Background: Plasma exchange (PE) is a therapeutic option for CNS demyelinating attacks unresponsive to corticosteroids, but the potential benefit of adding rituximab and IV immunoglobulins to PE (RTX-IVIG-PE), which has shown its efficacy and safety in other immune-mediated conditions, has not been investigated. Objective: We aimed to determine the overall effectiveness of PE in severe demyelinating attacks, identify predictors of response, and compare outcomes between standard PE and RTX-IVIG-PE protocols. Design: Retrospective analysis of patients with CNS demyelinating attacks treated with PE between 2012 and 2023 across five Spanish hospitals. Methods: Clinical response was measured as an improvement or a complete recovery at discharge and 6 months. Uni- and multivariable logistic regression models were developed to identify predictors of PE response. A logistic regression analysis, after inverse probability of treatment weighting (IPTW), was performed to compare the outcome of attacks treated with standard PE and RTX-IVIG-PE. Results: A total of 162 attacks in 150 patients (81 multiple sclerosis; 37 others acquired demyelinating syndromes; 27 neuromyelitis optica spectrum disorder; 5 myelin oligodendrocyte glycoprotein antibody-associated disease; 73% female; median age 43 years (interquartile range 33–52.75)) were analyzed. At discharge, 60% of all attacks showed clinical improvement, and 15% achieved complete recovery. At 6 months, these rates increased to 77% and 31%, respectively. Younger age, lower preattack Expanded Disability Status Scale, and treatment with RTX-IVIG-PE were independent predictors of complete recovery at 6 months. IPTW analysis showed that attacks treated with RTX-IVIG-PE (33) were associated with improvement (adjusted odds ratio (aOR) 5.4, p < 0.001) and complete recovery (aOR 4.55, p < 0.001) at 6 months compared to those treated with standard PE (129), without significant differences in the adverse event profile between the two protocols. Conclusion: PE improves the outcome of steroid-refractory CNS demyelinating attacks, and the addition of rituximab and IVIG to PE may increase the likelihood of long-term recovery.

BACKGROUND AND OBJECTIVES:Although acute disseminated encephalomyelity (ADEM) can be myelin oligodendrocyte glycoprotein-IgG (MOG-IgG) positive or negative, it is unclear whether other MOG-antibody-associated disease (MOGAD)-like encephalitis syndromes occur without MOG-IgG. We aimed to define the frequency, clinico-radiologic features, outcomes, and antibody associations of such cases in children. METHODS:Prospective cohort study of children (<18 years) with encephalitis meeting clinico-radiologic MOGAD criteria, regardless of MOG-IgG status. Serum from all patients and CSF when available were tested by live cell-based assays (CBA-IIF, CBA-FACS) at 2 laboratories. Brain MRIs were centrally reviewed for MOGAD-like patterns (ADEM, cortical encephalitis, isolated/predominant central gray matter). Additional testing included CBAs for MOG-IgA, MOG-IgM, PLP1-IgG, glial fibrillary acidic protein-IgG, and AQP4-IgG, along with rat brain immunohistochemistry. RESULTS:Among 160 patients with MOGAD-like encephalitis, 120 were MOG-IgG positive and 40 negative (20 ADEM, 11 cortical encephalitis, 9 isolated/predominant central gray matter encephalitis). Clinical-radiologic features were broadly comparable between groups, including lesion distribution, frequency of associated longitudinally extensive transverse myelitis, lesion resolution, and functional outcomes. Relapses were more frequent in MOG-IgG-positive patients (22, 18% vs 1, 3%; p = 0.017). Immunohistochemistry revealed myelin immunostaining in 14 (12%) MOG-IgG-positive cases (CBA confirmed cross-reactivity with rodent MOG-epitopes) and 10 (25%) MOG-IgG-negative patients (no cross-reactivity with rodent MOG-epitopes); this included a fulminant case with autopsy showing perivenous demyelination and C4d complement deposition, suggesting autoantibodies against an unknown myelin antigen. MOG-IgA, MOG-IgM, or PLP1-IgG occurred in 36/111 (32%) MOG-IgG-positive and 7/37 (19%) MOG-IgG-negative cases, without clinical differences between groups. DISCUSSION:Children can develop the full spectrum of MOGAD-like encephalitis without MOG-IgG. Clinical features and immunotherapy response are similar to MOGAD, but relapses are uncommon.

