Lambert-Eaton Myasthenic Syndrome

Postexercise reflex facilitation in Lambert-Eaton myasthenic syndrome

A 62-year-old woman had 6 months of proximal weakness, fatigue and occasional diplopia, symptoms normally suggesting myasthenia gravis or inflammatory myopathy. Postexercise reflex facilitation is a bedside clinical sign that points to a diagnosis of the rarer alternative, Lambert-Eaton myasthenic syndrome (LEMS). We confirmed this diagnosis using electrodiagnostic short exercise testing and serum assay for voltage-gated calcium channel antibodies. Further investigation identified a small cell neuroendocrine carcinoma of the gallbladder, not previously associated with LEMS. Postexercise reflex facilitation is an important bedside clinical finding that helps clinicians to distinguish LEMS from its mimics.

Nivolumab-induced Lambert-Eaton myasthenic syndrome: an immune-related adverse event in nonsmall cell lung cancer

Nivolumab is an anti-programmed cell death protein 1 (anti-PD-1) monoclonal antibody and was the first immune checkpoint inhibitor drug approved for use in advanced non-small cell lung cancer (NSCLC). In this report, we describe a rare case of Lambert-Eaton myasthenic syndrome (LEMS), which developed as a side effect of nivolumab in a patient with metastatic lung squamous cell carcinoma. Our patient, who was previously treated with nivolumab for metastatic squamous cell carcinoma of the lung, appeared with a headache, swollen face, dysarthria, asthenia, xerostomia, and drooping eyelid. Early testing indicated no thymomas or newly developing tumors in whole-body scans, and the blood workup was normal. We came to the conclusion that nivolumab-induced LEMS was the cause of the symptoms after performing nerve conduction investigations ruling out other differentials. We believe our clinical experience of this rare and unexpected adverse event should be shared.

Amifampridines are the Most Effective Drugs for Treating Lambert-Eaton Myasthenic Syndrome With a Focus on Pediatric Lambert-Eaton Myasthenic Syndrome

In 1983, the first successful trial of 3,4-diaminopyridine (3,4-DAP) in Lambert-Eaton myasthenic syndrome (LEMS) was reported. Efficacy of amifampridine (3,4-DAP and 3,4-diaminopyridine phosphate [3,4-DAPP]) for symptomatic treatment in LEMS was proven by seven randomized studies in 3,4-DAP and two randomized studies in 3,4-DAPP. US Food Drug Administration approved 3,4-DAPP usage for adult LEMS in 2018 and for pediatric LEMS in 2022. Nineteen pediatric LEMS cases were identified in the literature. Compared with adult LEMS, the rate of malignancy is low as expected and the rate of dysautonomia is also low in pediatric LEMS. Unexpected finding is two cases of pediatric LEMS following antecedent infection. Amifampridine can be safely used as long the daily dose is less than 80 mg a day for adult LEMS patients and less than 30 mg a day for pediatric LEMS patients. Amifampridines can be supplemented with a liberal amount of pyridostigmine for long term usage. Amifampridine was used as symptomatic treatment in eight (42%) of 19 pediatric LEMS patients: 3,4-DAP in six and 3,4-DAPP in two patients. The most common practice of 3,4-DAP was a combination with pyridostigmine in four patients. With 3,4-DAP, normal activity was reported in 3 cases and mild to moderate-improvement in other 3 cases. In two patients with 3,4-DAPP, significant improvement in one and no improvement in one. Amifampridines are proven to be effective and safe drugs for the symptomatic treatment without serious side reaction in adults as well as in children as long as the dosage is properly adhered.

Autoimmune retinopathy associated with systemic autoimmune disease: a case series

OBJECTIVE

To describe various presentations of autoimmune retinopathy (AIR) associated with systemic autoimmune diseases.

DESIGN

Case series.

PATIENTS AND METHODS

Four patients with systemic autoimmune disorders and AIR are described in this report. The clinical and multimodal imaging characteristics, systemic work-up, genetic testing results, management, and course of disease are detailed.

RESULTS

The multimodal retinal features of 4 cases of AIR including the findings of fundus autofluorescence, optical coherence tomography, and electrophysiology necessary to document progressive photoreceptor loss are described. Each case of AIR was associated with a complicated autoimmune disorder. Case 1 was associated with chronic inflammatory demyelinating polyneuropathy and showed marked improvement with systemic steroid and intravenous immunoglobulin therapy. Case 2 was associated with rheumatoid arthritis, and the AIR condition progressed despite systemic immune therapy. Case 3 was associated with Lambert-Eaton myasthenic syndrome, and AIR developed 6 years later and stabilized with systemic immune therapy. Case 4 was associated with necrobiotic xanthogranuloma followed by AIR and was managed by systemic immune therapy.

CONCLUSIONS

AIR in association with these systemic conditions is rarely reported. Our cases highlight the gaps in our current understanding of the definition, systemic associations, pathogenesis, and management of AIR and the importance of multimodal imaging and a multidisciplinary approach in managing patients with suspected AIR.

A Unique Case of Non-paraneoplastic Lambert-Eaton Myasthenic Syndrome Treated With Subcutaneous Immunoglobulin: A Case Report and Review of Literature

Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune neuromuscular disorder caused by pathogenic autoantibodies directed against voltage-gated calcium channels present on the presynaptic nerve terminal. For LEMS patients refractory to initial symptomatic treatment with amifampridine, immunomodulatory therapy with intravenous immunoglobulin (IVIG) is often utilized. However, in the authors' review of literature, the utility of subcutaneous immunoglobulin (SCIG) in the treatment of LEMS has been scarcely reported. Here, we present a unique case of non-paraneoplastic LEMS managed with SCIG with excellent clinical response and improvement on electromyography. SCIG therapy may be a reasonable alternative for patients with LEMS who do not tolerate the intravenous formulation.

