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Objective: To characterize the long-term outcomes of patients with "possible only" or "probable" autoimmune encephalitis (AE)., Background: Despite comprising one-third of AE cases, antibody-negative cases lacking typical AE-defining features are understudied., Design/methods: We conducted a retrospective analysis of adult patients evaluated at a tertiary center neuroimmunology practice from 2006 to 2020, meeting diagnostic criteria for "possible only" or "probable but antibody-negative" AE, with at least one year of follow-up. All patients underwent neural antibody testing., Results: Forty-five patients (median age, 61 years [range, 20-88]; female, 21 [47%]) were included, with a median follow-up of 36 months (range, 12-174). A change in diagnosis was noted in six additional patients, who were excluded from further analysis, with only two receiving a non-autoimmune diagnosis during follow-up. The majority (41/45 [91%]) presented with significant disability (modified Rankin Scale [mRS] ≥3) at baseline. CSF was inflammatory in 20/44 (45%) and MRI was abnormal in 21/45 (47%). Unclassified neural-specific IgG staining on tissue-based assay was detected in five (11%). Two cases (4%) had a paraneoplastic cause. The median time from onset to immunotherapy initiation was two months (range, 0-21), resulting in at least partial improvement in all 44 (98%) treated cases. Clinical relapses occurred in 14/45 (31%). At last follow-up, the most common symptoms were memory dysfunction (31/45 [69%]), attention deficits (17/45 [38%]), gait instability (13/45 [29%]), and visuospatial dysfunction (10/45 [22%]). Most patients achieved independence (median mRS, 2 [range, 0-6]); however, 11 patients had poor neurological outcome (mRS ≥3). Higher mRS score and gait assistance requirement at three months were predictive of poor outcome (P ≤0.01)., Conclusions: Despite significant disability at initial stages, patients with antibody-negative but clinically presumed AE show potential for improvement with immunotherapy, highlighting the importance of early intervention. Early functional status and gait assistance requirements may assist in predicting long-term prognosis.

Objective: This article discusses common principles in diagnosing and managing autoimmune neurologic conditions in children., Latest Developments: The key to improving outcomes in all patients with autoimmune neurologic diseases is making an early diagnosis, promptly initiating treatment, and identifying patients who will benefit from long-term maintenance treatment. Some neuroinflammatory syndromes can be diagnosed with an antibody biomarker (eg, aquaporin-4 antibodies, N-methyl-d-aspartate [NMDA] receptor antibodies), whereas others require clinical diagnostic criteria (eg, multiple sclerosis, opsoclonus-myoclonus syndrome). A proportion of children will be labeled as seronegative, and further investigations for other inflammatory or monogenetic etiologies need to be carried out in parallel with treating the central nervous system inflammation. Time to treatment and treatment escalation were shown to correlate with outcomes in many patients with these disorders. The choice and duration of treatment should be evaluated considering side effects and risks in the short and long terms. The presence of a highly inflammatory disease process in children supports the use of highly effective disease-modifying therapies in pediatrics., Essential Points: The phenotypes of pediatric autoimmune neurologic conditions may change across different age groups, as the brain is still actively developing. In general, the presentation in children is more inflammatory, but overall disability is lower, likely because of better neuroplasticity and repair. Convincing evidence has increasingly emerged to support the biological rationale that effective immunosuppressive therapies used in adult neuroimmunology are equally effective in children., (Copyright © 2024 American Academy of Neurology.)

Objective: Autoimmune neurologic disorders encompass a broad category of diseases characterized by immune system attack of the central, peripheral, or autonomic nervous systems. This article provides information on both acute and maintenance immunotherapy used to treat autoimmune neurologic disorders as well as a review of symptomatic management and special considerations when caring for patients with these diseases., Latest Developments: Over the past 20 years, more than 50 antibodies have been identified and associated with autoimmune neurologic disorders. Although advances in diagnostic testing have allowed for more rapid diagnosis, the therapeutic approach to these disorders has largely continued to rely on expert opinion, case series, and case reports. With US Food and Drug Administration (FDA) approval of biologic agents to treat neuromyelitis optica spectrum disorder (NMOSD) and myasthenia gravis as well as ongoing clinical trials for the treatment of autoimmune encephalitis, the landscape of immunotherapy options continues to expand. Consideration of the unique pathogenesis of individual autoimmune neurologic disorders as well as the mechanism of action of the diverse range of treatment options can help guide treatment decisions today while evidence from clinical trials informs new therapeutics in the future., Essential Points: Recognizing patients who have a clinical history and examination findings concerning for autoimmune neurologic disorders and conducting a thorough and directed imaging and laboratory evaluation aimed at ruling out mimics, identifying specific autoimmune syndromes, and screening for factors that may have an impact on immunotherapy choices early in the clinical course are essential to providing optimal care for these patients. Providers must consider immunotherapy, symptomatic treatment, and a multidisciplinary approach that addresses each patient's unique needs when treating patients with autoimmune neurologic disorders., (Copyright © 2024 American Academy of Neurology.)

