The Analysis Of The Clinical Features Of Myasthenia Gravis And Their Correlation With Thymic Abnormalities

Myasthenia gravis(MG) is an autoimmune disease which is mediated by auto-antibodies against the acetylcholine receptor(Ach R) at the postsynaptic membrane of the neuromuscular junction and dependents on the cellular immunity and has the participation of the complement. The characteristic pathogenic factor was acetycholine receptor antibody(Ach RAb). The Ach RAb can produce immune response with the Ach R at the postsynaptic membrane and can furthermore cause the transmission disorder of neuromuscular junction and disability of the skeletal muscle. The initial symptoms of 85% MG patients manifest as external ophthalmoplegia. Most of them progressed to generalized myasthenia gravis(GMG)in two years, some of the MG patients can manifest as respiratory failure and death. MG can be classified into ocular myasthenia gravis(OMG) and generalized myasthenia gravis(GMG) according to the location of the disable muscle. Some researches showed that the thymus of MG patients was in a chronic inflammatory condition. The thymic abnormalities of 80-90% MG patients manifest as thymic hyperplasia, thymic cyst or thymoma and so on. The Ach RAb decreased after the thymusectomy, both the cellular immunity and the humoral immunity was suppressed, the clinical symptoms of patients were remitted effectively. So we believe that the thymus can play an important role in the inducement, maintenance and progress of MG. ObjectiveRetrospectively analyzed the clinical features of MG patients, thymic abnormalities patients combined MG or not and MG patients combined thymic abnormalities from the inpatient of the Neurology and Chest Surgery department in Tangdu Hospital. We made a comparison about the curative effect between the patients with thymic abnormalities with thymectomy and the patients with thymic abnormalities but without thymectomy, with the hope to explore the influences of the thymectomy on the prognosis of MG patients and find the correlation between thymoma type and the clinical type of MG. MethodWe retrospectively analyzed the clinical data about inpatients of Department of Neurology, Tangdu Hospital, Fourth Military Medical University from January 2006 to September 2013 and the inpatients of Department of Chest Surgery, Tangdu Hospital, Fourth Military Medical University from January 2006 to October 2014.The collected data include basic information such as gender, age, onset age, disease duration, predisposing factors, diagnosis and complication, the data of patients with thymic abnormalities include thymectomy time, the pathological type after thymectomy. The follow-up visit of MG patients with or without thymic abnormalities whose disease duration was longer than 3 years was done by means of outpatient or QMGs. The analysis of the clinical features of the MG patients with or without thymic abnormalities in our country was done with SPSS17.0. ResultWe collected clinical data of 1855 patients, the number of MG patients from inpatient in Neurology department was 1221, the number of thymic abnormalities patients from inpatient in Chest Surgery department was 1056, the number of MG patients combined thymic abnormalities was 422. We analyze the clinical features of these three groups respectively. Among the 1221 MG patients, 595 male and 626 female, the proportion of male and female was 1:1.05. The onset age of these patients was 0.17-82 years, the average onset age was 34.12±21.14 years, the onset age of typeⅠ was the youngest.The first onset peak appeared before 20 years, the multiple age was before 5 years(include) and more common in female. Another onset peak appeared 40-49 years and there was no difference between male and female. The most common complication of MG patients was hyperthyroidism, the percentage about hyperthyroidism of thyroid dysfunction was 74.16%. There were 1056 cases of thymic abnormalities patient combined MG or not, 552 male and 504 female, the proportion of male and female was 1.10:1. The number of patients who did not have the thymoma was 250, the number of patients who had the thymoma was 490, the number of patients who had the thymic carcinoma was 109, the average onset age of thymoma and thymic carcinoma was older than thymic hyperplasia. The onset age of A and AB type thymoma was younger than B2 type thymoma. The most common pathological type of patients with thymoma was B2 and AB. Among these 422 MG patients combined thymic abnormalities, 210 male and 212 female, the proportion of the male and the female was 1:1.01. The number of MG patients combined thymoma was 316 and combined thymic hyperplasia was 106. The onset peak age of MG patients combined thymoma was 40-60 years, the onset peak age of MG patients combined thymic hyperplasia was20-30 years. The patients with thymic abnormabity were more common in Ⅱb of MGFA, and the type Ⅰ was second. The number of patients who accepted the thymectomy was 311 and the number of patients who did not accept the thymectomy was 111.The average onset age of the thymectomy was older than patients without thymectomy. The patients onset as MG with the most common thymic disease was thymic hyperplasia, patients occur MG after thymectomy were most common in type B1. The number of the follow-up visit patients whose disease duration was longer than 3 years in this study was 499, 184 MG patients without thymic disease, 280 MG combined thymic disease, 25 without exact pathological type, 10 dead. The QMG score of MG patients, MG patients combined thymic hyperplasia and MG patients combined thymomadeclined more obvious than they were in the hospital, and the QMG score of MG patients combined thymomadeclined more obvious than other groups. The improvement of clinical symptoms was most obvious in pathological type B1 and the lest in patients who had normal thymus and did not accept the thymectomy. ConclusionThe youngest onset age of MG patients was in MGFA typeⅠ and the type Ⅲa was the second. Among the patients with thymic abnormalities combined MG or not, the onset age of male and female patients who combined non- thymoma such as thymic hyperplasia and thymic cyst was younger than patients who combined thymoma and thymic carcinoma. The onset age of MG patients combined thymic abnormalities and accepted thymectomy was older than who did not accept thymectomy. The QMG score of patients accepted thymectomy was lower than who did not accept thymectomy. The most common pathological type was AB and B1. The most common MGFA type was Ⅰ and Ⅱb. The QMG score of patients who accepted the follow-up visitdeclined obvious compared with they were in hospital, and patients combined thymomadeclined more obvious than other groups, the improvement of pathological type B1 was most obvious.