Abstract
Conventional open thyroidectomy remains the standard treatment of surgery for benign thyroid tumors but leaves a permanent scar in the neck. We conducted this study to compare the surgical outcomes of transoral endoscopic thyroidectomy vestibular approach (TOETVA) versus conventional open thyroidectomy (COT), and thence analyze the safety and viability of this approach. Seventy-eight patients who had undergone either COT or TOETVA from 2020 to 2021 in our institution to treat benign thyroid tumors were prospectively studied. Outcomes between the two groups were analyzed, including time of operation, blood loss, hospital stay, postoperative complications, and level of satisfaction. A total of 78 patients, in which TOETVA was applied to 47 patients and COT thyroid surgery was applied to 31 patients, participated in this study. COT has a shorter operative time (59.8 ± 10.8 min versus 102.3 ± 34.9 min, p < .001). TOETVA is less painful postoperatively (visual analog scale score on day 4 of 1.1 ± 1.2 versus 1.8 ± 0.7, p < .001). There were no significant differences between TOETVA and COT groups regarding incidences of transient recurrent laryngeal nerve (RLN) injury (10.6% and 6.5%, respectively, p = .697) and both transient and permanent hypoparathyroidism (8.5% versus 3.5%, p = .644 with transient and 0% versus 6.7%, p = .166 with permanent). Other complications were comparable between two arms such as bleeding, seroma, and infection. At 3 months after surgery, the TOETVA group had the significantly higher proportion of the very satisfied level than the COT group (80.9% versus 35.4%, p < .001). TOETVA in patients with favorable features is a safe, viable alternative to open thyroidectomy regarding postoperative outcomes and provide higher satisfaction after surgery in the long term.
Keywords: Thyroidectomy, Transoral endoscopic thyroidectomy vestibular approach, Benign thyroid nodule
Introduction
The majority of benign thyroid nodules do not require any intervention. Indication of surgery would be taken for those with tracheal or esophageal obstruction by tumors, or cosmetic complaint [1]. For a long time, open thyroidectomy has been the standard surgical option for the thyroid condition, but it leaves a visible and permanent scar in the neck that many patients complain about.
Nowadays, surgery is expected to have not only the treatment effect but also the cosmetic aspect. Therefore, in the last 2 decades, endoscopic surgery has been developing continuously to overcome the aesthetic disadvantage of COT by removing the scar to a secret place. There have been various approaches of thyroidectomy such as axillo-breast, transaxillary, or retroauricular. Recently, thyroidectomy through the natural orifice has been of interest because of its potential for surgery with scar-free results [2–4]. The enhanced refinement of this transoral thyroidectomy technique was well-established and described in 2016 by Anuwong as the transoral endoscopic thyroidectomy vestibular approach (TOETVA) with maximum cosmetic results [5].
In Vietnam, TOETVA has been applied in selected patients with benign thyroid conditions since 2018 and showed safety in some initial reports [6, 7]. However, there have not been any significant data comparing the outcomes between TOETVA and COT approaches. Thus, we conducted this study to compare the outcomes of these approaches and to infer the safety and feasibility of TOETVA.
Material and Methods
Patients
This study was reviewed and approved by the Institutional Review Board of Hanoi Medical University Hospital. We prospectively performed the cohort study of patients with thyroid conditions admitted to the Department of Oncology and Palliative Care, Hanoi Medical University Hospital. All cases had a preoperative diagnosis of benign thyroid nodules based on clinical examination, hormonal level assessment, ultrasound, and accurate-indication fine needle aspiration results.
Among 78 candidates, 47 patients had TOETVA surgery, and the others had COT surgery. Inclusion criteria for TOETVA used in our study were (1) patients were willing not to have a cervical scar, (2) the volume of thyroid gland ≤ 10 cm3, (3) the diameter of nodule ≤ 6 cm, and (4) benign FNA diagnosed. Exclusion criteria were the following contraindications: (1) radiation of head and neck before surgery, (2) previous surgery in the neck or submental area, (3) oral abscesses, (4) condition of clinical hyperthyroidism, and (5) inability to perform surgery. Thyroid lobectomy was performed in patients with a single benign nodule or multinodules but localized in one lobe, and total thyroidectomy was for patients with multinodules in two lobes. Another category of surgical extent — lobectomy with tumor resection — was performed in patients who had a nodule that was located at the surface of the contralateral lobe. All of our patients were counseled, and it was thoroughly explained to them the benefit and the additional risk of mental nerve injury leading to lower lip paresthesia of TOETVA.