Objective: This article focuses on the clinical features and diagnostic evaluations that accurately identify patients with ever-expanding forms of antibody-defined encephalitis. Forms of autoimmune encephalitis are more prevalent than infectious encephalitis and represent treatable neurologic syndromes for which early immunotherapies lead to the best outcomes., Latest Developments: A clinically driven approach to identifying many autoimmune encephalitis syndromes is feasible, given the typically distinctive features associated with each antibody. Patient demographics alongside the presence and nature of seizures, cognitive impairment, psychiatric disturbances, movement disorders, and peripheral features provide a valuable set of clinical tools to guide the detection and interpretation of highly specific antibodies. In turn, these clinical features in combination with serologic findings and selective paraclinical testing, direct the rationale for the administration of immunotherapies. Observational studies provide the mainstay of evidence guiding first- and second-line immunotherapy administration in autoimmune encephalitis and, whereas these typically result in some clinical improvements, almost all patients have residual neuropsychiatric deficits, and many experience clinical relapses. An improved pathophysiologic understanding and ongoing clinical trials can help to address these unmet medical needs., Essential Points: Antibodies against central nervous system proteins characterize various autoimmune encephalitis syndromes. The most common targets include leucine-rich glioma inactivated protein 1 (LGI1), N-methyl-d-aspartate (NMDA) receptors, contactin-associated proteinlike 2 (CASPR2), and glutamic acid decarboxylase 65 (GAD65). Each antibody-associated autoimmune encephalitis typically presents with a recognizable blend of clinical and investigation features, which help differentiate each from alternative diagnoses. The rapid expansion of recognized antibodies and some clinical overlaps support panel-based antibody testing. The clinical-serologic picture guides the immunotherapy regime and offers valuable prognostic information. Patient care should be delivered in conjunction with autoimmune encephalitis experts., (Copyright © 2024 American Academy of Neurology.)

Background and Objectives: Aicardi Goutières syndrome (AGS) is type I interferonopathy characterized by severe neurologic impairment. Although many children with AGS demonstrate motor and expressive language deficits, the magnitude of receptive language impairment is uncharacterized. We sought to characterize cognitive function in AGS-affected children using assessment tools with reduced dependence on motor abilities and compare cognitive testing outcomes with overall severity and parental assessment of adaptive behavior., Methods: We performed a cross-sectional study. Children were recruited as part of the Myelin Disorders Biorepository Project at the Children's Hospital of Philadelphia. We included individuals with a confirmed diagnosis of AGS. We administered the Leiter International Performance Scale, third edition (Leiter-3), and the Vineland Adaptive Behavior Scale, third edition (VABS-3), in the context of research encounters. Motor skills were categorized by AGS Severity Scale mobility levels. Descriptive statistics and Spearman's rank correlation were used to compare assessments. Mann-Whitney and Kruskal-Wallis tests with correction with Dunn's multiple comparison test were used to compare test performance between mobility groups., Results: Cognitive and adaptive behavior performance was captured in 57 children. The mean age at encounters was 8.51 (SD 5.15) years. The median (IQR) Leiter-3 score was 51 (interquartile range [IQR] 60), with administration failure in 20 of 57 (35%) individuals. On the VABS-3, the Motor Domain (median 29, IQR 36.25) was more impacted than the Communication (median 50, IQR 52), Daily Living Skills (median 52, IQR 31), and Socialization (median 54, IQR 40) Domains ( p < 0.0001). The AGS Scale correlated with VABS-3 ( r = 0.86, p < 0.0001) and Leiter-3 ( r = 0.87, p < 0.0001). There was correlation between VABS-3 Domains and Leiter-3 ( r -range 0.83-0.97). Gross motor and fine motor categories, respectively, correlated with VABS-3 ( H = 39.37, p < 0.0001; U = 63, p < 0.0001) and Leiter-3 ( H = 40.43, p < 0.0001; U = 66, p < 0.0001). Within each gross motor and fine motor category of the AGS Scale, a subset of children scored within normal IQ range., Discussion: Parental assessment of function by the VABS-3 correlated with directly assessed performance measures. Our data underscore the potential value of VABS-3 and Leiter-3 as tools to assess psychometric function in AGS. With a deeper understanding of our patients' abilities, we can better guide clinicians and families to provide appropriate support and personalized interventions to empower children with leukodystrophies to maximize their communication and educational potential.

