodegeneration, may have multiple etiologies. Common secondary etiologies of parkinsonism such as drug-induced or vascular etiologies are well documented. Other secondary causes of parkinsonism such as infectious (mainly viral and prion-like diseases), autoimmune (systemic/drug-induced) and paraneoplastic etiologies are rare but are a topic of increasing interest. Older examples from the existing literature demonstrate the intricacies of viral infection from the last pandemic of the 20th century on the development of hypokinetic symptoms experienced in post-encephalitic patients. Viral and prion-like infections are only part of a complex interplay between the body's immune response and aberrant cell cycle perturbations leading to malignancy. In addition to the classic systemic autoimmune diseases (mainly systemic lupus erythematosus - SLE, and Sjögren syndrome), there have been new developments in the context of the current COVID-19 pandemic as well as more prominent use of immunotherapies such as immune checkpoint inhibitors in the treatment of solid tumors. Both of these developments have deepened our understanding of the underlying pathophysiologic process. Increased awareness and understanding of these rarer etiologies of parkinsonism is crucial to the modern diagnostic evaluation of a patient with parkinsonian symptoms as the potential treatment options may differ from the conventional levodopa-based therapeutic regimen of idiopathic Parkinson's disease. This review article aims to give an up-to-date review of the current literature on parkinsonian symptoms, their pathogenesis, diagnostic methods, and available treatment options. Many potential future directions in the field of parkinsonian conditions remain to be explored. This article is part of the Special Issue "Parkinsonism across the spectrum of movement disorders and beyond" edited by Joseph Jankovic, Daniel D. Truong and Matteo Bologna.

Progressive encephalomyelitis with rigidity: A Taiwanese case and review of literature

INTRODUCTION

Progressive encephalomyelitis with rigidity and myoclonus (PERM) is a rare disorder. However, the outcome is still variable with different serological and tumor associations, and the elements to good response with less relapse is yet to be elucidated.

METHOD

We present a case and obtain a literature review of patients with PERM and make comparisons based on different serological groups. We also analyze patients with idiopathic PERM that had detailed medical records.

RESULTS

81 patients were collected and analyzed. The largest group were glycine receptor-antibody (GlyR-Ab)-positive (70%), and the seropositive-GlyR-Ab-negative group had better response to immunotherapy. Malignancy can occur up to 2 years from the presentation of PERM. Among the 18 cases with detailed records, the patients who had good outcome initiate immunotherapy within 2 months from presentation. 9 of the 12 patients who experienced no relapse had non-steroid immunotherapy. The maximal interval time of relapse was 24 months.

CONCLUSION

We recommend tumor surveillance up to 2 years in patients with PERM and early administration of immunotherapies and maintain with non-steroid immunotherapy with or without oral corticosteroid for a minimum of 2 years to reduce the risk of relapse in GlyR-Ab-positive patients.

Involuntary movement in stiff-person syndrome with amphiphysin antibodies: A case report

RATIONALE

Stiff-person syndrome (SPS) is a rare neurological immune disorder characterized by progressive axial and proximal limb muscle rigidity, stiffness, and painful muscle spasms. Amphiphysin antibodies are positive in approximately 5% of SPS patients. To date, there have been no relevant reports on involuntary movement in cases of SPS with amphiphysin antibodies.

PATIENT CONCERNS

We describe the case of a 69-year-old man with a 2-year history of progressive stiffness in the neck, bilateral shoulders, and chest muscles, and a more-than-a-year history of dyspnea accompanied by mandibular involuntary movement. The patient was a vegetarian and had good health in the past. The family's medical history was unremarkable.

DIAGNOSES

He was diagnosed with SPS based on the progressive muscle stiffness, the amphiphysin antibody seropositivity, the continuous motor activity on electromyography, and the effective treatment with benzodiazepines.

INTERVENTIONS

The patient was orally administered clonazepam and baclofen, and corticosteroid IV followed by prednisone orally.

