Clinical characteristics and outcome of patients with autoimmune encephalitis: clues for paraneoplastic aetiology.

BACKGROUND AND PURPOSE: Autoimmune encephalitis (AE) represents a complex syndrome with diverse clinical manifestations and therapeutic outcomes. The aim of this study was to report the clinical characteristics and the long-term outcome of patients with paraneoplastic and idiopathic AE. METHODS: All patients with subacute encephalopathy admitted to the Neurology Department of our Institution from January 2012 to May 2019 were consecutively enrolled. Patients' serum and cerebrospinal fluid were tested for neural-specific autoantibodies by indirect immunofluorescence assays on mouse brain, rat neurons, cell-based assays and immunoblots. Outcome was assessed by the modified Rankin Scale score. RESULTS: From 107 adult patients with subacute encephalopathy, 50 patients were finally diagnosed with AE. Neural antibodies (Abs) were detected in 45/50 patients (90%). Leucine-rich glioma-inactivated protein 1 immunoglobulin G was the most frequent (6/50, 12%) Ab specific to neural surface antigens detected in adults with AE. Paraneoplastic encephalitis was diagnosed in 16/50 patients (32%). The presence of bilateral temporal lobe lesions on magnetic resonance imaging and cerebrospinal fluid restricted oligoclonal bands was associated with a higher probability to detect cancer at the time of AE diagnosis. All patients with Abs to neural surface antigens had a good outcome at last follow-up. Severe disability at AE onset and the lack of long-term immunosuppression predicted a poor outcome. CONCLUSIONS: Leucine-rich glioma-inactivated protein 1 immunoglobulin G was the most frequent Ab detected. Patients with bilateral temporal lobe lesions and oligoclonal bands have a higher probability to harbour an occult tumour. In these patients, a strict surveillance and monitoring for cancer detection is recommended.

Subgroup comparison according to clinical phenotype and serostatus in autoimmune encephalitis: a multicenter retrospective study.

BACKGROUND AND PURPOSE: Autoimmune encephalitides (AE) include a spectrum of neurological disorders whose diagnosis revolves around the detection of neuronal antibodies (Abs). Consensus-based diagnostic criteria (AE-DC) allow clinic-serological subgrouping of AE, with unclear prognostic implications. The impact of AE-DC on patients' management was studied, focusing on the subgroup of Ab-negative-AE. METHODS: This was a retrospective multicenter study on patients fulfilling AE-DC. All patients underwent Ab testing with commercial cell-based assays (CBAs) and, when available, in-house assays (immunohistochemistry, live/fixed CBAs, neuronal cultures) that contributed to defining final categories. Patients were classified as Ab-positive-AE [N-methyl-d-aspartate-receptor encephalitis (NMDAR-E), Ab-positive limbic encephalitis (LE), definite-AE] or Ab-negative-AE (Ab-negative-LE, probable-AE, possible-AE). RESULTS: Commercial CBAs detected neuronal Abs in 70/118 (59.3%) patients. Testing 37/48 Ab-negative cases, in-house assays identified Abs in 11 patients (29.7%). A hundred and eighteen patients fulfilled the AE-DC, 81 (68.6%) with Ab-positive-AE (Ab-positive-LE, 40; NMDAR-E, 32; definite-AE, nine) and 37 (31.4%) with Ab-negative-AE (Ab-negative-LE, 17; probable/possible-AE, 20). Clinical phenotypes were similar in Ab-positive-LE versus Ab-negative-LE. Twenty-four/118 (20.3%) patients had tumors, and 19/118 (16.1%) relapsed, regardless of being Ab-positive or Ab-negative. Ab-positive-AE patients were treated earlier than Ab-negative-AE patients (P = 0.045), responded more frequently to treatments (92.3% vs. 65.6%, P < 0.001) and received second-line therapies more often (33.3% vs. 10.8%, P = 0.01). Delays in first-line therapy initiation were associated with poor response (P = 0.022; odds ratio 1.02; confidence interval 1.00-1.04). CONCLUSIONS: In-house diagnostics improved Ab detection allowing better patient management but was available in a patient subgroup only, implying possible Ab-positive-AE underestimation. Notwithstanding this limitation, our findings suggest that Ab-negative-AE and Ab-positive-AE patients share similar oncological profiles, warranting appropriate tumor screening. Ab-negative-AE patients risk worse responses due to delayed and less aggressive treatments.

