Anomalies of the right vertebral vein increasing the difficulty of lymph-node dissection along the right recurrent laryngeal nerve: a single-institution, retrospective study

Background Radical lymph-node dissection along the recurrent laryngeal nerves (RLN) improves the prognosis of patients with esophageal cancer. The RLN is a landmark for achieving adequate lymph-node dissection. However, the right RLN is sometimes covered by the right vertebral veins (VVs), making it undetectable. We investigated the relationship between this anomaly of the right VVs and the challenges of performing lymphadenectomy along the right RLN. Methods Patients with esophageal cancer, who underwent thoracoscopic esophagectomy with radical lymph-node dissection, were registered. The patterns of the right VVs were evaluated by preoperative computed tomography. The time required for identifying the right RLN or completing the lymphadenectomy was determined by reviewing surgical videos. Results In total, 178 patients were enrolled. Eighty patients (45%) had right VVs passing dorsal to the right subclavian artery (Dorsal group). More time was required to detect the right RLN in these cases (11 vs 9.5 min for the other cases, p = 0.034). In the Dorsal group, there were 15 patients who had specific VV patterns: The right VV converged on the lower portion of the right brachiocephalic vein (BCV), or passed through to the more medial side of the mediastinum. These patients required more time for detecting the right RLN (25 vs 9 min, p < 0.0001) and for completing the lymphadenectomy (41 vs 32 min, p = 0.048) than the other cases. Conclusion The right VVs behind the subclavian artery, joining the lower part of the BCV or passing through the medial side, made it difficult to identify the right RLN and complete the lymphadenectomy.