Lambert-Eaton myasthenic syndrome: the 60th anniversary of Eaton and Lambert's pioneering article / Síndrome miastênica de Lambert-Eaton: o 60° aniversário do artigo pioneiro de Eaton e Lambert

ABSTRACT This historical review describes the contribution of Drs. Lee M. Eaton and Edward H. Lambert to the diagnosis of myasthenic syndrome on the 60th anniversary of their pioneering article (JAMA 1957) on the disease. There are important landmarks in their article on a disorder of the neuromuscular junction associated with thoracic neoplasm and the electrophysiological criteria for Lambert-Eaton myasthenic syndrome (LEMS). After 60 years, the main electrophysiological criteria described in Eaton and Lambert's pioneering article are still currently useful in the diagnosis of LEMS.

RESUMO Essa revisão histórica enfatiza a contribuição do Dr Lee M Eaton e do Dr Edward H. Lambert para o diagnóstico da síndrome miastênica no 60o aniversário do seu artigo pioneiro (JAMA 1957) para essa doença. Existem importantes marcos no artigo de Eaton e Lambert, como uma desordem da junção neuromuscular associada à neoplasia torácica e critério diagnóstico para síndrome miastênica de Lambert-Eaton (LEMS). Após 60 anos, os principais critérios diagnósticos descritos para LEMS no artigo pioneiro de Eaton e Lambert continuam úteis no diagnóstico da LEMS.

A Patient with Coexisting Myasthenia Gravis and Lambert-Eaton Myasthenic Syndrome

BACKGROUND: The coexistence of myasthenia gravis (MG) and Lambert-Eaton myasthenic syndrome (LEMS) is very rare and remains controversial. CASE REPORT: A 48-year-old woman initially presented with noticeable right ptosis and intermittent diplopia. She then developed fluctuating proximal limb weakness and difficulty in swallowing. The serum titer of anti-acetylcholine-receptor antibody was elevated and the edrophonium (Tensilon) test was positive. However, repetitive nerve stimulation revealed abnormalities typical of LEMS. The patient exhibited a good response to treatment with anticholinesterase inhibitors and steroids, and long-term evaluation disclosed that she presented with the clinical, electrophysiological, and immunological characteristics of both diseases. CONCLUSIONS: The reported clinical and electrophysiological features suggest that this patient was a very rare case of combined MG and LEMS.

A Case of Lambert-Eaton Myasthenic Syndrome with Small-Cell Lung Cancer and Transient Increase in Anti-Acetylcholine-Receptor-Binding Antibody Titer

BACKGROUND: Lambert-Eaton myasthenic syndrome (LEMS) is a presynaptic neuromuscular junction disorder that is most frequently associated with small-cell lung cancer (SCLC). The titers of antibodies against voltage-gated calcium channels are frequently increased in LEMS, but only rarely is titer of anti-acetylcholine-receptor-binding antibodies (AChR-abs) increased. CASE REPORT: A 57-year-old male was admitted to our hospital due to dry mouth and eyes and progressive proximal limb weakness of 2 months duration. The results of a repetitive nerve stimulation test disclosed all criteria for the electrophysiological LEMS pattern, and the patient's AChR-abs titer was 0.587 nmol/L. At a follow-up performed 5 years after successful treatment of SCLC and LEMS, his AChR-abs titer had decreased to 0.001 nmol/L. CONCLUSIONS: We suggest that this was a case of transient pseudopositivity of AChR-abs in SCLC with LEMS.

Seropositive Myasthenia Gravis Associated with Small-Cell Lung Carcinoma

BACKGROUND: Lambert-Eaton myasthenic syndrome is well known to be a classical paraneoplastic syndrome of small cell lung carcinoma (SCLC). Three cases of seronegative myasthenia gravis (MG) and SCLC were previously reported. CASE REPORT: A 65-year-old man developed a severe progressive respiratory failure with clinical features of MG. Tests showed a decremental response in the repetitive nerve stimulation test, abnormal single-fiber electromyography, and positive acetylcholine receptor antibody. SCLC was confirmed by the lung biopsy. CONCLUSIONS: This case represents the first case of seropositive MG and SCLC.