Titin antibodies in "seronegative" myasthenia gravis--A new role for an old antigen.

Myasthenia gravis (MG) is an autoimmune disease caused by antibodies targeting the neuromuscular junction of skeletal muscles. Triple-seronegative MG (tSN-MG, without detectable AChR, MuSK and LRP4 antibodies), which accounts for ~10% of MG patients, presents a serious gap in MG diagnosis and complicates differential diagnosis of similar disorders. Several AChR antibody positive patients (AChR-MG) also have antibodies against titin, usually detected by ELISA. We have developed a very sensitive radioimmunoprecipitation assay (RIPA) for titin antibodies, by which many previously negative samples were found positive, including several from tSN-MG patients. The validity of the RIPA results was confirmed by western blots. Using this RIPA we screened 667 MG sera from 13 countries; as expected, AChR-MG patients had the highest frequency of titin antibodies (40.9%), while MuSK-MG and LRP4-MG patients were positive in 14.6% and 16.4% respectively. Most importantly, 13.4% (50/372) of the tSN-MG patients were also titin antibody positive. None of the 121 healthy controls or the 90 myopathy patients, and only 3.6% (7/193) of other neurological disease patients were positive. We thus propose that the present titin antibody RIPA is a useful tool for serological MG diagnosis of tSN patients.

Prognostic grading after complete resection for thymic malignancies.

OBJECTIVE: Despite the World Health Organization (WHO) and Masaoka classifications have been widely accepted as the main describers of prognosis determinants in thymic malignancies, so far, these have been considered independently from one another. We have reviewed our single-centre 40-year results after surgical treatment of thymic malignancies evaluating the inter-relationships between the clinical, surgical and pathological variables and investigating their prognostic impact in completely resected patients. PATIENTS AND METHODS: A surgical series of 347 patients was reviewed and, of these, 305 with complete resection enrolled. Long-term and disease-free survival (LTS, DFS) analyses were performed. Kaplan-Meir curves for WHO histotypes and Masaoka-stages were inspected and matched with the log-rank test; the Cox regression analysis was adopted in a multivariable approach. RESULTS: Considered independently, the WHO-histotypes did not differentiate clearly from one to another in terms of LTS and DFS; however, types A-AB-B1-B2 and B3-C clustered in 2, statistically different, malignancy groups (LTS, DFS: Cox-p < 0.001). Masaoka staging was confirmed to be a relevant prognostic determinant, even if no evident difference between stages I vs II and stages III vs IV emerged when the Masaoka-classification was factored in. Thus, when investigating 13 surgical and pathological factors of invasiveness, these showed a clustering in 2 groups according to the presence/absence of pathological proven infiltration in the peri-thymic structures (LTS, DFS: Cox-p < 0.001). By matching the WHO-malignancy clusters and infiltration clusters, 4 classes may be identified, which proved to have a distinct prognostic significance: (LTS-Cox: stage-I vs stage-II, p = 0.003; III: p < 0.001, IV: p < 0.001; DFS-Cox: stage-I vs stage-II, p < 0.001; III: p < 0.001; IV: p < 0.001). CONCLUSIONS: When analyzing the long-term outcome of patients underwent complete resection for thymic malignancies, the combination between pathological and surgical variables showed accurate prognosis predictability.

MuSK autoantibodies in myasthenia gravis detected by cell based assay--A multinational study.

Seronegative myasthenia gravis (MG) presents a serious gap in MG diagnosis and understanding. We applied a cell based assay (CBA) for the detection of muscle specific kinase (MuSK) antibodies undetectable by radioimmunoassay. We tested 633 triple-seronegative MG patients' sera from 13 countries, detecting 13% as positive. MuSK antibodies were found, at significantly lower frequencies, in 1.9% of healthy controls and 5.1% of other neuroimmune disease patients, including multiple sclerosis and neuromyelitis optica. The clinical data of the newly diagnosed MuSK-MG patients are presented. 27% of ocular seronegative patients were MuSK antibody positive. Moreover, 23% had thymic hyperplasia suggesting that thymic abnormalities are more common than believed.