OUTCOMES

In the hospital, after treatment with methylprednisolone, clonazepam, and baclofen, the patient's rigidity, stiffness, and dyspnea significantly improved. The involuntary movement of the mandible persisted throughout the treatment process. Currently, under oral treatment with baclofen and clonazepam, the patient's symptoms of muscle stiffness and dyspnea exist, and follow-up is continued.

LESSONS

We report a rare and novel case of involuntary movement in SPS with amphiphysin antibodies. The present report explores the relationship between SPS and involuntary movement and expands the spectrum of clinical manifestations of SPS.

Movement disorders in primary central nervous system lymphoma: two unreported cases and a review of literature

BACKGROUND

Recognition of secondary movement disorders (SMDs) is fundamental either to alleviate disabling disturbances or to treat potentially life-threatening conditions, such as brain tumors. Primary CNS lymphoma (PCNSL) is a rare form of CNS cancer that is often located in subcortical areas, accounting for both neuropsychiatric and motoric disorders. Nevertheless, an overview on PCNSL-related movement disorders (MDs) phenomenology has not been provided yet.

OBJECTIVE

To outline the main features of PCNSL-related MDs.

METHODS

A retrospective analysis was conducted on a cohort of patients with PCNSL presenting with MDs, including all existing cases identified by a systematic literature review (source: Medline; period: 1946-2020) and two unreported cases. Data on phenomenology, neuroimaging, histology, and clinical course were collected.

RESULTS

A total cohort of fifteen subjects was defined, enrolling thirteen previously described patients extracted from eleven published studies, and our two unreported cases. A parkinsonian syndrome appearing at about 60 years of age, unresponsive to levodopa, associated to other neurological signs, resulted as the most common presentation of PCNSL-related MD. Chorea, dystonia, and dyskinesia occurred less frequently, with some degree of responsiveness to symptomatic treatments. Basal ganglia were involved in most cases and motoric disturbances often ameliorated after tumor mass reduction.

CONCLUSIONS

This study identified those features of PCNSL-related MDs that could support an appropriate approach to such a rare condition. In fact, while the outcome remains still poor, the therapeutic scenario of PCNSL is changing; an early diagnosis together with an adequate management will be thus crucial for timely and successful interventions.

Clinical diagnosis of LGI1 antibody encephalitis in an 83-year-old woman

An 83-year-old woman was referred to hospital with a 2-week history of short-lived episodic unpleasant sensations in her head and running down her body. This was accompanied by new short-term memory impairment and arm spasms. Initial investigations including blood tests and brain imaging did not reveal the diagnosis. The patient developed an increasing frequency of abnormal movements of her face and arm. These were clinically recognised as faciobrachial dystonic seizures (FBDS). FBDS are pathognomonic of an autoimmune encephalitis caused by an antibody directed against leucine-rich glioma-inactivated 1 (LGI1). The clinical diagnosis resulted in treatment with immunotherapy, leading to cessation of seizures and rapid cognitive recovery. Later, the predicted serology was confirmed. This reversible and under-recognised cause of cognitive impairment, typically affecting elderly patients, can be diagnosed clinically to enable early and effective treatment.

Current challenges in the pathophysiology, diagnosis, and treatment of paroxysmal movement disorders

INTRODUCTION

Paroxysmal movement disorders mostly comprise paroxysmal dyskinesia and episodic ataxia, and can be the consequence of a genetic disorder or symptomatic of an acquired disease.

AREAS COVERED

In this review, the authors focused on certain hot-topic issues in the field: the respective contribution of the cerebellum and striatum to the generation of paroxysmal dyskinesia, the importance of striatal cAMP turnover in the pathogenesis of paroxysmal dyskinesia, the treatable causes of paroxysmal movement disorders not to be missed, with a special emphasis on the treatment strategy to bypass the glucose transport defect in paroxysmal movement disorders due to GLUT1 deficiency, and functional paroxysmal movement disorders.

