Technical details of video‐assisted transcervical mediastinal dissection for esophageal cancer and its perioperative outcome

Abstract To reduce pulmonary complications after esophagectomy, the transthoracic procedure should be shortened or totally avoided. Transcervical approach assisted by mediastinoscope for the upper mediastinum may be advantageous for this purpose. We carried out video‐assisted transcervical mediastinal dissection (VATCMD) as part of totally non‐transthoracic radical esophagectomy. A single‐port laparoscopy device was adopted to a small cervical incision and the mediastinum was inflated with a positive pressure of 6 to 10 mmHg. Without assistant's retractor, the upper mediastinum and partially the middle mediastinum were dissected mainly by mediastinoscopic‐assisted surgery. Video of the operation is demonstrated with illustrations. We have carried out and reported 17 cases of esophagectomy including VATCMD and its perioperative outcome. Non‐transthoracic esophagectomy was completed without conversion to transthoracic procedure in all 17 cases. Procedure‐related adverse event was not observed and postoperative course was favorable with a zero occurrence (0%) of recurrent laryngeal nerve palsy, chyle leakage or pulmonary complications. Median number of harvested lymph nodes from the upper mediastinal stations was 10. VATCMD is suggested as a safe and feasible approach for the upper mediastinum in esophagectomy for malignancies. It enabled a totally non‐transthoracic radical esophagectomy in combination with a transhiatal approach. Video‐assisted transcervical mediastinal dissection is suggested as a safe and feasible approach for the upper mediastinum in esophagectomy for malignancies. It enabled a totally non‐transthoracic radical esophagectomy in combination with a transhiatal approach.


| INTRODUCTION
Progress has been made in the surgical technique of esophagectomy and its surgical mortality has drastically decreased. [1][2][3] Minimally invasive esophagectomy such as video-assisted surgery can reduce chest wall trauma and has been reported to reduce surgical mortality, preserve pulmonary function and improve patients' postoperative quality of life. 1,4,5 However, video-assisted transthoracic esophagectomy is technically demanding and its perioperative outcome depends on the skill of the surgeon. 6,7 In an effort to eliminate surgical mortality after esophagectomy, the most essential point is reduction of pulmonary complications. Transthoracic surgery is one of the most important risk factors contributing to the occurrence of pulmonary complications. 8,9 Even with smaller incisions, transthoracic manipulation mandates one-lung ventilation or collapsing the right lung with artificial pneumothorax. One-lung ventilation is reported to result in mechanical damage to both the ventilated and the collapsed lung. 8,10 To avoid transthoracic manipulation, transhiatal esophagectomy has been a preferred choice. However, the conventional transhiatal approach offers poor surgical view of the mediastinum, especially the upper mediastinum, and mediastinal dissection has been done by blind blunt finger dissections. Therefore, conventional transhiatal esophagectomy is associated with increased recurrent laryngeal nerve injury and inadequate mediastinal lymph dissection. 11,12 For transhiatal esophagectomy to be a feasible surgery for esophageal malignancies, it should preserve an adequate surgical view of the upper mediastinum.
In such a background, use of the mediastinoscope in the upper retromediastinum has been attempted and mediastinoscopic upper mediastinal dissection has been suggested to be feasible with an excellent surgical view. [13][14][15][16] Above all, the technique using a singleincision laparoscopic surgery device described by Fujiwara et al. 15 was highly reproducible. We have also adopted their technique and developed our understanding of the unfamiliar view of the mediastinum through the mediastinoscope. Hereafter, we describe the details of the video-assisted transcervical mediastinal dissection (VATCMD) with illustrations and a video. Its perioperative outcomes are also reported.

| Patients
We adopted the devices of the single-port laparoscopic surgery to  Table 1 and the histological type of all cases was squamous cell carcinoma.

| RESULTS
In all cases, esophagectomy and mediastinal lymph dissection were Upper mediastinal lymph stations often harbor metastatic disease and the efficacy of the lymph dissections in these stations were reported as high. 19 However, lymph dissection of the left paratracheal nodes, especially in the higher region, would be the most challenging part of radical esophagectomy through the right transthoracic approach. In this approach, these nodes are located behind the esophagus and the trachea and, therefore, skillful retractions of these bulky anatomies in a narrow surgical field are required to carry out lymph dissection for the paratracheal and tracheobronchial station ( Figure 3A,B). In addition, these lymph nodes are closely adjacent to the fine branches of blood vessels and the left recurrent laryngeal nerve. In contrast, VATCMD provided a surgical view in which these branches were viewed without effortful retractions and a sealing device can be easily placed in a suitable position to dissect these branches ( Figure 3C).
In summary, VATCMD is suggested as a reasonable and advantageous approach for upper mediastinal dissection in surgery for esophageal malignancies with its accessibility of the left upper mediastinum and its independence of the skill of the assistant.
Transthoracic procedures can be shortened or totally omitted with VATCMD incorporated into radical esophagectomy.

DISCLOSURE
The operative method of VATCMD was part of the surgical procedure of non-transthoracic robot-assisted esophagectomy which was approved by a suitably constituted Ethics Committee of the institution (P2011029-11Y) and it conforms to the provisions of the Declaration of Helsinki. All informed consent was obtained from the subject(s) and/or guardian(s).