Neural-specific Autoantibodies Research Articles

B-078 Prevelance of Autoimmune Factors in Patients with Seizures of Unknown Etiology in Western China

Abstract Objective To delineate the features of autoantibody in patients with seizure of unknown etiology in Western China and to analyze other potential risk factors of an epileptic seizure. Methods From January 2017 to June 2022, 639 patients with unexplained seizure were assessed retrospectively. Neuronal autoantibodies were assessed in 471 individuals, including 12 common neural-specific autoantibodies, antibodies against four common pathogens associated with central nervous system infections, or neurophagocytosis, and two thyroid-related autoantibodies. Results Sixty-nine patients were positive for neural-specific autoantibodies in CSF and serum. Among the patients, 32 (46.38%) expressed NMDAR-Ab, 14 (20.29%) expressed GABABR-Ab, 10 (14.49%) expressed LGI1-Ab, 7 (10.14%) expressed GFAP-Ab, 3 (4.34%) expressed Yo-Ab, 2 (2.90%) expressed CASP2-Ab, and 1 (1.45%) expressed Hu-Ab. Compared to patients with non-autoimmune epileptic seizure, the positive rates of thyroid-related antibody expression and the neurophagocytosis pathogen levels of HSV-IgG and T. gondii-IgG were significantly different in patients with autoimmune epileptic seizure. Conclusion This study elucidated the antibody status of autoimmune epilepsy in western China, allowing for better identification and diagnosis of autoimmune epilepsy in the future.

Identification of SKOR2 IgG as a novel biomarker of paraneoplastic neurologic syndrome.

The development of new autoantigen discovery techniques, like programmable phage immunoprecipitation sequencing (PhIP-Seq), has accelerated the discovery of neural-specific autoantibodies. Herein, we report the identification of a novel biomarker for paraneoplastic neurologic syndrome (PNS), Sloan-Kettering-Virus-Family-Transcriptional-Corepressor-2 (SKOR2)-IgG, utilizing PhIP-Seq. We have also performed a thorough clinical validation using normal, healthy, and disease/cancer control samples. Stored samples with unclassified staining at the junction of the Purkinje cell and the granule cell layers were analyzed by PhIP-Seq for putative autoantigen identification. The autoantigen was confirmed by recombinant antigen-expressing cell-based assay (CBA), Western blotting, and tissue immunofluorescence assay colocalization. PhIP-Seq data revealed SKOR2 as the candidate autoantigen. The target antigen was confirmed by a recombinant SKOR-2-expressing, and cell lysate Western blot. Furthermore, IgG from both patient samples colocalized with a commercial SKOR2-specific IgG on cryosections of the mouse brain. Both SKOR2 IgG-positive patients had central nervous system involvement, one presenting with encephalitis and seizures (Patient 1) and the other with cognitive dysfunction, spastic ataxia, dysarthria, dysphagia, and pseudobulbar affect (Patient 2). They had a refractory progressive course and were diagnosed with adenocarcinoma (Patient 1: lung, Patient 2: gallbladder). Sera from adenocarcinoma patients without PNS (n=30) tested for SKOR2-IgG were negative. SKOR2 IgG represents a novel biomarker for PNS associated with adenocarcinoma. Identification of additional SKOR2 IgG-positive cases will help categorize the associated neurological phenotype and the risk of underlying malignancy.

Characterization of Cardiac Bradyarrhythmia Associated With LGI1-IgG Autoimmune Encephalitis

