Perioperative management of patients with myasthenia gravis undergoing robotic-assisted thymectomy – a retrospective analysis and clinical evaluation

Muscle fiber types switched during the development of experimental autoimmune myasthenia gravis via the PI3K/Akt signaling pathway

As one of the largest organs of our human body, skeletal muscle has good research prospects in myasthenia gravis (MG), the symptoms of which include systemic skeletal muscle weakness. Skeletal muscle is composed of two types of muscle fibers. Different fiber subtypes can be converted into each other; however, the underlying mechanism is not yet clear. In this paper, we firstly established an experimental autoimmune myasthenia gravis (EAMG) rat model and found that the skeletal muscle fibers of the EAMG group were atrophied, with a change in the proportion of fiber subtypes, which switched from type IIa to type I in the EAMG group at the peak stage, as verified by histological and molecular analyses. Second-generation sequencing results predicted that the PI3K-Akt signaling pathway might be involved in the switch, and the mRNA expression levels of the PI3K-Akt pathway-related genesNr4a1, IL2rb, Col1A1 and Ddit4 were significantly different. In conclusion, this study indicates that the switch of muscle fiber subtypes in MG via the PI3K-Akt signaling pathway may be a potential target for the treatment of MG-related skeletal muscle atrophy in the future.

Thymectomy in myasthenia gravis

PURPOSE OF REVIEW

Thymectomy has long been used in the treatment of patients with myasthenia gravis and antibodies against the acetylcholine receptor. However, its effectiveness has only been proven a few years ago in a randomized controlled trial in patients under the age of 65. Here, we review the current literature focusing on patient subgroups, potential biomarkers for outcome prediction and the choice of surgical approach.

RECENT FINDINGS

Long-term follow-up studies after thymectomy confirmed that the benefits regarding clinical outcome parameters and a reduced need for immunosuppressive treatment persist. Nevertheless, a substantial proportion of patients in real-world cohorts do not reach complete stable remission after thymectomy indicating that the underlying autoimmune process is sustained in the periphery. Our understanding of the responsible mechanisms has improved with recent studies. Presently, outcome data after thymectomy in several patient subgroups, such as those aged over 50 years, those with juvenile onset or those with purely ocular symptoms are limited and have been the focus of recent research activities. Similarly, biomarkers guiding an appropriate patient selection for thymectomy are under investigation. A number of cohort studies demonstrated that minimal invasive surgical techniques such as extended robotic thymectomy lead to similar positive outcomes as a transsternal approach with potentially fewer short-term adverse effects.

SUMMARY

Thymectomy is an effective treatment option in adult patients with early onset acetylcholine-receptor positive myasthenia gravis but uncertainty remains with regard to certain patient subgroups.