Non-paraneoplastic Lambert-Eaton myasthenic syndrome: a brief review of 10 cases / Síndrome miastênica de Lambert-Eaton não paraneoplásica: uma breve revisão de dez casos

Lambert-Eaton myasthenic syndrome (LEMS) is an immune-mediated disorder of the presynaptic neuromuscular transmission, which more frequently occurs as the remote effect of a neoplasm, in the paraneoplastic form (P-LEMS), or in a non-paraneoplastic form (NP-LEMS); but few studies describe the clinical features of NP-LEMS. We analyzed the clinical manifestations, laboratory findings, electrophysiological studies, and treatment responses in ten Brazilian patients suffering from NP-LEMS. The mean age was 41.5 years. More often neurological findings were hyporeflexia or areflexia with a post-exercise improvement. Treatment response occurred with pyridostigmine, guanidine, prednisone, azathioprine, and cyclosporine; but not response was observed after intravenous immunoglobulin and plasma exchange. Age at onset, clinical manifestations, and electrophysiological abnormalities can help more in the diagnosis than serum antibodies; the symptomatic treatment with pyridostigmine was effective; and the immunosuppressive treatment with prednisone, azathioprine, or cyclosporine was more beneficial than plasma exchange or intravenous immunoglobulin treatment.

A síndrome miastênica de Lambert-Eaton (LEMS) é uma desordem imunomediada da transmissão neuromuscular pré-sinaptica, que mais frequentemente ocorre como efeito à distância de uma neoplasia, na forma paraneoplásica (P-LEMS), ou na forma não paraneoplásica (NP-LEMS); porém poucos estudos têm descrito as características da NP-LEMS. Nós analisamos as manifestações clínicas, laboratoriais, eletrofisiológicas, e resposta ao tratamento em dez pacientes brasileiros com NP-LEMS. A idade média foi de 41,5 anos. A manifestação neurológica mais freqüente foi hiporeflexia ou arreflexia com melhora após o exercício. A resposta ao tratamento ocorreu com piridostigmina, guanidina, prednisona, azatioprina, e ciclosporina; mas não com imunoglobulina intravenosa e plasmaférese. A idade de início, manifestações clínicas e eletrofisiológicas ajudaram mais no diagnóstico do que os anticorpos séricos; o tratamento sintomático com piridostigmina foi efetivo; e o tratamento imunossupressor com prednisona, azatioprina, ou ciclosporina beneficiou mais do que a plasmaférese ou a imunoglobulina intravenosa.

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

Se presenta el caso de una mujer de 70 años sin antecedentes patológicos de importancia, que ingresó a un hospital local con fatiga, debilidad muscular de las extremidades y visión doble. En el examen físico se observaba ptosis palpebral bilateral (figura 1), paresia facial, atrofia muscular proximal de las extremidades dominantes y arreflexia generalizada. Con el diagnóstico presuntivo de miastenia gravis, se practicó una electromiografía que mostró una amplitud anormalmente baja de los potenciales de acción muscular y un gran aumento después de repetidas estimulaciones a 50 Hz, lo cual es muy sugestivo del síndrome miasténico de Eaton-Lambert. Se hizo una tamización general en busca de neoplasias y se encontró en la radiografía de tórax una masa en el mediastino anterior (figura 2), razón por la cual se le practicó posteriormente timectomía total; la histopatología del timo concluyó que se trataba de un timoma de tipo B1 que mostraba aún áreas de corteza y médula de timo normales (figura 3). Luego de la timectomía, la paciente mejoró de la mayoría de sus síntomas miasténicos.Si bien la mayoría de casos de síndrome miasténico de Eaton-Lambert se asocian a carcinoma pulmonar de células pequeñas, aquí se presenta un raro pero ilustrativo caso asociado a timoma.

A 70-year-old woman without unusual medical history was admitted at a local hospital with complaints of fatigue, muscle weakness in the extremities and double vision. On examination, bilateral ptosis (figure 1), facial paresis, proximal-dominant limb muscle atrophy and generalized arreflexia were observed. On the basis of tentative diagnosis of myasthenia gravis, an electrodiagnostic study was conducted. It demonstrated abnormally low-amplitude muscular action potentials, but with a large increase after repetitive stimulation at 50 Hz. These responses are characteristic of the Eaton-Lambert myasthenic syndrome. A screening for malignant diseases was performed and chest radiography showed an anterior mediastinal mass (figure 2). The patient was scheduled for thymectomy, and subsequent histopathology of the thymus gland revealed a type B1 thymoma with areas reminiscent of a normal thymic cortex and medulla (figure 3). After the thymectomy most of the myasthenic symptoms were no longer in evidence. Generally, the Eaton-Lambert myasthenic syndrome is associated with small cell lung carcinoma, but this was an illustrative case associated with thymoma.

