Video-assisted Transcervical Thymectomy

Abstract

Myasthenia gravis (MG) is an autoimmune disorder diagnosed clinically for the first time at the end of the 17th century. Intense research into the pathogenesis of the disease has led to the discovery of an antibody directed against the muscle nicotinic acetylcholine receptor (AchR) in 1973 and, more recently, to the finding of a new antibody directed against the muscle-specific receptor tyrosine kinase (MuSK) in a subgroup of patients that remain seronegative for AchR antibodies. 1 Blalock’s initial experience in the early 1940s and subsequently published series of surgically treated patients led to the widespread acceptance of thymectomy in the treatment of MG despite the absence of a prospective randomized trial comparing surgery with medical treatment alone. 2 Controversiesremain,however,withregardtothetimingandextent of surgery to be performed. Some authors recommend thymectomyearlyinthecourseofthedisease,whereasothers reserve surgery for when medical therapy fails or if a thymoma is suspected. Different surgical approaches have been recommended including transcervical, transsternal, and more recently a transthoracic thoracoscopic thymectomy. All procedures allow extracapsular resection of the thymus and vary somewhat in the extent of mediastinal fat removal, which may contain foci of thymic tissue. The most extensive resection combines the transcervical and transsternal thymectomy procedures and includes removal of all mediastinal fatty tissue, both sheets of mediastinal pleura along with a sharp dissection of the pericardium. The transcervical approach was first described in the late 19th century for thymic enlargement in children and consisted of an enucleation of the thymus from within its capsule. Although initially reported in an adult patient with MG by Sauerbruch in 1912, the transcervical approach was modified to completely remove the thymus with its capsule and reintroduced in the 1960s for patients with MG. Through this approach, Kark and his colleagues reported fewer postoperative complications when compared with the transsternal approach. 3 Consequently, their patients were operated on earlier in the course of the disease and were shown to have more rapid rate of improvement. To improve exposure and to facilitate removal of the thymic gland and extracapsular thymic tissue through the neck, Cooper and colleagues described the use of a special rightangle manubrial retractor to elevate the sternum (Cooper retractor, Pilling Company, Fort Washington, PA). Using the same retractor, we observed that the routine use of a videothoracoscope introduced through the cervicotomy further improves visualization of the mediastinum and permits teaching of the technique under direct supervision. 4 Currently, the combination of early surgical referral, optimization of medical status when necessary by plasmapheresis, video-assisted transcervical thymectomy, and careful perioperative management have led to optimized care for patients with MG.