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Na et al. Mini-invasive Surg 2024;8:31 https://dx.doi.org/10.20517/2574-1225.2024.10 Page 5 of 12

[9]
In a study published in 2021 , the authors conducted measurements of the soft tissue area surrounding the
RLN. According to their findings, a larger soft tissue area correlates with an increased likelihood of RLN
2
palsy, aligning well with their surgical observations. Area around left RLN (> 174.3 mm ) was a significant
risk factor for left RLN palsy in multivariate logistic regression analysis (HR = 15.4286, 95%CI: 3.2522-
73.1929, P value = 0.0006). Notably, in cases of obesity or a substantial presence of fatty or lymphatic tissue
around the RLN, the incidence of palsy rises. This observation underscores the challenge of accurately
identifying the RLN and preserving it without surgical damage when confronted with a substantial amount
of soft tissue. Therefore, it is imperative to exercise caution during dissection when a significant soft tissue
volume is identified around the RLN.

Other critical factors to consider during RLN evaluation include the precise location of metastasis. Notably,
metastasis around the RLN predominantly occurs in the cervical area rather than the thoracic area. A study
in 2017 analyzed the exact locations in relation to the sternal notch and trachea . The findings revealed
[10]
that most right RLN metastases were detected above the sternal notch, while half of left RLN metastases
were situated in the cervical area. Additionally, substantial differences were observed in the depth of these
locations. On the right side, metastasis typically occurred in the posterolateral side of the trachea, indicating
a superficial area. Conversely, left RLN metastasis extended to much deeper areas. Consequently, LN
dissection along RLN on the right side may suffice with superficial dissection, whereas on the left side, a
more radical dissection into the deeper tracheal space becomes necessary. This discrepancy in the depth of
metastasis contributes to the higher incidence of left RLN palsy compared to the right side.

RE AND LN DISSECTION
In a study conducted by Ruurda et al. in 2015, the authors presented a wide range of the median number of
[11]
LNs harvested in REs over the past decade across different countries, ranging from 14 to 43 . Papers from
Japan and South Korea demonstrated a significantly higher number of LNs, attributable to the performance
of recurrent laryngeal LN dissection in these countries. Conversely, in other countries where LN dissection
along RLN was not conducted, the number remained around 20.

The key insight gleaned from this study is that robotic surgery alone does not guarantee a higher number of
harvested LNs. The quantity of harvested LNs is contingent on how the robot is utilized and whether
dissection around the RLN is performed. With increased surgeon experience, there is a potential for
improved LN yield and reduced palsy rates with robotic surgery.

Lastly, the extent of LN dissection can influence the removal of LNs around the thyroid gland, classified as
1R or 1L in AJCC classifications. As the number of harvested LNs is influenced by the surgeon’s policy and
experience, a direct comparison between different centers remains challenging, emphasizing the need for
caution in interpretation.

The efficacy of robotic surgery compared to conventional video-assisted thoracic surgery (VATS) in
enhancing the outcomes of LN dissection along RLN remains a subject of debate. Some studies have
suggested that robotic surgery yields a higher number of LNs and a lower incidence of vocal cord palsy.
Recently, three meta-analyses comparing robot esophagectomy and VATS esophagectomy were conducted
including the LN number and vocal cord palsy [Table 2].

While robotic surgery demonstrated a relatively higher number of dissected LNs especially in the field of
106recL in these meta-analyses, the disparity should be further investigated in more future studies. And the
rate of vocal cord palsy was comparable between the robotic and VATS esophagectomy groups.