Lambert-Eaton Myasthenic Syndrome Complicated by Anti-GABAB Receptor Encephalitis

A 74-year-old man experienced diplopia, generalized muscle weakness, and acute respiratory failure. He was diagnosed with Lambert-Eaton myasthenic syndrome (LEMS) and treated with immunotherapy, but no improvement was observed, and additional symptoms, including central apnea and hallucinations, appeared. Subsequent serum and cerebrospinal fluid (CSF) analyses confirmed the presence of GABAB receptor antibodies, indicating the coexistence of autoimmune encephalitis. Although there were no findings of malignancy, it is highly likely that occult small-cell lung carcinoma was present. When atypical symptoms occur in patients with LEMS, it is important to consider the possibility of concomitant autoimmune encephalitis.

Acute Respiratory Failure Resulting From Lambert-Eaton Myasthenic Syndrome: A Case Report and Literature Review

Lambert-Eaton myasthenic syndrome (LEMS) is a rare neuromuscular junction disorder due to auto-antibodies against presynaptic voltage-gated calcium channels (VGCC). The typical manifestation of LEMS is proximal muscle weakness, autonomic dysfunction, and areflexia; however, an atypical manifestation of LEMS is weakness of respiratory muscles, leading to acute respiratory failure. Herein, we describe a case of acute respiratory failure resulting from LEMS. Our patient was a 63-year-old woman with a past medical history of metastatic small cell lung cancer (SCLC) who presented with ambulatory dysfunction, dysarthria, and progressive dyspnea. She was intubated because of hypoxia and developed acute respiratory failure without a clear pulmonary etiology, raising the suspicion of a neuromuscular junction disorder. She was diagnosed with LEMS with a positive paraneoplastic panel for VGCC antibodies, confirmed by electromyography and nerve conduction study (EMG/NCS), and treated with intravenous immunoglobulin (IVIg). The patient's hospital stay was complicated by pneumonia, and comfort care was ultimately pursued. Our case highlights the importance of considering LEMS in patients presenting with isolated respiratory muscle weakness without focal neurological deficits. To our knowledge, this is the first report to review all reported cases of LEMS with resultant respiratory failure. We aim to establish the association of LEMS with respiratory failure so that appropriate treatment is initiated as early as possible.

SOX-1 antibodies positive Lambert-Eaton myasthenic syndrome with occult small cell lung cancer: A case report

Lambert-Eaton myasthenic syndrome (LEMS) is a rare paraneoplastic neurological syndrome of the neuromuscular transmission. The symptoms often progress slowly and can be misdiagnosed in early stage. Seropositive SOX-1 antibodies are support for the diagnosis of LEMS and have high specificity for small cell lung cancer (SCLC). In this paper, we report a case of a 56-year-old man with smoking history who was admitted to hospital with progressive muscle weakness of the proximal legs. LEMS was diagnosed by repetitive nerve stimulation (RNS) testing and seropositive SOX-1 antibodies. Primary screening with chest computed tomography (CT) and integrated PET/CT did not reveal any tumor. After continuous follow-up, SCLC was found by chest CT and confirmed with pathological examination 10 months after the diagnosis of LEMS. Long-term follow-up and screening for occult SCLC in LEMS patients with positive SOX-1 antibodies are very important.

Preoperative Management of the Adult Oncology Patient

Anesthesiologists are experiencing first-hand the aging population, given older patients more frequently presenting for surgery, often with geriatric syndromes influencing their anesthetic management. The overall incidence and health burden of cancer morbidity and mortality are also rapidly increasing worldwide. This growth in the cancer population, along with the associated risk factors and comorbidities often accompanying a cancer diagnosis, underscores the need for anesthesiologists to become well versed in the preoperative evaluation and management of the adult patient with cancer. This article will focus on the unique challenges and opportunities for the anesthesiologist caring for the adult oncology patient presenting for surgery.

Paraneoplastic autonomic neuropathies and GI dysmotility

A number of the well-recognized autoimmune and paraneoplastic neurologic syndromes commonly involve the autonomic nervous system. In some cases, the autonomic nerves or ganglia are primary targets of neurologic autoimmunity, as in immune-mediated autonomic ganglionopathies. In other disorders such as encephalitis, autonomic centers in the brain may be affected. The presence of autonomic dysfunction (especially gastrointestinal dysmotility) is sometimes overlooked even though this may contribute significantly to the symptom burden in these paraneoplastic disorders. Additionally, recognition of autonomic features as part of the clinical syndrome can help point the diagnostic evaluation toward autoimmune and paraneoplastic etiologies. As with other paraneoplastic disorders, the clinical syndrome and the presence and type of neurologic autoantibodies help to secure the diagnosis and direct the most appropriate investigation for malignancy. Optimal management for these conditions typically includes aggressive treatment of the neoplasm, immunomodulatory therapy, and symptomatic treatments for orthostatic hypotension and gastrointestinal dysmotility.

Call it as it is - Why medical education should reconsider disease eponyms

Medical disease names should be reflective of the pathophysiologic processes underlying them. Medical education has propagated the use of outdated eponyms when referring to diseases named after individuals who discovered or described the diseases in question. This is confusing and harmful to medical students learning about these diseases and can present a seemingly insurmountable barrier to understanding complex pathologies. The renaming of diseases that are colloquially referred to by individuals' names is proposed. Medical schools are encouraged to adopt this nomenclature so that students will effectively understand pathophysiology and eventually provide optimal patient care. While it is not feasible to be completely systematic in this approach, striving for this change will enable a spotlight to shine on the disease and not the individuals who popularized the condition. Numerous examples are given of diseases that are either appropriately or inappropriately named, with recommendations for renaming given where applicable. An exploration of the benefits and disadvantages of renaming includes both historical and modern contexts for making the change.

Spontaneous regression of small cell lung cancer associated with Lambert-Eaton Myasthenic Syndrome: Case report

Spontaneous regression (SR) of cancer is very rare, especially of small cell lung cancer (SCLC). Recently, an association of paraneoplastic neurological syndrome (PNS) has been reported as a cause of SR of cancer, and onconeural antibodies are a possible factor in the SR of cancer associated with PNS. We herein report the first case of SR of SCLC combined with anti-P/Q-type of voltage-gated calcium channel (VGCC) antibody-positive Lambert-Eaton myasthenic syndrome (LEMS), a subtype of PNS. This case report suggests that SCLC may be spontaneously reduced by an autoimmune response induced by VGCC antibodies associated with LEMS. Our finding may help elucidate the mechanisms that inhibit tumor growth and cause the regression of tumors.

