Does Thymectomy Improve Outcomes in Patients with Nonthymomatous Myasthenia Gravis?

Abstract

Thymectomy in cases of nonthymomatous myasthenia gravis has undergone investigation from multiple angles over the past several decades. Though many of the early, retrospective trials suggested a clinical benefit in patients with myasthenia gravis undergoing thymectomy, the completion of the MGTX trial (a randomized, multi-centered, rater blinded trial) has provided the strongest possible evidence of a multi-dimensional benefit of thymectomy compared to medical therapy alone in acetylcholine-receptor antibody positive myasthenia gravis. This therapeutic benefit not only manifests in clinical parameters (e.g., decreased medication requirements and decreased subsequent hospitalizations), but also in quality-of-life metrics. Furthermore, recent studies have shown the safety and efficacy of thoracoscopic, minimally-invasive thymectomy. To date, high-quality evidence only supports the routine use of thymectomy in patients 18–65 years of age with acetylcholine receptor positive myasthenia. There is no high-quality evidence to suggest this same benefit extends to acetylcholine-receptor antibody positive patients over 65 years of age, patients with ocular myasthenia, or patients with seronegative myasthenia. It is reasonable to consider and discuss thymectomy with patients that fall into one of these subgroups in cases of medically-refractory disease. Currently there is no data to support any benefit of thymectomy in patients with LRP4 or MuSK antibody positive myasthenia, thus, thymectomy is not recommended in these two subgroups.