Purpose of Review: This article provides a discussion of the current evidence and contemporary views on the relationship between sleep disorders and neurologic disease., Recent Findings: Disrupted or disordered sleep can be associated with increased morbidity and mortality, the risk of cardiovascular events, increased seizure frequency, and altered immune responses. Studies have implicated disrupted sleep and circadian rhythm dysfunction with both amyloid-β (Aβ) deposition and tau deposition. A bidirectional relationship exists between disrupted sleep and the progression of Alzheimer disease pathology. Insomnia has been reported as a prodromal symptom in autoimmune encephalitis. Primary sleep disorders have now been increasingly recognized as a common comorbid condition in multiple sclerosis, making it imperative that neurologists feel comfortable differentiating multiple sclerosis fatigue from excessive daytime sleepiness caused by primary sleep disorders to optimally treat their patients., Summary: Sleep disorders are common across the population. By recognizing sleep disorders in patients with neurologic conditions, neurologists can provide comprehensive care and, in some cases, reduce neurologic disease burden.

Objective: To define the clinicopathologic features of amphiphysin-immunoglobulin G (IgG)-mediated neuropathy., Methods: Patients examined at our institution from January 1, 1995, to September 30, 2018, with amphiphysin-IgG by indirect immunofluorescence and Western blot, were reviewed. Their phenotypes were compared to cases of coexisting collapsin response-mediator protein-5 (CRMP5)-IgG or anti-neuronal nuclear antibody type 1 (ANNA1-IgG) and CRMP5-IgG autoimmunity. Improvement in modified Rankin Scale (mRS) (≥1) on follow-up was considered a favorable outcome. Amphiphysin RNA expression was assessed in healthy nerves., Results: Fifty-three amphiphysin-IgG-positive cases were identified. Of 33 (60%) patients with neuropathy, 21 had amphiphysin-IgG alone, and 12 had coexisting autoantibodies (ANNA1-IgG, n = 8; CRMP5-IgG, n = 2; ANNA1-IgG and CRMP5-IgG, n = 2). The neuropathies in isolated amphiphysin-IgG autoimmunity included polyradiculoneuropathy (62%), diffuse sensory neuronopathy (35%), and facial neuropathy with gastroparesis (3%). Among these, pain (80%), breast cancer (63%), and CNS (57%) involvements commonly coexisted, and neuropathy frequently prompted breast cancer diagnosis (76%). Stiff-person spectrum disorder was the most common CNS accompaniment (45%). Nerve biopsies showed axonal loss (n = 6/6), subperineurial edema (n = 4/6), and CD4 predominant inflammation (n = 2/6). Median mRS score at last follow-up was 3.5; 58% of patients were immunotherapy-responsive. Patients with amphiphysin-IgG alone had more favorable immunotherapy response than patients with CRMP5-IgG polyneuropathy (n = 45) (44% vs 16%, p = 0.028, odds ratio 4.2, 95% confidence interval 1.1 to 15.5). Only 1/9 (11%) patients with amphiphysin-IgG with coexisting CRMP5-IgG or ANNA1-IgG had immunotherapy response. RNA amphiphysin expression occurred at low levels in nerve., Conclusion: Amphiphysin-IgG autoimmune neuropathy has a recognizable phenotype, is frequently immune responsive, and can prompt early diagnosis of breast cancer., (© 2019 American Academy of Neurology.)

Nodoparanodopathy is a recent concept in the field of peripheral neuropathy, corresponding to peripheral nerve disorders stemming from an autoimmune attack directed and limited to the nodal region. This concept was identified using modern techniques of electrophysiology, immunology, and pathology (including electron microscopy). We present here what we believe to be the earlier well-documented case of nodoparanodopathy in the medical literature, based on an article written by Samuel Gilbert Webber (1838-1926) in 1884., (© 2019 American Academy of Neurology.)