A Case of Primary Lung Adenocarcinoma With Two Uncommon Presentations: Neurological Paraneoplastic Syndrome and Pericardial Effusion

Lung cancer is the second most common cancer worldwide and remains the first cause of cancer death. The diagnosis of lung cancer is mostly made following evaluation for respiratory signs and symptoms but sometimes the first presentation may be atypical. Some symptoms may be related to the invasion of adjacent structures and others caused by an autoimmune-mediated process when cross-reactivity between tumor antigens and normal nervous tissues is responsible for paraneoplastic syndromes. We present a case of a young woman with a smoking history who first manifested with two uncommon presentations of lung cancer: a paraneoplastic neurological syndrome and a hemorrhagic pericardial effusion with cardiac tamponade.

Diagnosis and Management of Seronegative Myasthenia Gravis: Lights and Shadows

Myasthenia gravis (MG) is an antibody-mediated neuromuscular disease affecting the neuromuscular junction. In most cases, autoantibodies can be detected in the sera of MG patients, thus aiding in diagnosis and allowing for early screening. However, there is a small proportion of patients who have no detectable auto-antibodies, a condition termed "seronegative MG" (SnMG). Several factors contribute to this, including laboratory test inaccuracies, decreased antibody production, immunosuppressive therapy, immunodeficiencies, antigen depletion, and immune-senescence. The diagnosis of SnMG is more challenging and is based on clinical features and neurophysiological tests. The early identification of these patients is needed in order to ensure early treatment and prevent complications. This narrative review aims to examine the latest updates on SnMG, defining the clinical characteristics of affected patients, diagnostic methods, management, and therapeutic scenarios.

A MIDDLE-AGED PATIENT WITH BILATERAL VISION LOSS AND NYCTALOPIA

PURPOSE

To report a case of nonparaneoplastic autoimmune retinopathy in a patient with a diagnosis of Lambert-Eaton myasthenic syndrome.

METHODS

Case report. Main outcome measures included findings on retinal examination and analysis of fundus autofluorescence, spectral-domain optical coherence tomography, and full-field electroretinogram. Vitamin A levels and results of antiretinal antibody testing and paraneoplastic workup are also presented.

RESULTS

A 47-year-old male presented with a 1-year history of bilateral vision loss and nyctalopia. Past medical history was significant for Lambert-Eaton myasthenic syndrome, confirmed by positive voltage-gated calcium channel antibodies, and thymectomy reported as thymic follicular hyperplasia. Optical coherence tomography showed bilateral diffuse outer retinal atrophy and ellipsoid zone loss. Fundus autofluorescence displayed a bull's pattern of hyperautofluorescence around each fovea. Full-field electroretinogram showed an extinguished rod response and a severely depressed cone response in each eye.

CONCLUSION

We describe a case of nonparaneoplastic autoimmune retinopathy in a patient with Lambert-Eaton myasthenic syndrome. Multimodal retinal imaging and electroretinogram confirmed the presence of autoimmune retinopathy with severe rod-cone degeneration. The association of this myasthenic syndrome with AIR is novel.

Simulations of active zone structure and function at mammalian NMJs predict that loss of calcium channels alone is not sufficient to replicate LEMS effects

Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune-mediated neuromuscular disease thought to be caused by autoantibodies against P/Q-type voltage-gated calcium channels (VGCCs), which attack and reduce the number of VGCCs within transmitter release sites (active zones; AZs) at the neuromuscular junction (NMJ), resulting in neuromuscular weakness. However, patients with LEMS also have antibodies to other neuronal proteins, and about 15% of patients with LEMS are seronegative for antibodies against VGCCs. We hypothesized that a reduction in the number of P/Q-type VGCCs alone is not sufficient to explain LEMS effects on transmitter release. Here, we used a computational model to study a variety of LEMS-mediated effects on AZ organization and transmitter release constrained by electron microscopic, pharmacological, immunohistochemical, voltage imaging, and electrophysiological observations. We show that models of healthy AZs can be modified to predict the transmitter release and short-term facilitation characteristics of LEMS and that in addition to a decrease in the number of AZ VGCCs, disruption in the organization of AZ proteins, a reduction in AZ number, a reduction in the amount of synaptotagmin, and the compensatory expression of L-type channels outside the remaining AZs are important contributors to LEMS-mediated effects on transmitter release. Furthermore, our models predict that antibody-mediated removal of synaptotagmin in combination with disruption in AZ organization alone could mimic LEMS effects without the removal of VGCCs (a seronegative model). Overall, our results suggest that LEMS pathophysiology may be caused by a collection of pathological alterations to AZs at the NMJ, rather than by a simple loss of VGCCs.NEW & NOTEWORTHY We used a computational model of the active zone (AZ) in the mammalian neuromuscular junction to investigate Lambert-Eaton myasthenic syndrome (LEMS) pathophysiology. This model suggests that disruptions in presynaptic active zone organization and protein content (particularly synaptotagmin), beyond the simple removal of presynaptic calcium channels, play an important role in LEMS pathophysiology.

Paraneoplastic Lambert-Eaton myasthenic syndrome: a diagnostic challenge

Lambert-Eaton myasthenic syndrome (LEMS) is a rare neuromuscular junction disorder. Underlying small cell lung cancer is found in more than half of patients. Proximal muscle weakness, autonomic features and areflexia are typical manifestations. However, LEMS is often misdiagnosed. We report a rare case of paraneoplastic LEMS, identified amid admission due to a different diagnosis. Our patient was initially admitted due to aspiration pneumonia. Further investigation revealed clinical and electrophysiological manifestations of LEMS. High clinical suspicion and early diagnostic workup were paramount in the patient outcome. Nevertheless, paraneoplastic aetiology was difficult to confirm and revealed itself a difficult challenge. Clinical awareness is crucial to diagnose LEMS and urge cancer screening and early treatment.

