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Abstract(s)
Os distúrbios miasténicos são um conjunto heterogéneo de doenças que afectam a junção neuromuscular. Caracterizam-se por fraqueza muscular selectiva que se agrava com a actividade física. Estes distúrbios podem ter origem auto-imune, genética ou tóxica. As formas genéticas são denominadas de síndromas miasténicas congénitas. Algumas toxinas (toxina botulínica, venenos de cobra) mas também fármacos podem induzir ou exacerbar a disfunção neuromuscular. As doenças auto-imunes (miastenia gravis e síndroma miasténica de Lambert-Eaton) são normalmente adquiridas e a formação de anticorpos contra componentes da junção neuromuscular tem, com algumas excepções, origem desconhecida. A miastenia gravis, embora rara é o distúrbio da junção neuromuscular mais prevalente e a sua incidência está a aumentar, sobretudo nas faixas etárias mais velhas da população. O diagnóstico baseia-se largamente nas manifestações clínicas específicas, sem que no entanto existam sinais patognomónicos. As alterações electromiográficas, a presença no soro de anticorpos dirigidos contra a junção neuromuscular e/ou a resposta positiva aos fármacos anti-colinesterásicos confirmam o diagnóstico. À medida que o conhecimento sobre a fisiopatologia, clínica e epidemiologia da doença avança, torna-se necessário organizá-lo de forma a facilitar o estabelecimento de relações terapêuticas e prognósticas. Surge assim a classificação clínico-serológica da miastenia gravis, actualmente recomendada por vários autores e guidelines sobre o tema. Com o diagnóstico precoce e a instituição de terapêutica apropriada, a miastenia gravis tem um bom prognóstico, com esperança média de vida próxima do normal.
Myasthenic disorders are a heterogeneous group of diseases that affect the neuromuscular junction. They are characterized by muscular weakness that worsens with physical activity. These disorders may have an auto immune, genetic or toxic source. The genetic forms are called congenital myasthenic syndromes. Some toxins (botulinum toxin, snake venom) but also drugs may induce or exacerbate neuromuscular dysfunction. The auto immune diseases (myasthenia gravis and Lambert-Eaton myasthenic syndrome) are normally acquired and the formation of antibodies against components of the neuromuscular junction has, with some exceptions, unknown origin. Myasthenia gravis, although rare, is the neuromuscular junction disorder more prevalent and its incidence is rising, mainly in the older age groups of the population. The diagnosis is based largely, in the specific clinic manifestations; however there aren´t pathognomonic signs. The electromyografic alterations, the presence in the serum of antibodies directed against the neuromuscular junction and/or the positive response of the anticholinesterase drugs confirms the diagnosis. As the knowledge about the pathophysiology, clinic and epidemiology of the disease progresses, it becomes necessary to organize it, so that the establishment of therapeutic and prognostic relationships renders easier. Thus, emerges the serologic-clinic classification of myasthenia gravis, currently recommend by several authors and guidelines about the subject. With early diagnosis and appropriate therapeutic institution, myasthenia gravis has a good prognosis with expectancy close to normal life.
Myasthenic disorders are a heterogeneous group of diseases that affect the neuromuscular junction. They are characterized by muscular weakness that worsens with physical activity. These disorders may have an auto immune, genetic or toxic source. The genetic forms are called congenital myasthenic syndromes. Some toxins (botulinum toxin, snake venom) but also drugs may induce or exacerbate neuromuscular dysfunction. The auto immune diseases (myasthenia gravis and Lambert-Eaton myasthenic syndrome) are normally acquired and the formation of antibodies against components of the neuromuscular junction has, with some exceptions, unknown origin. Myasthenia gravis, although rare, is the neuromuscular junction disorder more prevalent and its incidence is rising, mainly in the older age groups of the population. The diagnosis is based largely, in the specific clinic manifestations; however there aren´t pathognomonic signs. The electromyografic alterations, the presence in the serum of antibodies directed against the neuromuscular junction and/or the positive response of the anticholinesterase drugs confirms the diagnosis. As the knowledge about the pathophysiology, clinic and epidemiology of the disease progresses, it becomes necessary to organize it, so that the establishment of therapeutic and prognostic relationships renders easier. Thus, emerges the serologic-clinic classification of myasthenia gravis, currently recommend by several authors and guidelines about the subject. With early diagnosis and appropriate therapeutic institution, myasthenia gravis has a good prognosis with expectancy close to normal life.
Description
Keywords
Classificação Clínica Diagnóstico Distúrbios Miasténicos Miastenia Gravis