Lambert-Eaton myasthenic syndrome as a cause of persistent neuromuscular weakness after a mediastinoscopic biopsy: A case report / 대한마취과학회지

There are many causes of prolonged postoperative muscle weakness, including drugs, residual anesthetics, cerebrovascular events, electrolyte imbalance, hypothermia, and neuromuscular disease. Neuromuscular diseases are relatively rare, with the most common being myasthenia gravis and Lambert-Eaton myasthenic syndrome (LEMS). We report an unusual case in which a patient who was given a muscle relaxant during mediastinoscopy developed postoperative muscle weakness that was ultimately diagnosed as secondary to LEMS.

Lambert-Eaton Myasthenic Syndrome (LEMS) Presented With Ocular Symptoms

Lambert-Eaton myasthenic syndrome (LEMS) is characterized clinically by fluctuating muscular weakness; presentation with ocular symptoms is unusual. A 60-year-old man had developed diplopia and ptosis 2 years previously. The findings of a neurologic examination were normal except for bilateral ptosis and ophthalmoplegia. The amplitude of compound muscle action potentials recorded on the abductor digiti minimi increased (by more than 500%) during 50-Hz stimulation. This case demonstrates that LEMS should be included in the differential diagnosis of myasthenic symptom confined to the ocular muscles.

Surgical correction of strabismus in Lambert-Eaton myasthenic syndrome: case reports / Correção cirúrgica do estrabismo na síndrome de Lambert-Eaton: relato de dois casos

Lambert-Eaton myasthenic syndrome is a rare and acquired autoimmune disorder. We describe two female patients with medial rectus paresis as the only ocular manifestation. After a unilateral medial rectus recession and lateral rectus resection procedure, both patients recovered normal adduction. To our knowledge, this is the first report of surgery for extraocular muscle paresis in Lambert-Eaton myasthenic syndrome.

A síndrome de Lambert-Eaton é um distúrbio autoimune raro e adquirido. Apresentamos duas pacientes com paresia do reto medial como única manifestação ocular. Após retrocesso do reto lateral e ressecção do reto medial, unilateral, ambas as pacientes apresentaram normalização da adução. Até onde sabemos, este é o primeiro relato de cirurgia para paresia do reto medial na síndrome de Lambert-Eaton.

Adenocarcinoma pulmonar, dermatomiosite e síndrome miastênica de Lambert-Eaton: uma rara associação / Lung adenocarcinoma, dermatomyositis, and Lambert-Eaton myasthenic syndrome: a rare combination

A incidência das neoplasias pulmonares vem aumentando no Brasil e no mundo, provavelmente como resultado do aumento do tabagismo. Com o maior número de casos, surgem as apresentações atípicas. Relatamos o caso de um paciente do sexo masculino, 66 anos, tabagista e hipertenso, que apresentava quadro de fraqueza muscular proximal progressiva e, em dois meses, evoluiu com disfagia para alimentos sólidos, disfonia e lesões cutâneas em forma de "V" no tórax. O radiograma de tórax mostrou um nódulo pulmonar espiculado no lobo superior direito. A análise bioquímica revelou aumento da creatinoquinase. Após exames complementares e biópsias, o paciente foi submetido à lobectomia superior direita. A histopatologia evidenciou um adenocarcinoma moderadamente diferenciado. A análise global do caso e a revisão de literatura permitem sugerir que o quadro clínico do paciente era resultante da sobreposição de duas síndromes paraneoplásicas, a saber, a dermatomiosite e a síndrome miastênica de Lambert-Eaton, secundárias a um adenocarcinoma pulmonar.

The incidence of lung neoplasms is increasing in Brazil and in the world, probably as a result of the increase in smoking. Due to the greater number of cases, atypical presentations appear. We report the case of a 66-year-old hypertensive male smoker who presented progressive proximal muscular weakness and, in two months, evolved to dysphagia, dysphonia, and V-shaped skin lesions on the chest. A chest X-ray showed a spiculated pulmonary nodule in the right upper lobe. The biochemical analysis revealed elevated creatine kinase levels. After complementary tests and biopsies, the patient underwent right upper lobectomy. Histopathology showed a moderately differentiated adenocarcinoma. The overall analysis of the case and a review of the literature allow us to suggest that the clinical profile of the patient was a result of an overlap of two paraneoplastic syndromes (dermatomyositis and Lambert-Eaton myasthenic syndrome) secondary to lung adenocarcinoma.

Electrophysiological Changes in Lambert-Eaton Myasthenic Syndrome With Intravenous Immunoglobulin Therapy

No abstract available.