Exploring the role of immune checkpoint inhibitors in the etiology of myasthenia gravis and Lambert-Eaton myasthenic syndrome: A systematic review

Background

While immune checkpoint inhibitors (ICIs) have been revolutionary in the treatment of cancer, their administration has been associated with a variety of immune-related adverse events (irAEs), including myasthenia gravis (MG), and Lambert-Eaton myasthenic syndrome (LEMS).

Objective

To provide a comprehensive synthesis of the evidence supporting an etiological role for ICIs in MG and LEMS in patients with no prior history of autoimmune disease.

Hypothesis

ICIs may trigger MG and LEMS in patients with no prior susceptibility to autoimmune disease.

Methods

Relevant primary research on Medline was interrogated using a series of search algorithms. Search terms were constructed based on the PICOS tool endorsed by the Cochrane Collaboration, which describes population, intervention, comparison, outcomes, and study design. Papers were screened according to inclusion and exclusion criteria. Additional papers were retrieved from the reference lists of screened papers. Each paper included in the qualitative synthesis was assigned an integrated metric of evidence (IME) value, ranging from 0 to 7, based on study design, quality of data, likelihood of a causal link between the immune checkpoint inhibitor(s) and MG/LEMS, confidence of MG/LEMS diagnosis, and the number of patients treated with an ICI prior to MG/LEMS diagnosis.

Results

Ninety-four papers describing at least one patient treated with ICI(s) prior to the onset of MG and/or LEMS were documented. Overall evidence for a causal link between ICI administration and MG/LEMS was low, with a median IME value of 2.88 (range 2.05-6.61).

Conclusions

There is a paucity of evidence in support of an etiological relationship between ICIs and MG/LEMS, due largely to the lack of mechanistic studies and/or prospective clinical trials with relevant study endpoints. The current literature is dominated by case reports and retrospective cohort studies, which inherently yield only low-level evidence, supporting the need for further work in this area. A role of ICIs in the etiology of MG/LEMS remains plausible, arguing for continued vigilance for irAEs in patients treated with these drugs. We argue that there is a need for future mechanistic, high quality, large-scale studies specifically investigating the possible etiological role of ICIs in MG/LEMS.

The role of ion channels in immune-related diseases

Ion channel is an integral membrane protein that allows the permeation of charge ions across hydrophobic phospholipid membranes, including plasma membranes and organelle membranes (such as mitochondria, endoplasmic reticulum and vacuoles), which are widely distributed in various cells and tissues, such as cardiomyocytes, smooth muscle cells, and nerve cells. Ion channels establish membrane potential by regulating ion concentration and membrane potential. Membrane potential plays an important role in cells. Studies have shown that ion channels play a role in a number of immune-related diseases caused by functional defects in ion channels on immune or non-immune cells in major human organs, usually affecting specific organs or multiple organs. The present review discusses the relationship between ion channels and immune diseases in major organs of the human body.

Lambert-Eaton Myasthenic Syndrome and Botulism

PURPOSE OF REVIEW

This article reviews the pathophysiology, epidemiology, clinical features, diagnosis, and treatment of Lambert-Eaton myasthenic syndrome (LEMS) and botulism, presynaptic disorders of neuromuscular transmission in which rapid diagnosis improves long-term outcomes.

RECENT FINDINGS

Therapy for LEMS has seen significant advances in recent years due to the approval of amifampridine-based compounds. LEMS is likely still underdiagnosed, particularly when no underlying malignancy is identified. Clinicians must have a strong suspicion for LEMS in any patient presenting with proximal weakness and autonomic dysfunction. Botulism is another rare disorder of presynaptic neuromuscular transmission that is most commonly associated with improper storage or preservation of food products. Over the past 2 decades, wound botulism has been increasingly reported among users of black tar heroin. A high degree of clinical suspicion and electrodiagnostic studies can be beneficial in distinguishing botulism from other acute neurologic disorders, and early involvement of state and federal health authorities may assist in confirming the diagnosis and obtaining treatment. When botulism is suspected, electrodiagnostic studies can provide clinical evidence of disordered neuromuscular transmission in advance of serologic confirmation, and providers should not wait for confirmation of the diagnosis to initiate treatment.

SUMMARY

A targeted clinical history and a thorough neurologic examination with support from serologic and electrodiagnostic studies are key to early diagnosis of LEMS and botulism. Early diagnosis of both conditions creates opportunities for therapy and improves outcomes.

Antibody Diversity in Cancer: Translational Implications and Beyond

Patients with cancer tend to develop antibodies to autologous proteins. This phenomenon has been observed across multiple cancer types, including bladder, lung, colon, prostate, and melanoma. These antibodies potentially arise due to induced inflammation or an increase in self-antigens. Studies focusing on antibody diversity are particularly attractive for their diagnostic value considering antibodies are present at an early diseased stage, serum samples are relatively easy to obtain, and the prevalence of antibodies is high even when the target antigen is minimally expressed. Conversely, the surveillance of serum proteins in cancer patients is relatively challenging because they often show variability in expression and are less abundant. Moreover, an antibody’s presence is also useful as it suggests the relative immunogenicity of a given antigen. For these reasons, profiling antibodies’ responses is actively considered to detect the spread of antigens following immunotherapy. The current review focuses on expanding the knowledge of antibodies and their diversity, and the impact of antibody diversity on cancer regression and progression.

Lambert-Eaton Myasthenic Syndrome in Lung Cancer

The aim is to study lung cancer with Lambert-Eaton myasthenic syndrome (LEMS) with clinical and electrical characteristics of physiology and prognosis. Fourteen LEMS patients with lung cancer were studied retrospectively. The data including demographics, clinical presentation, treatments, and prognosis from the medical records were analyzed. Lung cancer coexisting with LEMS is more common in men (10/14). The median age was 67.1 years. Eleven (78.6%) patients experienced gradual onset of disease. Most patients presented nervous system lesions prior to occult tumors. The most common symptoms reported were proximal muscle weakness (92.9%), decreased or absent tendon reflexes (50%), and autonomic dysfunction (71.4%). All the patients showed reduction in action potential amplitude after repetitive peripheral never stimulation at low frequency and increased amplitude at high frequency. LEMS usually occurs prior to lung cancer with complicated and various clinical manifestations in our centers. We should improve awareness and knowledge of such disease to shorten the diagnostic delay and lead to few misdiagnoses.

