Qualitative evidence of Ri specific IgG-synthesis in the cerebrospinal fluid from patients with paraneoplastic neurological syndromes

Pearls & Oy-sters: Gait Instability, Jaw Dystonia, and Horizontal Diplopia in a Woman With Anti-Ri Antibodies and Breast Cancer

A 40-year-old woman was admitted for 6 months of progressive gait disturbance, lower limb-predominant weakness, stiffness, falls, jaw dystonia, horizontal diplopia, and weight loss. Neurologic examination revealed horizontal gaze paresis, limited jaw opening with palpable masseter hypertrophy, and spastic paraparesis with sustained clonus and upgoing plantar responses. MRI revealed T2-hyperintense signal abnormalities in the dorsal pons, medulla, and upper cervical cord central gray matter extending to C3, without gadolinium enhancement. CSF showed mildly elevated protein and immunoglobulin (IgG) index with CSF-specific oligoclonal bands. Neural autoantibody testing was positive for anti-Ri in CSF and serum by mouse brain indirect immunofluorescence and immunoblot. Testing for aquaporin-4 (AQP4)-IgG and myelin oligodendrocyte glycoprotein (MOG)-IgG by cell-based assay was negative. The patient received methylprednisolone 1 g for 5 days and IV immunoglobulin 2 g/kg over 2 days with prednisone taper and botulinum toxin injections for jaw dystonia. PET-CT revealed an enlarged left axillary lymph node with high FDG uptake. Left axillary lymph node biopsy confirmed high-grade, locally invasive breast adenocarcinoma. Neurologic stabilization was documented at 2-week follow-up after hospital discharge before modified radical mastectomy. Our case demonstrates a clinical triad highly suggestive of anti-Ri-associated paraneoplastic neurologic syndrome (Ri-PNS): gait instability, jaw dystonia, and horizontal gaze paresis. The more slowly progressive course and poor response to immunotherapy help distinguish it from AQP4-IgG-seropositive neuromyelitis optica spectrum disorder (NMOSD) and MOG-IgG-associated disease (MOGAD) that share similar radiographic features. Early diagnosis, prompt immunotherapy, and cancer treatment are paramount for disease stabilization.

Cerebrospinal fluid findings in COVID-19: a multicenter study of 150 lumbar punctures in 127 patients

BACKGROUND

Comprehensive data on the cerebrospinal fluid (CSF) profile in patients with COVID-19 and neurological involvement from large-scale multicenter studies are missing so far.

OBJECTIVE

To analyze systematically the CSF profile in COVID-19.

METHODS

Retrospective analysis of 150 lumbar punctures in 127 patients with PCR-proven COVID-19 and neurological symptoms seen at 17 European university centers RESULTS: The most frequent pathological finding was blood-CSF barrier (BCB) dysfunction (median QAlb 11.4 [6.72-50.8]), which was present in 58/116 (50%) samples from patients without pre-/coexisting CNS diseases (group I). QAlb remained elevated > 14d (47.6%) and even > 30d (55.6%) after neurological onset. CSF total protein was elevated in 54/118 (45.8%) samples (median 65.35 mg/dl [45.3-240.4]) and strongly correlated with QAlb. The CSF white cell count (WCC) was increased in 14/128 (11%) samples (mostly lympho-monocytic; median 10 cells/µl, > 100 in only 4). An albuminocytological dissociation (ACD) was found in 43/115 (37.4%) samples. CSF L-lactate was increased in 26/109 (24%; median 3.04 mmol/l [2.2-4]). CSF-IgG was elevated in 50/100 (50%), but was of peripheral origin, since QIgG was normal in almost all cases, as were QIgA and QIgM. In 58/103 samples (56%) pattern 4 oligoclonal bands (OCB) compatible with systemic inflammation were present, while CSF-restricted OCB were found in only 2/103 (1.9%). SARS-CoV-2-CSF-PCR was negative in 76/76 samples. Routine CSF findings were normal in 35%. Cytokine levels were frequently elevated in the CSF (often associated with BCB dysfunction) and serum, partly remaining positive at high levels for weeks/months (939 tests). Of note, a positive SARS-CoV-2-IgG-antibody index (AI) was found in 2/19 (10.5%) patients which was associated with unusually high WCC in both of them and a strongly increased interleukin-6 (IL-6) index in one (not tested in the other). Anti-neuronal/anti-glial autoantibodies were mostly absent in the CSF and serum (1509 tests). In samples from patients with pre-/coexisting CNS disorders (group II [N = 19]; including multiple sclerosis, JC-virus-associated immune reconstitution inflammatory syndrome, HSV/VZV encephalitis/meningitis, CNS lymphoma, anti-Yo syndrome, subarachnoid hemorrhage), CSF findings were mostly representative of the respective disease.