Objective To evaluate and characterize cardiac arrhythmias associated with LGI1-IgG (Leucine-rich glioma inactivated 1–IgG) autoimmune encephalitis (AE). Background AE is increasingly identified as a potentially treatable cause of encephalitis. LGI1-IgG is one of the most common pathogenic neural specific autoantibodies associated with AE in adults. Prior cases of bradyarrhythmias and sudden death have been reported in LGI1-IgG AE, however, larger cohort studies are lacking. Design/Methods In this retrospective descriptive study, we identified Mayo Clinic patients (May 1, 2008–December 31, 2020) with LGI1-IgG AE who had electrocardiogram proven bradyarrhythmias during the initial presentation. Inclusion criteria were 1) LGI1-IgG positivity with a consistent clinical syndrome; 2) electrocardiographic evidence of bradyarrhythmia; and 3) sufficient clinical details. We excluded patients with alternate reason for bradyarrhythmias. We collected demographic/clinical data including details of bradyarrhythmia (severity, duration, treatments), and neurologic and cardiac outcomes. Results We found that patients with LGI1-IgG AE had bradyarrhythmia at a frequency of 8% during the initial presentation. The bradyarrhythmia was often asymptomatic (6/11, 55%); however, the episode was severe with one patient requiring a pacemaker. Outcome was also generally favorable with the majority (8/11, 73%) having full resolution without further cardiac intervention. Lastly, we found that mouse and human cardiac tissues express LGI1 (mRNA and protein), suggesting that LGI1-IgG may influence cardiac tissue itself. Conclusions LGI1-IgG AE can be rarely associated with bradyarrhythmias. Although the disease course is mostly favorable, some cases may require pacemaker placement to avoid devastating outcomes.

Improving Early Recognition of Creutzfeldt-Jakob Disease Mimics.

Diagnostic criteria emphasize the use of sensitive and disease-specific tests to distinguish patients with rapidly progressive dementia (RPD) due to Creutzfeldt-Jakob disease (CJD) vs other causes (mimics). These tests are often performed in specialized centers, with results taking days to return. There is a need to leverage clinical features and rapidly reporting tests to distinguish patients with RPD due to CJD from those due to other causes (mimics) early in the symptomatic course. In this case-control series, clinical features and the results of diagnostic tests were compared between mimics (n = 11) and patients with definite (pathologically proven, n = 33) or probable CJD (with positive real-time quaking-induced conversion [RT-QuIC], n = 60). Patients were assessed at Mayo Clinic Enterprise or Washington University from January 2014 to February 2021. Mimics were enrolled in prospective studies of RPD; mimics met the diagnostic criteria for probable CJD but did not have CJD. Mimics were ultimately diagnosed with autoimmune encephalitis (n = 6), neurosarcoidosis, frontotemporal lobar degeneration with motor neuron disease, dural arteriovenous fistula, cerebral amyloid angiopathy with related inflammation, and systemic lupus erythematous with polypharmacy. Age at symptom onset, sex, presenting features, and MRI and EEG findings were similar in CJD cases and mimics. Focal motor abnormalities (49/93, 11/11), CSF leukocytosis (4/92, 5/11), and protein >45 mg/dL (39/92, 10/11) were more common in mimics (p < 0.01). Positive RT-QuIC (77/80, 0/9) and total tau >1149 pg/mL (74/82, 2/10) were more common in CJD cases (all p < 0.01). Protein 14-3-3 was elevated in 64/89 CJD cases and 4/10 mimics (p = 0.067). Neural-specific autoantibodies associated with autoimmune encephalitis were detected within the serum (5/9) and CSF (5/10) of mimics; nonspecific antibodies were detected within the serum of 9/71 CJD cases. Immune-mediated, vascular, granulomatous, and neurodegenerative diseases may mimic CJD at presentation and should be considered in patients with early motor dysfunction and abnormal CSF studies. The detection of atypical features-particularly elevations in CSF leukocytes and protein-should prompt evaluation for mimics and consideration of empiric treatment while waiting for the results of more specific tests.

Immunity, Ion Channels and Epilepsy.

Epilepsy is a common chronic neurological disorder in modern society. One of the major unmet challenges is that current antiseizure medications are basically not disease-modifying. Among the multifaceted etiologies of epilepsy, the role of the immune system has attracted considerable attention in recent years. It is known that both innate and adaptive immunity can be activated in response to insults to the central nervous system, leading to seizures. Moreover, the interaction between ion channels, which have a well-established role in epileptogenesis and epilepsy, and the immune system is complex and is being actively investigated. Some examples, including the interaction between ion channels and mTOR pathways, will be discussed in this paper. Furthermore, there has been substantial progress in our understanding of the pathophysiology of epilepsy associated with autoimmune encephalitis, and numerous neural-specific autoantibodies have been found and documented. Early recognition of immune-mediated epilepsy is important, especially in cases of pharmacoresistant epilepsy and in the presence of signs of autoimmune encephalitis, as early intervention with immunotherapy shows promise.

