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Robotic Bilateral Thymectomy
The patient is a sixty-seven-year-old woman, nonsmoker, with a history of ocular myasthenia gravis and a strong family history of autoimmune disease. First, a chest CT scan was performed, which demonstrated two nodular opacities in the anterior mediastinum, the largest measuring 5.9 mm. Given the concern for thymoma, the presence of mild to moderate myasthenia gravis, and the difficulty of distinguishing lymph nodes from thymomas on CT imaging, it was recommended that the patient undergo robotic thymectomy. To facilitate complete removal of the thymus, a bilateral approach was used.
After induction of general anesthesia, a double lumen endotracheal tube was placed. The patient was initially positioned supine with the left side bumped up and the left shoulder positioned posteriorly and was prepped for a possible sternotomy.
For port placement, an 8 mm incision was made for a camera port slightly inferior to the middle of the sternum and laterally in the fourth intercostal space. A subxiphoid port was then placed but led to compression of the heart and was therefore removed. A lateral and inferior 12 mm AirSeal port was then placed. This was followed with an 8 mm superior port in the third intercostal space. A final port was placed inferior in the fifth intercostal space. When placing ports, it is important to avoid going too far lateral so that the heart is not in the way of the dissection. Finally, an intercostal nerve block was performed with Exparel. Cadiere forceps were inserted in arm one and a long bipolar is inserted in arm three.
The operation began with identification of the left phrenic nerve, and a plane was created 1 cm medial, between the mediastinal fat and the pericardium. The left side is always done first in a bilateral approach because adequate insufflation is more important on the left, given the presence of the heart. The safest plane is directly on top of the pericardium. By beginning the dissection 1 cm medial to the phrenic nerve, thermal injury to the nerve was safely avoided. Using both blunt dissection and cautery, the dissection proceeded superiorly. The phrenic nerve was visualized in its entirety to avoid injury, which can be catastrophic in myasthenia gravis patients. Care was taken to avoid entering the right pleural space during this portion of the dissection.
The superior dissection continued to the level of the innominate vein. The thymic fat inferior to the innominate vein was then dissected free. Great care was taken in this area, as the innominate vein often has several venous tributaries that, if injured, can lead to bleeding.
The dissection then continued medially to the left internal mammary vein which allowed for an improved dissection of the thymus surrounding to the innominate vein. Clips were used liberally in this area to avoid injury to the venous tributaries of the innominate vein and ensured adequate hemostasis. Next, the innominate vein was skeletonized. The superior horn, located superior to the innominate vein, was dissected free, and additional clips were placed.
The aortopulmonary window was then dissected and a lymph node was sent for pathology. Rarely, there can be thymic tissue in this area. The inferior horn of the thymus was then harvested off the left diaphragm using a combination of blunt dissection and cautery. The bilateral approach allowed for complete removal of the inferior thymic tissue from the diaphragm. A 24 Fr chest tube was placed and the left thymus was removed in a large endocatch bag through the 12 mm port and sent for pathology.
Next, the ports were removed from the left side, and the patient was repositioned with right-sided ports placed in a similar manner to the left side. Again, the phrenic nerve was identified and a plane of dissection began 1 cm medial to it, between the mediastinal fat and pericardium. The dissection continued medially along the pericardium, and the left pleural space was entered, completing the left sided dissection. The major advantage of the bilateral approach is that the contralateral phrenic nerve is visualized, decreasing the risk of nerve injury, and allowing for complete removal of the thymus, including the inferior horns.
The superior vena cava was then identified, and the dissection proceeded superiorly and medial to the phrenic nerve. The junction of the innominate vein and superior vena cava was identified. The thymic fat inferior to the innominate vein was dissected free, using clips to ensure hemostasis. Dissection directly on top of the innominate vein helps with identification of venous tributaries.
Dissection then continued medially to the right internal mammary vessels, completing the previous plane of dissection on the left side. The superior horn of the thymus was then dissected free from the area superior to the innominate vein, with liberal usage of clips. The plane medial to the inferior mammary vein, between the mediastinal fat and the sternum, was continued inferiorly toward the diaphragm.
The inferior horn of the right thymus was then dissected free from the diaphragm. The right thymus was placed in a large endocatch bag and removed. A second 24 Fr chest tube was placed and the operation concluded.
The patient was successfully extubated in the operating room and admitted to the ICU for close monitoring given the risk for possible myasthenic crisis. Her chest tubes were removed on postoperative day one, and she was discharged home. She was seen in clinic on postoperative day ten for a follow-up visit, where she was recovering appropriately.
Her final pathology was consistent with benign lymph nodes and benign thymic tissue without evidence of thymic hyperplasia or thymoma. At her one-month neurology follow-up, the patient noted significant improvement in her myasthenia gravis symptoms. She continues to follow up with neurology and will have a one-year clinical follow-up with thoracic surgery.
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