Risk Factors for the Exacerbation of Myasthenic Symptoms After Surgical Therapy for Myasthenia Gravis and Thymoma
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Thymectomy
Thymectomy
Antibody titer
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To explore the clinical characteristics and outcome of myasthenia gravis with and without thymoma after operation.Two hundred and forty-three patients with myasthenia gravis surgically treated in our department from 1978 to 2003 were studied retrospectively. The clinical characteristics, complication, remission and survival were compared between myasthenia gravis with and without thymoma.The patients of myasthenia gravis with thymoma were significantly older (t = 6.138, P = 0.000), had shorter duration of symptom (t = 3.783, P = 0.000), and also had higher myasthenia crisis rates after operation (chi(2) = 64.77, P = 0.000) than those of myasthenia gravis without thymoma. No differences of Osserman classification was found between the two groups (chi(2) = 7.678, P = 0.104). The complete remission rates and partial remission rates of myasthenia gravis with thymoma were significantly lower than those of myasthenia gravis without thymoma at 1 and 3 years (P = 0.049, P = 0.000; P = 0.015, P = 0.010), but no differences at 5 year (P = 0.457; P = 0.699). The survival rates of MG with thymoma were lower than that of MG without thymoma (Log-rank = 18.58, P = 0.000).The clinical characteristics are different between myasthenia gravis with and without thymoma. The remission of symptom of myasthenia gravis with thymoma is worse than that of myasthenia gravis without thymoma in the near future, but is similar in the long future. The death rates of MG with thymoma is significantly higher than that of MG without thymoma.
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Thymus Neoplasm
Thymectomy
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OBJECTIVE. The authors evaluated the role of antibodies to striated muscle and acetylcholine receptors in diagnostics of myasthenia gravis and thymoma, as well as outcomes of thymectomy and prognosis of myasthenia course. MATERIAL AND METHODS. The study investigated correlations of antibody content to striated muscles and acetylcholine receptors from the presence and size of thymoma, myasthenia in 157 patients with various pathologies of the thymus. The dynamics of antibody concentrations was followed up after thymectomy. RESULTS. Antibody titer to striated muscle depended on the presence and size of thymoma, severity of myasthenia and changed after thymectomy. Concentration of antibodies was associated with the presence of thymoma and it didn’t change after surgical treatment. Thymoma wasn’t revealed in patients who were seronegative to both antibodies. CONCLUSIONS. Seropositivity according to one of antibody could indicate the presence of thymoma, but its absence to both antibodies allowed doctors to eliminate this diagnosis. Antibodies to acetylcholine receptors are important markers of myasthenia. Monitoring of antibody titer dynamics to striated muscles after thymectomy could be useful for assessment of response to surgical treatment and prognosis of course of myasthenia.
Thymectomy
Antibody titer
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Thymus Neoplasm
Ocular myasthenia
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Thymectomy
Mediastinal tumor
Anterior mediastinum
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Ocular myasthenia
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Ryanodine receptor (RyR) antibodies are detected in about 50% of patients with myasthenia gravis who have a thymoma. The RyR is a calcium release channel involved in the mechanism of excitation-contraction coupling in striated muscle. In this study the severity of myasthenia gravis assessed by a five point disability score was compared between 12 patients with myasthenia gravis, a thymoma, and RyR antibodies and 10 patients with myasthenia gravis and a thymoma but without such antibodies. Symptoms of myasthenia gravis were significantly more severe in patients with RyR antibodies. The mean (SD) disability scores were 3.7(0.5) in patients with antibodies and 2.7 (0.9) in those without at peak of illness, (p = 0.01) and 3.4(1.4) v 1.6(0.7) at the end of an average observation period of five years (p = 0.002). The number of deaths due to myasthenia gravis was five of 12 RyR antibody positive patients, and none of 10 RyR antibody negative patients (p = 0.04). RyR antibody levels correlated positively with severity of myasthenia gravis. The presence of circulating RyR antibodies seems to be associated with a severe form of thymoma associated myasthenia gravis.
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Myasthenia gravis is a disease that affects the neuromuscular junction causing abnormal weakness,
fatigue, and muscle decay. Loss or dysfunction of acetylcholine receptors occurs mostly due to the
presence of antibodies to nicotinic acetylcholine receptors (NAChR). The thymus and thymoma
have a special role in the pathophysiology of myasthenia gravis due to the role of the thymus in
the maturation and distribution of lymphocytes where cross-reactivity and consequent
autoimmunity to NAChR can occur. The most commonly used diagnostic method for myasthenia
gravis is the measurement of antibody levels to NAChR which is a highly specific test for the
diagnosis of myasthenia gravis. CT is the method of choice in the diagnosis of thymoma. Due to
the importance of the thymus in the pathophysiology of myasthenia gravis the disease can be
treated surgically, by removing the thymus. If there is thymoma present, to plan the operation,
Masaoka and TNM classification are used. Methods that can be used to remove the thymus /
thymoma are transsternal thymectomy, transcervical thymectomy, video-assisted thoracoscopic
surgery (VATS) and robotic surgery. Some of the factors influencing the prognosis after
thymectomy are age and sex, presence of thymoma, surgical technique, extent of resection and
severity and duration of symptoms of myasthenia gravis. New methods of thymectomy are
minimally invasive and with rapid recovery, and most patients show remission of the disease after
removal of thymus.
Thymectomy
Pathophysiology
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