Long-Standing Lambert–Eaton Myasthenic Syndrome Caused by Undetectable Small-Cell Lung Cancer: Why We Should Follow-Up LEMS

Physicians often encounter patients with unexplained muscle weakness and dysphagia. Lambert–Eaton myasthenic syndrome (LEMS) can cause unexplained weakness or dysphagia and is often accompanied by neoplastic conditions. A 64-year-old man who had several risk factors—14 kg weight loss over the last 4 years, 20 years of experience working as a coal miner, and being a 50 pack-year ex-smoker—complained of dysphagia, intermittent diplopia, mild weakness, and hypotonia. The initial computed tomography (CT) and follow-up positron emission tomography (PET) CT did not reveal any malignancy. After continuous follow-up for this LEMS, small-cell lung cancer (SCLC, cTxN1M0) was found on a serial follow-up chest CT 21 months after the LEMS diagnosis. The patient was treated with chemotherapy. LEMS is rare and is often accompanied by malignancy. This case highlights the importance of being concerned about LEMS diagnoses and of long-term follow-up for unexplained LEMS.

Paraneoplastic syndromes in ophthalmology

Paraneoplastic syndromes consist on systemic manifestations associated with certain cancers which are not a direct consequence of tumor invasion or its metastases. It is known that autoimmunity and autoantibody synthesis play an important role in its pathophysiology due to a process of molecular mimicry. Paraneoplastic syndromes in ophthalmology are rare, but it is important to recognize them clinically because in some cases symptoms preceded the diagnosis of an underlying neoplasia. Most frequently involved cancer is small cell lung carcinoma, but there is also a relationship with other tumor etiologies such as thymoma, gynecological tumors or neuroblastoma in children. Paraneoplastic syndromes with ocular involvement can be divided into those that affect the afferent visual pathway, such as cancer-associated retinopathy, melanoma-associated retinopathy, or paraneoplastic optic neuropathy; and the ones that affect the efferent visual pathway, such as bilateral tonic pupils, Myasthenia Gravis, Lambert-Eaton syndrome or paraneoplastic cerebellar degeneration. The presence of autoantibodies is helpful in clinical practice but negativity does not exclude this diagnosis. Although evolution and prognosis is linked to primary disease, in some cases specific treatment, usually immunosuppressive therapy, can help improving patients quality of life.

Neuromuscular Active Zone Structure and Function in Healthy and Lambert-Eaton Myasthenic Syndrome States

The mouse neuromuscular junction (NMJ) has long been used as a model synapse for the study of neurotransmission in both healthy and disease states of the NMJ. Neurotransmission from these neuromuscular nerve terminals occurs at highly organized structures called active zones (AZs). Within AZs, the relationships between the voltage-gated calcium channels and docked synaptic vesicles govern the probability of acetylcholine release during single action potentials, and the short-term plasticity characteristics during short, high frequency trains of action potentials. Understanding these relationships is important not only for healthy synapses, but also to better understand the pathophysiology of neuromuscular diseases. In particular, we are interested in Lambert-Eaton myasthenic syndrome (LEMS), an autoimmune disorder in which neurotransmitter release from the NMJ decreases, leading to severe muscle weakness. In LEMS, the reduced neurotransmission is traditionally thought to be caused by the antibody-mediated removal of presynaptic voltage-gated calcium channels. However, recent experimental data and AZ computer simulations have predicted that a disruption in the normally highly organized active zone structure, and perhaps autoantibodies to other presynaptic proteins, contribute significantly to pathological effects in the active zone and the characteristics of chemical transmitters.

Lambert-Eaton myasthenic syndrome (LEMS) in a patient with lung cancer under treatment with pembrolizumab: a case study

Pembrolizumab is an immune checkpoint inhibitor (ICI) against the programmed death-1 receptor. Herein, we introduce a rare adverse effect during using pembrolizumab. We present the case of an 80-year-old man with biopsy-proven unresectable double primary squamous cell carcinoma and large cell neuroendocrine carcinoma of the lung. After using pembrolizumab for 10 months, he complained of muscle weakness of both upper and lower extremities. In a nerve conduction study, the repetitive nerve stimulation test in the abductor digiti minimi was diagnostic of Lambert-Eaton myasthenic syndrome (LEMS): low in the amplitude of compound muscle action potential (1.4 mV), 28.6% decrement in the 5-Hz stimulation, and 579% increment in the 50-Hz stimulation. The disease did not progress after the discontinuation of pembrolizumab, even without any anti-cancer treatment for 12 months. We believe our clinical experience of this rare and unexpected adverse effect should be shared.

Ion Transporting Proteins and Cancer: Progress and Perspectives

Ion transporting proteins (ITPs) comprise a wide range of ion channels, exchangers, pumps and ionotropic receptors many of which are expressed in tumours and contribute dynamically to the different components and stages of the complex cancer process, from initiation to metastasis. In this promising major field of biomedical research, several candidate ITPs have emerged as clinically viable. Here, we consider a series of general issues concerning the oncological potential of ITPs focusing on voltage-gated sodium channels as a 'case study'. First, we outline some key properties of 'cancer' as a whole. These include epigenetics, stemness, metastasis, heterogeneity, neuronal characteristics and bioelectricity. Cancer specificity of ITP expression is evaluated in relation to tissue restriction, splice variance, functional specificity and macro-molecular complexing. As regards clinical potential, diagnostics is covered with emphasis on enabling early detection. For therapeutics, we deal with molecular approaches, drug repurposing and combinations. Importantly, we emphasise the need for carefully designed clinical trials. We highlight also the area of 'social responsibility' and the need to involve the public (cancer patients and healthy individuals) in the work of cancer research professionals as well as clinicians. In advising patients how best to manage cancer, and live with it, we offer the following four principles: Awareness and prevention, early detection, specialist, integrated care, and psychological support. Finally, we highlight four key prerequisites for commercialisation of ITP-based technologies against cancer. We conclude that ITPs offer significant potential as regards both understanding the intricacies of the complex process of cancer and for developing much needed novel therapies.

