Objective:To evaluate the predictive effect of the loss of signal (LOS) on the recurrent laryngeal nerve (RLN) injury.Methods:The literatures on PubMed, Web of Science, CNKI, and Wanfang Medical Network database were published before 30 April 2023. English search terms included "thyroid gland surgery" "thyroidectomy" "intraoperative neuromonitoring" "intraoperative nerve monitoring" and "recurrent laryngeal nerve". Chinese search terms included "thyroidectomy", "thyroid surgery" "recurrent laryngeal nerve" "intraoperative nerve monitoring". Two evaluators screened the literature, extracted the materials and evaluated the risk of bias of the study independently. If there were different opinions, researchers should resolve which through consultation and ask the third-party researcher when necessary. The Meta-analysis was performed with the Review Manager 5.4 software.Results:A total of thirty-three studies were included and were all analyzed for primary outcome measures while only twenty-six of which were analyzed for secondary outcome measures. Meta-analysis showed that the positive predictive value of LOS in intraoperative nerve monitoring (IONM) was 65% [ OR=1.88, 95% CI: 1.36-2.60]. Then these thirty-three articles included in IONM were divided into I-IONM, C-IONM and mixed groups. Subgroup analysis showed that the positive predictive value of LOS in I-IONM, C-IONM and mixed groups were 62% [ OR=1.63, 95% CI: 1.05-2.52], 75% [ OR=2.93, 95% CI: 1.64-5.22] and 70% [ OR=2.38, 95% CI: 1.77-3.12] respectively. When these thirty-three included articles were divided into Asian, European, North American and Oceania, subgroup analysis showed that the positive predictive value of LOS was 50% [ OR=1.01, 95% CI: 0.44-2.31], 70% [ OR=2.29, 95% CI: 1.60-3.28], 82% [ OR=4.68, 95% CI: 3.79-5.78] and 83% [ OR=4.81, 95% CI: 3.10-7.46] respectively. Meta-analysis of secondary outcome measures in twenty-six articles showed that the negative predictive value of LOS was 99.6% [ RD=1.51, 95% CI: 1.48-1.53], with the sensitivity of 89% [ RD=1.24, 95% CI: 1.11-1.37] and specificity of 98%[ RD=1.43, 95% CI: 1.40-1.47]. Conclusion:The occurrence of LOS during IONM in thyroidectomy has a positive prediction effect and a higher negative prediction effect, sensitivity and specificity on RLN injury.

Objective To determine the radiation dose of sensitive organs under different protective methods in lung CT scanning environment, and to explore the best protective scheme of corresponding organs. Methods Annealed thermoluminescence dose elements were placed in the stomach, liver, colon, and thyroid gland of a simulated human body model. The dose effect experiment of protective methods included non-protective group, half lead apron group, and full lead apron group. The dose effect experiment of protective thickness included 0.50 mmpb full lead apron group and 0.35 mmpb full lead apron group. The same exposure conditions of lung CT scan were used in the above experiments. Results Compared with the non-protective group, the exposure dose of the stomach, liver, colon, and thyroid gland increased significantly in the half lead apron group (P < 0.05), and the exposure dose of the thyroid gland and colon decreased significantly in the full lead apron group (P < 0.05). There were no significant differences in the exposure dose of the liver, stomach, and colon in the simulated human body model between the 0.35 mmpb full lead apron group and the 0.50 mmpb full lead apron group. Conclusion For lung CT scan, the protective measure of lead apron may not reduce the exposure dose of subjects. The protective thickness of lead apron does not necessarily have a substantial influence on the exposure dose of human body.