Pittock, Sean J.

Abstract Background Lambert-Eaton myasthenic syndrome (LEMS) is caused by IgG-mediated disruption of certain voltage-gated Ca2+-channel (VGCC) functions and diminished peripheral motor nerve-stimulated release of acetylcholine by presynaptic terminals at the neuromuscular junction and selected autonomic synapses. Both P/Q-type (Cav2.1) and N-type (Cav.2) channels are the targets of IgG-mediated autoimmunity in LEMS. Functional presynaptic VGCCs at the healthy mature mammalian neuromuscular junction are P/Q-type. About 60% of LEMS cases are paraneoplastic, of which a majority are associated with small-cell lung cancer (SCLC-LEMS). LEMS can also have a non-paraneoplastic etiology (idiopathic, non-tumor LEMS [NT-LEMS]). It is important to have reliable autoantibody biomarkers to aid the serological diagnosis of LEMS and to distinguish between SCLC-LEMS and NT-LEMS, because the treatment and prognosis differ. Previous studies have reported seropositivity for SOX1/AGNA-1-IgG in ∼ 64% of SCLC-LEMS cases, but in no NT-LEMS cases. When coexisting with P/Q-type VGCC IgG in LEMS patients, IgGs of both N-type VGCC and SOX1/AGNA-1 IgG specificities have been suggested as useful biomarkers for predicting SCLC. Here we compared the clinical utility of serological tests for P/Q-type and N-type VGCCs and SOX1/AGNA-1 IgGs as diagnostic aids for LEMS and for differentiating paraneoplastic from idiopathic LEMS. Methods This is a retrospective study of 102 patients with a clinical (electrophysiologically confirmed) diagnosis of LEMS who were tested for both P/Q-type and N-type VGCC IgGs by radioimmunoprecipitation assays performed at the Mayo Clinic Neuroimmunology Laboratory. 95 patients had comprehensive clinical screening for cancer; 66 had NT-LEMS, 21 had SCLC-LEMS and 8 had LEMS with non-SCLC cancers. Historical data were reviewed retrospectively. Of the NT-LEMS and SCLC-LEMS patients, 76 were tested for SOX1/AGNA-1 IgG. 122 healthy sex and age-matched controls were tested. Results Among the 102 LEMS patients, 92 (90%) were P/Q-VGCC IgG positive (P/Q+) and 26 (26%) were N-VGCC IgG positive (N+); 67 (66%) were P/Q+ only, 1 (0.9%) was N+ only, 25 (25%) were P/Q+N+, and 9 (9%) were seronegative for both. Three of the 122 healthy control subjects (2.5%) were N+ only, the rest were seronegative. The frequency of isolated N-type VGCC seropositivity did not differ significantly for LEMS patients and healthy controls (P = 0.69). All 21 SCLC-LEMS cases (100%) were P/Q-VGCC IgG positive, compared with 58 of the 66 NT-LEMS cases (88%). The rate of N-type VGCC IgG positivity in P/Q+ LEMS patients did not differ significantly for SCLC-LEMS (5 of 21) and NT-LEMS (13 of 58) diagnoses (24% vs 22%, P = 0.90). The frequency of SOX1/AGNA-1 IgG was 35% for the SCLC-LEMS cases (7 of 20), but none of the NT-LEMS cases (n = 56) was SOX1/AGNA-1 IgG positive. Conclusion N-type VGCC improved neither sensitivity for LEMS nor positive predictive value for cancer and has limited diagnostic utility in assessing patients with suspected LEMS. PQ-type VGCC IgG negativity does not exclude a diagnosis of LEMS. SOX1/AGNA-1 positivity has high specificity but low sensitivity for SCLC. Therefore, while antibody testing confirms a diagnosis of autoimmune LEMS, electrophysiology (to confirm neurological diagnosis) and body imaging (for cancer detection) remain important for the diagnostic evaluation.