The detection of neural autoantibodies in patients with antiepileptic-drug-resistant epilepsy predicts response to immunotherapy.

BACKGROUND AND PURPOSE: The detection of antibodies binding neural antigens in patients with epilepsy has led to the definition of 'autoimmune epilepsy'. Patients with neural antibodies not responding to antiepileptic drugs (AEDs) may benefit from immunotherapy. Aim of this study was to evaluate the frequency of autoantibodies specific to neural antigens in patients with epilepsy and their response to immunotherapy. METHODS: Eighty-one patients and 75 age- and sex-matched healthy subjects (HS) were enrolled in the study. Two groups of patients were included: 39 patients with epilepsy and other neurological symptoms and/or autoimmune diseases responsive to AEDs (group 1) and 42 patients with AED-resistant epilepsy (group 2). Patients' serum and cerebrospinal fluid were evaluated for the presence of autoantibodies directed to neural antigens by indirect immunofluorescence on frozen sections of mouse brain, cell-based assays and a radioimmunoassay. Patients with AED-resistant epilepsy and neural autoantibodies were treated with immunotherapy and the main outcome measure was the reduction in seizure frequency. RESULTS: Neural autoantibodies were detected in 22% of patients (18/81), mostly from the AED-resistant epilepsy group (P = 0.003), but not in HS. Indirect immunofluorescence on mouse brain revealed antibodies binding to unclassified antigens in 10 patients. Twelve patients received immunotherapy and nine (75%) achieved >50% reduction in seizure frequency. CONCLUSIONS: A significant proportion of patients with AED-resistant epilepsy harbor neural-specific autoantibodies. The detection of these antibodies, especially of those binding to synaptic antigens, may predict a favorable response to immunotherapy, thus overcoming AED resistance.

Italian recommendations for Lambert-Eaton myasthenic syndrome (LEMS) management.

Lambert-Eaton myasthenic syndrome (LEMS) is a pre-synaptic disorder of the neuromuscular and autonomic transmission mediated by antibodies to voltage-gated calcium channels at the motor nerve terminal. LEMS is a quite rare and probably under-diagnosed disease: the onset may be slow and clinical signs are typically fluctuating, thus adding to the delay in diagnosis. LEMS weakness typically involves lower and upper limbs and the proximal muscles are predominantly affected. A significant proportion of patients also have dysfunction of the autonomic nervous system that may include dry mouth, constipation, blurred vision, impaired sweating, and orthostatic hypotension. LEMS recognition is based on clinical, electrophysiological and immunological criteria. Nearly 50-60% of patients with LEMS have an underlying tumour that, in almost all cases, is a small-cell lung cancer; the onset of neurological symptoms generally precedes tumour detection. A careful screening for the early detection of the possible associated cancer is a crucial step for optimal disease management. The Italian Working Group on Myasthenic Syndromes developed diagnostic and therapeutic algorithms that could serve in routine clinical practice as tools for a patient-tailored approach.

EFNS/ENS Guidelines for the treatment of ocular myasthenia.

BACKGROUND AND PURPOSE: The symptoms of acquired autoimmune ocular myasthenia are restricted to the extrinsic eye muscles, causing double vision and drooping eyelids. These guidelines are designed to provide advice about best clinical practice based on the current state of clinical and scientific knowledge and the consensus of an expert panel. SEARCH STRATEGY: Evidence for these guidelines was collected by searches in the MEDLINE and Cochrane databases. The task force working group reviewed evidence from original articles and systematic reviews. The evidence was classified (I, II, III, IV) and consensus recommendation graded (A, B or C) according to the EFNS guidance. Where there was a lack of evidence but clear consensus, good practice points are provided. CONCLUSIONS: The treatment of ocular myasthenia should initially be started with pyridostigmine (good practice point). If this is not successful in relieving symptoms, oral corticosteroids should be used on an alternate-day regimen (recommendation level C). If steroid treatment does not result in good control of the symptoms or if it is necessary to use high steroid doses, steroid-sparing treatment with azathioprine should be started (recommendation level C). If ocular myasthenia gravis is associated with thymoma, thymectomy is indicated. Otherwise, the role of thymectomy in ocular myasthenia is controversial. Steroids and thymectomy may modify the course of ocular myasthenia and prevent myasthenia gravis generalization (good practice point).