P.009 Improving Detection of Creutzfeldt-Jakob Disease Mimics in Clinical Practice

Background: Assays capable of detecting prions in CSF (e.g., RT-QuIC) have greatly improved the antemortem diagnosis of Creutzfeldt-Jakob disease (CJD) yet take time to conduct and are not widely accessible. There is a need to identify clinical features and common tests that identify mimics at presentation. Methods: Mimics were identified within longitudinal studies of rapidly progressive dementia at study sites. Mimics met clinical criteria for probable CJD but did not have CJD. Clinical features were compared between mimics and patients with CJD assessed at Mayo Clinic Enterprise (n=79) and Washington University in St. Louis (n=10; Jan-2014 to Oct-2020). Results: Mimics (10/155; 6.5%) were diagnosed with autoimmune encephalitis (n=7), neurosarcoidosis, frontotemporal lobar degeneration with motor neuron disease, and unknown dementia. Age-at-symptom onset, gender, presenting symptoms, and EEG and MRI findings were similar between mimics and CJD patients. Focal motor abnormalities (49/93, 10/10), elevations in CSF leukocytosis (4/92, 5/10) and protein (39/92, 9/10) were more common in mimics (p&lt;0.01). Neural-specific autoantibodies associated with autoimmune encephalitis were detected within the serum (4/9) and CSF (5/10) of mimics, but not CJD cases. Conclusions: Autoimmune encephalitis, neurosarcoidosis and neurodegenerative diseases may mimic CJD at presentation and should be considered in patients with early motor dysfunction and abnormal CSF studies.

Neurologic Complications of Immune Checkpoint Inhibitors in Thoracic Malignancies.

Immune checkpoint inhibitors (ICIs) have transformed the prognosis of cancers previously considered lethal. The spectrum of therapeutic indications is rapidly expanding, including the vast majority of thoracic malignancies. By enhancing the immune responses against cancer, the ICI treatments lead to the development of immune-related adverse events (irAEs) that may affect any organ. Severity varies from mild to fatal clinical manifestations. Neurologic involvement is relatively rare and highly heterogeneous, including central and peripheral nervous system diseases associated with neural-specific autoantibodies or not, central nervous system vasculitis, and granulomatous and demyelinating disorders. Symptoms often manifest within the first four cycles of treatment and can develop regardless of the class of ICI used. An unfavorable outcome is found in up to one-third of patients and is generally associated with the patients' clinical characteristics (e.g., age, coexistence of systemic adverse events), cancer type (e.g., lung cancer versus other), and specific clinical setting (e.g., ICI treatment in patients with preexisting paraneoplastic neurologic autoimmunity, ICI rechallenge after a first neurologic irAE). Diagnosis should be suspected in patients with new-onset neurologic symptoms while on ICI treatment which are not explained by metastatic disease or other metabolic/infectious disorders. Recommended treatment is based on clinical severity and consists of ICI discontinuation with or without immunosuppressive/immunomodulatory therapy, although alternative approaches are reasonable depending on cancer status (e.g., aggressive immunosuppression without discontinuing ICI in patients with initial cancer response). Early recognition and appropriate treatment of these neurologic irAEs are crucial for improved patient outcomes and therapeutic planning.

Neurologic autoimmunity and immune checkpoint inhibitors

To describe neural autoantibody profiles and outcomes in patients with neurologic autoimmunity associated with immune checkpoint inhibitor (ICI) cancer immunotherapy. In this retrospective descriptive study, 63 patients with ICI-related neurologic autoimmunity were included: 39 seen at the Mayo Clinic Neurology Department (clinical cohort) and 24 whose serum/CSF was referred to the Mayo Clinic Neuroimmunology Laboratory for autoantibody testing. Serum/CSF samples were tested for neural-specific autoantibodies. Predictors of unfavorable outcome (residual adverse event severity grade ≥3) were explored (logistic regression). Median age at neurologic symptom onset was 65 years (range 31-86); 40% were female. Neurologic manifestations were CNS-restricted (n = 26), neuromuscular (n = 30), combined (n = 5), or isolated retinopathy (n = 2). Neural-specific autoantibodies were common in patients with CNS involvement (7/13 [54%] in the unbiased clinical cohort) and included known or unidentified neural-restricted specificities. Only 11/31 patients with CNS manifestations had neuroendocrine malignancies typically associated with paraneoplastic autoimmunity. Small-cell lung cancer (SCLC)-predictive antibodies were seen in 3 patients with non-neuroendocrine tumors (neuronal intermediate filament immunoglobulin G [IgG] and antineuronal nuclear antibody 1 with melanoma; amphiphysin IgG with non-SCLC). A median of 10 months from onset (range, 0.5-46), 14/39 in the clinical cohort (36%) had unfavorable outcomes; their characteristics were age ≥70 years, female, CNS involvement, lung cancer, higher initial severity grade, and lack of systemic autoimmunity. By multivariate analysis, only age remained independently associated with poor outcome (p = 0.01). Four of 5 patients with preexistent neurologic autoimmunity experienced irreversible worsening after ICI. Neural-specific autoantibodies are not uncommon in patients with ICI-related CNS neurologic autoimmunity. Outcomes mostly depend on the pre-ICI treatment characteristics and clinical phenotype.