Abstract Background Ma-2 is a neuronal nucleolar protein with purported involvement in RNA transcription and apoptosis regulation. Patients with Ma2 antibodies present with autoimmune encephalitis (limbic or brainstem). Ma-2 antibodies are a high-risk marker for paraneoplastic neurologic cause for autoimmune encephalitis (>75% of patients having either testicular cancer or non-small cell lung cancer). In older patients, there is a higher frequency of small cell lung cancer or other cancers especially when Ma 1 antibodies are also detected. Identification of Ma2 antibodies is important to help diagnose autoimmune encephalitis, guide the cancer search and aid treatment selection. The objective of this study was to develop and document the performance of a qualitative enzymatically amplified sandwich-type Ma2 Antibody ELISA. Methods The Ma2 ELISA was produced in-house utilizing commercially available protein and was performed on a Hamilton Star liquid handling instrument equipped with a plate washer and plate reader. Each assay plate included patient samples along with 3 independent negative serum calibrators and 4 quality controls (Both positive and negative controls per matrix [CSF or serum]) each tested in duplicate. Mean optical densities (OD) for patient specimens were compared to the average OD of the negative serum calibrators to generate a ratio. A ratio cut-off of 8 was selected for reporting positivity based on preliminary studies and was validated during the method performance assessment. To assess assay performance we measured precision (3 positive pools at or above the cut-off ratio for each specimen type were tested 20 times in one assay and in duplicate across 10 independent assays), accuracy comparing to the current reference method at Athena® Diagnostics (N = 10 positives / 40 negatives), analytical specificity (20 samples with high titer autoantibodies directed against other proteins), and the impact of common interferences (lipids, bilirubin, hemolysate were spiked into 2 positive and 1 negative sample per interference). Clinical performance of the assay for differentiating healthy donors without disease (N = 140) and those with non-Ma2 neurological autoimmunity (N = 23) from those with clinical phenotypes consistent with Ma-2 associated encephalitis (N = 8) was measured. Results Serum intra-assay imprecision (coefficient of variation; %CV) ranged from 3.0–6.5%. Inter-assay imprecision ranged from 21–29%. CSF intra-assay imprecision ranged from 3.5–10%. Inter-assay imprecision ranged from 13–15.5%. Accuracy was assessed via qualitative comparison to a reference method [western blot or nanoliter scale immunoassay]. There was perfect agreement between methods. To assess analytical specificity, samples with high concentrations of immunoglobulins (hypergammaglobulinemia [N = 10] or Systemic Lupus Erythematosus [N = 10]) were tested in serum (and spiked into CSF); all were negative. Interference studies were conducted on 2 positive Ma2 serum and CSF samples, spiked for highly hemolytic (1000 mg/dL), lipemic (2000 mg/dL) and icteric (60 mg/dL) conditions. All samples remained positive under given interferents. A negative sample was tested for each matrix, both remained negative. Clinical specificity was 100% with all samples from patients without Ma-2 encephalitis testing negative (N = 183). All ELISA positives identified in this study had phenotypes consistent with Ma-2 autoimmune encephalitis (N = 8). Conclusion The performance of the Ma2 ELISA was acceptable for clinical laboratory implementation.

ObjectiveCo‐occurring anti‐tripartite motif‐containing protein 9 and 67 autoantibodies (TRIM9/67‐IgG) have been reported in only a very few cases of paraneoplastic cerebellar syndrome. The value of these biomarkers and the most sensitive methods of TRIM9/67‐IgG detection are not known.MethodsWe performed a retrospective, multicenter study to evaluate the cerebrospinal fluid and serum of candidate TRIM9/67‐IgG cases by tissue‐based immunofluorescence, peptide phage display immunoprecipitation sequencing, overexpression cell‐based assay (CBA), and immunoblot. Cases in which TRIM9/67‐IgG was detected by at least 2 assays were considered TRIM9/67‐IgG positive.ResultsAmong these cases (n = 13), CBA was the most sensitive (100%) and revealed that all cases had TRIM9 and TRIM67 autoantibodies. Of TRIM9/67‐IgG cases with available clinical history, a subacute cerebellar syndrome was the most common presentation (n = 7/10), followed by encephalitis (n = 3/10). Of these 10 patients, 70% had comorbid cancer (7/10), 85% of whom (n = 6/7) had confirmed metastatic disease. All evaluable cancer biopsies expressed TRIM9 protein (n = 5/5), whose expression was elevated in the cancerous regions of the tissue in 4 of 5 cases.InterpretationTRIM9/67‐IgG is a rare but likely high‐risk paraneoplastic biomarker for which CBA appears to be the most sensitive diagnostic assay. ANN NEUROL 2023;94:1086–1101

