When performing thyroid surgery, the parathyroid gland, a vital organ on the dorsal side of the thyroid gland that requires total thyroidectomy and perhaps lymphadenectomy, is particularly vulnerable to damage 10 . Rich experience in thyroid surgery and surgical meticulous dissection is considered to be successful in the process of the main factor that protect the parathyroid gland32. Injury, however, may not be preventable due to the features of the thyroid anatomy and the anatomical changes brought on by thyroid disease33. The causes of hypocalcemia after surgery for papillary thyroid carcinoma (PTC) may include accidental removal of one or more parathyroids, vascular destruction during thyroid surgery resulting in damaged blood supply to the parathyroids, and destruction of the parathyroids caused by lymph node dissection. We have proposed a number of treatments for these potential complications. One of the most efficient procedures is to perform an intraoperative frozen section on a small piece of suspected parathyroid tissue, examine it for pathology, and then re-implant it if PG is found to be present34. However, excision reduces the volume of the parathyroid gland, and hypoparathyroidism is possible even after autologous transplantation. After autotransplantation of one or two parathyroids, Kihara et al. found that the incidence of permanent hypoparathyroidism was 1.4% and 21.4%, respectively.35,36. Therefore, we generally prefer to preserve PG in situ rather than autologous transplantation. Clinicians lack a way to distinguish thyroid and parathyroid glands during surgery, so near-infrared autofluorescence recognition for parathyroid glands, nano iron oxide recognition technology, 3D printing models before thyroid surgery, etc., are considered to reduce parathyroid injury37–40. But these emerging technologies are not being used on a large scale.
In addition, the use of lymph node tracer in thyroid surgery has a theoretical protective effect on parathyroid glands. Carbon nanoparticles are a new type of lymph node tracer. It has the characteristics of simple operation, fast dyeing speed, not easy to disperse to the surrounding tissue and will not cause damage to the human body 2,41,42 . These excellent characteristics make it more and more widely used in the operation of various malignant tumors. However, due to its short clinical application time, whether radical resection of its PTC is helpful remains to be determined. The 14 cases studied in this meta-analysis were all operated on by different operators. The specific methods, proficiency and application of surgical instruments of different surgeons are different, and the proficiency level of pathologists in lymph node detection is also different. Some literature did not give the number of parathyroid misexcision, but in the study of the same literature, the postoperative hypocalcemia rate of the nano carbon group was lower than that of the non-nano carbon group. It shows that nano carbon is helpful to avoid parathyroid injury.
Carbon nanoparticles are mainly diffused through the lymphatic network, and play a guiding role for surgeons through their black stain tracer and negative development. The scope of operation is more clear and the damage to the surrounding tissue is reduced. The parathyroid gland does not have a separate blood supply. It needs to supply blood through the thyroid gland, most of which comes from the inferior thyroid artery. Intraoperative resection of the primary PTC may damage the inferior thyroid artery or its branches, which may also affect the blood supply to the parathyroid gland 43 . However, the effect of carbon nanoparticles on the protection of parathyroid blood supply is not very clear, which is one of the reasons why the application of carbon nanoparticles as tracers cannot completely avoid parathyroid damage. Therefore, some patients in the nano carbon group still have low calcium after surgery.
A total of 2214 papillary thyroid cancer patients who underwent surgery were chosen for this meta-analysis from 14 studies.In the experiment of Rao and Yu, there was no statistical significance between the experimental group and the control group. Some scholars argue that the role of carbon nanoparticles should not be overstated 44Based on the results of our literature review, this paper shows that carbon nanoparticles can reduce the incidence of hypocalcium after thyroid papillary carcinoma surgery and have a protective effect on parathyroid glands.
Despite its advantages, carbon nanoparticles are not suitable for all thyroid cancer surgeries. (1) When the primary lesion was large (diameter > 3cm), especially occupied the whole thyroid gland lobe, and the normal thyroid tissue was not obvious; (2) retrosternal thyroid tumor 10 ; (3) Cases of secondary operation for thyroid cancer. Because the original lymphatic system may be destroyed during the initial operation, the nano-carbon may leak from the lymphatic system to the operative field, increasing the difficulty of the operation. (4) Thyroid carcinoma with obvious cystic changes; (5) Edema of thyroid tissue. As a new tracer, it has some limitations. 1. It is difficult to standardize the dosage. The recommended usage instruction is to take 1ml nano-carbon suspension after exposure to tumor tissue and inject it under the serous membrane at 4–6 points around the tumor with a skin test needle, and inject about 0.1-0.3ml at each point. However, the tracer effect is poor due to the variable size and location of the tumor, and the small amount of injection. Too much injection is easy to produce leakage and stain the surrounding tissue. 2. There are certain requirements on the operating level of the operating physician. The injection into blood vessels must be avoided, and the needle should be pushed slowly after prowling the tissue for some distance.3. After the completion of carbon nanoparticles injection, it is necessary to wait for sufficient black staining of the thyroid gland and surrounding lymph nodes before continuing the follow-up operation, so as to prolong the operation time accordingly. 4. The high price causes a certain economic burden to patients, and it is difficult to apply it to all patients. As for the analysis of article bias, the study was retrospective in nature, which could easily lead to some bias. Second, most research conducted or published in China, whether in Chinese or English, is done for analysis, so publication bias is almost inevitable. Third, a small selection of files were chosen for analysis. In the future, more extensive research and randomized controlled trials are required.