EXPERT OPINION

Treatment of genetic causes of paroxysmal movement disorders is evolving towards precision medicine with targeted gene-specific therapy. Alteration of the cerebellar output and modulation of the striatal cAMP turnover offer new perspectives for experimental therapeutics, at least for paroxysmal movement disorders due to selected causes. Further characterization of cell-specific molecular pathways or network dysfunctions that are critically involved in the pathogenesis of paroxysmal movement disorders will likely result in the identification of new biomarkers and testing of innovative-targeted therapeutics.

Emergency presentations of movement disorders

Movement disorders are typically perceived as being gradually progressive conditions that are managed in outpatient settings. However, they may manifest de novo with an acute severe phenotype or an acute decompensation. A movement disorder becomes an emergency when it evolves acutely or subacutely over hours to days; delays in its diagnosis and treatment may cause significant morbidity and mortality. Here we address the clinical presentation, diagnosis and management of those movement disorder emergencies that are principally encountered in emergency departments, in acute receiving units or in intensive care units. We provide practical guidance for management in the acute setting where there are several treatable causes not to be missed. The suggested medication doses are predominantly based on expert opinion due to limited higher-level evidence. In spite of the rarity of movement disorder emergencies, neurologists need to be familiar with the phenomenology, potential causes and treatments of these conditions. Movement disorder emergencies divide broadly into two groups: hypokinetic and hyperkinetic, categorised according to their phenomenology. Most acute presentations are hyperkinetic and some are mixed.

Treatment of Movement Disorder Emergencies in Autoimmune Encephalitis in the Neurosciences ICU

Immune response against neuronal and glial cell surface and cytosolic antigens is an important cause of encephalitis. It may be triggered by activation of the immune system in response to an infection (para-infectious), cancer (paraneoplastic), or due to a patient's tendency toward autoimmunity. Antibodies directed toward neuronal cell surface antigens are directly pathogenic, whereas antibodies with intracellular targets may become pathogenic if the antigen is transiently exposed to the cell surface or via activation of cytotoxic T cells. Immune-mediated encephalitis is well recognized and may require intensive care due to status epilepticus, need for invasive ventilation, or dysautonomia. Patients with immune-mediated encephalitis may become critically ill and display clinically complex and challenging to treat movement disorders in over 80% of the cases (Zhang et al. in Neurocrit Care 29(2):264-272, 2018). Treatment options include immunotherapy and symptomatic agents affecting dopamine or acetylcholine neurotransmission. There has been no prior published guidance for management of these movement disorders for the intensivist. Herein, we discuss the immune-mediated encephalitis most likely to cause critical illness, clinical features and mechanisms of movement disorders and propose a management algorithm.

Chorea

PURPOSE OF REVIEW

This article provides an overview of the approach to chorea in clinical practice, beginning with a discussion of the phenomenologic features of chorea and how to differentiate it from other movement disorders. The diagnostic approach, clinical features of important acquired and genetic choreas, and therapeutic principles are also discussed. Practical clinical points and caveats are included.

RECENT FINDINGS

C9orf72 disease is the most common Huntington disease phenocopy, according to studies in the European population. Anti-IgLON5 disease can present with chorea. The role of immunotherapies in Sydenham chorea has increased, and further clinical studies may be useful. Benign hereditary chorea is a syndrome or phenotype due to mutations in several genes, including NKX2-1, ADCY5, GNAO1, and PDE10A. New-generation presynaptic dopamine-depleting agents provide more options for symptomatic treatment of chorea with fewer adverse effects. Deep brain stimulation has been performed in several choreic disorders, but features other than chorea and the neurodegenerative nature should be taken into consideration. Studies on genetic interventions for Huntington disease are ongoing.