Patient characteristics and outcomes, including operative time (incision to closure time), estimated intraoperative blood loss, and pain as measured by the visual analog scale (VAS), were reviewed in medical records. VAS scores in days 1, 4, and 7 were postoperatively reported. Complications were identified in this study by following up at least 6 months after surgery. A recurrent laryngeal nerve (RLN) injury was defined as impaired movement of one or both vocal cords on laryngoscopy, clinically manifested as the hoarseness symptom. A permanent RLN injury was defined as an injury that did not recover within 6 months. Seroma that required aspiration was recorded. Hypoparathyroidism was defined as a parathyroid hormone level less than 13 pg/mL (to convert to nanograms per liter, multiply by 1) 24 h postoperatively and was identified clinically by paranesthesia in the fingertips, toes, and lips. Permanent hypoparathyroidism was defined as recovery of function that has not occurred within 6 months. Mental nerve injury was characterized as lower lip paresthesia after surgery and was defined as a permanent condition if symptoms last less than 6 months. Bleeding was defined as obvious postoperative bleeding that caused neck swelling and required a subsequent operation. Infection was defined as postoperative local abscess or high-grade fever with evidence of systemic bacterial spread that required treatment.
Surgical Procedure for TOETVA Surgery
The procedure of the TOETVA approach was described in detail in our previous articles [7, 8].
Statistical Analysis
Data were analyzed using Stata version 14. Continuous variables were presented as mean ± standard deviation and range where appropriate, and categorical variables as the number with percentage. The means were compared using the Mann–Whitney U test or t-test, and the proportions were compared by Fisher’s exact or chi-square test when appropriate. All tests were two-tailed, and differences were considered statistically significant at p-values ≤ 0.05.
Result
A total of 78 patients, in which TOETVA was applied to 47 patients and COT thyroid surgery was applied to 31 patients, participated in this study. The mean age of the TOETVA group was significantly younger compared to that of the COT group (38 ± 10.5 versus 52.5 ± 13.4, p < 0.001). Women were the majority in both groups (97.9% and 90.3%, respectively, p = 0.295), and there was no significant difference of tumor diameters among these groups (25.65 ± 10.47 mm versus 26.52 ± 12.45 mm, p = 0.740) (Table 1).
Table 1.
Patients’ characteristics
| Variables | TOETVA (n = 47) | COT (n = 31) | p |
|---|---|---|---|
| Age, mean ± SD (range) | 38 ± 10.5 (21–59) | 52.5 ± 13.4 (13–71) | < .001a |
| Gender, n (%) | |||
| Male | 1 (2.1) | 3 (9.7) | .295b |
| Female | 46 (97.9) | 28 (90.3) | |
| Pathological diagnosis | |||
| Benign nodule(s) | 47 (100) | 31 (100) | |
| Tumor size (mm), mean ± SD (range) | 25.65 ± 10.47 (6–46) | 26.52 ± 12.45 (7–60) | .740a |
| Total thyroidectomy (mm) | 23 ± 4.55 (19–29) | 34.5 ± 13.67 (16–60) | .140a |
| Hemithyroidectomyc (mm) | 25.89 ± 10.86 (6–46) | 23.74 ± 10.98 (7–50) | .447a |
| Extent of surgery, n (%) | |||
| Total thyroidectomy | 4 (8.5) | 8 (25.8) | .002d |
| Lobectomy | 38 (80.9) | 13 (41.9) | |
| Lobectomy + tumor resection | 5 (10.6) | 10 (32.3) | |
at-test
bFisher’s exact test
cConcluding lobectomy and lobectomy + tumor resection
dChi-square test
All patients were pre- and postoperatively diagnosed with benign conditions. We performed three types of operation depending on the location and the quantity of tumors including total thyroidectomy, lobectomy, and lobectomy with tumor resection. The percentages of these categories in each group were 8.5%, 80.9%, and 10.6% and 25.8%, 41.9%, and 32.3%, respectively, which means lobectomy was major in both groups (Table 1).
