Preoperative Plasmapheresis for Elective Thymectomy in Myasthenia Patient: Is It Necessary?

Background. Role of plasmapheresis before thymectomy remains controversial. The aim of this study is to determine the peri-operative and post-operative outcome of a thymectomy between performing and not performing a pre-operative plasmaphreresis. Patients and Methods. A retrospective chart review study was conducted in Chiang Mai University Hospital between January 2006 and December 2011. There were 86 myasthenia patients divided into two groups; Preoperative plasmapheresis group (PPG) and no preoperative plasmapheresis group (NPPG). The primary outcome involved post-operative extubation and the secondary outcome included post-operative complications, 28 day mortality and length of hospital stay. Results. Eighty-six patients were enrolled in this study. The number of patients who had a history of myasthenic crisis at any time or within one month in the PPG was significantly more than those in the NPPG. Muscle power and forced expiratory vital capacity in the NPPG was higher than that in the PPG. The postoperative extubation rate was similar in both groups. After controlling for the propensity score, there were no statistically significant differences in both of primary and secondary outcomes. Conclusion. The results of this study shows no significant differences between both groups in all outcomes, therefore the pre-operative plasmaphresis is not necessary for elective thymectomy. 1. Introduction Myasthenia gravis is an acquired, neuromuscular, autoimmune disorder. The basic pathogenesis of the disease understood so far is the production of autoantibodies against the acetylcholine receptors of the endplate [1, 2] and thereby causing immunologic destruction and reduction of the number of the receptors. The miniature endplate potential amplitude is decreased, and the endplate potentials are largely subthreshold leading to easy fatigability and weakness. The thymus is believed to play an integral role in the pathogenesis of myasthenia gravis. The role of the thymus in the development of antibodies against the acetylcholine receptors has been clearly established; therefore the relationship between myasthenia and thymic abnormalities has been suggested [2, 3]. The myasthenia patient presents with a varied degree of muscle weakness such as ptosis (ocular involvement), proximal muscle weakness, respiratory failure (involving respiratory muscle), or dysphagia (bulbar involvement). Current treatment strategies include anticholinesterases for the minimal symptoms patients while nonresponders require treatment with steroids and immunosuppressants. Considering the