Aspects of Clinical Preparation of Thymectomy in Myasthenic Cases with or without Thymoma and the Clinico-Biological Follow-up of the Thymectomized Patients

Abstract

Several uncontrolled studies performed since the 1950s proved that thymectomy is effective in Myasthenia Gravis (MG). MG is an autoimmune disease characterized by muscle weakness and fatigability in which autoantibodies (AntiAChR-Ab) are targeted to the acetylcholine receptor (AChR) at the neuromuscular junction.¹ Aim of surgery is to remove the site of autoantigen sensibilization and self-sustainment of the autoimmune response. Previous studies showed that the efficacy of thymectomy is positively correlated with the time from diagnosis, young age and absence of thymoma.^2,3,4 Furthermore, over the last two decades there has been considerable debate on the best surgical technique in terms of tolerability and clinical outcome.^5,6 Transcervical thymectomy, a relatively easy procedure with minimal postoperative morbidity,⁷ may fail to remove the entire gland and miss ectopic thymic tissue often present in the neck and mediastinum.⁸ In this regard, transsternal thymectomy is required to remove all thymic tissue and is now accepted as the technique associated with the higher remission rate in MG.⁹ Extended transsternal thymectomy (ETT) combines the removal of thymus and fat tissue from the pericardic and cervical regions in which functional thymic remnants may persist, usually in the space from the thyroid gland to the diaphragm, between the two phrenic nerves.¹⁰ Since the extended approach requires a median sternotomy, ETT is a major surgical procedure which may limit the indication of thymectomy in patients with bulbar or ocular MG, and in patients in which surgical morbidity may have detrimental effects on patients’ condition. Moreover, a median sternotomy is sometimes not easily accepted by female patients for aesthetical reasons.