Background: Neurology has been continuously transforming by the refinement of molecular diagnostics and the development of disease-modifying treatments. The discovery of new antibody markers has elucidated the pathogenesis, provided the means of diagnostics, and offered cure or treatment for several immune-mediated neurological and neuropsychiatric disorders. The identification of pathogenic and marker autoantibodies has also facilitated defining the associated phenotypic spectra and the overlap among the phenotypes linked to individual immune markers., Review Summary: This survey presents the list of currently known autoimmune encephalitis entities along with the associated marker autoantibodies, highlights the phenotypic and immune pathogenic relationships, calls attention to the recently described rare syndromes, discusses the biological significance of the autoantibodies and targeted molecules, points out the potential postinfectious origin of immune pathogenesis in several of the disorders, and directs the readers to the latest diagnostic guidelines as well as to the generally used treatment approaches., Conclusions and Future Directions: Owing to the successful and usually combined use of various methods to detect serum and cerebrospinal fluid autoantibodies on rodent brain sections, in primary neuronal cell culture, in immune precipitation, and cell-based assays, or in other antigen-specific immune assays (Western blot, enzyme-linked immunosorbent assay, and radioimmune assay), the subgroup of antibody marker-negative autoimmune encephalopathy syndromes is contracting, whereas the numbers of entities within the overall group are expanding. Recognition of the correct diagnosis is becoming increasingly rewarding not only for neurologists, but also for pediatric neurologists and psychiatrists.

Objective: To search for antibodies against neuronal cell surface proteins., Methods: Using immunoprecipitation from neuronal cultures and tandem mass spectrometry, we identified antibodies against the α1 subunit of the γ-aminobutyric acid A receptor (GABAAR) in a patient whose immunoglobulin G (IgG) antibodies bound to hippocampal neurons. We searched 2,548 sera for antibodies binding to GABAAR α, β, and γ subunits on live HEK293 cells and identified the class, subclass, and GABAAR subunit specificities of the positive samples., Results: GABAAR-Abs were identified in 40 of 2,046 (2%) referred sera previously found negative for neuronal antibodies, in 5/502 (1%) previously positive for other neuronal surface antibodies, but not in 92 healthy individuals. The antibodies in 40% bound to either the α1 (9/45, 20%) or the γ2 subunits (9/45, 20%) and were of IgG1 (94%) or IgG3 (6%) subclass. The remaining 60% had lower antibody titers (p = 0.0005), which were mainly immunoglobulin M (IgM) (p = 0.0025), and showed no defined subunit specificity. Incubation of primary hippocampal neurons with GABAAR IgG1 sera reduced surface GABAAR membrane expression. The clinical features of 15 patients (GABAAR α1 n = 6, γ2 n = 5, undefined n = 4) included seizures (47%), memory impairment (47%), hallucinations (33%), or anxiety (20%). Most patients had not been given immunotherapies, but one with new-onset treatment-resistant catatonia made substantial improvement after plasma exchange., Conclusions: The GABAAR α1 and γ2 are new targets for antibodies in autoimmune neurologic disease. The full spectrum of clinical features, treatment responses, correlation with antibody specificity, and in particular the role of the IgM antibodies will need to be assessed in future studies., (© 2015 American Academy of Neurology.)

Purpose of Review: The human central nervous system (CNS) can mistakenly be the target of adaptive cellular and humoral immune responses causing both functional and structural impairment. We here provide an overview of neuron-directed autoimmunity as a novel class of inflammatory CNS disorders, their differential diagnoses, clinical hallmarks, imaging features, characteristic laboratory, electrophysiological, cerebrospinal fluid and neuropathological findings, cellular and molecular disease mechanisms, as well as therapeutic options., Recent Findings: A growing number of immune-mediated CNS disorders of both autoimmune and paraneoplastic origin have emerged, in which neurons seem to be the target of the immune response. Antibodies binding to a variety of synaptic and extrasynaptic antigens located on the neuronal surface membrane can define distinct entities. Clinically, these disorders are characterized by subacute CNS-related [and sometimes peripheral nervous system (PNS)-related] symptoms involving a variety of cortical and subcortical gray matter areas, which often reflect the expression pattern and function of the respective target antigen. Antibodies seem to be pathogenic and cause (reversible) disturbance of synaptic transmission and neuronal excitability by selective functional inhibition or crosslinking and internalization of their antigen in the absence of overt cytotoxicity, at least at early disease stages. Whether at later disease stages antibody-mediated cytotoxicity, cytotoxic CD8+ T cells, or other detrimental immune mechanisms contribute to neuronal impairment is unclear at present., Summary: Adaptive humoral autoimmunity directed to neuronal cell-surface antigens offers first and unique insights and provokes further investigation into the systemic, cellular, and molecular consequences of immune-mediated disruption of distinct neuronal signaling pathways within the living human CNS.

