Lambert-Eaton myasthenic syndrome.

Lambert-Eaton myasthenic syndrome (LEMS) is a rare autoimmune disease characterized by proximal muscle weakness, loss of tendon reflexes, and autonomic dysfunction. Muscle weakness usually starts in the upper legs and can progress to oculobulbar and in severe cases respiratory muscles. P/Q-type voltage-gated calcium channels (VGCCs) localized in the presynaptic motor nerve terminal and in the autonomic nervous system are targeted by antibodies in LEMS patients. These antibodies can be detected in about 90% of patients, and the presence of decrement and increment upon repetitive nerve stimulation is also a highly sensitive diagnostic test. Rapid diagnosis is important because of the association with SCLC in 50%-60% of patients, which stresses the need for vigorous tumor screening after diagnosis. Clinical parameters can predict tumor probability and guide frequency of tumor screening. Treatment of the tumor as well as symptomatic treatment and immunosuppression can effectively control symptoms in the majority of patients.

[Diagnosis and Treatment of Lambert-Eaton Myasthenic Syndrome].

Approximately 90% of patients with Lambert-Eaton myasthenic syndrome (LEMS) show positive P/Q-type voltage-gated calcium channels antibodies, which can be broadly classified clinically as paraneoplastic, particularly with small cell lung carcinoma and non-paraneoplastic without cancer. The first Japanese guideline for LEMS was developed in May 2022 as MG/LEMS Practice Guideline 2022. This article describes the epidemiology, symptoms, diagnosis, examination, treatment, and prognosis of this condition, based on the LEMS guidelines.

[A 50 year old man with progressive weakness in lower limbs].

Lambert-Eaton Myasthenic Syndrome (LEMS) is a rare neurological disorder caused by autoimmune antibodies attacking the presynaptic neuromuscular junction, in some cases caused by underlying cancer. The main clinical finding is fluctuating weakness of the extremities and a triad of symtoms can help physicians suspect the disease. A key to the diagnosis are the electrophysiological abnormalities seen in this group of diseases. Treatment with symtomatic and/or immunosuppressive therapy is important as well as a workup for possible malignancy. This article identifies the clinical features, diagnosis and treatment of this uncommon disease.

What Is in the Neuromuscular Junction Literature?

ABSTRACT: This update covers several articles on diagnosis and misdiagnosis of myasthenia gravis (MG), the role of complement in MG, and then an impressive number of recent treatment trials. There is a negative study on any corticosteroid-sparing effect of intravenous immunoglobulin. A number of positive studies are reviewed. Open-label extension studies of phase 3 trials showed benefit regarding quality of life with efgartigimod and in functional measures with ravulizumab. The phase 3 RAISE trial of zilucoplan, a self-administered complement C5 inhibitor, is covered as well as the MyCarinG trial of rozanolixizumab. The notion of using fast-acting therapies early in the course of MG is addressed. The last sections center on MG and Lambert-Eaton myasthenic syndrome as a consequence of immune checkpoint inhibitor therapy.

Advances and ongoing research in the treatment of autoimmune neuromuscular junction disorders.

Myasthenia gravis and Lambert-Eaton myasthenic syndrome are antibody-mediated autoimmune diseases of the neuromuscular junction that usually present with weakness in ocular muscles and in proximal muscles of the limb and trunk. Prognosis regarding muscle strength, functional abilities, quality of life, and survival is generally good. However, some patients do not respond to treatment. Symptomatic drugs, corticosteroids, and steroid-sparing immunosuppressive drugs remain the cornerstone of treatment. In the past few years, new biological agents against complement, the FcRn receptor, or B-cell antigens have been tested in clinical trials. These new therapies extend the possibilities for targeted immunotherapies and promise exciting new options with a relatively rapid mode of action. Challenges in their use might occur, with barriers due to an increase in cost of care and additional considerations in the choice of drugs, and potential consequences of infection and vaccination due to the COVID-19 pandemic.

Effects of Natural Products on Neuromuscular Junction.

