Dubey, Divyanshu

ABSTRACTCavin‐4 was identified as a potential autoantigen for immune‐mediated rippling muscle disease (iRMD). To validate this, we developed and tested various immunoassays, including a cell‐based assay (CBA), cavin‐4 recombinant protein ELISA, and multi‐peptide ELISA. Among 19 iRMD patients, all exhibited muscle rippling, and 13 had percussion‐induced mounding. All immunoassays demonstrated clinical and analytical specificities greater than 95%. The protein ELISA had the highest sensitivity (94.7%) and specificity (99.9%), outperforming CBA (sensitivity 89.5%, specificity 99.6%) and the multi‐peptide ELISA (sensitivity 79.0%, specificity 97.2%). Our results suggest that the cavin‐4 protein ELISA is a promising tool for high‐throughput clinical testing in iRMD.

AbstractDefining the CSF cytokine/chemokine and injury biomarker signature of glial fibrillary acidic protein (GFAP) autoimmunity can inform immunopathogenesis. CSF GFAP‐IgG‐positive samples (N = 98) were tested for 17 cytokines/chemokines, neurofilament light chain (NfL), and GFAP (ELLA, Bio‐Techne). Controls included non‐inflammatory (N = 42), AQP4‐IgG‐positive (N = 83), CNS infections (N = 13), and neurosarcoidosis (N = 32). IL5, IL6, IL10, IL8/CXCL8, CXCL9, CXCL10, CXCL13, BAFF, GM‐CSF, IFN‐gamma, and TNF‐alpha concentrations were higher compared to non‐inflammatory controls (P < 0.01). GFAP concentrations were similar to those of AQP4‐IgG‐positive patients; NfL was higher (P < 0.001) and correlated with MRI changes and outcomes. CSF cytokine/chemokine findings in GFAP autoimmunity correlate with histopathology; GFAP and NfL hold promise as disease biomarkers.

Background Data regarding long-term recovery from autoimmune encephalitis (AE) remain limited. Methods This retrospective observational study investigated outcomes in 182 patients who met the 2016 criteria for definite AE. Recovery data were available in 172 patients. Follow-up data at ≥24 months post-attack were available for 119. Recovery trajectory, residual symptoms, outcome predictors and causes of post-AE death were assessed. Results Of 172 patients, 138 (80%) achieved good recovery (modified Rankin Scale (mRS) ≤2) with a median recovery time of 4 months (95% CI: 2 to 6 months). Recovery varied by associated neural antibody, with the best recovery observed in leucine-rich glioma-inactivated 1 (97% good recovery, median recovery time 0 (0 to 2) months). Paraneoplastic AE (p=0.007), severe attacks (eg, mRS ≥4 at attack, p=0.007) and cerebrospinal fluid pleocytosis (p=0.005) were associated with a lower likelihood of good recovery, while seizure presentation (p=0.026) was associated with better recovery. Despite good recovery, several residual symptoms persisted ≥24 months post-AE, including cognitive deficits (53%), seizures (26%), depression (23%), sleep disorders (25%), brainstem/cerebellar symptoms (13%), other movement disorders (14%) and autonomic symptoms (12%). Predictors of long-term sequelae included disabling cognitive deficit at onset and delayed immunotherapy for post AE-dementia, and medial temporal atrophy as well as escalation to cyclophosphamide therapy for both drug-resistant epilepsy and chronic depression. Of 182 patients, 20 (11%) died; the most common cause of death was progression of AE (6/20 (30%)). Conclusion While the majority of patients achieved functional independence after AE, several residual symptoms persisted. Several clinical and paraclinical features were associated with long-term sequelae.