Purpose of Review: This review highlights recent advances in our understanding of autoimmune autonomic ganglionopathy (AAG) including serological diagnosis, clinical observations, pathophysiology, and treatment., Recent Findings: Classical AAG is a subacute disorder associated with antibodies against ganglionic acetylcholine receptors. Recent observations demonstrate that these antibodies cause a specific inhibition of synaptic transmission in autonomic ganglia and antibody levels correlate in a predictable way with severity of autonomic failure. Ganglionic acetylcholine receptor antibodies can be associated with other neurological disorders including chronic or restricted forms of autonomic dysfunction and with neurological or paraneoplastic disorders unrelated to the autonomic nervous system. Treatment of AAG is based on case reports. It is clear that AAG patients respond to immunomodulatory treatments but combination immunotherapy may be required to achieve a clinical response. Recently, additional clinical observations indicate that AAG patients may also show signs of treatment-responsive cognitive impairment., Summary: The pathophysiology and varied clinical presentation of AAG are becoming more clear. AAG is a treatable antibody-mediated disorder of autonomic ganglionic synaptic transmission. Future studies will continue to define the optimal diagnostic and therapeutic approach to autoimmune autonomic disorders.

Complex regional pain syndrome, which is characterised by pain and trophic disturbances, develops frequently after peripheral limb trauma. There is an increasing evidence of an involvement of the immune system in CRPS, and recently we showed that CRPS patients have autoantibodies against nervous system structures. Therefore we tested the sera of CRPS patients, neuropathy patients and healthy volunteers for surface-binding autoantibodies to primary cultures of autonomic neurons and differentiated neuroblastoma cell lines using flow cytometry. Thirteen of 30 CRPS patients, but none of 30 healthy controls and only one of the 20 neuropathy sera had specific surface binding to autonomic neurons (p<0.001). The majority of the sera reacted with both sympathetic and myenteric plexus neurons. Interestingly, 6/30 CRPS sera showed binding to undifferentiated SH-SY5Y neuroblastoma cells. However, differentiation of SH-SY5Y into a cholinergic phenotype induced a surface antigen, which is recognised by 60% of CRPS sera (18/30), but not by controls (p<0.001). Our data show that about 30-40% of CRPS patients have surface-binding autoantibodies against an inducible autonomic nervous system autoantigen. These data support an autoimmune hypothesis in CRPS patients. Further studies must elucidate origin and function of these autoantibodies in CRPS.

Background and Purpose: Animals subjected to an inflammatory insult at the time of stroke are predisposed to the development of an inflammatory autoimmune response to brain. This response is associated with worse neurological outcome. Because induction of immunologic tolerance to brain antigens before stroke onset is associated with improved outcome, we sought to determine whether this paradigm could prevent the deleterious autoimmune response to brain provoked by an inflammatory stimulus at the time of ischemia., Methods: Male Lewis rats were tolerized to myelin basic protein (MBP) or ovalbumin by intranasal administration before middle cerebral artery occlusion. At the time of reperfusion, all animals received lipopolysaccharide (1 mg/kg intraperitoneal). Behavioral tests were performed at set time intervals., Results: One month after middle cerebral artery occlusion, lymphocytes from the spleens of MBP-tolerized animals were less likely to evidence an autoimmune response and more likely to evidence a regulatory response (Treg) toward MBP than those from ovalbumin-tolerized animals. Animals that had an inflammatory response toward MBP (a Th1 response) performed worse on behavioral tests than those that did not. Fractalkine, a surrogate marker of inflammation, was elevated in animals with a Th1 response to MBP., Conclusions: These data extend our previous findings and suggest that deleterious autoimmunity to brain antigens can be prevented by prophylactically inducing regulatory T-cell responses to those antigens.

Background: Aseptic meningitis is one of the most infrequent neuropsychiatric manifestations of systemic lupus erythematosus (SLE) with multifactorial etiologies including medications such as nonsteroidal anti-inflammatory drugs, azathioprine, and trimethoprim-sulfamethoxasole, as well as viruses and malignancy. Recurrent aseptic meningitis in SLE is rare, and remains a diagnostic challenge., Methods: We report a unique SLE patient with recurrent (10 episodes), benign (self-limited) lymphocytic aseptic meningitis, which suggests the diagnosis of Mollaret meningitis. There was no prior use of medications known to provoke meningitis. No infectious etiology was identified and chronic meningitis was not observed. The patient had spontaneous resolution of symptoms with no neurologic sequelae., Conclusion: Recurrent benign lymphocytic aseptic meningitis is recognized in this SLE patient. We propose that noninfectious Mollaret meningitis be classified as a feature of neuropsychiatric SLE syndromes.