Neuromuscular junction (NMJ) disorders result from damage, malfunction or absence of one or more key proteins involved in neuromuscular transmission, comprising a wide range of disorders. The most common pathology is antibody-mediated or downregulation of ion channels or receptors, resulting in Lambert-Eaton myasthenic syndrome, myasthenia gravis, and acquired neuromyotonia (Isaac's syndrome), and rarely congenital myasthenic syndromes caused by mutations in NMJ proteins. A wide range of symptomatic treatments, immunomodulating therapies, or immunosuppressive drugs have been used to treat NMJ diseases. Future research must be directed at a better understanding of the pathogenesis of these diseases, and developing novel disease-specific treatments. Numerous secondary metabolites, especially alkaloids isolated from plants, have been used to treat NMJ diseases in traditional and clinical practices. An ethnopharmacological approach has provided leads for identifying new treatments for NMJ diseases. In this review, we performed a literature survey in Pubmed, Science Direct, and Google Scholar to gather information on drug discovery from plant sources for NMJ disease treatments. To date, most research has focused on the effects of herbal remedies on cholinesterase inhibitory and antioxidant activities. This review provides leads for identifying potential new drugs from plant sources for the treatment of NMJ diseases.

Síndrome miasteniforme de Lambert-Eaton / Lambert-Eaton myasthenic syndrome

Introducción: El síndrome miasteniforme de Lambert-Eaton (LEMS) es una patología paraneoplásica (T-LEMS) o idiopática autoinmunitaria (NT-LEMS) ocasionada por autoanticuerpos contra los canales de calcio dependientes del voltaje presinápticos de la unión neuromuscular. El 60% de los T-LEMS se asocia a carcinoma de pulmón de células pequeñas. Una puntuación Dutch-English LEMS Tumor Association Prediction (DELTA-P) mayor de 3 denota un riesgo elevado de dicha asociación. El diagnóstico precoz fundado en los hallazgos clínicos, estudios neurofisiológicos y dosificación de títulos de anticuerpos en el suero permite iniciar tempranamente el tratamiento sintomático y la búsqueda oncológica. Son escasos los informes de pacientes con LEMS en Latinoamérica. Objetivo: Describir las características de pacientes con LEMS de un centro privado de Buenos Aires, Argentina, y compararlas con las de otras series publicadas. Pacientes y métodos: Se revisaron historias clínicas de 13 pacientes con LEMS con hallazgos clínicos, electromiograma compatible y/o anticuerpos positivos. Se realizó seguimiento hasta descartar o confirmar una neoplasia asociada de acuerdo con los algoritmos recomendados. Resultados: Cuatro pacientes presentaron diagnóstico de T-LEMS, dos de ellos con carcinoma de pulmón de células pequeñas. De los nueve pacientes con NT-LEMS, cinco presentaron una puntuación DELTA-P de 3 y 4. Nueve pacientes presentaron la tríada clínica clásica desde el inicio. Todos los pacientes presentaron en el electromiograma hallazgos compatibles con defecto de placa neuromuscular presináptico. El 70% mejoró sintomáticamente con piridostigmina. Conclusiones: Los hallazgos clínicos, junto con los estudios neurofisiológicos compatibles, resultan suficientes para el diagnóstico de LEMS. No pudo replicarse la relación entre puntuación DELTA-P y riesgo de carcinoma de pulmón de células pequeñas...(AU)

Introduction: Early diagnosis based on clinical findings, neurophysiological studies and serum antibody titres allows early initiation of symptomatic treatment and oncological screening. Reports of patients with LEMS in Latin America are scarce. Aim: This article aims to describe the characteristics of patients with LEMS from a private centre in Buenos Aires, Argentina, and to compare them with those of other series that have been published. Patients and methods: The medical records of 13 patients with LEMS with clinical findings, compatible electromyogram and/or positive antibodies were reviewed. Follow-up was performed until associated neoplasia was ruled out or confirmed according to the recommended algorithms. Results: Four patients were diagnosed with T-LEMS, two of them with small-cell lung carcinoma. Of the nine patients with NT-LEMS, five had a DELTA-P score of 3 and 4. Nine patients presented with the classic clinical triad from the onset of the disease. All patients had electromyogram findings compatible with presynaptic neuromuscular plaque defect. Of the total, 70% improved symptomatically with pyridostigmine. Conclusions: The clinical findings, together with compatible neurophysiological studies, are sufficient for the diagnosis of LEMS. The relationship between the DELTA-P score and the risk of small-cell lung carcinoma could not be replicated. Symptomatic treatment with pyridostigmine represents an effective therapeutic alternative.(AU)

[Paraneoplastic neurological syndromes]. / Les syndromes neurologiques paranéoplasiques.

Neurological paraneoplastic syndromes are non-metastatic complications of systemic cancers, often resulting from an immune response triggered by the crossed expression of neuronal antigens by tumour cells. Several neurological syndromes such as cerebellar degeneration, sensory neuronopathy, limbic encephalitis, encephalomyelitis or the Lambert-Eaton myasthenic syndrome are most often paraneoplastic and require prompt cancer screening, particularly if the patient shows risk factors for cancer. Although there are many exceptions to this rule, a given syndrome is often associated with a particular antibody and the corresponding tumour. A prompt diagnosis of neurological paraneoplastic syndrome is of major importance as it often reveals the underlying tumour. The treatment relies on both the elimination of the neoplasia and the control of the immune response.