Application of the APE2-CHN and RITE2-CHN scores for autoimmune seizures and epilepsy in Chinese patients: A retrospective study

PurposeTo assess the performance of the Antibody Prevalence in Chinese Patients with Epilepsy and Encephalopathy (APE2-CHN) and Response to Immunotherapy in Chinese Patients with Epilepsy and Encephalopathy (RITE2-CHN) scores in Chinese patients with epilepsy of unknown etiology. MethodsWe conducted a retrospective study of selected patients from Xiangya Hospital, Central South University (01/01/2017-02/28/2019) whose serum and/or cerebrospinal fluid (CSF) samples were examined for autoimmune encephalitis antibodies. Of these, patients with diagnostic code of seizure or epilepsy were selected in our study. An APE2-CHN score was assigned to each patient and a RITE2-CHN score was calculated for each patient who received immunotherapy. Receiver-operating characteristic (ROC) curve was used to assess each score. Results191 patients were enrolled in our study. 36 were identified with specific etiologies. The remaining 155 patients had unknown etiology. Central nervous system-specific antibodies were detected in 76 (49.0 %) patients, after excluding patients with only anti-thyroid peroxidase or glutamic acid decarboxylase antibodies. N-methyl-d-aspartate receptor (NMDAR) antibody (48.7 %, 37/76) was the most common subtype of our sample, followed by γ-aminobutyric acid type B receptor (GABAR) (14.5 %, 11/76). Clinical features including new-onset epilepsy, neuropsychiatric changes, speech disorder, movement disorder and inflammatory CSF profile correlated with positive antibody results. The sensitivity and specificity of APE2-CHN ≥ 5 in predicting the presence of neural-specific autoantibodies in our study were 85.5 % and 58.9 % respectively. In the subset of patients who received immunotherapy (n = 112), sensitivity and specificity of a RITE2 -CHN ≥ 8 in predicting favorable seizure outcome were 98.6 % and 63.2 % respectively. The area under the curve (AUC) of RITE2-CHN was greater than that of RITE2 (Z = 3.196, p < 0.05) while there was no significant difference in AUC between APE2 and APE2-CHN (Z = 1.058, p = 0.290). ConclusionThe APE2-CHN and RITE2-CHN scores may be useful screening tools in predicting positive antibody findings and prognosis of suspected autoimmune seizures or associated epilepsy in the Chinese population.

Clinical characteristics and outcome of patients with autoimmune encephalitis: clues for paraneoplastic aetiology.

Autoimmune encephalitis (AE) represents a complex syndrome with diverse clinical manifestations and therapeutic outcomes. The aim of this study was to report the clinical characteristics and the long-term outcome of patients with paraneoplastic and idiopathic AE. All patients with subacute encephalopathy admitted to the Neurology Department of our Institution from January 2012 to May 2019 were consecutively enrolled. Patients' serum and cerebrospinal fluid were tested for neural-specific autoantibodies by indirect immunofluorescence assays on mouse brain, rat neurons, cell-based assays and immunoblots. Outcome was assessed by the modified Rankin Scale score. From 107 adult patients with subacute encephalopathy, 50 patients were finally diagnosed with AE. Neural antibodies (Abs) were detected in 45/50 patients (90%). Leucine-rich glioma-inactivated protein 1 immunoglobulin G was the most frequent (6/50, 12%) Ab specific to neural surface antigens detected in adults with AE. Paraneoplastic encephalitis was diagnosed in 16/50 patients (32%). The presence of bilateral temporal lobe lesions on magnetic resonance imaging and cerebrospinal fluid restricted oligoclonal bands was associated with a higher probability to detect cancer at the time of AE diagnosis. All patients with Abs to neural surface antigens had a good outcome at last follow-up. Severe disability at AE onset and the lack of long-term immunosuppression predicted a poor outcome. Leucine-rich glioma-inactivated protein 1 immunoglobulin G was the most frequent Ab detected. Patients with bilateral temporal lobe lesions and oligoclonal bands have a higher probability to harbour an occult tumour. In these patients, a strict surveillance and monitoring for cancer detection is recommended.