Background: Neonatal-onset multi-system inflammatory disease (NOMID), a rare autosomal dominantly inherited disease, belongs to a growing spectrum of autoinflammatory diseases, is characterized by urticarial rash, arthropathy, and chronic aseptic meningitis, and is associated with mutations in the cold-induced autoinflammatory gene, CIAS1, the gene that encodes the protein, cryopyrin. As little is known about the anesthetic considerations of the disease, we sought to identify the main features and respective anesthetic and perioperative implications of NOMID., Methods: We examined perianesthetic records of children with NOMID who were anesthetized for invasive diagnostic and therapeutic interventions between 2003 and 2006. In addition, we conducted an extensive literature review of the genetic, clinical, and biochemical abnormalities of the disease., Results: Seventeen children with NOMID (median age 8 yr, range 9 mo to 11 yr) were anesthetized for diagnostic and therapeutic procedures. All patients had neurological involvement, including increased intracranial pressure, chronic aseptic meningitis, and developmental delay; 7 had bony overgrowth, 15 ocular, and 14 otological manifestations of NOMID. Despite the complexity of the disease, the perioperative course was uncomplicated, and no serious adverse events were observed., Conclusions: This study is the first to investigate the anesthetic implications of NOMID, an autoinflammatory disease associated with arthropathy, recurrent fevers, urticarial rash, and chronic aseptic meningitis. While for the pediatric anesthesiologist, the presence of fever and aseptic meningitis might make the conduct of anesthetics for elective procedures less desirable, our findings suggest that without evidence of active infection, even in the presence of fever and chronic aseptic meningitis, general and regional anesthesia may be conducted in patients with NOMID without untoward complications.

Purpose of Review: The aim of this article is to review opsoclonus, with particular emphasis on its immunopathogenesis and pathophysiology., Recent Findings: Infections (West Nile virus, Lyme disease), neoplasms (non-Hodgkin's lymphoma, renal adenocarcinoma), celiac disease, and allogeneic hematopoietic stem cell transplantation can cause opsoclonus. Newly identified autoantibodies include antineuroleukin, antigliadin, antiendomysial, and anti-CV2. Evidence suggests that the autoantigens of opsoclonus reside in postsynaptic density, or on the cell surface of neurons or neuroblastoma cells (where they exert antiproliferative and proapoptotic effects). Most patients, however, are seronegative for autoantibodies. Cell-mediated immunity may also play a role, with B and T-cell recruitment in the cerebrospinal fluid linked to neurological signs. Rituximab, an anti-CD20 monoclonal antibody, seems efficacious as an adjunctive therapy. Although changes in synaptic weighting of saccadic burst neuron circuits in the brainstem have been implicated, disinhibition of the fastigial nucleus in the cerebellum, or damage to afferent projections to the fastigial nucleus, is a more plausible pathophysiologic mechanism which is supported by functional magnetic resonance imaging findings in patients., Summary: There is increasing recognition that both humoral and cell mediated immune mechanisms are involved in the pathogenesis of opsoclonus. Further studies are needed to further elucidate its immunopathogenesis and pathophysiology in order to develop novel and efficacious therapy.

Purpose of Review: Immune-mediated inner-ear disorders may present to different medical disciplines and new research findings emerge rapidly. The purpose of this review is to draw the different strands together to produce an overview describing the clinical presentation of immune-mediated inner-ear disorders and to discuss useful diagnostic criteria with a focus on tissue-specific and tissue-non-specific antibodies., Recent Findings: The importance of diagnosing an immune-mediated inner-ear disorder is highlighted in the context of it being one of few forms of treatable inner-ear disorder with a good response to immunosuppressive therapy. Due to a lack of reliable tests, the criteria upon which the diagnosis of immune-mediated inner-ear disease is based are often arbitrary. Previous and current research focuses mainly on the investigation of the aetiology of immune-mediated disorders, studying the presence of autoantibodies and the antigens responsible for their production. The prognostic and therapeutic values of inner-ear-specific antibodies are still unclear. Various antigens have been suggested. However, most antigens identified have been ubiquitous proteins not specific to the inner ear and therefore lack logical association with localized inner-ear pathology., Summary: Early diagnosis of immune-mediated inner-ear disorders with prompt treatment may prevent irreversible damage to inner-ear structures. Accordingly, it is important to include immune-mediated inner-ear disorders in the differential diagnosis of patients presenting with 'idiopathic' audiovestibular dysfunction. To enable early diagnosis, we recommend that the current available routine immunological laboratory tests (antinuclear, antineutrophil cytoplasmic, antiendothelial cell, antiphospholipid/anticardiolipin and antithyroid antibodies) are used when assessing a patient with suspected immune-mediated inner-ear disorder.