SUMMARY

Clinical features remain crucial in guiding the differential diagnosis and appropriate investigations in chorea. Given the complexity of most choreic disorders, treating only the chorea is not sufficient. A comprehensive and multidisciplinary approach is required.

Stiff Person Syndrome and Acetylcholine Receptor Ganglionic Neuronal Antibodies

The association between stiff person syndrome and paraneoplastic syndromes has been described, linking intracellular or extracellular antibodies. We describe the case of a 64-year-old woman with stiff person syndrome and positivity for acetylcholine receptor ganglionic neuronal antibodies, which can also be seen in muscular hyperexcitability conditions, as well as other paraneoplastic syndromes. The relevance of this report is the possible direct elevation of this antibody due to a direct immunological cause. Acetylcholine receptor ganglionic neuronal antibodies have been reported with autoimmune autonomic neuropathy and paraneoplastic syndromes linked to lung cancer and myastheniform syndromes, as well as in some muscular hyperexcitability states, but not in stiff person syndrome.

Leucine-Rich Glioma-Inactivated 1 Encephalitis: Broadening the Sphere

Background

Leucine-rich glioma-inactivated 1 (LGI1) encephalitis is a rare entity. Its typical features are seizures, faciobrachial dystonic seizures (FBDS), cognitive impairment, and personality changes.

Case report

We report the case of a 66-year-old man with an unusual presentation, consisting of two types of FBDS, one starting in the foot and the other consisting of asynchronous myoclonic and dystonic jerks of the face triggered by noise and chin stimulation. The patient displayed no personality changes or cognitive impairment.

Discussion

LGI1 encephalitis is a heterogeneous disease. Many different forms of FBDS may be observed, and these seizures can be the only symptom. This type of encephalitis should be suspected in presenting very frequent episodic events with dystonic features, regardless of the part of the body affected.

The autoantibody-mediated encephalitides: from clinical observations to molecular pathogenesis

The autoimmune encephalitis (AE) syndromes have been characterised by the detection of autoantibodies in serum and/or cerebrospinal fluid which target the extracellular domains of specific neuroglial antigens. The clinical syndromes have phenotypes which are often highly characteristic of their associated antigen-specific autoantibody. For example, the constellation of psychiatric features and the multi-faceted movement disorder observed in patients with NMDAR antibodies are highly distinctive, as are the faciobrachial dystonic seizures observed in close association with LGI1 antibodies. These typically tight correlations may be conferred by the presence of autoantibodies which can directly access and modulate their antigens in vivo. AE remains an under-recognised clinical syndrome but one where early and accurate detection is critical as prompt initiation of immunotherapy is closely associated with improved outcomes. In this review of a rapidly emerging field, we outline molecular observations with translational value. We focus on contemporary methodologies of autoantibody detection, the evolution and distinctive nature of the clinical phenotypes, generalisable therapeutic paradigms, and finally discuss the likely mechanisms of autoimmunity in these patients which may inform future precision therapies.

Daratumumab treatment for therapy-refractory anti-CASPR2 encephalitis

The anti-CD38 antibody daratumumab is approved for treatment of refractory multiple myeloma and acts by depletion of plasma cells and modification of various T-cell functions. Its safety, immunological effects and therapeutic potential was evaluated in a 60-year old patient with life-threatening and treatment-refractory anti-CASPR2 encephalitis requiring medical care and artificial ventilation in an intensive care unit. His autoimmune dysfunction was driven by exceptional high anti-CASPR2 autoantibody titers combined with an abnormally increased T-cell activation. As he remained unresponsive to standard and escalation immunotherapies (methylprednisolone, plasma exchange, immunoadsorption, immunoglobulins, rituximab and bortezomib), therapy was escalated to 13 cycles of 16 mg/kg daratumumab. During the treatment period, clinical, radiological, histological and laboratory findings, including quantification of autoreactive and protective antibody levels and FACS-based immune phenotyping, were analyzed. Daratumumab treatment was associated with significant clinical improvement, substantial reduction of anti-CASPR2 antibody titers, especially in CSF, decrease of immunoglobulin levels and protective vaccine titers, as well as normalization of initially increased T-cell activation markers. However, the patient died of Gram-negative septicemia in a neurorehabilitation center. In conclusion, our findings suggest that daratumumab induces not only depletion of autoreactive long-lived plasma cells associated with improvements of neurological sequelae, but also severe side effects requiring clinical studies investigating efficacy and safety of anti-CD38 therapy in antibody-driven autoimmune encephalitis.