In general, patients who underwent TOETVA had an operative time significantly longer than those with the COT approach (102.3 ± 34.9 min versus 59.8 ± 10.8 min). However, the blood loss volume was similar between the two groups (~ 6.5 mL) on average. The length of hospital stay of the two groups was also comparable (6.0 ± 1.1 days in TOETVA versus 6.3 ± 0.9 days in COT, p = 0.118). Interestingly, patients who had TOETVA surgery have significantly less postoperative pain, especially during the first 4 days (see details in Table 2).
Table 2.
Surgical outcomes of patients
| Variables | TOETVA (n = 47) | COT (n = 31) | p |
|---|---|---|---|
| Operative time (min) | 102.3 ± 34.9 | 59.8 ± 10.8 | < .001a |
| Total thyroidectomy | 120 ± 27.1 | 63.1 ± 13.4 | .005a |
| Lobectomy | 100.8 ± 36.4 | 58.2 ± 11.2 | < .001a |
| Lobectomy + tumor resection | 100.0 ± 28.3 | 59.2 ± 8.2 | .002a |
| Blood loss | 6.7 ± 2.8 | 6.3 ± 2.5 | .745a |
| Total thyroidectomy | 8.8 ± 4.8 | 6.5 ± 3.5 | .362a |
| Lobectomy | 6.3 ± 2.5 | 5.5 ± 1.5 | .441a |
| Lobectomy + tumor resection | 8 ± 2.7 | 7.2 ± 2.5 | .584a |
| Pain score (VAS) | |||
| Day 1 | 2.9 ± 0.7 | 3.3 ± 0.6 | .011a |
| Day 4 | 1.1 ± 1.2 | 1.8 ± 0.7 | .005a |
| Day 7 | 0.2 ± 0.7 | 0.2 ± 0.6 | .740a |
| Hospital stays (days) | 6.3 ± 0.9 | 6.1 ± 1.0 | .118a |
| Hoarseness, n (%) | |||
| Transient | 5 (10.6) | 2 (6.5) | .697b |
| Permanent | 0 | 0 | ___ |
| Hypoparathyroidism, n (%) | |||
| Transient | 4 (8.5) | 1 (3.5) | .644b |
| Permanent | 0 | 2 (6.7) | .166b |
| Bleeding, n (%) | 0 | 0 | ___ |
| Seroma, n (%) | 1 (2.1) | 0 | 1.00b |
| Number of infections, n (%) | 0 | 0 | ___ |
| Mental nerve injury (transient), n (%) | 2 (4.3) | 0 | .515b |
| Paresthesia, n (%) | 6 (12.8) | 3 (9.7) | 1.00b |
| Neck movement limitation, n (%) | 3 (6.4) | 2 (6.5) | 1.00b |
aMann–Whitney U test
bFisher’s exact test
Only 5 patients (10.6%) with TOETVA surgery and 2 patients (6.5%) with COT surgery had transient vocal cord palsy, whereas no permanent RLN palsy was recorded in both groups. Among 4 patients who underwent total thyroidectomy in TOETVA, 2 patients (50%) had transient hypoparathyroidism but fully recovered afterward. By contrast, 2 out of 8 patients (25%) had permanent hypoparathyroidism. In the lobectomy category, we recorded 2 patients (5.3%) in the TOETVA group and 1 patient (7.7%) in the COT group having transient hypoparathyroidism. There was 1 TOETVA patient (2.1%) who had seroma and recovered after drain insertion. However, no complications including bleeding and post-surgery infection were recorded.
In the TOETVA arm, 2 cases had postoperative lower lip paresthesia that was indicative of mental nerve injury and 4 other patients had paresthesia in the flap dissection area of the neck. Meanwhile, 3 COT patients had paresthesia of the neck. The number of patients having neck movement limitation in TOETVA and COT groups was 3 and 2, respectively. All cases resolved within 6 months. We provided 5 levels of postoperative satisfaction evaluated by patients 3 months after surgery, and the result was in favor of the TOETVA group, in which above 80% cases rated the highest level. This was a significantly higher outcome when comparing to the COT group, with p < 0.001 (Table 3).