Despite an extensive diagnostic workup, some cases of acute transverse myelitis (ATM) remain of unknown etiology and have been referred to as "idiopathic" by the Transverse Myelitis Consortium group. In a retrospective study of 288 patients with ATM, 45 cases (15.6%) met the criteria for idiopathic ATM. The patients formed a relatively homogeneous group in terms of clinical and MRI data, but the prognosis was highly variable.

Rasmussen encephalitis (RE) sera were screened for antibodies to human alpha7 nicotinic acetylcholine receptors (nAChRs) using electrophysiology, calcium imaging, and ligand binding assays. Sera from two of nine patients with RE blocked ACh-induced currents through alpha7 nAChRs and the ACh-induced rise in intracellular free calcium ([Ca2+]i) and inhibited (125)I-alpha-bungarotoxin binding in cells expressing alpha7 nAChRs. Thus, the alpha7 nAChR is a potential target for pathogenic antibodies in patients with RE.

The authors report four patients with a syndrome of painless bilateral isolated phrenic neuropathy. Electrophysiologic testing demonstrated active denervation restricted to the diaphragm. Long-term recovery was poor. The authors conclude that bilateral isolated phrenic neuropathy is a cause of painless diaphragmatic paralysis distinguishable from immune brachial plexus neuropathy and other neuromuscular disorders with similar clinical presentation.

Background: Narcolepsy with cataplexy is associated with a loss of orexin/hypocretin. It is speculated that an autoimmune process kills the orexin-producing neurons, but these cells may survive yet fail to produce orexin., Objective: To examine whether other markers of the orexin neurons are lost in narcolepsy with cataplexy., Methods: We used immunohistochemistry and in situ hybridization to examine the expression of orexin, neuronal activity-regulated pentraxin (NARP), and prodynorphin in hypothalami from five control and two narcoleptic individuals., Results: In the control hypothalami, at least 80% of the orexin-producing neurons also contained prodynorphin mRNA and NARP. In the patients with narcolepsy, the number of cells producing these markers was reduced to about 5 to 10% of normal., Conclusions: Narcolepsy with cataplexy is likely caused by a loss of the orexin-producing neurons. In addition, loss of dynorphin and neuronal activity-regulated pentraxin may contribute to the symptoms of narcolepsy.

The authors report a 46-year-old woman with antibodies to the nicotinic acetylcholine receptor (NiAchR) of the autonomic ganglia. She presented with severe orthostatic intolerance refractory to treatment with midodrine, fludrocortisone, erythropoietin, vasopressin, salt, and fluid loading. Addition of L-threo-3,4-dihidroxyphenylserine (L-DOPS) substantially improved blood pressure and orthostatic tolerance. L-DOPS may benefit patients with severe orthostatic intolerance and be particularly effective in patients with ganglionic NiAchR antibodies.

A patient with thymoma-associated neuromyotonia and voltage-gated potassium channel (Kv1.2 and Kv1.6) antibodies by immunoprecipitation and rat brain immunolabeling was treated successfully with immunoadsorption and cyclophosphamide. Curiously, glutamic acid decarboxylase antibodies, absent at onset, appeared later. Stiff-person syndrome was absent, but fast blink reflex recovery suggested enhanced brainstem excitability. The range of antibodies produced in thymoma-associated neuromyotonia is richer, and the timing of antibody appearance more complex, than previously suspected.

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.

Objective: S: To investigate whether motor cortex excitability is enhanced in both stiff-person syndrome (SPS) and its "plus" variant, progressive encephalomyelitis with rigidity (PER), and related to autoimmunity against glutamic acid decarboxylase (GAD)., Methods: The authors compared 21 patients with SPS or PER (7 untreated, 14 treated) with 14 age-matched healthy controls and used transcranial magnetic stimulation (TMS, paired-pulse paradigm) to investigate intracortical inhibition (ICI) and intracortical facilitation (ICF). GAD autoantibody levels in serum and CSF were determined by radioimmunoassay., Results: The authors found significantly enhanced motor cortex excitability in untreated SPS and PER patients. GABAmimetic medication significantly reduced ICF but did not affect ICI. Motor cortex excitability was more enhanced in patients with GAD antibodies than in patients without GAD antibodies and correlated positively with GAD antibody levels in CSF., Conclusions: The motor cortex is hyperexcitable in SPS and PER patients. However, hyperexcitability is partly masked by GABAmimetic treatment. Correlation of elevated GAD antibody levels with enhanced ICF suggests that motor cortex hyperexcitability in SPS and PER is related to anti-GAD autoimmunity.