Therapeutic Potential of CKD-504, a Novel Selective Histone Deacetylase 6 Inhibitor, in a Zebrafish Model of Neuromuscular Junction Disorders

The neuromuscular junction (NMJ), which is a synapse for signal transmission from motor neurons to muscle cells, has emerged as an important region because of its association with several peripheral neuropathies. In particular, mutations in GARS that affect the formation of NMJ result in Charcot-Marie-Tooth disease and distal hereditary motor neuropathy. These disorders are mainly considered to be caused by neuronal axon abnormalities; however, no treatment is currently available. Therefore, in order to determine whether the NMJ could be targeted to treat neurodegenerative disorders, we investigated the NMJ recovery effect of HDAC6 inhibitors, which have been used in the treatment of several peripheral neuropathies. In the present study, we demonstrated that HDAC6 inhibition was sufficient to enhance movement by restoring NMJ impairments observed in a zebrafish disease model. We found that CKD-504, a novel HDAC6 inhibitor, was effective in repairing NMJ defects, suggesting that treatment of neurodegenerative diseases via NMJ targeting is possible.

Adaptive Remodeling of the Neuromuscular Junction with Aging

Aging is associated with gradual degeneration, in mass and function, of the neuromuscular system. This process, referred to as “sarcopenia”, is considered a disease by itself, and it has been linked to a number of other serious maladies such as type II diabetes, osteoporosis, arthritis, cardiovascular disease, and even dementia. While the molecular causes of sarcopenia remain to be fully elucidated, recent findings have implicated the neuromuscular junction (NMJ) as being an important locus in the development and progression of that malady. This synapse, which connects motor neurons to the muscle fibers that they innervate, has been found to degenerate with age, contributing both to senescent-related declines in muscle mass and function. The NMJ also shows plasticity in response to a number of neuromuscular diseases such as amyotrophic lateral sclerosis (ALS) and Lambert-Eaton myasthenic syndrome (LEMS). Here, the structural and functional degradation of the NMJ associated with aging and disease is described, along with the measures that might be taken to effectively mitigate, if not fully prevent, that degeneration.

Autonomic dysfunction detected by skin sympathetic response in Lambert-Eaton myasthenic syndrome: a case report

Background

Lambert-Eaton myasthenic syndrome (LEMS) is a type of paraneoplastic syndrome that may initially manifest itself with proximal weakness and gait abnormalities. Approximately up to 50% of LEMS patients have a primary autonomic dysfunction.

Case presentation

We present here a case of a 75-year-old male with symmetric proximal muscle weakness, dry mouth and constipation. The cutaneous response to scratch and upright tilt-table testing were positive. A repetitive nerve stimulation test showed that there was a decremental response of compound muscle action potential (CMAP) amplitude at 3 Hz while an incremental response at 20 Hz. The presence of antibodies against voltage-gated calcium channels (VGCC) confirmed the diagnosis. Because of the prominent symptom of autonomic disorder, the patient further underwent the test of skin sympathetic response (SSR). Lower amplitude and longer response duration were found in palms, while it evoked no response in soles.

Conclusions

In this case, we present the detailed results of SSR test on a patient suffering LEMS with autonomic disorder. Since autonomic dysfunction has a significant impact on clinical management and SSR test is an effective detection method, we recommend that SSR test be performed on patients with LEMS regularly.

Myasthenia Gravis and Lambert-Eaton Myasthenic Syndrome: New Developments in Diagnosis and Treatment

"Myasthenia Gravis is, like it or not, the neurologist's disease!" (Thomas Richards Johns II, MD Seminars in Neurology 1982). The most common disorders in clinical practice involving defective neuromuscular transmission are myasthenia gravis (MG) and Lambert-Eaton myasthenic syndrome (LEMS). The hallmark of weakness related to malfunction of the neuromuscular junction (NMJ) is variability in severity of symptoms from minute to minute and hour to hour. Fatigable weakness and fluctuation in symptoms are common in patients whether the etiology is autoimmune, paraneoplastic, genetic, or toxic. Autoimmune MG is the most common disorder of neuromuscular transmission affecting adults with an estimated prevalence of 1 in 10,000. While LEMS is comparatively rare, the unique clinical presentation, the association with cancer, and evolving treatment strategies require the neurologist to be familiar with its presentation, diagnosis, and management. In this paper we provide a summary of the meaningful recent clinical developments in the diagnosis and treatment of both MG and LEMS.

Neurological Adverse Events Induced by Immune Checkpoint Inhibitors in Non-Small Cell Lung Cancer: Current Perspectives and New Development

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of multiple malignancies, especially in non-small cell lung cancer (NSCLC). With the extensive application of ICIs in clinical practice, clinicians have to manage their toxicities, which are often termed immune-related adverse events (irAEs). Several ICIs, such as nivolumab, pembrolizumab, atezolizumab, and durvalumab, have been approved by the US Food and Drug Administration (FDA) to treat advanced NSCLC, accompanied by a broad spectrum of toxicity reactions. However, ICIs-associated neurological toxicities, regarding polyneuropathy, Bell palsy, encephalopathy, and myasthenia gravis, as uncommon emerging toxicities have not been well recognized, present a challenge for clinicians to improve awareness of supervision, recognition, and management before death from them. Herein, we have summarized the incidence, diagnosis, clinical manifestations, potential mechanisms, treatments, and outcomes of ICIs-related neurotoxicity and optimized the management approach for NSCLC patients. Prompt recognition and proper management are indispensable to reduce the morbidity of these patients with immune-related neurological toxicities.