Paraneoplastic neurological syndromes.

Paraneoplastic neurological syndromes (PNS) constitute a heterogeneous group of cancer-related disorders that can affect any level of the central and peripheral nervous system. There is compelling evidence that PNS are caused by an immune response directed against neural antigens that are abnormally expressed by the tumour. PNS are frequently associated with neural-specific autoantibodies whose characterization has direct implications for diagnostic workup, treatment and outcome. The last decade has seen a dramatic rise in the discovery of novel autoantibodies associated with PNS, which has led to more accurate diagnoses and earlier treatments, potentially resulting in better outcomes. The latest advancements in the field of autoimmune neurology have paved the way to a more comprehensive understanding of PNS; yet, many aspects of their immunopathogenesis remain to be elucidated and patient-tailored treatment strategies still need to be optimized.

Predictors of neural-specific autoantibodies and immunotherapy response in patients with cognitive dysfunction

Recognition of autoimmunity as a cause of encephalopathy has increased. Recent studies have validated the use of Antibody-Prevalence-in-Epilepsy (APE) and Responsive-to-immunotherapy-in-Epilepsy (RITE) scores in the evaluation and management of autoimmune-epilepsy. We aim to assess the utility of these models for patients with cognitive dysfunction. Among the evaluated patients, 17% had antibodies universally associated with autoimmune-encephalopathy. NMDA-R-IgG and LGI1-IgG were the most common antibody specificities. Antibody-Prevalence-in-Epilepsy-and-Encephalopathy (APE2) score ≥ 4 was 99% sensitive and 93% specific for neural-specific-antibodies. Responsive-to-immunotherapy-in-Epilepsy-and-Encephalopathy (RITE2) score ≥ 7 had 96% sensitivity and 86% specificity for favorable initial immunotherapy response. Application of these models may optimize autoantibody evaluations and immunotherapeutic trials.

Paraneoplastic neurological syndromes associated with mediastinal tumors

Clinical presentation of mediastinal tumors may be related to the invasion of the adjacent structures leading, in some cases, to life-threatening emergencies. However in some patients, these tumors may be heralded by non-local symptoms due to paraneoplastic neurological diseases (PND) caused by an autoimmune response to antigens co-expressed by the cancer and the nervous system. PND may affect multiple levels of the nervous system from the cerebral cortex to the neuromuscular junction and the muscle. Early diagnosis of PND can be critical for the detection of a new or recurrent occult tumor. Neural-specific autoantibodies serve as diagnostic markers for PND and in some cases may predict the presence of a specific type of cancer. This review focuses on the clinical and immunological characteristics of the PND associated with the most frequent mediastinal cancers, namely thymoma, lymphoma and germ cell tumors.

Seizure semiology: an important clinical clue to the diagnosis of autoimmune epilepsy.