Table 3.
Satisfied level 3 months after surgery
| Satisfied level | TOETVA (n = 47) n (%) | COT (n = 31) n (%) | p |
|---|---|---|---|
| Very satisfied | 38 (80.9) | 11 (35.4) | < 0.001a |
| Satisfied | 4 (8.5) | 18 (58.1) | |
| Normal | 5 (10.6) | 2 (6.5) | |
| Dissatisfied | 0 | 0 | |
| Terribly dissatisfied | 0 | 0 |
aFisher’s exact test
Discussion
Our study included 78 cases of endoscopic thyroid surgery performed by a single surgeon through two approaches, TOETVA and COT. This survey aims to show that TOETVA is a safe and feasible alternative to traditional open thyroidectomy for patients. There are no significantly higher incidences of bleeding, seroma, RLN injury, or hypoparathyroidism when compared to conventional open thyroidectomy. Besides, these two techniques had comparable surgical outcomes including blood loss and length of hospital stay. Interestingly, the TOETVA group was associated with less postoperative pain although it had the longer surgical time.
The conventional open approach remains the standard of surgical treatment for benign thyroid tumors [9]. However, along with advances in minimally invasive surgery and a mainly young female population, there have been many advances in procedures that avoid a cervical incision [10]. Initially, they used cervical [11, 12], parasternal [13], and breast [14] approaches. Jeong et al., [15] Shimazu et al. [16], and Lee et al. [17] then improved the technique with the axillary and axillo-bilateral breast approach to minimize the visible scar by moving it to the axilla that can be covered completely by the patient’s arm. However, this approach still leaves cutaneous scars and requires a large amount of flap dissection. Therefore, natural orifice transluminal endoscopic surgery (NOTES) has been applied for thyroidectomy through the oral cavity that completely avoids visible scarring [18, 19].
Transoral endoscopic thyroidectomy can be performed through the sublingual approach, the periosteal approach, or the oral vestibular approach, in which sublingual and periosteal approaches cause severe tissue damage as well as high complications [20, 21]. In 2016, Anuwong reported the expected results of TOETVA with excellent cosmetic outcomes and minimal complications [5]. Since then, there has been accumulating evidence that demonstrated potential safety and efficacy of TOETVA [9, 22, 23].
In this study, the clinical characteristics of the two groups were comparable except for the mean age. The patients who underwent TOETVA were younger than those who underwent COT. The difference is most likely due to the patient’s choice, in which young patients, especially women, would like to have scar-free operation.
The longer operative time observed in TOETVA can be attributed to the additional time required to set up the laparoscopic instruments and the working space. In contrast, TOETVA was supposed to have less postoperative pain than COT in the first 4 days. This is consistent with the findings in a study of Anuwong et al. comparing the surgical outcome of TOETVA and COT approaches [9]. The incision inside the oral vestibule seems to cause less pain compared with skin incision, and patients rarely experienced pain from the oral vestibular incision [9].
In our study, TOETVA was shown to be as safe as COT since there were no significant differences in estimated blood loss or postoperative complication rates between the two groups. However, TOETVA has its own approach-related complications, such as mental nerve injury [7]. There were no postoperative infections recorded in this study, same as those in our recent published study [24]. Because of the high rate of surgical site infections in Vietnam, we routinely gave intravenous amoxicillin with clavulanic antibiotic 30 min before skin incision and up to 5 days after surgery. In terms of the mean hospital stay, we also found that the times of hospital discharge after operation in both groups were not significantly different. However, the average length of a hospital stay in our study was longer than those of Western authors (i.e., 1–3 days in the study of Fernández-Ranvier et al. [10]) because the patients’ home health care services in Vietnam is not as good as in the West; hence, the Vietnamese patients desire to be treated in the hospital for a longer time.
We recorded 5 cases (10.6%) with temporary RLN injury in the TOETVA group and 2 cases (6.5%) in the COT group. The complication rate in the TOETVA approach was slightly higher than that of Anuwong,[5] Anuwong et al. [9], and Hong et al. [25]. However, all cases fully recovered within 6 months after surgery, and this may be claimed to be related to the learning curve of the surgeon. The transient RLN injury rate might be reduced by more meticulous dissection and by avoiding thermal injury from the harmonic scalpel [9]. After initial cases, we started using a wet endoscopic gauze to reduce the heat from the harmonic scalpel while dissecting the RLN, which improved the rate of transient postoperative hoarseness.