CONCLUSIONS

The CSF profile in COVID-19 with neurological symptoms is mainly characterized by BCB disruption in the absence of intrathecal inflammation, compatible with cerebrospinal endotheliopathy. Persistent BCB dysfunction and elevated cytokine levels may contribute to both acute symptoms and 'long COVID'. Direct infection of the CNS with SARS-CoV-2, if occurring at all, seems to be rare. Broad differential diagnostic considerations are recommended to avoid misinterpretation of treatable coexisting neurological disorders as complications of COVID-19.

The role of the laboratory in the expanding field of neuroimmunology: Autoantibodies to neural targets

Accelerated identification of autoantibodies associated with previously idiopathic neurological disease has provided insights into disease mechanisms, enhanced understanding of neurological function, and opportunities for improved therapeutic interventions. The role of the laboratory in the expanding field of neuroimmunology is critical as specific autoantibody identification provides guidance to clinicians in diagnosis, prognosis, tumor search strategies, and therapeutic interventions. The number of specific autoantibodies identified continues to increase and newer testing strategies increase efficiencies in the laboratory and availability to clinicians. The need for broadly targeted efficient testing is underscored by the variability in clinical presentation and tumor associations attributable to a specific autoantibody, and conversely the various autoantibody specificities that can be the cause of a given clinical presentation. While many of the antineural antibodies were first recognized in the setting of neoplastic disease, idiopathic autoimmune neurological disease in the absence of underlying tumor is increasingly recognized. Appropriation of therapeutic modalities used to treat autoimmune disease to treat these autoantibody mediated neurological diseases has improved patient outcomes. Interaction between clinicians and laboratorians is critical to our understanding of these diseases and optimization of the clinical benefits of our increasing knowledge in neuroimmunology.

The MRZ reaction as a highly specific marker of multiple sclerosis: re-evaluation and structured review of the literature

BACKGROUND

It has long been known that the majority of patients with multiple sclerosis (MS) display an intrathecal, polyspecific humoral immune response to a broad panel of neurotropic viruses. This response has measles virus, rubella virus and varicella zoster virus as its most frequent constituents and is thus referred to as the MRZ reaction (MRZR).

OBJECTIVE

Re-evaluation of the specificity of MRZR as a marker of MS.

METHODS

Structured review of the existing English-, German- and Spanish-language literature on MRZR testing, with evaluation of MRZR in a cohort of 43 unselected patients with MS and other neurological diseases as a proof of principle.

RESULTS

A positive MRZ reaction, defined as a positive intrathecal response to at least two of the three viral agents, was found in 78% of MS patients but only in 3% of the controls (p < 0.00001), corresponding to specificity of 97%. Median antibody index values were significantly lower in non-MS patients (measles, p < 0.0001; rubella, p < 0.006; varicella zoster, p < 0.02). The 30 identified original studies on MRZR reported results from 1478 individual MRZR tests. A positive MRZR was reported for 458/724 (63.3%) tests in patients with MS but only for 19/754 (2.5%) tests in control patients (p < 0.000001), corresponding to cumulative specificity of 97.5% (CI 95% 96-98.4), cumulative sensitivity of 63.3% (CI 95% 59.6-66.8) (or 67.4% [CI 95% 63.5-71.1] in the adult MS subgroup), a positive likelihood ratio of 25.1 (CI 95% 16-39.3) and a negative likelihood ratio of 0.38 (CI 95% 0.34-0.41). Of particular note, MRZR was absent in 52/53 (98.1%) patients with neuromyelitis optica or MOG-IgG-positive encephalomyelitis, two important differential diagnoses of MS.

CONCLUSION

MRZR is the most specific laboratory marker of MS reported to date. If present, MRZR substantially increases the likelihood of the diagnosis of MS. Prospective and systematic studies on the diagnostic and prognostic impact of MRZR testing are highly warranted.