ObjectiveThe purpose of this study is to analyze the seizure semiologic characteristics of patients with autoimmune epilepsy (AE) and describe the investigation characteristics of AE using a larger sample size.MethodsThis observational retrospective case series study was conducted from a tertiary epilepsy center between May 2014 and March 2017. Cases of new‐onset seizures were selected based on laboratory evidence of autoimmunity. At the same time, typical mesial temporal lobe epilepsy (MTLE) patients with hippocampal sclerosis (HS) were recruited as the control group from the subjects who underwent presurgical evaluation during the same period.ResultsA total of 61 patients with AE were identified. Specific autoimmune antibodies were detected in 39 patients (63.93%), including anti‐VGKC in 23 patients (37.70%), anti‐NMDA‐R in 9 patients (14.75%), anti‐GABAB‐R in 6 patients (9.84%), and anti‐amphiphysin in 1 patient (1.64%). Regarding the seizure semiology, no significant differences were noted between AE patients with autoantibody and patients with suspected AE without antibody. Compared to typical MTLE patients with HS, both AE patients with autoantibody and patients with suspected AE without antibody had the same seizure semiologic characteristics, including more frequent SPS or CPS, shorter seizure duration, rare postictal confusion, and common sleeping SGTC seizures.SignificanceThis study highlights important seizure semiologic characteristics of AE. Patients with autoimmune epilepsy had special seizure semiologic characteristics. For patients with autoimmune epilepsy presenting with new‐onset seizures in isolation or with a seizure‐predominant neurological disorder, the special seizure semiologic characteristics may remind us to test neuronal nuclear/cytoplasmic antibodies early and initiate immunomodulatory therapies as soon as possible. Furthermore, the absence of neural‐specific autoantibodies does not rule out AE.

Autoimmune factors and epilepsy

Epilepsy is a common chronic brain disorder with multiple causes, and now autoimmune factors are believed to be an independent cause for epilepsy. Accumulating data support an autoimmune basis in patients with antiepileptic drug-resistant seizures. Moreover, systemic autoimmune diseases and epilepsy co-occur frequently. Neural specific autoantibodies can also mediate the process of seizures through different pathways. The diagnosis of autoimmune epilepsy is based on frequency of antiepileptic drug-resistant seizures, the presence of neural specific autoantibodies, inflammatory changes in serum or spinal fluid or on magneticresonanceimaging, the change in electroencephalogram, a personal or family history of autoimmunity. Once autoimmune epilepsy is diagnosed, the immunotherapy is required. Early immunotherapy is crucial for improving the prognosis of the patients.

Autoantibody-Associated Central Nervous System Neurologic Disorders

Autoimmune neurology is a rapidly evolving new subspecialty driven by the discovery of novel neural- (neuronal- or glial-) specific autoantibodies and their target antigens. The neurologic manifestations affecting the central nervous system include encephalitis, dementia, epilepsy, and movement and sleep disorders. Laboratory testing is now available for most of these neural-specific autoantibodies, which serve as diagnostic markers, in some instances directing the physician toward specific cancer types (e.g., N-methyl-D-aspartic acid receptor antibodies for teratoma, collapsin response mediator protein 5 for small-cell lung cancer) and assisting in therapeutic decision making. Antibodies targeting intracellular proteins serve as markers of cytotoxic effector T-cell-mediated injury, which is generally poorly responsive to immunotherapy. By contrast, antibodies targeting extracellular plasma membrane proteins may act as pathogenic effectors and often infer good responses to immunotherapy. Diagnosing these conditions and implementing treatment as early into the clinical course as possible ensures the best possible clinical outcomes. An adequate immunotherapy trial to assess maximum reversibility of symptoms, as assessed through objective functional measures, is crucial and can help to determine whether maintenance therapy is needed.

Chapter 14 - Autoimmune dementia and encephalopathy

Autoimmune dementia and encephalopathies (ADE) are complex disorders that can cause immune-mediated cognitive deficits and have confusing nomenclature. Presentation varies from acute limbic encephalitis to subacute or chronic disorders of cognition mimicking neurodegenerative dementia. It may occur as a paraneoplastic phenomenon or an idiopathic autoimmune phenomenon. The presence of a personal/family history of autoimmunity, inflammatory spinal fluid, serologic evidence of autoimmunity (neural or nonorgan-specific), or mesial temporal magnetic resonance imaging abnormalities are clues to diagnosis. Bedside cognitive assessment and/or detailed neuropsychologic testing are useful. Neural-specific autoantibodies, mostly discovered in the past two decades, may bind antigens on the cell surface (e.g., N-methyl-d-aspartate receptor autoantibodies) and are likely to be pathogenic, with treatment aimed at antibody-depleting agents often with success, while antibodies binding intracellular antigens (e.g., antineuronal nuclear autoantibody type 1 (ANNA1 or anti-Hu)) are a marker of a T-cell-mediated process and treated with T-cell-depleting immunotherapies, with variable responses. Detection and treatment of cancer (when present) are essential. High-dose corticosteroids are the initial treatment in most patients and may serve as a diagnostic test when the diagnosis is uncertain. Repeat cognitive testing after immunotherapy helps document objective improvements. Maintenance immunotherapy is recommended in those at risk for relapse. Prognosis is variable, but paraneoplastic ADE with antibodies to intracellular antigens have a worse prognosis. The field is still developing and future studies should provide guidelines for diagnosis and treatments.