ABSTRACTBackground and AimsChronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is difficult to distinguish from mimicking disorders, with misdiagnosis resulting in IVIG overutilization. We evaluate a clinical‐electrophysiological model to facilitate CIDP versus mimic neuropathy prediction.MethodsUsing the European Academy of Neurology/Peripheral Nerve Society (EAN/PNS) 2021 CIDP guidelines we derived 26 clinical and 144 nerve conduction variables. The model was generated and validated utilizing total CIDP (n = 129) and mimics (n = 309); including (1) IgG4‐nodopathies; (2) POEMS (polyneuropathy–organomegaly–endocrinopathy–monoclonal protein‐skin changes); (3) anti‐myelin‐associated‐glycoprotein; (4) paraneoplastic; (5) Waldenström B‐cell lymphoma; (6) diabetic neuropathies; (7) amyloidosis; (8) Charcot–Marie–Tooth; (9) motor neuropathies/neuronopathies; and (10) idiopathic‐inflammatory‐myopathies.ResultsWe analyzed 9282 clinical and 51 408 electrophysiological data points. Univariate analysis identified 11 of 26 clinical variables with significant odds ratios. A multivariate regression model using four clinical and two electrophysiologic variables achieved 93% area‐under‐curve (95% CI 91–95): progression over 8 weeks (OR 40.66, 95% CI 5.31–311.36), absent autonomic involvement (OR 17.82, 95% CI 2.93–108.24), absent muscle atrophy (OR 16.65, 95% CI 3.27–84.73), proximal weakness (OR 3.63, 95% CI 1.58–8.33), ulnar motor conduction velocity slowing < 35.7 m/s (OR 5.21, 95% CI 2.13–12.76), and ulnar motor conduction block (OR 13.37, 95% CI 2.47–72.40). A web‐based probability calculator (https://news.mayocliniclabs.com/cidp‐calculator/) was developed, with 100% sensitivity and 68% specificity at a 92% probability threshold. Specificity improved to 93% when considering “red flags,” electrophysiologic criteria, and laboratory testing.InterpretationA probability calculator using clinical electrophysiological variables assists CIDP differentiation from mimics, with scores below 92% unlikely to have CIDP. The highest specificity is achieved by considering clinical “red flags,” electrophysiologic demyelination, and laboratory testing.

AbstractObjectiveWe describe neurologic phenotype, clinical associations, and outcomes in autoimmune brainstem encephalitis.MethodsMedical records of neural‐IgG positive autoimmune brainstem encephalitis patients diagnosed at Mayo Clinic (January 1, 2006–December 31, 2022) were reviewed.ResultsNinety‐eight patients (57 male) were included. Median age of symptom onset was 51 years (range, 8 months‐85 years). Frequent presenting features were ≥1: diplopia (80%), ataxia (78%), dysarthria (68%), vestibulocochlear symptoms (67%), dysphagia (61%), nausea/vomiting (42%), and facial weakness (32%). Altered mental status (11%) was uncommon. Neural antibodies detected were as follows: KLHL‐11 (26 patients), GAD65 (high titer, 12), ANNA‐1 (anti‐Hu, 8), ANNA‐2 (anti‐Ri, 8), Ma2 (7), IgLON‐5 (6), AQP4 (6), MOG (4), glycine receptor (4), GQ1B (4), PCA‐1 (anti‐Yo, 4), DPPX (2), neurochondrin (2), neurofilament (2), NMDA‐R (2), AGNA‐1 (SOX‐1, 1), ANNA‐3 (DACH1, 1), amphiphysin (1), CRMP‐5 (1), ITPR‐1 (1), PCA‐Tr (DNER, 1), and PDE10A (1). Cancer was identified in 55 patients: germ cell (23 patients; 3 extra‐testicular), ductal breast adenocarcinoma (8), small cell carcinoma (6, lung 4), adenocarcinomas (6), neuroendocrine carcinoma (3), hematologic (2), squamous cell (2), and other (7). Median modified Ranking score (mRS) at last follow‐up was 3 (range, 0–6). Factors associated with poor outcome included abnormal brain MRI, bulbar symptoms, and elevated CSF IgG index. Kaplan–Meier analysis revealed faster progression to wheelchair in patients who were immunotherapy refractory and with elevated CSF IgG index. Diagnostic criteria for autoimmune brainstem encephalitis (definite and probable) are proposed.InterpretationAutoimmune brainstem encephalitis is a distinct clinical subphenotype of autoimmune encephalitis. Abnormal brain MRI, bulbar symptoms, and elevated CSF‐IgG index associate with poor outcome.

AbstractObjectiveTo describe the phenotypes, oncological associations, biomarker profiles, and outcomes across different age groups in patients with ANNA1 (anti‐Hu) autoimmunity.MethodsA retrospective review of patients with ANNA1‐IgG in serum/CSF between January 1, 2001, and December 31,2019 was performed. Patients were classified into three groups based on the age of symptom onset. Phage immunoprecipitation sequencing (PhIP‐Seq) and neurofilament light chain (NfL) measurements were done in patient sera/CSF with archived samples.ResultsOf 122 patients, 81 (66%), 20 (16%), and 21 (17%) patients belonged to older adults, young adults, and pediatric groups, respectively. Lung cancer and neuromuscular presentations were more common in older adults (p < 0.001), while limbic encephalitis and neuroblastoma were more common in pediatric patients (p < 0.005). Most young adults (75%) did not have cancer identified. Proportions of patients with a favorable response to immunotherapy were 20%, 30%, and 52% among older adults, young adults, and pediatric groups, respectively. PhIP‐Seq demonstrated significant enrichment for ELAVL4 peptides especially for amino acids 240–289, in the majority of samples evaluated (36/67, 54%). ZIC and SOX2 peptides were significantly enriched in those with central nervous system presentations. Serum NfL levels were elevated in patients with cancer and those with poor long‐term outcomes.InterpretationYoung adults with ANNA1 autoimmunity phenotypically resembled older adults but rarely had an underlying cancer. Pediatric patients frequently presented with limbic encephalitis and neuroblastoma and often responded favorably to immunotherapy. Distinct antigenic signatures may underlie differences in clinical presentations. Serum NfL levels may be a biomarker of poor long‐term outcomes in ANNA1 autoimmunity.