Background: Immune treatments are recommended for patients with Guillain-Barré syndrome (GBS) who cannot walk independently, but a considerable number of GBS patients are in the progressive phase at the first examination., Objective: To investigate whether progression patterns differ in demyelinating and axonal subtypes of GBS., Methods: Clinical, laboratory, and electrophysiologic data on 131 consecutive patients with GBS were reviewed. Patients were classified as having acute inflammatory demyelinating polyneuropathy (AIDP) or acute motor axonal neuropathy (AMAN) based on electrodiagnostic criteria., Results: Forty-one patients had AIDP, 62 AMAN, and 28 were unclassified. Age, sex, and Hughes Functional Grading Scale score at the first medical examination did not differ for the AIDP and AMAN patients. Mean periods between neurologic onset and first examination (5.3 vs 4.2 days; p = 0.01) and neurologic onset and nadir (18.0 vs 11.5 days; p = 0.001) were longer for the AIDP group. In the subgroup of those with mild disability (able to walk independently at the first neurologic examination), 88% of the AMAN patients had reached the nadir, whereas 65% of the AIDP patients had reached it. The remaining 35% progressed to it over the next 1 to 2 weeks and were unable to walk at nadir., Conclusions: The patterns and speeds of progression differ in AMAN and AIDP, AMAN having a rapid progression and an early nadir. AIDP patients frequently have a significantly long progression after the first examination; therefore, they need to be carefully monitored.

The use of intravenous immune globulin (IVIg) has increased significantly in the past decade, benefiting a wide variety of immune diseases. Seven different formulations of IVIg are now licensed in the United States. Although all contain pooled IgG, there are differences in their production and composition that affect their efficacy, tolerability, and side-effect profile. Important variables include concentration, volume, osmolality, sodium, and sugar content. This article reviews what is known about the composition and properties of the various IVIg formulations that might affect the therapeutic outcome.

Purpose of Review: The physiological properties of nerve and muscle are influenced by pathological changes and the aim of this review is to discuss recent contributions of electrophysiological studies to the understanding and diagnosis of selected peripheral nerve disorders. The relationships between pathology and physiology emphasize the close interdependence between electrophysiological studies, clinical deficits and other laboratory information. Attention should be paid to the strengths and limitations of electrophysiological methods, considering their impact on diagnosis and treatment of patients., Recent Findings: Several studies have shown particular pathophysiological profiles associated with different antibody subtypes in autoimmune peripheral neuropathies and this association further supports the suggestion of pathological specificity in both acute and chronic neuropathy. The sensitivity and specificity of physiological profiles therefore become increasingly important since some of these neuropathies are accessible to treatment. On the other hand, the pathophysiological and clinical profiles may be heterogeneous in patients with some disorders. This could be related to a more indistinct division between different types of pathology with increased understanding of pathogenetic mechanisms. Moreover, new insights into disturbed axonal function have stimulated attempts to develop methods to explore normal and diseased human nerve function., Summary: The exploration of axonal membrane and ion-channel function has become accessible using studies of excitability and are of potential value where conventional studies only provide nonspecific evidence of the number of fibers and the integrity of myelin. These studies will presumably become increasingly important in the years ahead considering the lack of understanding of the functional disturbances in axonal neuropathies.

Purpose of Review: To update recent advances in the pathogenesis, pathophysiology and treatment of some autonomic neuropathies., Recent Findings: When evaluating a patient with subacute autonomic neuropathy, certain autoantibodies are important in diagnosis and may influence management. Ganglionic antibody may be pathogenetically important while the paraneoplastic antibodies alert the clinician to the presence of an occult neoplasm. Autonomic failure is an integral component of diabetic neuropathy. Sildenafil is safe and efficacious in treating erectile dysfunction in diabetic patients. Sympathetic cardiac hyperinnervation can occur concurrently with denervation in diabetic neuropathy The gene mutations for hereditary sensory and autonomic neuropathies I, III, and IV are now known and there is clear unmyelinated fiber loss. Additional options for treatment of orthostatic hypotension include erythropoietin and, surprisingly, water. Botulinum toxin is efficacious, at least for a time, for the treatment of palmar and axillary hyperhidrosis., Summary: Ganglionic antibody likely mediates autoimmune autonomic neuropathy. Sympathetic cardiac hyperinnervation can occur and could potentially cause arrhythmia and sudden death. Knowledge of gene mutations of hereditary sensory and autonomic neuropathies I, III and IV could lead to more secure diagnosis of the disorders. Effective treatment of essential hyperhidrosis with botulinum toxin injection has been demonstrated. It might be possible to improve treatment of orthostatic hypotension acutely with water imbibation and chronically with erythropoieting.