Les syndromes neurologiques paranéoplasiques sont des complications neurologiques non métastatiques de cancers systémiques résultant, le plus souvent, d'une réaction immunitaire croisée dirigée contre des antigènes neuronaux membranaires ou intracellulaires. Certains de ces syndromes paranéoplasiques sont classiques comme les ataxies cérébelleuses, les neuronopathies sensitives ou ganglionopathies, l'encéphalite limbique, les encéphalomyélites ou le syndrome de Lambert-Eaton. Devant de tels tableaux cliniques, une étiologie paranéoplasique doit, surtout chez les patients présentant des facteurs de risque, être systématiquement recherchée. Bien que cette règle souffre de nombreuses exceptions, il y a souvent concordance entre un syndrome clinique spécifique, un type d'anticorps et une tumeur associée. Le diagnostic d'un syndrome neurologique paranéoplasique est essentiel puisqu'il révèle souvent le cancer sous-jacent. Le traitement comporte deux axes principaux : celui du cancer responsable et le contrôle de la réponse immunitaire.

Use of therapeutic plasma exchange for pediatric neurological diseases.

Therapeutic plasma exchange is used to treat neurological diseases in the pediatric population. Since its first use in pediatric patients with hepatic coma in the form of manual whole blood exchange, therapeutic plasma exchange has been increasingly used to treat these disorders of the nervous system. This expansion is a result of improved techniques and apheresis instruments suitable for small children, as well as the recognition of its applicability to many diseases in the pediatric population. This review provides a historical overview of the use of therapeutic apheresis in children and highlights the most common applications for therapeutic plasma exchange to treat neurological disorders in children.

Update in the Management of Myasthenia Gravis and Lambert-Eaton Myasthenic Syndrome.

Myasthenia gravis (MG) and Lambert-Eaton myasthenic syndrome (LEMS) are the most common disorders of neuromuscular transmission in clinical practice. Disorders of the neuromuscular junction (NMJ) are characterized by fluctuating and fatigable weakness and include autoimmune, toxic, and genetic conditions. Adults with NMJ disorders are most often antibody mediated, with MG being the most common, having a prevalence of approximately 1 in 10,000, and with women being affected about twice as often as men. This article focuses on advances in management of autoimmune MG and LEMS.

Long-term follow-up, quality of life, and survival of patients with Lambert-Eaton myasthenic syndrome.

OBJECTIVE: To study survival and to characterize long-term functional impairments and health-related quality of life (HRQOL) of patients with Lambert-Eaton myasthenic syndrome (LEMS). METHODS: In this observational study, survival of patients with LEMS, separately for nontumor (NT) and small cell lung cancer (SCLC), was compared to that of the Dutch general population and patients with SCLC. Disease course in patients with LEMS was recorded retrospectively. Several scales for functional impairments and health-related quality of life were assessed. RESULTS: We included 150 patients with LEMS. Survival was similar to that of the general population in 65 patients with NT-LEMS. Tumor survival was significantly longer in 81 patients with SCLC-LEMS compared to patients with non-LEMS SCLC (overall median survival 17 vs 7.0 months, p < 0.0001). At diagnosis, 39 (62%) of 63 patients with complete follow-up data were independent for activities of daily living, improving to 85% at the 1-year follow-up. The physical HRQOL composite score (55.9) was significantly lower than in the general population (76.3, p < 0.0001) and comparable to that of patients with myasthenia gravis (60.5). The mental HRQOL composite score was 71.8 in patients with LEMS, comparable to that of the general population (77.9, p = 0.19) and patients with myasthenia gravis (70.3). CONCLUSIONS: This study shows that patients with NT-LEMS have normal survival. Patients with SCLC-LEMS have an improved tumor survival, even after correction for tumor stage. A majority of patients with LEMS report a stable disease course and remain or become independent for self-care after treatment.

A Case of Triple-Negative Myasthenia Gravis Lambert-Eaton Overlap Syndrome With Negative Agrin and LRP-4 Antibodies.

