ABSTRACT
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.
Subject(s)
Humans , History, 20th Century , History, 21st Century , Lambert-Eaton Myasthenic Syndrome/history , Electromyography/history , Periodicals as Topic , Lambert-Eaton Myasthenic Syndrome/diagnosis , Lambert-Eaton Myasthenic Syndrome/physiopathology , Electromyography/methods , Electrophysiological PhenomenaABSTRACT
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.
Subject(s)
Adult , Female , Humans , Male , Middle Aged , Lambert-Eaton Myasthenic Syndrome , Electrophysiology , Immunoglobulins, Intravenous/therapeutic use , Immunosuppressive Agents/therapeutic use , Lambert-Eaton Myasthenic Syndrome/diagnosis , Lambert-Eaton Myasthenic Syndrome/physiopathology , Lambert-Eaton Myasthenic Syndrome/therapy , Plasmapheresis , Retrospective StudiesABSTRACT
The Lambert-Eaton myasthenic syndrome (LEMS) heralds the occurrence of malignancy, especially small-cell lung cancer (SCLC), but it can also occur in the absence of cancer. Twelve patients were diagnosed as LEMS by clinical features and the classical electrophysiological triad, which includes a low amplitude of compound muscle action potentials (CMAP), decremental responses on low-rate stimulation, and incremental responses on high-rate stimulation on the repetitive nerve stimulation (RNS) test. There were 6 male and 6 female patients, ranging in age from 49 to 66 years. Malignancy(all were SCLC) was found in 7 patients. Males predominantly expressed the paraneoplastic form; whereas the primary autoimmune form was found only in women, who showed a good response to corticosteroid treatment. The neurological features were similar in both groups: proximal lower limb weakness, depressed muscle stretch reflexes, and dryness of mouth in nearly all patients. Bulbar dysfunction and limb paresthesia were a little more frequent in the paraneoplastic form. In RNS tests, the characteristic electrophysiological abnormalities were found in all patients and were more profound in the paraneoplastic form. We concluded that LEMS is commonly associated with malignancy, especially SCLC, but it should also be stressed that there are many female LEMS patients who do not harbor any malignancy at all, and that other treatment strategies such as immunotherapy should be considered for these patients.
Subject(s)
Aged , Female , Humans , Male , Carcinoma, Small Cell/complications , Lambert-Eaton Myasthenic Syndrome/therapy , Lambert-Eaton Myasthenic Syndrome/physiopathology , Lung Neoplasms/complications , Middle Aged , Paraneoplastic Syndromes/physiopathologyABSTRACT
El síndrome de Lambert-Eaton (L-E) es un padecimiento autoinmunitario descrito por Eaton y Lambert en 1957. Afecta con mayor frecuencia a hombres y se caracteriza por debilidad, mialgias y fatiga en extremidades inferiores e hiporeflexia. Se pueden presentar ptósis y son frecuentes las alteraciones de tipo disautonómico como sequedad de boca y ojos, impotencia, disminución de la sudoración y sintomatología ortostática. En la mayoría de los casos está asociado a neoplasias, principalmente a cáncer de células pequeñas de pulmón; también se ha asociado a enfermedades autoinmunes y en un porcentaje de los casos no es posible demostrar enfermedad subyacente. El propósito de este escrito es informar el caso de un paciente que presentó como manifestación inicial un Síndrome de Lambert-Eaton en el que se descartó cáncer de pulmón y otras enfermedades autoinmunes. Seis meses después se encontró cáncer de páncreas
Subject(s)
Humans , Female , Aged , Pancreatic Neoplasms/diagnosis , Lambert-Eaton Myasthenic Syndrome/diagnosis , Lambert-Eaton Myasthenic Syndrome/physiopathology , Tomography, X-Ray Computed , Lung NeoplasmsABSTRACT
Tres pacientes con el Síndrome de Eaton-Lambert fueron considerados para este estudio. Los pacientes se quejaban de debilidad, y fatigabilidad con dolor (sugiriendo artritis), sequedad de boca, parestesias, impotencia y menos frecuente, ptosis. Los estudios electrofisiológicos fueron de gran ayuda en el diagnósticodel Síndrome Eaton-Lambert. Los hallazgos electrodiagnósticos enfatizan la importancia de los test de estudios de estimulación de la moto neurona para desórdenes de transmisión neuromuscular en pacientes con debilidad muscular proximal primaria. Los resultados electrofisiológicos no mostraron anormalidades en los potenciales evocados presinápticocon las diferentes frecuencias de estimulación. Un solo estímulo de la neurona puede conducir a un potencial muscular post-sináptico de baja amplitud, mientras que una rata rápida (10-50 Hz) mostró un marcado incremento en la amplitud de los potenciales. Esos resultados electrofisiológicos son fuertemente soportados y sugieren que hay un defecto en el incremento de la quanta de Acetil Colina de los nervios terminales. Algunos factores elaborados por tumores, hiperplasias y displasias parece que interfieren con el incremento de ACh. Estos factores inmunológicos también interfieren con receptores presinápticos y bloquean al mecanismo de retroalimentación básico sobre la terminal nerviosa y que concierne al incremento de transmisor