Miễn dịch miễn dịch là cần thiết cho hầu hết các bệnh nhân với MG và nói chung là hiệu quả hơn so với điều trị triệu chứng. Pháp miễn dịch mục tiêu sinh lý bệnh tự miễn dịch: hoặc bằng cách giảm sản xuất kháng thể gây bệnh hoặc làm giảm thiệt hại | Autoimmune myasthenic syndromes 159 Immunotherapy Immunotherapy is necessary for most patients with MG and is generally more effective than symptomatic therapy. Immunotherapy targets the autoimmune pathophysiology either by reducing pathogenic antibody production or by reducing damage to the end plate caused by pathogenic antibodies. Immunotherapies in MG can be divided into two groups based on their onset and duration of response those that provide rapid improvement but have short-lived benefits and those that have relatively slower onset but provide long-term benefits. The therapeutic responses of the various therapies dictate their strategic use in the treatment of patients with MG. Long-term immunotherapy Thymectomy Thymectomy has two roles in the management of MG. Thymectomy is indicated for all patients with thymoma in order to prevent local spread and invasion of the tumor. Thymectomy also is an accepted therapy for nonthymomatous MG. The rationale is based on the presumed role of the thymus gland in the initiation and or maintenance of the immune dysfunction in MG. Numerous studies give support for beneficial effects of thymectomy on the clinical course of MG. An evidenced-based review of 21 studies conducted between 1953 and 1998 found that thymectomy led to clinical improvements and two times the likelihood of achieving a medication-free clinical remission Gronseth and Barohn 2000 . The onset of benefit tends to occur 6 to 12 months following surgery and the maximal benefit may require 2 to 5 years Masaoka et al. 1996 . Unfortunately all studies have suffered from significant confounding factors none were randomized many were not controlled. Thus significant limitations and controversies exist regarding their interpretations. Currently most practitioners consider thymectomy more effective if performed within the first years of symptom onset for patients who are younger usually less than 60 years old and if more invasive and complete operative procedures .