Background and Objectives Detecting neural surface antibodies (NSAbs) is essential for diagnosing autoimmune encephalitis. The recommended diagnostic strategy involves initial screening with tissue-based assays (TBAs), followed by confirmation with cell-based assays (CBAs). While specialized centers use in-house TBAs, many clinical laboratories depend on commercial TBAs, whose accuracy is yet to be fully assessed. Methods We selected 92 CSF and 99 serum samples from patients with autoimmune encephalitis and NSAbs confirmed by in-house TBAs and CBAs (20 samples each for AMPAR, GABA(A)R, GABA(B)R, IgLON5, LGI1, NMDAR, and CASPR2; 19 for mGluR5; 17 for DPPX; and 15 for mGluR1 antibodies), along with 50 CSF and 50 serum samples from negative controls. We assessed the performance of a commercial indirect immunofluorescence (IIF)-TBA (EUROIMMUN). Slides were evaluated as "positive" or "negative" by 2 experienced investigators and 2 less experienced raters. Discordant results were re-evaluated through interrater discussion and assessed using Cohen's kappa. Results The experienced raters agreed on 94% (133/142) of CSF and 88% (131/149) of serum classifications (Cohen's kappa = 0.87 and 0.75, respectively, p < 0.001). Among CSF samples, 75% (106/142) were correctly identified while 19% (27/142) were misclassified (13 false positives, 14 false negatives). Among serum samples, 66% (98/149) were correctly identified while 22% (33/149) were misclassified (11 false positives, 22 false negatives). The poorest performance was seen in detecting NMDAR, GABA(A)R, and mGluR5 Abs, which were not identified in 5 of 10, 6 of 10, and 5 of 9 serum samples and in 4 of 10, 5 of 10, and 5 of 10 CSF samples, respectively. The overall sensitivity of the commercial IIF-TBA was 84% for CSF and 76% for serum while the specificity was 72% for CSF and 73% for serum. Less experienced raters correctly identified 69% (98/142) of CSF samples and 73% (109/149) of serum samples and misclassified 13% (18/142) of CSF samples and 11% (16/149) of serum samples, and 18% (26/142) of CSF samples and 16% (24/149) of serum samples remained discordant. Discussion The diagnostic performance of EUROIMMUN IIF-TBA in detecting NSAbs in autoimmune encephalitis is suboptimal. NMDAR antibodies, among the most common NSAbs, can be missed in 50% of cases. This commercial TBA should not be used alone as a screening method nor as a confirmatory technique for NSAbs.

BACKGROUND AND OBJECTIVES:The aim of this study was to describe the clinical features and long-term outcome of patients with glycine receptor (GlyR) antibody-mediated progressive encephalomyelitis with rigidity and myoclonus (PERM), a disease commonly included under the term of stiff-person spectrum disorders (SPSDs). METHODS:We conducted a retrospective analysis of patients with PERM and GlyR antibodies diagnosed in our laboratory and a systematic literature review (following Preferred Reporting Items for Systematic Reviews and Meta-Analyses [PRISMA] 2020 reporting guideline) of previously reported patients with sufficient clinical information and ≥12 months of follow-up. Neurologic disability was measured with the modified Rankin Scale (mRS). Relapses were defined as any event occurring >6 months after the first episode that required immunotherapy. RESULTS:Forty-one patients were identified, 22 from our database and 19 from the literature. The median age was 58 years (IQR: 43-66 years), and 36 (88%) were male and 5 female. The median time from symptom onset to admission was 2 weeks (IQR: 1-4 weeks). Predominant presentations included brainstem symptoms, mainly dysphagia and trismus, in 23 patients (56%); muscle stiffness and myoclonus in 9 (22%); dysesthesias or pruritus in 7 (17%); and cacosmia with dysgeusia in 2 (5%). Five patients (12%) never developed muscle stiffness. The median (range) mRS score at nadir was 5 (3-5). All patients received immunotherapy. Eleven patients died, 8 from complications of PERM. There were 12 relapses in 10 (28%) of 36 patients who lived >6 months. All relapses responded to immunotherapy. The functional status at the last visit, median time 24 months (IQR: 18-72 months), was good (mRS score <3) in 23 (70%) of the 33 patients who did not die from PERM. Age (HR: 1.06; 95% CI 1.01-1.11; p = 0.019) and admission to the intensive care unit (HR: 5.26; 95% CI 1.41-19.57, p = 0.013) were independent predictors of bad outcome (mRS score ≥3). DISCUSSION:GlyR antibody-mediated PERM is a rapidly progressive and severe disease that predominantly affects men and frequently presents with brainstem involvement. Its distinct demographic and clinical features suggest that it should be considered separately from SPSDs, which typically follows a chronic course and is more commonly associated with glutamic acid decarboxylase antibodies.

