A systematic review and meta-analysis of intraoperative neuromonitoring (IONM) of the recurrent laryngeal nerve during minimally invasive esophagectomy.

Background: Minimally invasive esophagectomy (MIE) can lead to a severe complication known as recurrent laryngeal nerve paralysis (RLNP). Existing literature supports that recurrent laryngeal nerve (RLN) injury is the principal etiology of RLNP, a complication potentially mitigated through intraoperative neuromonitoring (IONM). In this study, we examined the comprehensive effectiveness of IONM during esophageal resection by performing a meta-analysis.

Methods: We searched the EBSCO Information Services (EBSCO), PubMed, China National Knowledge Infrastructure (CNKI), Excerpta Medica Database (EMBASE), and Cochrane libraries for all relevant literature up to the 1^st of November 2022. Search terms included ((esophageal cancer [MeSH Terms]) OR (esophageal cancer [Title/Abstract])) AND (((Recurrent Laryngeal Nerve [MeSH Terms]) OR (Recurrent Laryngeal Nerve [Title/Abstract])) OR (nerve monitoring [Title/Abstract])).

Results: The primary outcome of this study was the incidence of postoperative RLNP. In addition to the secondary outcomes, we also assessed the sensitivity and specificity of IONM, as well as the positive and negative predictive values of IONM, post-esophageal complications, lymph node dissection, operative time, intraoperative bleeding, and hospital stay. Two investigators conducted independent screening of the literature, extraction of data, and assessment of study quality based on stringent inclusion and exclusion criteria. The relative risk (RR) with 95% confidence intervals (CIs) was calculated using either a fixed or random-effects model. Meta-analysis was conducted using RevMan 5.4 software. Following thoracoscopic esophageal surgery, 10 of 1,362 studies identified were significantly associated with a reduced rate of RLNP following IONM (RR: -0.15, 95% CI: -0.21 to -0.09; P<0.001). In the IONM group, the incidence of pneumonia was significantly lower compared to the non-IONM group (RR: 0.65; 95% CI: 0.43 to 0.98; P<0.05). In comparison to non-IONM group, the IONM group experienced significantly higher rates of mediastinal lymph node dissection (mean difference: 3.69; 95% CI: 2.39 to 5.00; P<0.001). Non-IONM patients had a significantly shorter hospital stay than IONM patients (mean difference: -13.40; 95% CI: -19.97 to -6.83; P<0.001). IONM patients had significantly lower mean bleeding volumes than non-IONM patients, according to the pooled analysis (mean difference: -68.15; 95% CI: -114.33 to -21.97; P<0.01). In the non-IONM and IONM groups, there was no significant difference in operation time (mean difference: -1.35; P>0.05).

Conclusions: Collectively, the findings from this systematic review and meta-analysis suggest that during MIE, IONM is linked to a reduced rate of RLNP and postoperative pneumonia, as well as enhanced efficacy in lymphadenectomy for esophageal cancer (EC); furthermore, both hospital stay and blood loss are reduced. However, IONM has no significant benefit in reducing operative time.