The rate of hypoparathyroidism in our study was 8.5% in the TOETVA group, which was slightly lower than that of Anuwong et al. [9] and higher than that of Fernández-Ranvier et al. [10] with the corresponding approach. No patients were reported with permanent hypoparathyroidism in the TOETVA group, whereas 2 patients in the COT group on which total thyroidectomy had been performed suffered permanent hypoparathyroidism. In the lobectomy category, we recorded 2 patients (5.3%) in the TOETVA group and 1 patient (7.7%) in the COT group having transient hypoparathyroidism, but all recovered fully just after 2 months. The surgical technique and the extent of thyroidectomy are related to parathyroid injury, edema, infarction, ischemia, or incidental parathyroidectomy [26–28]. Dissection of parathyroid glands and RLN can lead to venous congestion and edama of these glands. In addition, ligating of thyroid veins is among the causes of venous stasis. Venous stasis and edema slow down parathyroid function and may cause a temporary hypoparathyroidism [29]. A well-known study of 2108 patients shows that the incidence of hypoparathyroidism after thyroid lobectomy was 13.8% [30]. Although the magnified view through the endoscope may make identification of the parathyroid glands easier, close attention must be paid to protect the nutrient vessels when exposing the gland. The transient hypoparathyroid incidence of thyroid lobectomy in our study was lower than the result of Del Rio et al. [31], because we only did hormone test for patients having postoperative symptoms. Nonetheless, no permanent severe complications were reported. Given to the satisfaction level after operation, we conducted 5 grades and recorded the result expectedly that most patients felt the highest level of satisfaction. This should be partly related to the cosmetic advantage of TOETVA.
Conclusion
We conclude that when thyroidectomy, whether total or partial, is pursued for the management of benign thyroid conditions, TOETVA is a safe and feasible option to consider in selected patients when compared to open thyroidectomy with regard to postoperative cosmetic outcomes.
Acknowledgements
We thank our colleagues at Hanoi Medical University Hospital for their valuable help in the study.
Author Contribution
Conception and design: Hau Xuan Nguyen, Hien Xuan Nguyen, Quang Van Le.
Administrative support: Hau Xuan Nguyen, Quang Van Le.
Collection and assembly of data: Hien Xuan Nguyen, Anh Duc Le.
Data analysis and interpretation: Hau Xuan Nguyen, Hien Xuan Nguyen, Anh Duc Le.
Manuscript writing: All authors.
Final approval of manuscript: All authors.
Accountable for all aspects of the work: All authors.
Data Availability
All data underlying the results are available as part of the article, and no additional source data are required. All data sources described in this study are directed at the corresponding author.
Declarations
Ethics Considerations
This study was approved by the ethics committee of the Hanoi Medical University Hospital. Written informed consent was obtained from the patients.
Conflict of Interest
The authors declare no competing interests.
Footnotes
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Contributor Information
Hau Xuan Nguyen, Email: nguyenxuanhau@hmu.edu.vn.
Hien Xuan Nguyen, Email: dr.nguyenxuanhien@gmail.com.
Anh Duc Le, Email: drleducanh.hmu@gmail.com.
Quang Van Le, Email: lequang@hmu.edu.vn.