Detecting neural surface antibodies (NSAbs) is essential for diagnosing autoimmune encephalitis. The recommended diagnostic strategy involves initial screening with tissue-based assays (TBAs), followed by confirmation with cell-based assays (CBAs). While specialized centers use in-house TBAs, many clinical laboratories depend on commercial TBAs, whose accuracy is yet to be fully assessed. We selected 92 CSF and 99 serum samples from patients with autoimmune encephalitis and NSAbs confirmed by in-house TBAs and CBAs (20 samples each for AMPAR, GABAAR, GABABR, IgLON5, LGI1, NMDAR, and CASPR2; 19 for mGluR5; 17 for DPPX; and 15 for mGluR1 antibodies), along with 50 CSF and 50 serum samples from negative controls. We assessed the performance of a commercial indirect immunofluorescence (IIF)-TBA (EUROIMMUN). Slides were evaluated as "positive" or "negative" by 2 experienced investigators and 2 less experienced raters. Discordant results were re-evaluated through interrater discussion and assessed using Cohen's kappa. The experienced raters agreed on 94% (133/142) of CSF and 88% (131/149) of serum classifications (Cohen's kappa = 0.87 and 0.75, respectively, p < 0.001). Among CSF samples, 75% (106/142) were correctly identified while 19% (27/142) were misclassified (13 false positives, 14 false negatives). Among serum samples, 66% (98/149) were correctly identified while 22% (33/149) were misclassified (11 false positives, 22 false negatives). The poorest performance was seen in detecting NMDAR, GABAAR, and mGluR5 Abs, which were not identified in 5 of 10, 6 of 10, and 5 of 9 serum samples and in 4 of 10, 5 of 10, and 5 of 10 CSF samples, respectively. The overall sensitivity of the commercial IIF-TBA was 84% for CSF and 76% for serum while the specificity was 72% for CSF and 73% for serum. Less experienced raters correctly identified 69% (98/142) of CSF samples and 73% (109/149) of serum samples and misclassified 13% (18/142) of CSF samples and 11% (16/149) of serum samples, and 18% (26/142) of CSF samples and 16% (24/149) of serum samples remained discordant. The diagnostic performance of EUROIMMUN IIF-TBA in detecting NSAbs in autoimmune encephalitis is suboptimal. NMDAR antibodies, among the most common NSAbs, can be missed in 50% of cases. This commercial TBA should not be used alone as a screening method nor as a confirmatory technique for NSAbs.

OBJECTIVES:The aim of this study was to report the clinical features, disease-modifying treatment (DMT) response, and outcomes of children with MOG-IgG who fulfill the 2017 McDonald criteria for multiple sclerosis (MS). METHODS:This prospective observational study included children (<18 years) with a suspected acquired demyelinating syndrome (ADS) whose serum or CSF was positive for MOG-IgG, who met the indicated MS criteria, and who had ≥1 year of clinical follow-up. MOG-IgG was tested using live cell-based assays. RESULTS:Of 554 children with confirmed ADS (196 with MOG-IgG), 8 (median age 11 years, interquartile range 9-14) harbored MOG-IgG and fulfilled MS criteria: 2 had typical MS and 6 had overlapping MOGAD-MS features at onset, but 5 of the latter group developed an MS-like course during follow-up. Five of 7 patients with assessable samples were Epstein-Barr virus seropositive at disease onset, and all 8 had persistent silent radiologic activity with lesional location and morphology suggestive of MS, leading to initiation of DMT. All initial treatments were well tolerated, but eventually, 7 of 8 children (88%) required high-efficacy DMT. DISCUSSION:In this pediatric cohort, 4% of patients with MOG-IgG met criteria for MS. The clinical-radiologic spectrum ranged from typical MS to overlapping MOGAD-MS, and patients usually required high-efficacy DMT.