A case of triple-negative myasthenia gravis Lambert-Eaton overlap syndrome with negative Agrin and LRP-4 antibodies. Myasthenia gravis (MG) is an autoimmune disorder that shares similar features with Lambert-Eaton myasthenic syndrome. The combined clinical and electrophysiological findings of MG and Lambert-Eaton myasthenic syndrome have been reported, these cases represent the so-called "myasthenia gravis Lambert-Eaton overlap syndrome" (MLOS). A total of 55 MLOS cases have been identified, 13 cases were reported before the acetylcholine receptor (AChR) antibody (ab) testing era, 14 during the AChR-ab era, 26 during the voltage-gated calcium channel (VGCC)-ab era, and 2 cases have been reported during the muscle-specific kinase (MuSK)-ab era, of these; only 1 patient tested negative for all 3 antibodies. New immunological markers have been identified in the study of MG [Agrin and the low-density lipopro-tein receptor-related protein 4 (LRP-4)]. We present a patient with MLOS who tested negative for all 5 (AChR, MuSK, VGCC, Agrin, and LRP-4) serologic markers.

[Paraneoplastic Cerebellar Degeneration with Lambert-Eaton Myasthenic Syndrome: A Report of an Effectively Treated Case and Systematic Review of Japanese Cases].

A 63-year-old female who developed dizziness, diplopia and subsequent gait disturbance from September X-1 year was analyzed. The first neurological findings in May X year revealed cerebellar ataxia, weakness in the proximal limbs, decreased tendon reflexes, and autonomic symptoms (ADL:mRS 3). Furthermore, an incremental phenomenon was observed in the repetitive nerve stimulation test, and she was diagnosed with Lambert-Eaton myasthenic syndrome (LEMS) based on the serum P/Q-type calcium channel (VGCC) antibody positivity. In addition, small cell lung cancer was detected by chest CT and bronchoscopy, and her cerebellar ataxia was diagnosed as paraneoplastic cerebellar degeneration (PCD). Therefore, the patient underwent chemotherapy and radiotherapy from June in X year. Six months after initiation of treatment, her cerebellar ataxia had almost disappeared and she could walk without assistance (ADL:mRS 1). The P/Q-type VGCC antibodies were also negative at that time. Cases wherein cerebellar ataxia resolved almost completely in parallel with disappearance of the serum P/Q-type VGCC antibodies are of great interest. We conducted a systematic literature review of PCD-LEMS cases in Japan reported since P/Q-type calcium channel antibody measurement was reported in 1995. As a result, 13 cases (including our study) that concurrently displayed cerebellar ataxia and LEMS were selected. The average age of the 13 patients (10 males and 3 females) was 61.5 years. Small cell carcinoma was complicated in 11 patients (10 in the lung and 1 in the oropharynx); in the other 2 patients, cancer was not found at the time of reporting (the observation period was as short as 1-2 months). The time from onset to treatment ranged between 1 week and 10 months. While 1 of the 13 patients developed cerebellar ataxia during the subsequent course of the treatment, the remaining 12 had already developed cerebellar ataxia and LEMS symptoms, although their main neurologic finding was cerebellar ataxia and they were subsequently diagnosed with LEMS after electrophysiological testing and autoantibody detection. Small cell carcinoma was found in 11 patients. We define the pathology following such a certain clinical course as PCD-LEMS. The P/Q-type VGCC antibodies were positive in 11 of the 13 cases, although their antibody titers were not necessarily very high. Treatment for the associated small cell carcinoma might have improved the neurological findings in 9 of the 11 PCD-LEMS patients. The P/Q-type VGCC antibodies were measured before and after the treatment. The PCD-LEMS symptoms improved in all patients and their antibody titers decreased. These findings indicate that P/Q-type VGCC antibodies are involved in the pathology of PCD-LEMS. Appropriate and timely treatment, at least in PCD-LEMS patients in Japan, that actively treats any associated cancer can be expected to improve not only life prognosis but also cerebellar ataxia. (Received October 15, 2018; Accepted November 5, 2018; Published January 1, 2019).

[P/Q-type Calcium Channel Antibodies in Lambert-Eaton Myasthenic Syndrome].

Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disease of the neuromuscular junction. Approximately 50-60% of patients with LEMS have a tumor, most often small cell lung cancer (SCLC), making LEMS a paraneoplastic neurological syndrome. In Japan, the clinical picture is a male: female ratio of 3:1; mean age, 62 years (17-80 years); and 61% of LEMS patients have SCLC (SCLC-LEMS), with the remainder of patients having no cancer. Patients with LEMS develop a unique set of clinical characteristics, which include proximal muscle weakness, depressed tendon reflexes with post-tetanic potentiation, and autonomic symptoms. Interestingly, less than 10% of patients with LEMS have cerebellar ataxia (LEMS with paraneoplastic cerebellar degeneration). Considering its pathomechanisms, LEMS is a presynaptic disorder of neuromuscular transmission in which quantal release of acetylcholine is impaired by autoantibodies against P/Q-type voltage-gated calcium channels (P/Q-VGCCs) at active zones reducing quantal release of acetylcholine, although an animal model using immunization with purified P/Q-VGCCs has not yet been established. The diagnosis can be confirmed by finding a reduced compound muscle action potential amplitude that increases by over 60% following maximum voluntary activation or 50 Hz nerve stimulation. Approximately 90% of patients who satisfy the above electrophysiological diagnostic criteria are positive for P/Q-VGCC antibodies have their diagnosis confirmed. Specific tumor therapy in SCLC-LEMS will often improve the neurologic deficit. Tumor removal is the primary treatment for LEMS. If primary tumor screening is negative, screening should be repeated after 3-6 months, followed by screening every 6 months until 2 years post diagnosis. Most patients benefit from 3,4-diaminopyridine being administered with pyridostigmine. In those with severe weakness, high-dose intravenous gamma-globulin (IVIg) or plasmapheresis confers short-term benefits. Prednisone, alone or combined with immunosuppressive drugs, can achieve long-term control of the disorder. The results of a prospective cohort study showed that the presence of LEMS with SCLC had a significant survival advantage independent of other prognostic factors including disease extent, age, sex, performance status, and serum sodium values.

Lambert-Eaton Myasthenic Syndrome Associated with Synchronous Double Cancer: A Combination of Small Cell Carcinoma of the Cervix and Breast Carcinoma.

Lambert-Eaton myasthenic syndrome (LEMS) is most commonly associated with small cell lung carcinoma, while it is rarely associated with gynecological and breast carcinoma. We herein report a case of LEMS associated with synchronous double cancer, which was a combination of small cell carcinoma of the cervix and breast carcinoma. The early diagnosis and treatment of LEMS are important for achieving a good outcome. The possibility of accompanying paraneoplastic neurological syndrome must be sufficiently considered in gynecology and breast cancer patients. To our knowledge, this is the first report of LEMS associated with synchronous double cancer.

Lambert-Eaton myasthenic syndrome: mouse passive-transfer model illuminates disease pathology and facilitates testing therapeutic leads.

Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disorder caused by antibodies directed against the voltage-gated calcium channels that provide the calcium ion flux that triggers acetylcholine release at the neuromuscular junction. To study the pathophysiology of LEMS and test candidate therapeutic strategies, a passive-transfer animal model has been developed in mice, which can be created by daily intraperitoneal injections of LEMS patient serum or IgG into mice for 2-4 weeks. Results from studies of the mouse neuromuscular junction have revealed that each synapse has hundreds of transmitter release sites but that the probability for release at each one is likely to be low. LEMS further reduces this low probability such that transmission is no longer effective at triggering a muscle contraction. The LEMS-mediated attack reduces the number of presynaptic calcium channels, disorganizes transmitter release sites, and results in the homeostatic upregulation of other calcium channel types. Symptomatic treatment is focused on increasing the probability of release from dysfunctional release sites. Current treatment uses the potassium channel blocker 3,4-diaminopyridine (DAP) to broaden the presynaptic action potential, providing more time for calcium channels to open. Current research is focused on testing new calcium channel gating modifiers that work synergistically with DAP.

Lambert-Eaton myasthenic syndrome: Epidemiology and therapeutic response in the national veterans affairs population.

INTRODUCTION: One nationwide study (The Netherlands) of Lambert-Eaton myasthenic syndrome (LEMS) has been published. We report LEMS epidemiology and its therapeutic response in the United States Veterans Affairs (VA) population. METHODS: Medical records for all active patients (12.5 million) in the VA health system were queried for relevant ICD-9 codes for the period October 1, 1999 to September 30, 2013. Clinical, electrophysiologic, and serologic features were evaluated to confirm diagnosis; epidemiologic and treatment data were collected. RESULTS: Point prevalence was estimated at 2.6 per 1,000,000 (confirmed cases) and 3.3 per 1,000,000 (combined confirmed and probable cases). Crude prevalence was similarly estimated at 9.2 and 10.9 per 1,000,000 respectively. A total of 18 of 48 (38%) patients received 3,4-diaminopyridine (3,4-DAP); 14 of 18 (78%) improved. CONCLUSIONS: This investigation was a large North American epidemiologic study of LEMS. LEMS prevalence in the national VA population was found to be similar to previously published rates in other large international populations. Most patients experienced improvement with therapy, including a majority with 3,4-DAP. Muscle Nerve 56: 421-426, 2017.