A comprehensive analysis of the epidemiology and clinical characteristics of anti-LRP4 in myasthenia gravis.

Double-seronegative myasthenia gravis (dSN-MG, without detectable AChR and MuSK antibodies) presents a serious gap in MG diagnosis and understanding. Recently, autoantibodies against the low-density lipoprotein receptor-related protein 4 (LRP4) have been identified in several dSN-MG sera, but with dramatic frequency variation (∼2-50%). We have developed a cell based assay (CBA) based on human LRP4 expressing HEK293 cells, for the reliable and efficient detection of LRP4 antibodies. We have screened about 800 MG patient sera from 10 countries for LRP4 antibodies. The overall frequency of LRP4-MG in the dSN-MG group (635 patients) was 18.7% but with variations among different populations (range 7-32.7%). Interestingly, we also identified double positive sera: 8/107 anti-AChR positive and 10/67 anti-MuSK positive sera also had detectable LRP4 antibodies, predominantly originating from only two of the participating groups. No LRP4 antibodies were identified in sera from 56 healthy controls tested, while 4/110 from patients with other neuroimmune diseases were positive. The clinical data, when available, for the LRP4-MG patients were then studied. At disease onset symptoms were mild (81% had MGFA grade I or II), with some identified thymic changes (32% hyperplasia, none with thymoma). On the other hand, double positive patients (AChR/LRP4-MG and MuSK/LRP4-MG) had more severe symptoms at onset compared with any single positive MG subgroup. Contrary to MuSK-MG, 27% of ocular dSN-MG patients were LRP4 antibody positive. Similarly, contrary to MuSK antibodies, which are predominantly of the IgG4 subtype, LRP4 antibodies were predominantly of the IgG1 and IgG2 subtypes. The prevalence was higher in women than in men (female/male ratio 2.5/1), with an average disease onset at ages 33.4 for females and 41.9 for males. Overall, the response of LRP4-MG patients to treatment was similar to published responses of AChR-MG rather than to MuSK-MG patients.

Reliability of SFEMG in diagnosing myasthenia gravis: sensitivity and specificity calculated on 100 prospective cases.

OBJECTIVE: The study aimed to determine the utility of single-fibre electromyography (SFEMG) in the diagnosis of myasthenia gravis (MG) in subjects with a clinical suspicion of the disease. METHODS: We performed a prospective, single-blinded study on 100 consecutive patients. SFEMG was not considered a criterion in making the MG diagnosis. For all cases, a different physician than the one performing SFEMG made the diagnosis of MG. All subjects underwent standard SFEMG of a single muscle, the orbicularis oculi. RESULTS: SFEMG was abnormal in 67 of 100 patients. A final diagnosis of definite MG was made in 54 patients (30 men/24 women). SFEMG was positive in 53 of 54 patients diagnosed with MG. The sensitivity of SFEMG in diagnosing MG was 98% (95% CI: 0.94-1.02), while the specificity was 70% (95% CI: 0.54-0.86), with a positive predictive value of 79% (95% CI: 0.74-0.79) and a negative predictive value of 97% (95% CI: 0.94-0.99). CONCLUSIONS: In this cohort of patients, normal SFEMG findings were unlikely to occur in patients with MG. SIGNIFICANCE: SFEMG is not a confirmatory test for the diagnosis of MG, but it has a high negative predictive value in identifying patients without MG.

Guidelines for treatment of autoimmune neuromuscular transmission disorders.

