Citations

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.

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

AbstractBackgroundStiff person spectrum disorder (SPSD) is heterogeneous, and accurate diagnosis can be challenging.MethodsPatients referred for diagnosis/suspicion of SPSD at the Mayo Autoimmune Neurology Clinic from July 01, 2016, to June 30, 2021, were retrospectively identified. SPSD diagnosis was defined as clinical SPSD manifestations confirmed by an autoimmune neurologist and seropositivity for high‐titer GAD65‐IgG (>20.0 nmol/L), glycine‐receptor‐IgG or amphiphysin‐IgG, and/or confirmatory electrodiagnostic studies (essential if seronegative). Clinical presentation, examination, and ancillary testing were compared to differentiate SPSD from non‐SPSD.ResultsOf 173 cases, 48 (28%) were diagnosed with SPSD and 125 (72%) with non‐SPSD. Most SPSD were seropositive (41/48: GAD65‐IgG 28/41, glycine‐receptor‐IgG 12/41, amphiphysin‐IgG 2/41). Pain syndromes or functional neurologic disorder were the most common non‐SPSD diagnoses (81/125, 65%). SPSD patients more commonly reported exaggerated startle (81% vs. 56%, p = 0.02), unexplained falls (76% vs. 46%, p = 0.001), and other associated autoimmunity (50% vs. 27%, p = 0.005). SPSD more often had hypertonia (60% vs. 24%, p < 0.001), hyperreflexia (71% vs. 43%, p = 0.001), and lumbar hyperlordosis (67% vs. 9%, p < 0.001) and less likely functional neurologic signs (6% vs. 33%, p = 0.001). SPSD patients more frequently had electrodiagnostic abnormalities (74% vs. 17%, p < 0.001), and at least moderate symptomatic improvement with benzodiazepines (51% vs. 16%, p < 0.001) or immunotherapy (45% vs. 13% p < 0.001). Only 4/78 non‐SPSD patients who received immunotherapy had alternative neurologic autoimmunity.InterpretationMisdiagnosis was threefold more common than confirmed SPSD. Functional or non‐neurologic disorders accounted for most misdiagnoses. Clinical and ancillary testing factors can reduce misdiagnosis and exposure to unnecessary treatments. SPSD diagnostic criteria are suggested.

Abstract Background and purpose Outcome and rechallenge data on central nervous system (CNS) autoimmunity triggered by immune checkpoint inhibitors (ICIs) are limited. We aim to describe a large series of patients with ICI‐triggered CNS autoimmunity, and to compare these patients with spontaneous paraneoplastic syndromes (PNS). Methods We retrospectively reviewed Mayo Clinic patients with ICI‐triggered CNS autoimmunity (February 2015–June 2021). Clinical characteristics were compared to spontaneous PNS patients (with antineuronal nuclear antibody [ANNA]‐1 or anti‐Hu neurological autoimmunity, and/or neuroendocrine tumors [NET]) evaluated within the same period. Results Thirty‐one patients were included (55% female, median age = 63 years, range = 39–76). Median time from ICI initiation was 3.65 months (range = 0.8–44.5). The most common associated malignancies were melanoma and small cell lung cancer. CNS manifestations included encephalitis ( n = 16), meningoencephalitis ( n = 8), cerebellar ataxia ( n = 4), demyelinating syndrome ( n = 2), and myelopathy ( n = 1). Magnetic resonance imaging was abnormal in 62%. Cerebrospinal fluid was inflammatory in 70%. Neural autoantibodies were identified in 47%, more frequently in patients with NET ( p = 0.046). ICI was discontinued in 97%; 90% received immunosuppressive treatment. After median 6.8 months follow‐up (range = 0.7–46), 39% had unfavorable outcomes (grade ≥ 3). This was associated with higher severity degree at onset, shorter period from ICI to neurological symptom onset, and encephalitis. Four patients were rechallenged with ICI, and one relapsed. Patients with NET and with ANNA‐1 ICI‐triggered CNS autoimmunity had associated peripheral nervous system manifestations more frequently than their spontaneous counterparts ( p = 0.007 and p = 0.028, respectively). Conclusions One third of ICI‐related CNS autoimmunity patients have unfavorable outcomes. Relapses may occur after ICI rechallenge. Neural autoantibodies are often present, more commonly in patients with NET.