Neuromuscular Complications of Targeted Anticancer Agents: Can Tyrosine Kinase Inhibitors Induce Myasthenia Gravis? Getting Answers From a Case Report up to a Systematic Review

More than 40 tyrosine kinase inhibitors (TKIs) have received hematological or oncological indications over the past 20 years, following the approval of imatinib, and many others are currently being tested in clinical and preclinical level. Beyond their common toxicities, no certain agent from this large class of molecularly targeted therapies was strongly associated with “off-target” impairment of neuromuscular transmission, and although myasthenia gravis (MG) is a well-characterized autoimmune disorder, only few sporadic events proven by serologically detected causative autoantibodies and/or by positive electrophysiological tests are reported in the literature. Herein, we present the first case of anti-MUSK (+) MG in a woman with metastatic BRAF-mutant melanoma after long-term treatment with dabrafenib (BRAF inhibitor) and trametinib (MEK inhibitor). Triggered by this report, a systematic literature review was conducted, summarizing all other cancer cases that developed MG, after exposure to any type of targeted agent and regardless of the underlying malignancy. All available data on the clinical diagnosis, the potential of administered TKIs to induce a seropositive myasthenic syndrome, the immune and non-immune-mediated pathogenesis of postsynaptic damage, and the challenging management of this neuromuscular toxicity were collected and discussed. In the presented case, MG was confirmed by both autoantibodies and nerve-conduction tests, while its reactivation after TKIs rechallenge supports a more than coincidental association. The following review identified 12 cancer cases with TKI-related MG in six case reports and one case series. In most of them, the myasthenia diagnosis was challenging, since the clinical symptomatology of fatigable weakness was not corroborating with consistent laboratory and electrophysiological findings. In fact, anti-AchR titers were positive in five and anti-MuSK only in the abovementioned individual. The symptomatology corresponded to TKI discontinuation and standard treatment with pyridostigmine and prednisolone; intravenous immunoglobulin was added only in three, and two required mechanical ventilation. In an era where TKIs will be prescribed more frequently for various malignancies, even in combinations with immune-checkpoint inhibitors, this report synthesizes their risk for neuromuscular complications and increases the clinicians’ awareness in order to extend the on-treatment and overall survival of TKI-treated cancer patients.

Lambert-Eaton myasthenic syndrome revealed after surgery of lung adenocarcinoma

We report a very rare case of cT1N0M0 lung adenocarcinoma reveling Lambert-Eaton myasthenic syndrome (LEMS). A 69-year-old nonsmoking woman, with several comorbidities consulted for cough and dyspnea. Chest radiograph and CT scanning detected a left lower lobe mass; Needle biopsy confirmed differentiated adenocarcinoma; 18FDG-PET scan and Brain MRI eliminated metastatic disease dissemination. Our patient underwent a left lower lobectomy with mediastinal lymphadenectomy (pT1N0M0), no adjuvant chemotherapy was administrated. One month later patient present a muscle weakness in both lower limbs and fatigability followed by an inability to walk. The diagnosis of LEMS was made from the distinctive electromyogram (EMG) findings and a treatment with Amifampridine (3, 4-diaminopyridine phosphate [3, 4-DAP]) was prescribed with evident efficacy for symptoms.

3,4-diaminopyridine treatment for Lambert-Eaton myasthenic syndrome in adults: a meta-analysis of randomized controlled trials

BACKGROUND

Lambert-Eaton myasthenic syndrome (LEMS) is a rare autoimmune disorder of neuromuscular transmission. The objective was to examine the efficacy and safety of 3,4-diaminopyridine (3,4-DAP) in patients with LEMS.

METHODS

We searched several databases to identify relevant studies, including PubMed, EMBASE, Web of Science, MEDLINE, Cochrane Neuromuscular Disease Group Specialized Register and the Cochrane Central Register of Controlled Trials(CENTRAL). The primary outcome, quantitative myasthenia gravis (QMG) score and the secondary outcome, compound muscle action potentials (CMAP) amplitude were pooled by meta-analysis.

RESULTS

Six randomised controlled trials (RCTs) involving 115 patients with LEMS were included. QMG score showed a significant decrease (improvement) of 2.76 points (95 % CI, -4.08 to -1.45, p < 0.001) after treatment with 3, 4-DAP. Moreover, the overall mean CMAP amplitude improved significantly in LEMS patients with 3, 4-DAP treatment, compared with placebo treatment (mean difference 1.34 mV, 95 % CI, 0.98 to 1.70, p < 0.001). The overall assessment of all included trials showed a low risk of bias and low heterogeneity.

CONCLUSIONS

The pooled results of RCTs demonsrated with moderate to high evidence that 3,4-DAP has a significant effect on LEMS treatment, with improvements in muscle strength score and CMAP amplitude.

Discordant SOX-1 antibodies results in paraneoplastic Lambert-Eaton syndrome diagnosis by the clinical laboratory

BACKGROUND

Anti-Sry-like high mobility group box 1 (anti SOX-1) proteins are rare onconeural antibodies associated with paraneoplastic Lambert-Eaton myasthenic syndrome (LEMS). Few patients with anti-SOX-1 antibodies and negative anti-glial nuclear antibody reactivity have been described to date.

CASE SUBJECT AND METHODS

Our case involves a 72-year-old female patient with progressive girdle weakness, sensation of heaviness in the lower limbs, predominantly distal and associated with circulatory problems together with instability when walking, with a high suspicion of an autoimmune myopathic disorder. Immunoblot test for autoimmune myopathies antibodies detection were all negative. Onconeuronal antibodies were determined in serum by indirect immunofluorescence being negative as well. Given the high suspicion, we also checked for the presence of other antineuronal antibodies whose patterns are not visible by IIF.

RESULTS

Onconeuronal antibodies by immunoblot for the following antibodies: Hu, Ri, Yo, Zic4, Tr, PCA-2, MA-TA, CV2, GAD65, Zic4, Titin, SOX1, Recoverin and Amp, revealed an unexpected clear band in SOX-1, which are highly suggestive of paraneoplastic LEMS.

DISCUSSION

We hypothesize that discordant onconeuronal antibodies results were due to the fact that positivity in IIF is associated with other SOX-B group proteins (normally related to cases of non-paraneoplastic neuropathy), while negativity in IIF and subsequent confirmed presence of specific SOX1 antibody by immunoblot could indicate an underlying tumor.

