Thoracoscopic Total Thymectomy Via the Left Thoracic Approach for a Pediatric Patient with Refractory Myasthenia Gravis

Introduction: Myasthenia gravis (MG) is a rare autoimmune disease in which neuromuscular junction receptors are destroyed by autoantibodies. Total thymectomy is applied to intractable cases when medical treatments fail to maintain remission.1 In recent years, as the safety and efficacy of endoscopic surgery have been verified, thoracoscopic or mediastinoscopy approaches have been adopted.2,3 We herein report thoracoscopic total thymectomy performed through the left thoracic approach. Case and Operative Procedure: Refractory MG was diagnosed in an 11-year-old girl. The disease could not be controlled medically, and side effects of long-term steroid therapy appeared. Eventually, total thymectomy was indicated. Under general anesthesia, the patient was placed in a mild right lateral decubitus position with left arm elevation. A 5-mm 30° endoscope was inserted in the fifth intercostal space on the mid-axillary line using the optical method. After collapsing the left lung with right single-lung ventilation and artificial left pneumothorax with a positive pressure of 6 mm Hg, two 5-mm working ports were inserted (at the third intercostal space on the mid-axillary line and the sixth intercostal space on the anterior axillary line). The area of dissection was set dorsally at the ventral side of the phrenic nerve, caudally at the level of pericardial adipose tissue, cranially at the level of the thyroid-thymus ligament, and ventrally at the level of the sternum. An incision was made in the parietal pleura, and the microvessels in the adipose tissue were cauterized with vessel sealing system (LigaSure™ Maryland; Medtronic, Minneapolis, MN), whereas taking care not to thermally damage the left phrenic nerve. Dissection proceeded toward the cranial side. The root of the left thymic vein was exposed, treated with a polymer clip (Weck Hem-o-lok; Teleflex, Morrisville, NC) and resected with LigaSure. The left thyroid-thymus ligament was coagulated and divided. Dissection then proceeded caudally and ventrally to reach the right thyroid-thymus ligament, whereas taking care not to leave the anterior mediastinum adipose tissue. The right thymic vein was treated similar to the left side, and the entire thymus gland was excised. The excised specimen was collected in an endosurgical bag, and the third intercostal wound was extended 15 mm and removed. The patient was discharged on the sixth postoperative day without any symptoms of respiratory distress, hoarseness, or phrenic nerve palsy. Conclusion: Thoracoscopic total thymectomy for pediatric patients is rare, but it can be performed safely under a good and clear surgical field of view by applying the combination of single-lung ventilation and artificial pneumothorax. The therapeutic effect is reportedly the same, regardless of approaching from the right or left chest.4 Considering the narrow surgical space in pediatric patients, we prefer the approach from the left thoracic cavity, which is closer to the contralateral phrenic nerve. Although the right phrenic nerve is not directly observed, we believe that its injury can be prevented by avoiding the use of an ultrasonic incision coagulating device, and by assessing the operative bed carefully while altering the direction of traction of the thymus gland. Acknowledgments: We thank Brian Quinn for his comments and help with the article. This study was supported by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (JSPS, No. 16K11350, 19K09150), a research grant from the JFE (The Japanese Foundation for Research and Promotion of Endoscopy), a research grant from the J-CASE (Japanese Consortium of Advanced Surgical Endoscopy), a research grant from the Kyushu Society of Endoscopic and Robotic Surgery, a research grant in the form of the Karl Storz Award from the Japan Society for Endoscopic Surgery, a research grant from The Mother and Child Health Foundation, and a research grant from the Kawano Masanori Memorial Public Interest Incorporated Foundation for Promotion of Pediatrics. No competing financial interests exist. Runtime of video: 6 mins 13 secs