Chapter 19 - Autoimmune myelopathies

Autoimmune myelopathies are a heterogeneous group of immune-mediated spinal cord disorders with a broad differential diagnosis. They encompass myelopathies with an immune attack on the spinal cord (e.g., aquaporin-4-IgG (AQP4-IgG) seropositive neuromyelitis optica (NMO) and its spectrum disorders (NMOSD)), myelopathies occurring with systemic autoimmune disorders (which may also be due to coexisting NMO/NMOSD), paraneoplastic autoimmune myelopathies, postinfectious autoimmune myelopathies (e.g., acute disseminated encephalomyelitis), and myelopathies thought to be immune-related (e.g., multiple sclerosis and spinal cord sarcoidosis). Spine magnetic resonance imaging is extremely useful in the evaluation of autoimmune myelopathies as the location of signal change, length of the lesion, gadolinium enhancement pattern, and evolution over time narrow the differential diagnosis considerably. The recent discovery of multiple novel neural-specific autoantibodies accompanying autoimmune myelopathies has improved their classification. These autoantibodies may be pathogenic (e.g., AQP4-IgG) or nonpathogenic and more reflective of a cytotoxic T-cell-mediated autoimmune response (collapsin response mediator protein-5(CRMP5)-IgG). The presence of an autoantibody may help guide cancer search, assist treatment decisions, and predict outcome/relapse. With paraneoplastic myelopathies the initial goal is detection and treatment of the underlying cancer. The aim of immunotherapy in all autoimmune myelopathies is to maximize reversibility, maintain benefits (while preventing relapse), and minimize side effects.

Chapter 10 - Paraneoplastic and idiopathic autoimmune neurologic disorders: approach to diagnosis and treatment

Autoimmune neurology is a rapidly emerging new subspecialty that encompasses the diagnosis and treatment of neurologic disorders with an autoimmune (paraneoplastic or noncancer-associated) basis. The last decade has seen a dramatic rise in the discovery of neural-specific autoantibodies and their target antigens. Laboratory testing, on a service basis, is now available for most of these neural-specific autoantibodies and they serve as diagnostic markers, in some instances directing the physician toward specific cancer types (e.g., N-methyl-d-aspartate receptor antibodies for teratoma; CRMP5-IgG for small-cell cancer) and assisting in therapeutic decision making. Antibodies targeting intracellular proteins (nuclear and intracytoplasmic enzymes, transcription factors, and RNA binding proteins) serve as markers of cytotoxic effector T-cell-mediated injury and are generally poorly responsive to immunotherapy. By contrast, antibodies targeting plasma membrane proteins that are extracellular and accessible (neurotransmitter receptors, ion channels, water channels, and channel-complex proteins) may act as pathogenic effectors and often imply immunotherapy responsiveness. Magnetic resonance imaging, electrophysiologic studies, functional imaging, and neuropsychologic evaluations provide objective evidence of neurologic dysfunction by which the success of immunotherapy may be measured.

Autoimmune Epilepsy

Seizures are recognized as a common manifestation of autoimmune limbic encephalitis and multifocal paraneoplastic disorders, but accumulating evidence supports an autoimmune basis for seizures in the absence of syndromic manifestations of encephalitis. Autoimmune encephalitis and epilepsy have been linked to neural-specific autoantibodies targeting both intracellular and plasma membrane antigens. The detection of these antibodies can serve as a diagnostic marker directing physicians toward specific cancers and can assist in therapeutic decision-making, but are not necessary to establish the diagnosis. Response to an immunotherapy trial can support the diagnosis and help establish prognosis. Early recognition is important because expedited diagnosis can facilitate recovery. In this review, the authors summarize the clinical presentation, pathophysiology, and management of autoimmune epilepsies for which neural antigen-specific autoantibodies serve as diagnostic aids.