Classically Described, Paradoxically Underrecognized: A Case of Proximal Weakness, Hyporeflexia/Areflexia, and Dysautonomia

ABSTRACT

We present a case of chronic, progressive proximal weakness with dysautonomia and hyporeflexia/areflexia ultimately diagnosed with Lambert-Eaton myasthenic syndrome. An approach to neuroanatomical localization is discussed leading to the appropriate selection of electrodiagnostic studies. The electrophysiologic triad of Lambert-Eaton myasthenic syndrome is demonstrated with diffusely reduced motor amplitudes, decrement with low-frequency repetitive nerve stimulation, and increment of motor amplitudes after maximum voluntary contraction. Subsequent serologic testing for P/Q-type voltage-gated calcium channel antibodies are markedly elevated. We highlight the clinical features and pitfalls of examining a patient with Lambert-Eaton myasthenic syndrome when suspecting this challenging diagnosis. The neurophysiological underpinning of the electrodiagnostic results is explained, and the diagnostic utility of single-fiber electromyography is briefly discussed.

Paraneoplastic Cerebellar Degeneration and Lambert-Eaton Myasthenic Syndrome with SOX-1 Antibodies

A 69-year-old man was admitted to our hospital for progressive muscle weakness in both lower limbs and limb ataxia (day 0). Nerve conduction studies showed low compound muscle action potential amplitudes at rest and increased amplitudes after maximum voluntary contraction. Blood testing revealed SOX-1 antibodies. He was diagnosed with paraneoplastic cerebellar degeneration and Lambert-Eaton myasthenic syndrome (PCD-LEMS). He died from aspiration pneumonia on day 9. Small-cell lung carcinoma (SCLC), which had not been obvious on computed tomography, was found during the autopsy. Patients with PCD-LEMS who test positive for SOX-1 antibodies should be carefully evaluated for SCLC.

Problem-solving in clinical practice: breathing difficulty and muscle weakness following allogeneic haematopoietic stem cell transplantation

Acute weakness and dyspnoea are unusual presentation after allogeneic haematopoietic stem cell transplantation (HSCT) complicated by chronic graft-versus-host disease (GVHD). The differential diagnosis and management are challenging for the paediatrician. This case chronicles the diagnostic journey of a child who presented with weakness, dyspnoea and difficulty in speech, 2 years after allogeneic HSCT and GVHD and explores the approach to neurological manifestations in this context.

Lambert-Eaton Myasthenic Syndrome and Dermatomyositis With Anti-TIF1-gamma Autoantibody: A Unique Association of Autoimmune Neuromuscular Conditions Without Malignancy

ABSTRACT

Lambert-Eaton myasthenic syndrome (LEMS) is a presynaptic neuromuscular junction disorder, and dermatomyositis (DM) is an idiopathic inflammatory myopathy. LEMS and DM are uncommon conditions that can present similarly and are often associated with autoantibodies. Concomitant LEMS and DM have only been reported a few times, and most of those cases were paraneoplastic. We present the first reported case of a patient with antivoltage gated calcium channel antibody positive LEMS who subsequently developed DM with antitranscription intermediary factor 1-gamma (anti-TIF1-γ) antibodies. Interestingly, both conditions occurred without evidence of malignancy. This diagnosis of LEMS and DM with characteristic clinical, electrodiagnostic, and histopathological evidence led to a beneficial modification of the patient's therapeutic regimen. Due to the fact that overlapping concurrent neuromuscular conditions are rare, a high clinical suspicion is needed to identify, evaluate (including appropriate cancer screenings), and appropriately treat these patients.

Five-Month Trial of Whole-Food Plant-Based Diet in a Patient With Coexisting Myasthenia Gravis and Lambert-Eaton Myasthenic Syndrome

Introduction: Nutritional intervention, such as a whole-food plant-based (WFPB) diet, is suggested to improve symptoms of autoimmune disorders. Its effects on neuromuscular junction (NMJ) diseases are less known. Case Description: A 56-year-old female with a combined myasthenia gravis and Lambert-Eaton myasthenic syndrome presented with persistent musculoskeletal weakness and pain, fatigue, and diminished concentration. Methods: A WFPB diet was implemented for 5 months in this case study. Functionality, biometrics, and quality of life were assessed at regular intervals via blood work, vital signs, and patient surveys. Results: After 10 weeks, 2 medications were de-prescribed due to improvement in blood glucose levels and blood pressure readings. Neuromuscular symptoms lessened as measured by the Myasthenia Gravis Illness Index. Weight loss of 18.7 pounds was achieved. No deterioration in physical activity was reported throughout the 5-month trial of WFPB diet. Discussion: Our results have implications that an individualized dietary strategy may be considered as one component of management of NMJ diseases. The effects of WFPB diet on NMJ diseases remain inconclusive.

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.

The Impact of Mitochondrial Deficiencies in Neuromuscular Diseases

Neuromuscular diseases (NMDs) are a heterogeneous group of acquired or inherited rare disorders caused by injury or dysfunction of the anterior horn cells of the spinal cord (lower motor neurons), peripheral nerves, neuromuscular junctions, or skeletal muscles leading to muscle weakness and waste. Unfortunately, most of them entail serious or even fatal consequences. The prevalence rates among NMDs range between 1 and 10 per 100,000 population, but their rarity and diversity pose difficulties for healthcare and research. Some molecular hallmarks are being explored to elucidate the mechanisms triggering disease, to set the path for further advances. In fact, in the present review we outline the metabolic alterations of NMDs, mainly focusing on the role of mitochondria. The aim of the review is to discuss the mechanisms underlying energy production, oxidative stress generation, cell signaling, autophagy, and inflammation triggered or conditioned by the mitochondria. Briefly, increased levels of inflammation have been linked to reactive oxygen species (ROS) accumulation, which is key in mitochondrial genomic instability and mitochondrial respiratory chain (MRC) dysfunction. ROS burst, impaired autophagy, and increased inflammation are observed in many NMDs. Increasing knowledge of the etiology of NMDs will help to develop better diagnosis and treatments, eventually reducing the health and economic burden of NMDs for patients and healthcare systems.