Background: The potential therapeutic benefit of intravenous immunoglobulins (IVIGs) for acute attacks of myelin oligodendrocyte glycoprotein antibody disease (MOGAD) is unknown. Objective: The objective was to describe the outcomes of IVIG treatment for acute MOGAD attacks. Methods: A retrospective observational study involving seven tertiary neuroimmunology centers. Data collection included patients’ demographics, Expanded Disability Status Scale (EDSS), and visual acuity (VA) before the attack, at the nadir of the attack before IVIG treatment, and at follow-up visits ⩾3 months after treatment. Results: Thirty-nine patients were included, of which 21 (53.8%) were female. The median age was 23 years (range 5–74 years), and the median disease duration was 4 months (range 0–93 months). The most common type of attack treated with IVIG was isolated optic neuritis (ON) (unilateral n = 14, bilateral n = 5, associated with transverse myelitis (TM), n = 1), followed by acute disseminated encephalomyelitis (ADEM) ( n = 8), multifocal ( n = 7), TM ( n = 3), brainstem ( n = 1), and other encephalitis ( n = 1). A significant improvement in both the EDSS and VA measures was observed at follow-up compared to the time of IVIG treatment initiation ( p < 0.0001 for both outcome measures). Conclusion: IVIG may be an effective treatment option for acute MOGAD attacks. Further prospective studies are warranted to validate our results.

Objective Myelin oligodendrocyte glycoprotein antibody‐associated disease (MOGAD) can be monophasic or relapsing, with early relapse being a feature. However, the relevance of early relapse on longer‐term relapse risk is unknown. Here, we investigate whether early relapses increase longer‐term relapse risk in patients with MOGAD. Methods A retrospective analysis of 289 adult‐ and pediatric‐onset patients with MOGAD followed for at least 2 years in 6 specialized referral centers. “Early relapses” were defined as attacks within the first 12 months from onset, with “very early relapses” defined within 30 to 90 days from onset and “delayed early relapses” defined within 90 to 365 days. “Long‐term relapses” were defined as relapses beyond 12 months. Cox regression modeling and Kaplan–Meier survival analysis were used to estimate the long‐term relapse risk and rate. Results Sixty‐seven patients (23.2%) had early relapses with a median number of 1 event. Univariate analysis revealed an elevated risk for long‐term relapses if any “early relapses” were present (hazard ratio [HR] = 2.11, p < 0.001), whether occurring during the first 3 months (HR = 2.70, p < 0.001) or the remaining 9 months (HR = 1.88, p = 0.001), with similar results yielded in the multivariate analysis. In children with onset below aged 12 years, only delayed early relapses were associated with an increased risk of long‐term relapses (HR = 2.64, p = 0.026). Interpretation The presence of very early relapses and delayed early relapses within 12 months of onset in patients with MOGAD increases the risk of long‐term relapsing disease, whereas a relapse within 90 days appears not to indicate a chronic inflammatory process in young pediatric‐onset disease. ANN NEUROL 2023;94:508–517

Autoimmune movement disorders are increasingly recognized, but isolated tremor is extremely rare. We describe a 70‐year‐old male with rapidly progressive, severe postural and intention tremor and weight loss. His cerebrospinal fluid was inflammatory and harbored a neural tissue‐restricted antibody. The autoantigen was identified by immunoprecipitation and mass spectrometry and confirmed by antigen‐specific assays to be specific for tenascin‐R. He was investigated for cancer and diagnosed with follicular lymphoma that expressed tenascin‐R suggesting a paraneoplastic origin; cancer treatment and immunotherapy led to complete recovery. With this individualized patient approach and antibody discovery, we expand the spectrum of antibodies accompanying autoimmune hyperkinetic movement disorders. ANN NEUROL 2023;94:502–507