'Medusa-head ataxia': the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 1: Anti-mGluR1, anti-Homer-3, anti-Sj/ITPR1 and anti-CARP VIII

Serological testing for anti-neural autoantibodies is important in patients presenting with idiopathic cerebellar ataxia, since these autoantibodies may indicate cancer, determine treatment and predict prognosis. While some of them target nuclear antigens present in all or most CNS neurons (e.g. anti-Hu, anti-Ri), others more specifically target antigens present in the cytoplasm or plasma membrane of Purkinje cells (PC). In this series of articles, we provide a detailed review of the clinical and paraclinical features, oncological, therapeutic and prognostic implications, pathogenetic relevance, and differential laboratory diagnosis of the 12 most common PC autoantibodies (often referred to as 'Medusa-head antibodies' due to their characteristic somatodendritic binding pattern when tested by immunohistochemistry). To assist immunologists and neurologists in diagnosing these disorders, typical high-resolution immunohistochemical images of all 12 reactivities are presented, diagnostic pitfalls discussed and all currently available assays reviewed. Of note, most of these antibodies target antigens involved in the mGluR1/calcium pathway essential for PC function and survival. Many of the antigens also play a role in spinocerebellar ataxia. Part 1 focuses on anti-metabotropic glutamate receptor 1-, anti-Homer protein homolog 3-, anti-Sj/inositol 1,4,5-trisphosphate receptor- and anti-carbonic anhydrase-related protein VIII-associated autoimmune cerebellar ataxia (ACA); part 2 covers anti-protein kinase C gamma-, anti-glutamate receptor delta-2-, anti-Ca/RhoGTPase-activating protein 26- and anti-voltage-gated calcium channel-associated ACA; and part 3 reviews the current knowledge on anti-Tr/delta notch-like epidermal growth factor-related receptor-, anti-Nb/AP3B2-, anti-Yo/cerebellar degeneration-related protein 2- and Purkinje cell antibody 2-associated ACA, discusses differential diagnostic aspects and provides a summary and outlook.

'Medusa head ataxia': the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 3: Anti-Yo/CDR2, anti-Nb/AP3B2, PCA-2, anti-Tr/DNER, other antibodies, diagnostic pitfalls, summary and outlook

Serological testing for anti-neural autoantibodies is important in patients presenting with idiopathic cerebellar ataxia, since these autoantibodies may indicate cancer, determine treatment and predict prognosis. While some of them target nuclear antigens present in all or most CNS neurons (e.g. anti-Hu, anti-Ri), others more specifically target antigens present in the cytoplasm or plasma membrane of Purkinje cells (PC). In this series of articles, we provide a detailed review of the clinical and paraclinical features, oncological, therapeutic and prognostic implications, pathogenetic relevance, and differential laboratory diagnosis of the 12 most common PC autoantibodies (often referred to as 'Medusa head antibodies' due to their characteristic somatodendritic binding pattern when tested by immunohistochemistry). To assist immunologists and neurologists in diagnosing these disorders, typical high-resolution immunohistochemical images of all 12 reactivities are presented, diagnostic pitfalls discussed and all currently available assays reviewed. Of note, most of these antibodies target antigens involved in the mGluR1/calcium pathway essential for PC function and survival. Many of the antigens also play a role in spinocerebellar ataxia. Part 1 focuses on anti-metabotropic glutamate receptor 1-, anti-Homer protein homolog 3-, anti-Sj/inositol 1,4,5-trisphosphate receptor- and anti-carbonic anhydrase-related protein VIII-associated autoimmune cerebellar ataxia (ACA); part 2 covers anti-protein kinase C gamma-, anti-glutamate receptor delta-2-, anti-Ca/RhoGTPase-activating protein 26- and anti-voltage-gated calcium channel-associated ACA; and part 3 reviews the current knowledge on anti-Tr/delta notch-like epidermal growth factor-related receptor-, anti-Nb/AP3B2-, anti-Yo/cerebellar degeneration-related protein 2- and Purkinje cell antibody 2-associated ACA, discusses differential diagnostic aspects and provides a summary and outlook.

Anti-yo associated paraneoplastic cerebellar degeneration in a man with large cell cancer of the lung

Purkinje cell cytoplasmic antibody type 1 (PCA-1), or anti-Yo, is the most frequently detected autoantibody in paraneoplastic cerebellar degeneration (PCD). The vast majority of cases of anti-Yo PCD, however, occur in females over 60 years old and are associated with gynecologic tumors. Only 10 cases have been reported in males, and only 2 were associated with cancer of the lung. Here we describe the youngest known case of PCA-1 positive PCD in a male, whose lung tumor was undetectable even on FDG-PET.

