| Objective:Temporary vocal cord paralysis after thyroid surgery is a severe complication,and the protection of the recurrent laryngeal nerve during thyroid surgery has always been a focus of research.With the deepening understanding of factors that may cause temporary vocal cord paralysis by domestic and foreign experts,from intraoperative nerve traction,suture compression,cutting or thermal injury,to the exploration of preoperative factors such as height,BMI,and diabetes that may indicate the risk of recurrent laryngeal nerve injury.However,previous studies have small sample sizes and limited factors involved,and there is currently no comprehensive coverage of risk factors for temporary vocal cord paralysis after thyroid surgery,nor any literature that focuses on establishing a risk prediction model.This study aims to explore the related factors of temporary vocal cord paralysis after thyroid surgery,establish a risk model,and validate it.Methods:A retrospective analysis of thyroid cancer patients who underwent surgery at our center between January 2018 and December 2020 was conducted.Medical history and clinical characteristics were collected,including gender,age,height,weight,BMI,etc.;baseline disease information,including diabetes,hypertension,family history,etc.;and perioperative diagnostic and treatment-related information such as preoperative ultrasound,intraoperative nerve monitoring data,operation duration,operation scope,intraoperative rapid pathology information,preoperative laryngoscopy,and postoperative laryngoscopy.By comparing preoperative and postoperative laryngoscopy information,patients were divided into vocal cord paralysis and non-vocal cord paralysis groups.Univariate and multivariate analyses were performed using statistical methods to determine the influencing factors of temporary vocal cord paralysis after thyroid surgery,and a risk model was established and validated.Results:According to the inclusion and exclusion criteria,a total of 8340 patients with thyroid cancer were included in this study,among which 308 patients developed temporary vocal cord paralysis after surgery,and the rate of temporary vocal cord paralysis after surgery was 3.6%(308/8340).All patients were divided into vocal cord paralysis group and non-vocal cord paralysis group.First,in order to explore the relationship between preoperative factors and temporary vocal cord paralysis after thyroid surgery,a separate analysis of preoperative factors was conducted.Univariate analysis showed that the following factors may be related to temporary vocal cord paralysis after thyroid surgery: Compared with the non-vocal paralysis group,the number of hypertension patients in the vocal paralysis vs.non-vocal paralysis group was 14.9% vs.10.3%(χ2 = 4.310,P = 0.038),and the number of dorsal masses was higher.43.8% vs 36.6%(χ2 = 4.145,P = 0.042)in the vocal paralysis group versus the non-vocal paralysis group,and the maximum nodule diameter > 1cm was more in the vocal paralysis group than in the non-vocal paralysis group,47.4% vs 36.3%(χ2 = 9.984,P = 0.002).There were fewer patients with thyroid nodule FNA before operation,85.6% vs 91.4% in vocal cord paralysis vs non-vocal cord paralysis group(χ2 = 8.058,P = 0.005).The results of multivariate logistic regression analysis showed that hypertension(OR = 1.507,P =0.047,95%CI: 1.006-2.258)and tumor were located in the dorsal side(OR = 1.414,P = 0.019,95%CI: 1.058-1.89)and maximum nodule diameter > 1cm(OR = 1.524,P = 0.005,95%CI: 1.137-2.042)were independent risk factors for postoperative temporary vocal cord paralysis.Based on this,a nomogram model for predicting postoperative vocal cord paralysis was established.The C index was 0.58,and the calibration curve showed a good agreement with the actual rate of vocal cord paralysis.Similarly,intraoperative factors were included in the model,and the results showed that the following factors were associated with postoperative vocal cord paralysis after univariate analysis.Compared with the non-vocal paralysis group,patients in the vocal paralysis group had longer operation time,130 min vs 100 min in the vocal paralysis vs non-vocal paralysis group(Z = 7.245,P < 0.001),and the maximum tumor diameter was larger,and the vocal paralysis vs non-vocal paralysis group was 0.8cm vs 0.7cm(Z = 4.284,P < 0.001),multiple focal cancers accounted for more,57.2% vs 39.4%(χ2 = 24.755,P < 0.001)in the vocal cord paralysis group versus the non-vocal cord paralysis group,and more invasive surrounding organizers(21.6% vs 13.0%,χ2 = 12.777,P = 0.005),more patients had central lymph node metastases(51.5% vs 43.9%,χ2 = 4.485,P = 0.034),more patients had lateral cervical lymph node metastases(22.2% vs 10.0%,χ2 = 29.669,P < 0.001),more positive total lymph nodes(1.0 vs 0.0,Z = 2.924,P = 0.003),double-lobe +CND accounted for 36.1%,followed by single lobe +CND,accounting for 35.1%(χ2 =67.213,P < 0.001),T4(6.7% vs 0.4%,χ2 = 120.095,P < 0.001),and N1b(22.2% vs9.9%,χ2 = 30.673,P < 0.001)were higher in T stage than in N stage.The results of multivariate analysis showed: operation duration(OR = 1.009,P < 0.001,95%CI:1.006-1.012),multifocal cancer(OR = 1.532,P = 0.013,95%CI: 1.095-2.144)and T stage(OR = 1.411,P = 0.013,95%CI: 1.075-1.853)were independent risk factors for vocal cord paralysis after thyroid surgery.N stage is not an independent risk factor for vocal cord paralysis after thyroid surgery.Based on this,a nomogram model for predicting vocal cord paralysis after thyroid operation was established.The C index was 0.67,and the calibration curve showed a good agreement with the actual rate of vocal cord paralysis.The sample size was reduced to further analyze the risk factors of left and right postoperative vocal cord paralysis.The analysis results of left recurrent laryngeal nerve showed that the operation duration(OR = 1.013,P < 0.001,95%CI:1.008-1.018)and V2 amplitude decreased(OR = 1.373,P = 0.019,95%CI:1.054-1.789)and decreased R2 amplitude(OR = 1.371,P = 0.021,95%CI:1.048-1.794)were independent risk factors for vocal cord paralysis after thyroid surgery.Analysis of the right recurrent laryngeal nerve showed that operation duration(OR = 1.007,P = 0.025,95%CI: 1.001-1.014)and amplitude of V2decreased(OR = 2.351,P < 0.001,95%CI: 1.692-3.268)and decreased R2amplitude(OR = 1.85,P < 0.001,95%CI: 1.33-2.572)were independent risk factors for vocal cord paralysis after thyroid surgery.To construct nomogram models of left and right postoperative vocal cord paralysis.The C-indices of the prediction models were 0.74 and 0.82,respectively,and the calibration curves showed that the actual rate of vocal cord paralysis of the prediction models was in good agreement with the prediction probability.Conclusion:When analyzing only preoperative factors,hypertension,the presence of a tumor at the dorsal side,and a maximum nodule diameter >1cm were found to be independent risk factors for temporary vocal cord paralysis after thyroid surgery.The model established based on these factors has a satisfactory prediction ability.When analyzing both preoperative and intraoperative factors,operation duration,multifocal cancer,and T staging were identified as independent risk factors for temporary vocal cord paralysis after thyroid surgery.N staging cannot be considered an independent risk factor.The model established based on these factors has a satisfactory prediction ability.When focusing on the analysis of intraoperative nerve monitoring data,operation duration,reduced V2 amplitude,and reduced R2 amplitude were found to be independent risk factors for temporary vocal cord paralysis after thyroid surgery.The model established based on these factors can accurately predict temporary vocal cord paralysis after thyroid surgery. |
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