Síndrome miasteniforme de Lambert-Eaton idiopático: Report of one case / Idiopathic Lambert-Eaton myasthenic syndrome

Lambert-Eaton myasthenic syndrome (LEMS) is an autoinmune idiopathic or paraneoplastic syndrome producing antibodies agaisnt presynaptic voltage calcium channels. The clinical features of patients with LEMS are muscle weakness and autonomic dysfunction. We report a 40 years old man with a four years history of proximal weakness, absent tendon reflexes and dry mouth. The diagnosis was confirmed by characteristic electromyographic findings, showing a low-amplitude muscle response that increased dramatically after activation. Circulating antibodies to voltage-gated calcium channel were present. The search for malignant tumors was negative. The patient was treated with prednisone and azathioprine and after four months, he was able to walk and signs of autonomic dysfunction started to subside.

Marked Improvement of Lambert-Eaton Myasthenic Syndrome with the Chemotherapy of Small Cell Lung Carcinoma

No abstract available.

A Case of Lambert-Eaton Myasthenic Syndrome with Positive VGCC Antibodies Diagnosed in Small Cell Lung Cancer / 결핵및호흡기질환

Lambert-Eaton myasthenic syndrome (LEMS), a rare autoimmune neurological syndrome, is caused by defects in the secretion of acetylcholine from the presynaptic membrane, and is associated with the destruction of voltage gated calcium channels (VGCC) in the neuromuscular junction. LEMS can be confirmed by repetitive nerve stimulation and by the clinical symptoms, which are characterized by proximal muscle weakness in the lower extremities, decreased deep tendon reflexes and autonomic dysfunctions. In about 60% of patients with this disorder, underlying cancer-small cell lung cancer may be detected. Clinical symptoms may precede the diagnosis of malignancy, with the early diagnosis and treatment of the underlying malignancy being possible through the diagnosis of LEMS. A case of LEMS, with positive VGCC antibodies, in a 48-year-old man, which improved after chemotherapy of the underlying small cell lung cancer, is reported.

Exacerbation of symptoms due to diltiazem in a patient with Lambert-Eaton myasthenic myopathic syndrome.

A 65-year old man on treatment for ischaemic heart disease presented with a history of pain and weakness of all four limbs and dry mouth. He had clinical and neurophysiological features of Lambert-Eaton myasthenic syndrome. His symptoms improved after withdrawal of diltiazem, although neurophysiological changes remained even after 3 months.

A Case of Lambert-Eaton Myasthenic Syndrome Associated with Atypical Bronchopulmonary Carcinoid Tumor

The Lambert-Eaton myasthenic syndrome (LEMS) is typically recognized as a paraneoplastic syndrome associated with a small cell lung carcinoma (SCLC), whereas LEMS with other neuroendocrine lung tumors, including carcinoids or large cell lung carcinoma, are highly unusual. Here, we report a rare case of LEMS with atypical bronchopulmonary carcinoid tumor: A 65-yr-old man presented with progressive leg weakness and a diagnosis of LEMS was made by serial repetitive nerve stimulation test. Chest CT revealed a lung nodule with enlargement of paratracheal lymph nodes, and surgically resected lesion showed pathological features of atypical carcinoid tumor. We concluded that LEMS could be associated with rare pulmonary neuroendocrine tumor other than SCLC, which necessitates pathologic confirmation followed by aggressive treatment for optimal management in these rare cases.

Paraneoplastic Syndrome

Paraneoplastic syndrome is a rare neurologic disorder caused not by the direct invasion or metastasis of cancer, but by the remote effects of cancer. The central- and peripheral-nervous system or neuromuscular junction area were involved in this syndrome. The pathogenesis was thought as the autoimmune disease, the result of an immunologic response to cancer and to cross-react with self-cells of the nervous system or of the neuromuscular junction, causing neuronal dam-age. Specific forms of this syndrome are often associated with specific paraneoplastic autoantibodies and cancer. The onset of neurological symptoms and detection of these antibodies often precede the diagnosis of the cancer; therefore, detection of these antibodies greatly assists the diagnosis of this syndrome and prompts investigations for the underly-ing cancer. Some paraneoplastic central neurological syndromes, such as cerebellar degeneration, limbic encephalitis, and necrotizing myelitis, were not improved by putative pathogenic autoantibodies, or by immunosuppresant or tumor removal, inspite of improvement in other peripheral neurologic syndrome, Lambert-Eaton myasthenic syndrome, neu-romyotonia, and Stiff-man syndrome. A more detailed understanding of the relationship between the cancer and the neural involvement from the molecular biological standpoint may lead to rational tumor therapy and elucidation of the mechanism of neural death. Here, major clinical forms with well-known antineuronal antibodies and specific cancers are reviewed.