AbstractObjectiveSeizures are a common manifestation of paraneoplastic neurologic syndromes. The objective of this study was to describe the seizure characteristics and outcomes in patients with high‐risk paraneoplastic autoantibodies (>70% cancer association) and to determine factors associated with ongoing seizures.MethodsPatients from 2000 to 2020 with seizures and high‐risk paraneoplastic autoantibodies were retrospectively identified. Factors associated with ongoing seizures at last follow‐up were evaluated.ResultsSixty patients were identified (34 males, median age at presentation = 52 years). ANNA1‐IgG (Hu; n = 24, 39%), Ma2‐IgG (n = 14, 23%), and CRMP5‐IgG (CV2; n = 11, 18%) were the most common underlying antibodies. Seizures were the initial presenting symptom in 26 (43%), and malignancy was present in 38 (63%). Seizures persisted for >1 month in 83%, and 60% had ongoing seizures, with almost all patients (55/60, 92%) still being on antiseizure medications at last follow‐up a median of 25 months after seizure onset. Ongoing seizures at last follow‐up were associated with Ma2‐IgG or ANNA1‐IgG compared to other antibodies (p = .04), highest seizure frequency being at least daily (p = .0002), seizures on electroencephalogram (EEG; p = .03), and imaging evidence of limbic encephalitis (LE; p = .03). Death occurred in 48% throughout the course of follow‐up, with a higher mortality in patients with LE than in those without LE (p = .04). Of 31 surviving patients at last follow‐up, 55% continued to have intermittent seizures.SignificanceSeizures in the setting of high‐risk paraneoplastic antibodies are frequently resistant to treatment. Ongoing seizures are associated with ANNA1‐IgG and Ma2‐IgG, high seizure frequency, and EEG and imaging abnormalities. Although a subset of patients may respond to immunotherapy and achieve seizure freedom, poor outcomes are frequently encountered. Death was more common among patients with LE.

Objective This study was undertaken to investigate factors associated with aquaporin‐4 (AQP4)‐IgG serostatus change using a large serological database. Methods This retrospective study utilizes Mayo Clinic Neuroimmunology Laboratory data from 2007 to 2021. We included all patients with ≥2 AQP4‐IgG tests (by cell‐based assay). The frequency and clinical factors associated with serostatus change were evaluated. Multivariable logistic regression analysis examined whether age, sex, or initial titer was associated with serostatus change. Results There were 933 patients who had ≥2 AQP4‐IgG tests with an initial positive result. Of those, 830 (89%) remained seropositive and 103 (11%) seroreverted to negative. Median interval to seroreversion was 1.2 years (interquartile range [IQR] = 0.4–3.5). Of those with sustained seropositivity, titers were stable in 92%. Seroreversion was associated with age ≤ 20 years (odds ratio [OR] = 2.25; 95% confidence interval [CI] = 1.09–4.63; p = 0.028) and low initial titer of ≤1:100 (OR = 11.44, 95% CI = 3.17–41.26, p < 0.001), and 5 had clinical attacks despite seroreversion. Among 62 retested after seroreversion, 50% returned to seropositive (median = 224 days, IQR = 160–371). An initial negative AQP4‐IgG test occurred in 9,308 patients. Of those, 99% remained seronegative and 53 (0.3%) seroconverted at a median interval of 0.76 years (IQR = 0.37–1.68). Interpretation AQP4‐IgG seropositivity usually persists over time with little change in titer. Seroreversion to negative is uncommon (11%) and associated with lower titers and younger age. Seroreversion was often transient, and attacks occasionally occurred despite prior seroreversion, suggesting it may not reliably reflect disease activity. Seroconversion to positive is rare (<1%), limiting the utility of repeat testing in seronegative patients unless clinical suspicion is high. ANN NEUROL 2023;94:727–735