BACKGROUND: Important progress has been made in our understanding of the autoimmune neuromuscular transmission (NMT) disorders; myasthenia gravis (MG), Lambert-Eaton myasthenic syndrome (LEMS) and neuromyotonia (Isaacs' syndrome). METHODS: To prepare consensus guidelines for the treatment of the autoimmune NMT disorders, references retrieved from MEDLINE, EMBASE and the Cochrane Library were considered and statements prepared and agreed on by disease experts. CONCLUSIONS: Anticholinesterase drugs should be given first in the management of MG, but with some caution in patients with MuSK antibodies (good practice point). Plasma exchange is recommended in severe cases to induce remission and in preparation for surgery (recommendation level B). IvIg and plasma exchange are effective for the treatment of MG exacerbations (recommendation level A). For patients with non-thymomatous MG, thymectomy is recommended as an option to increase the probability of remission or improvement (recommendation level B). Once thymoma is diagnosed, thymectomy is indicated irrespective of MG severity (recommendation level A). Oral corticosteroids are first choice drugs when immunosuppressive drugs are necessary (good practice point). When long-term immunosuppression is necessary, azathioprine is recommended to allow tapering the steroids to the lowest possible dose whilst maintaining azathioprine (recommendation level A). 3,4-Diaminopyridine is recommended as symptomatic treatment and IvIG has a positive short-term effect in LEMS (good practice point). Neuromyotonia patients should be treated with an antiepileptic drug that reduces peripheral nerve hyperexcitability (good practice point). For paraneoplastic LEMS and neuromyotonia optimal treatment of the underlying tumour is essential (good practice point). Immunosuppressive treatment of LEMS and neuromyotonia should be similar to MG (good practice point).

The difficulty in confirming clinical diagnosis of myasthenia gravis in a seronegative patient: a possible neurophysiological approach.

In seronegative myasthenia gravis repetitive nerve stimulation and single-fibre EMG have a crucial diagnostic value but they may be negative, particularly in repetitive nerve stimulation studies. We report the case of a 43-year-old patient with generalized seronegative myasthenia gravis with negative 3 Hz repetitive nerve stimulation at Erb's point and voluntary single-fibre EMG in the orbicularis oculi. We also performed 6 and 12 Hz repetitive nerve stimulation at Erb and stimulated single-fibre EMG in the extensor digitorum communis and our findings were pathological. Our data suggest that, for individual patients with an atypical picture characterised by dissociation between a severe clinical pattern and no definite neurophysiological findings on conventional tests, repetitive nerve stimulation with a stimulation rate higher than 3 Hz and/or stimulated single-fibre EMG with an increasing stimulation rate may be helpful.

Myasthenia gravis: an unrecognized cause of head drop in Parkinson's disease.

Head drop is characterized by marked anterior flexion of the cervical spine, caused by weakness of the neck extensors or by increased tone of the flexor muscles. We report a woman with Parkinson's disease and head drop not due to cervical dystonia (a common cause of antecollis in parkinsonisms). Clinical, radiological, and neurophysiological features together with responsiveness to anticholinesterases and plasma exchanges indicated the possibility of a concomitant myasthenia gravis.

Anti-MuSK antibodies: correlation with myasthenia gravis severity.

The authors measured anti-muscle-specific tyrosine kinase (anti-MuSK) antibodies (Abs) in 83 serum samples from 40 patients and evaluated their correlation with myasthenia gravis severity and treatment response. Ab concentrations were often reduced by immunosuppression but not after thymectomy. Both in individual cases and in the whole population, a correlation between Ab levels and disease severity was found.

Guidelines for the treatment of autoimmune neuromuscular transmission disorders.