ObjectivesTo report an autoimmune paraneoplastic encephalitis characterized by immunoglobulin G (IgG) antibody targeting synaptic protein calmodulin kinase‐like vesicle‐associated (CAMKV).MethodsSerum and cerebrospinal fluid (CSF) samples harboring unclassified antibodies on murine brain‐based indirect immunofluorescence assay (IFA) were screened by human protein microarray. In 5 patients with identical cerebral IFA staining, CAMKV was identified as top‐ranking candidate antigen. Western blots, confocal microscopy, immune‐absorption, and mass spectrometry were performed to substantiate CAMKV specificity. Recombinant CAMKV‐specific assays (cell‐based [fixed and live] and Western blot) provided additional confirmation.ResultsOf 5 CAMKV‐IgG positive patients, 3 were women (median symptom‐onset age was 59 years; range, 53–74). Encephalitis‐onset was subacute (4) or acute (1) and manifested with: altered mental status (all), seizures (4), hyperkinetic movements (4), psychiatric features (3), memory loss (2), and insomnia (2). Paraclinical testing revealed CSF lymphocytic pleocytosis (all 4 tested), electrographic seizures (3 of 4 tested), and striking MRI abnormalities in all (mesial temporal lobe T2 hyperintensities [all patients], caudate head T2 hyperintensities [3], and cortical diffusion weighted hyperintensities [2]). None had post‐gadolinium enhancement. Cancers were uterine adenocarcinoma (3 patients: poorly differentiated or neuroendocrine‐differentiated in 2, both demonstrated CAMKV immunoreactivity), bladder urothelial carcinoma (1), and non‐Hodgkin lymphoma (1). Two patients developed encephalitis following immune checkpoint inhibitor cancer therapy (atezolizumab [1], pembrolizumab [1]). All treated patients (4) demonstrated an initial response to immunotherapy (corticosteroids [4], IVIG [2]), though 3 died from cancer.InterpretationCAMKV‐IgG is a biomarker of immunotherapy‐responsive paraneoplastic encephalitis with temporal and extratemporal features and uterine cancer as a prominent oncologic association. ANN NEUROL 2024;96:21–33

Objective The aim of this study was to assess the diagnostic utility of cerebrospinal fluid (CSF) myelin oligodendrocyte glycoprotein antibodies (MOG‐IgG) testing. Methods We retrospectively identified patients for CSF MOG‐IgG testing from January 1, 1996, to May 1, 2023, at Mayo Clinic and other medical centers that sent CSF MOG‐IgG for testing including: controls, 282; serum MOG‐IgG positive MOG antibody‐associated disease (MOGAD), 74; serum MOG‐IgG negative high‐risk phenotypes, 73; serum false positive MOG‐IgG with alternative diagnoses, 18. A live cell‐based assay assessed CSF MOG‐IgG positivity (IgG‐binding‐index [IBI], ≥2.5) using multiple anti‐human secondary antibodies and end‐titers were calculated if sufficient sample volume. Correlation of CSF MOG‐IgG IBI and titer was assessed. Results The pan‐IgG Fc‐specific secondary was optimal, yielding CSF MOG‐IgG sensitivity of 90% and specificity of 98% (Youden's index 0.88). CSF MOG‐IgG was positive in: 4/282 (1.4%) controls; 66/74 (89%) serum MOG‐IgG positive MOGAD patients; and 9/73 (12%) serum MOG‐IgG negative patients with high‐risk phenotypes. Serum negative but CSF positive MOG‐IgG accounted for 9/83 (11%) MOGAD patients, and all fulfilled 2023 MOGAD diagnostic criteria. Subgroup analysis of serum MOG‐IgG low‐positives revealed CSF MOG‐IgG positivity more in MOGAD (13/16[81%]) than other diseases with false positive serum MOG‐IgG (3/15[20%]) ( p = 0.01). CSF MOG‐IgG IBI and CSF MOG‐IgG titer (both available in 29 samples) were correlated (Spearman's r = 0.64, p < 0.001). Interpretation CSF MOG‐IgG testing has diagnostic utility in patients with a suspicious phenotype but negative serum MOG‐IgG, and those with low positive serum MOG‐IgG results and diagnostic uncertainty. These findings support a role for CSF MOG‐IgG testing in the appropriate clinical setting. ANN NEUROL 2024;96:34–45