Multiplex serology of paraneoplastic antineuronal antibodies

Paraneoplastic neurological syndromes (PNS) are devastating neurological disorders secondary to cancer, associated with onconeural autoantibodies. Such antibodies are directed against neuronal antigens aberrantly expressed by the tumor. The detection of onconeural antibodies in a patient is extremely important in diagnosing a neurological syndrome as paraneoplastic (70% is not yet known to have cancer) and in directing the search for the underlying neoplasm. At present six onconeural antibodies are considered 'well characterized' and recognize the antigens HuD, CDR62 (Yo), amphiphysin, CRMP-5 (CV2), NOVA-1 (Ri), and Ma2. The gold standard of detection is the characteristic immunohistochemical staining pattern on brain tissue sections combined with confirmation by immunoblotting using recombinant purified proteins. Since all six onconeural antibodies are usually analyzed simultaneously and objective cut-off values for these analyses are warranted, we developed a multiplex assay based on Luminex technology. Reaction of serial dilutions of six onconeural standard sera with microsphere-bound antigens showed lower limits of detection than with Western blotting. Using the six standard sera at a dilution of 1:200, the average within-run coefficient of variation (CV) was 4% (range 1.9-7.3%). The average between-run within-day CV was 5.1% (range 2.9-6.7%) while the average between-day CV was 8.1% (range 2.8-11.6%). The shelf-life of the antigen coupled microspheres was at least two months. The sensitivity of the multiplex assay ranged from 83% (Ri) to 100% (Yo, amphiphysin, CV2) and the specificity from 96% (CV2) to 100% (Ri). In conclusion, Luminex-based multiplex serology is highly reproducible with high sensitivity and specificity for the detection of onconeural antibodies. Conventional immunoblotting for diagnosis of onconeural antibodies in the setting of a routine laboratory may be replaced by this novel, robust technology.

Usefulness of antibody index assessment in cerebrospinal fluid from patients negative for total-IgG oligoclonal bands

Background

Testing for cerebrospinal fluid (CSF)-restricted oligoclonal bands (OCB) by isoelectric focusing is used to detect intrathecally produced total IgG. By contrast, antibody indices (AI) are assessed to test for intrathecally produced antigen-specific IgG. A number of previous cases reports have suggested that AI testing might be more sensitive than OCB testing in detecting intrathecal IgG synthesis.

Findings

Here we report on 21 patients with positive AI for either herpes simplex virus, varicella zoster virus, cytomegalovirus, measles virus, rubella virus, or Borrelia burgdorferi in the absence of total-IgG OCB and, accordingly, in the presence of a normal total-IgG CSF/serum ratio.

Conclusion

Our findings indicate that AI testing should not generally be omitted in OCB-negative patients and provide a rationale for systematic and prospective studies on the comparative sensitivity and specificity of AI and total-IgG OCB testing in infectious and other diseases of the CNS.

Cerebrospinal fluid oligoclonal bands in childhood opsoclonus-myoclonus

Oligoclonal bands in cerebrospinal fluid reflect local B-cell responses associated with various neuroinflammatory disorders. In opsoclonus-myoclonus syndrome, cerebrospinal fluid B-cell expansion was demonstrated, but no studies of oligoclonal bands are available. In a prospective case-control study of 132 children (103 with opsoclonus-myoclonus, 29 neurologic control subjects), cerebrospinal fluid oligoclonal bands, measured by isoelectric focusing with immunofixation, were observed in 35% with opsoclonus-myoclonus and none of the control subjects, with the highest frequency in severe cases (56%). In oligoclonal band-positive patients, the mean band number was 5 ± 3 S.D. (range, 2-10) and the total severity score was significantly higher than in band-negative patients, whereas the frequency of CD19(+) B cells, opsoclonus-myoclonus duration, neuroblastoma detection, and relapse history did not differ. The cerebrospinal fluid immunoglobulin G synthesis rate, immunoglobulin index, and Q albumin were normal. In 17 untreated children receiving adrenocorticotropic hormone, intravenous immunoglobulins, and rituximab, the number of oligoclonal band-positive decreased by 75%, and the mean band count fell by 80%. Oligoclonal band detection adds useful information to neuroimmunologic "staging" in opsoclonus-myoclonus. However, flow cytometry provides a more sensitive measure of B-cell infiltration. Cerebrospinal fluid oligoclonal bands warrant monitoring in long-term follow-up studies of disease-modifying drugs for opsoclonus-myoclonus.