[Recent progress in autoimmune encephalitis and its related disorders]

After the discovery of a series of autoantibodies against neuronal cell surface antigens (NSAs) of the CNS in the past 10 years, the concept of encephalitis has changed dramatically. Accordingly, a practical, syndrome-based diagnostic approach to autoimmune encephalitis was proposed in 2016. These autoantibodies have also been identified in a subset of overlapping encephalitis and demyelinating syndrome, epilepsy, first episode psychosis, movement disorders, post-herpes simplex encephalitis, progressive dementia, postpartum psychosis, stiff-person spectrum disorders, or non-REM/REM sleep behavior disorder. Although not all neuronal antibody tests are available in Japan, we have entered a new era that we have to make a correct diagnosis and start appropriate immunotherapy based on initial neurological assessment and conventional tests, without being constrained by conventional fixed ideas or normal-appearing brain MRIs while waiting for neuronal antibody test results. Although many issues need to be resolved in Japan in terms of diagnosis and treatment in autoimmune encephalitis, this review focusses on recent progress in autoimmune encephalitis and its related disorders closely related to clinical practice, including Hashimoto encephalopathy and new-onset refractory status epilepticus (NORSE).

Phosphodiesterase 10A IgG: A novel biomarker of paraneoplastic neurologic autoimmunity

OBJECTIVE

To describe a novel antibody biomarker of neurologic paraneoplastic autoimmunity specific for phosphodiesterase 10A (PDE10A), a striatum-enriched phosphodiesterase, and to characterize the clinical phenotype of patients with PDE10A immunoglobulin G (IgG).

METHODS

We describe 7 patients with autoantibodies specific for PDE10A identified in the Mayo Clinic Neuroimmunology Laboratory. Patient specimens (sera, 7; CSF, 4) produced identical basal ganglia-predominant synaptic staining of murine brain tissue by indirect immunofluorescence. The autoantigen was identified by immunoprecipitation and mass spectrometry as PDE10A, and confirmed by antigen-specific recombinant Western blot and cell-based assays, and immune absorption experiments.

RESULTS

The median patient age was 70 years (range 66-76); 4 were men. Four patients with clinical information available had movement disorders (hyperkinetic in 3 [chorea, ballismus, dystonia] and parkinsonism in 1). All patients but one had cancer (lung [adenocarcinoma 1, squamous cell carcinoma 1, poorly differentiated mesenchymal carcinoma 1], renal adenocarcinoma 2, and pancreatic adenocarcinoma 1). Two of the 7 patients developed hyperkinetic movement disorders during treatment with immune checkpoint inhibitors (nivolumab and pembrolizumab), though none of 26 cancer control patients treated with immune checkpoint inhibitors harbored PDE10A IgG in their serum. MRIs from those 2 patients with hyperkinetic movement disorders demonstrated fluid-attenuated inversion recovery/T2 basal ganglia hyperintensities, and their CSF harbored unique oligoclonal bands. One of those 2 patients had substantial improvement after corticosteroids. One patient's renal adenocarcinoma expressed PDE10A by immunohistochemistry.

CONCLUSIONS

PDE10A IgG defines a novel rare neurologic autoimmune syndrome and expands the spectrum of diagnosable paraneoplastic CNS disorders. The intracellular location of PDE10A suggests a T-cell-mediated pathology targeting cells displaying MHC1-bound PDE10A peptides.