Cognitive impairment in people with multiple sclerosis (pwMS) is highly heterogeneous, highlighting the need to better understand the underlying pathophysiological processes of cognitive decline and the brain's mechanisms for adapting to MS damage. This longitudinal study explores functional connectivity (FC) changes and their relationship with cognitive trajectories over seven years in pwMS. We aimed to determine whether individuals with cognitive decline exhibited different FC patterns compared to those with stable cognitive performance. For this purpose, we analysed data from 58 pwMS, including cognitive assessments using the Rao's battery and functional MRI at two-time points with an interval of seven years. Cognitive worsening was defined as 25% decline in global cognitive scores. Graph-based networks metrics, including global and node-based strength, efficiency and clustering coefficient, alongside regional normalized grey matter (GM) volumes, were computed using MRI. We used mixed effect regression models with random subject-specific intercepts to explore FC and GM volume differences and the association between FC and cognition. The cohort was predominantly female (78%), with a mean age of 46.8 years and a median disease duration of 11.6 years. We found a significant group-by-time interaction, patients with cognitive decline showed reductions in node strength (21.1% of nodes), local efficiency (64.4%), and clustering coefficient (85.5%) particularly in the deep GM and parietal cortex at follow-up, and reduced global graph metrics. In contrast, the cognitively stable group exhibited increased node strength (15.8%) and local efficiency (5.3%), mainly in the temporal and prefrontal cortices. Both groups showed reduced GM volume in 84.2 and 79% of regions at follow-up, respectively. Several links were found between FC changes and cognitive performance. Findings confirm distinct FC trajectories in pwMS associated with their ability to cope with structural damage, impacting cognitive outcomes at mid-term. These findings indicate that patients with stable cognitive performance may engage compensatory network reorganization processes, which could mitigate the progression of cognitive decline.

INTRODUCTION:Anti-GAD65 is an established diagnostic biomarker for autoimmune diabetes and neurological syndromes associated with GAD antibody-spectrum disorders. Automated chemiluminescence-based immunoassays such as Maglumi are increasingly used, but their behavior at high antibody concentrations remains poorly characterized. We report the analytical concordance between Maglumi and radioimmunoassay (RIA), the cut-off titer that differentiates neurological from diabetic patients, and the hook effect of the immunoassay. MATERIALS AND METHODS:Anti-GAD65 levels were analyzed in samples from 90 patients with suspected autoimmune diabetes or neurological syndromes, using Maglumi 2000® and RIA (Medipan®). Analytical concordance was assessed by Passing-Bablok regression, Bland-Altman plots, and Cohen's kappa. ROC curve analysis identified diagnostic thresholds, and dilution studies were performed in samples with unexpectedly low values to assess a potential hook effect. RESULTS:Maglumi results were approximately five times higher than RIA results (slope = 5.364; R2 = 0.908); agreement was higher in endocrine (R2 = 0.998) than in neurological patients (R2 = 0.891). A cutoff of 6778 IU/mL discriminated neurological patients from diabetic patients (AUC = 0.96). Sixteen samples showed a hook effect, with direct (undiluted) values ≤273 IU/mL, while the corrected titers after dilution exceeded 20,000 IU/mL. A linear regression confirmed an inverse relationship between direct and true titers (r = -0.79, p < 0.05). DISCUSSION:Maglumi anti-GAD65 immunoassay provides reliable discrimination between endocrine and neurological patients but requires method-specific cutoffs to avoid misclassification. Hook effect was frequent in high-titer neurological samples, potentially leading to misdiagnosis, underscoring the need for routine dilution protocols to improve diagnostic reliability. CONCLUSIONS:Standardized dilution protocols and appropriate cutoffs are essential to ensure reliable anti-GAD65 testing with Maglumi chemiluminescent immunoassay, particularly in neurological indications.

BACKGROUND AND OBJECTIVES:Anti-leucine-rich glioma-inactivated 1 (anti-LGI1) encephalitis is the most common antibody-mediated encephalitis in adults older than 50 years. In addition to antibody effects, cytokines and chemokines drive neuroinflammation in other autoimmune encephalitides. However, their role in anti-LGI1 encephalitis is underexplored. We evaluated cytokine profiles in serum and CSF, correlating them with acute severity and long-term outcome. METHODS:Cytokine/chemokine levels from 57 untreated patients with anti-LGI1 encephalitis were measured in serum and CSF (34 paired samples) with a bead-based multiplex assay and compared with those of patients with noninflammatory neurologic disorders (serum = 24; CSF = 21). Clinical information including degree of severity (modified Rankin Scale, mRS) and 12-month functional outcomes (resume previous activities and work) was assessed. RESULTS:Patients with anti-LGI1 encephalitis exhibited an increased proinflammatory profile in CSF and serum, with elevated levels of IL-1β, IL-1RA, IL-6, IL-8, IL-10, IL-18, IL-35, IP-10, granzyme B, CX3CL1, MIG, TNFα, and SDF1. A higher CSF/serum IL-6 ratio correlated with disease severity at onset (mRS score >2: 1.67 [0.50-7.20] vs 0.39 [0.07-1.22], p = 0.0069). Elevated acute-phase serum IL-35 predicted poorer 12-month outcomes (81.34 vs 9.19 pg/mL in partial vs complete recovery, p = 0.0003). Increased B cell-related markers (IL-21, BAFF, APRIL, CXCL13) in CSF (all p < 0.05) were also observed. DISCUSSION:In this study, we show that the acute-phase IL-6 CSF/serum ratio and serum IL-35 levels in immunotherapy-naive patients with anti-LGI1 encephalitis are associated with disease severity and poor outcomes, respectively, highlighting their potential as biomarkers for risk stratification and therapeutic targeting.

