Abstract

ALBISU, Silvana et al. Thymectomy in Non Thymomatous Myasthenia Gravis patients: Systematic Literature Review. Arch. Med Int [online]. 2015, vol.37, n. 2, pp.87-93. ISSN 0250-3816.

Background: Thymectomy is a frequently used treatment for myasthenia gravis (MG) and is virtually always indicated in MG patients who have a thymoma. However, the evidence for thymectomy in non-thymomatous MG remains less certain. Objectives: Evaluate the published evidence on the effectiveness of thymectomy in patients with non-thymomatous myasthenia gravis. Methods: Systematic review of the literature published between 01/2003-01/2015. Keywords: “Myasthenia Gravis” “Thymectomy” and “Thymoma”. Search Tools used: Lilacs and Pubmed. Search method: 2 authors read all retrieved abstracts and reviewed the full texts of potentially relevant articles. Selection criteria: randomized clinical trials, non-randomized clincal trials, Cohort (prospective and retrospective) of different surgical modalitis of thymectomy against no treatment or any medical treatment, and thymectomy plus medical treatment against medical treatment alone, in people with non-thymomatous MG older than 18 years old. Case reports were excluded. Outcome assessed: improvement of myasthenic clinical status after thymectomy. Results: The primary search keywords provided 391 articles, of which 325 were excluded according to de proposed inclusion and exclusion criteria. We selected 66 articles: 5 prospective articles (1 non-randomized non-controlled clinical trial, 4 prospective cohort) and 61 retrospective (4 case series study, 27 single cohort study, 24 cohort study, 6 cohort study with a control group). 63/66 studies measure severity of MG using MGFA (Myasthenia Gravis Foundation of America) clinical classification. In 50% of the studies thymectomy was performed after at least 24 months since diagnose of MG. Only 15/66 studies had a predetermined pattern of pre-thymectomy medical treatement. Ectopic thymic tissue was detected in 18/66 studies. The long term clinical status post thymectomy was assessed using the MGFA Post Intervention Status (1) in 56% (37/66) of the studies, MGFA Clinical Classification (1) 6% (4/66), Keynes criteria (69) in 3% of studies (2/66), classification of De Filippi (69) 6% (4/66), and according to self proposed criteria in 21.2% (14/66) of studies. Conclusion: The indication and timing of thymectomy in non thymomatous myasthenia gravis is still under debate and there is insufficient evidence to date to provide evidence based clinical practice parameters, regardless of clinical practice on experienced centers. However, the trend that emerges from available studies shows: benefit on clinical outcome (improvement/remission) regarding thymectomy in non thymomatous myasthenia gravis, promising good results with the new minimally invasive techniques and draws attention to the favorable impact of early thymectomy in AChRA + patientes as well as the increasingly important role of ectopic thymic tissues.

Keywords : Myasthenia Gravis; Thymectomy; Systematic review.