Important progress has been made in our understanding of the cellular and molecular processes underlying the autoimmune neuromuscular transmission (NMT) disorders; myasthenia gravis (MG), Lambert-Eaton myasthenic syndrome (LEMS) and neuromyotonia (peripheral nerve hyperexcitability; Isaacs syndrome). To prepare consensus guidelines for the treatment of the autoimmune NMT disorders. References retrieved from MEDLINE, EMBASE and the Cochrane Library were considered and statements prepared and agreed on by disease experts and a patient representative. The proposed practical treatment guidelines are agreed upon by the Task Force: (i) Anticholinesterase drugs should be the first drug to be given in the management of MG (good practice point). (ii) Plasma exchange is recommended as a short-term treatment in MG, especially in severe cases to induce remission and in preparation for surgery (level B recommendation). (iii) Intravenous immunoglobulin (IvIg) and plasma exchange are equally effective for the treatment of MG exacerbations (level A Recommendation). (iv) For patients with non-thymomatous autoimmune MG, thymectomy (TE) is recommended as an option to increase the probability of remission or improvement (level B recommendation). (v) Once thymoma is diagnosed TE is indicated irrespective of the severity of MG (level A recommendation). (vi) Oral corticosteroids is a first choice drug when immunosuppressive drugs are necessary in MG (good practice point). (vii) In patients where long-term immunosuppression is necessary, azathioprine is recommended together with steroids to allow tapering the steroids to the lowest possible dose whilst maintaining azathioprine (level A recommendation). (viii) 3,4-diaminopyridine is recommended as symptomatic treatment and IvIg has a positive short-term effect in LEMS (good practice point). (ix) All neuromyotonia patients should be treated symptomatically with an anti-epileptic drug that reduces peripheral nerve hyperexcitability (good practice point). (x) Definitive management of paraneoplastic neuromyotonia and LEMS is treatment of the underlying tumour (good practice point). (xi) For immunosuppressive treatment of LEMS and NMT it is reasonable to adopt treatment procedures by analogy with MG (good practice point).

Seronegative myasthenia gravis: comparison of neurophysiological picture in MuSK+ and MuSK- patients.

The aim of this study was to compare the neurophysiological and clinical pictures of a large sample of seronegative myasthenia gravis (SNMG) patients with and without anti-MuSK antibodies. Fifty-two consecutive SNMG patients were retrospectively evaluated. They had undergone an extended neurophysiological evaluation: repetitive nerve stimulation (RNS), single fiber EMG (SFEMG), and electromyography (EMG) with nerve conduction study. A muscle biopsy was performed in 11 of 52 patients, the edrophonium test in 44 of 52 patients and anti-AChR antibodies and anti-MuSK antibodies were tested in all patients. Anti-MuSK antibodies were detected in 25 SNMG patients (48.1%). The number of women in the MuSK+ group was significantly higher (P = 0.01) than in the MuSK- group. Seronegative MuSK+ patients are more severely affected and the deficit often involves the bulbar and the respiratory muscles. No statistically significant differences were observed in the edrophonium test between MuSK+ and MuSK- groups. The RNS test was abnormal in a significantly higher number of MUSK- patients than MUSK+ patients (P < 0.00001). With regard to SFEMG data, MuSK- patients were characterized to have more severe neurophysiological pattern. Our observations showed several differences between the clinical and neurophysiological pictures of MUSK+ and MUSK- patients.

Circulating CD4+CD25+ T regulatory and natural killer T cells in patients with myasthenia gravis: a flow cytometry study.

The number of circulating CD4+ T cells constitutively expressing CD25 (T regulatory, Treg) and natural killer T (NK T) cells, the two major lymphocyte populations that help to maintain immune homeostasis, was studied in 22 unselected myasthenia gravis (MG) patients, 16 healthy subjects and 24 patients with cancer, the latter as a disease model of a relative immune suppression status. Treg cells were assessed according to their intermediate or high level of expression of CD25, i.e., CD25int and CD25bright, and to the expression of HLA-DR, CD62L, CD45RO and CD152. There were no differences in the number of NK T cells and CD4+CD25bright cells among the three series of individuals. MG patients and healthy subjects had also similar numbers of CD4+CD25int cells. However, the whole CD4+ cell compartment in MG patients was in an activated status, as indicated by the higher level of expression of CD152. By contrast, and consistent with a relative immune suppression status, cancer patients had higher numbers of CD4+CD25int cells and larger proportions of HLA-DR expressing CD4+CD25int and CD4+CD25bright cells. Immunomagnetically purified CD4+CD25+ cells from MG, healthy subjects and cancer patients were anergic and suppressed the proliferative response of other T cells.