BACKGROUND:We investigated the association between changes in retinal thickness and cognition in people with MS (PwMS), exploring the predictive value of optical coherence tomography (OCT) markers of neuroaxonal damage for global cognitive decline at different periods of disease. METHOD:We quantified the peripapillary retinal nerve fibre (pRFNL) and ganglion cell-inner plexiform (GCIPL) layers thicknesses of 207 PwMS and performed neuropsychological evaluations. The cohort was divided based on disease duration (≤5 years or >5 years). We studied associations between changes in OCT and cognition over time, and assessed the risk of cognitive decline of a pRFNL≤88 µm or GCIPL≤77 µm and its predictive value. RESULTS:Changes in pRFNL and GCIPL thickness over 3.2 years were associated with evolution of cognitive scores, in the entire cohort and in patients with more than 5 years of disease (p<0.01). Changes in cognition were related to less use of disease-modifying drugs, but not OCT metrics in PwMS within 5 years of onset. A pRFNL≤88 µm was associated with earlier cognitive disability (3.7 vs 9.9 years) and higher risk of cognitive deterioration (HR=1.64, p=0.022). A GCIPL≤77 µm was not associated with a higher risk of cognitive decline, but a trend was observed at ≤91.5 µm in PwMS with longer disease (HR=1.81, p=0.061). CONCLUSIONS:The progressive retinal thinning is related to cognitive decline, indicating that cognitive dysfunction is a late manifestation of accumulated neuroaxonal damage. Quantifying the pRFNL aids in identifying individuals at risk of cognitive dysfunction.

Background Multiple sclerosis patients would benefit from machine learning algorithms that integrates clinical, imaging and multimodal biomarkers to define the risk of disease activity. Methods We have analysed a prospective multi-centric cohort of 322 MS patients and 98 healthy controls from four MS centres, collecting disability scales at baseline and 2 years later. Imaging data included brain MRI and optical coherence tomography, and omics included genotyping, cytomics and phosphoproteomic data from peripheral blood mononuclear cells. Predictors of clinical outcomes were searched using Random Forest algorithms. Assessment of the algorithm performance was conducted in an independent prospective cohort of 271 MS patients from a single centre. Results We found algorithms for predicting confirmed disability accumulation for the different scales, no evidence of disease activity (NEDA), onset of immunotherapy and the escalation from low- to high-efficacy therapy with intermediate to high-accuracy. This accuracy was achieved for most of the predictors using clinical data alone or in combination with imaging data. Still, in some cases, the addition of omics data slightly increased algorithm performance. Accuracies were comparable in both cohorts. Conclusion Combining clinical, imaging and omics data with machine learning helps identify MS patients at risk of disability worsening.

The encounter of disorders associated with antibodies to neuronal enzymes caused a paradigm shift in understanding the CNS autoimmunity.The autoimmune disorders targeting the 65kDa isoform of glutamic acid decarboxylase (GAD65) not only comprehends type 1 diabetes mellitus (T1DM), but also rather rare neurological disorders, including stiff-person syndrome (SPS), cerebellar ataxia, limbic encephalitis, and epilepsy.The patients with these autoimmune neurological disorders usually present with T1DM and suggests the presence of GAD65 antibodies.This is suggestive of autoimmune mechanisms for the development and worsening of these disorders.For better prognosis, its advanced screening and swift treatment are essential.Mesenchymal stem cells (MSCs) can be a promising salvage to these autoimmune disorders as they have proven hypoimmunogenic and immunomodulatory properties along with excellent regenerative ability.These self-renewing progenitor cells can differentiate into numerous cell types under explicit conditions, which includes neurons and pancreatic beta cells.MSCs annul the proinflammatory response in autoimmune disorders, may be through paracrine secretions, and hence, can help managing the hurricane of disturbed immunity.We present a link between the mechanisms driving autoimmune neurological diseases and T1DM in this review, based on the existence of GAD65 antibodies and an MSC-mediated solution for their treatment.