References
- 1.Holzheimer RG (2001) Benign nodular thyroid disease. Zuckschwerdt. Accessed May 28, 2021. https://www.ncbi.nlm.nih.gov/books/NBK6893/
- 2.Wilhelm T, Metzig A. Endoscopic minimally invasive thyroidectomy (eMIT): a prospective proof-of-concept study in humans. World J Surg. 2011;35(3):543–551. doi: 10.1007/s00268-010-0846-0. [DOI] [PubMed] [Google Scholar]
- 3.Nakajo A, Arima H, Hirata M, et al. Trans-oral video-assisted neck surgery (TOVANS). A new transoral technique of endoscopic thyroidectomy with gasless premandible approach. Surg Endosc. 2013;27(4):1105–1110. doi: 10.1007/s00464-012-2588-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Wang C, Zhai H, Liu W, et al. Thyroidectomy: a novel endoscopic oral vestibular approach. Surgery. 2014;155(1):33–38. doi: 10.1016/j.surg.2013.06.010. [DOI] [PubMed] [Google Scholar]
- 5.Anuwong A. Transoral endoscopic thyroidectomy vestibular approach: a series of the first 60 human cases. World J Surg. 2016;40(3):491–497. doi: 10.1007/s00268-015-3320-1. [DOI] [PubMed] [Google Scholar]
- 6.Le QV, Ngo DQ, Ngo QX. Transoral endoscopic thyroidectomy vestibular approach (TOETVA): a case report as new technique in thyroid surgery in Vietnam. Int J Surg Case Rep. 2018;50:60–63. doi: 10.1016/j.ijscr.2018.07.018. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Nguyen HX, Nguyen LT, Nguyen HV, et al. Comparison of transoral thyroidectomy vestibular approach and unilateral axillobreast approach for endoscopic thyroidectomy: a prospective cohort study. J Laparoendosc Adv Surg Tech. 2020;31(1):11–17. doi: 10.1089/lap.2020.0272. [DOI] [PubMed] [Google Scholar]
- 8.Al HNX et al. Preliminary experience with transoral endoscopic thyroidectomy and parathyroidectomy via vestibular approach. Ann Romanian Soc Cell Biol. Published online February 1, 2021:3206–3215
- 9.Anuwong A, Ketwong K, Jitpratoom P, Sasanakietkul T, Duh QY. Safety and outcomes of the transoral endoscopic thyroidectomy vestibular approach. JAMA Surg. 2018;153(1):21–27. doi: 10.1001/jamasurg.2017.3366. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Fernández-Ranvier GG, Guevara D, Alawwa G, Meknat A, Lieberman B, Inabnet WB. Transoral endoscopic thyroidectomy vestibular approach (TOETVA): treatment for benign thyroid diseases. J Endocr Surg. 2021;21(1):13–19. doi: 10.16956/jes.2021.21.1.13. [DOI] [Google Scholar]
- 11.Yamashita H, Watanabe S, Koike E, et al. Video-assisted thyroid lobectomy through a small wound in the submandibular area. Am J Surg. 2002;183(3):286–289. doi: 10.1016/s0002-9610(02)00801-2. [DOI] [PubMed] [Google Scholar]
- 12.Bellantone R, Lombardi CP, Bossola M, et al. Video-assisted vs conventional thyroid lobectomy: a randomized trial. Arch Surg Chic Ill 1960. 2002;137(3):301–304. doi: 10.1001/archsurg.137.3.301. [DOI] [PubMed] [Google Scholar]
- 13.Shimizu K, Akira S, Jasmi AY, et al. Video-assisted neck surgery: endoscopic resection of thyroid tumors with a very minimal neck wound. J Am Coll Surg. 1999;188(6):697–703. doi: 10.1016/s1072-7515(99)00048-4. [DOI] [PubMed] [Google Scholar]
- 14.Ohgami M, Ishii S, Arisawa Y, et al. Scarless endoscopic thyroidectomy: breast approach for better cosmesis. Surg Laparosc Endosc Percutan Tech. 2000;10(1):1–4. doi: 10.1097/00019509-200002000-00001. [DOI] [PubMed] [Google Scholar]
- 15.Jeong JJ, Kang SW, Yun JS, et al. Comparative study of endoscopic thyroidectomy versus conventional open thyroidectomy in papillary thyroid microcarcinoma (PTMC) patients. J Surg Oncol. 2009;100(6):477–480. doi: 10.1002/jso.21367. [DOI] [PubMed] [Google Scholar]
- 16.Shimazu K, Shiba E, Tamaki Y, et al. Endoscopic thyroid surgery through the axillo-bilateral-breast approach. Surg Laparosc Endosc Percutan Tech. 2003;13(3):196–201. doi: 10.1097/00129689-200306000-00011. [DOI] [PubMed] [Google Scholar]
- 17.Lee MC, Mo JA, Choi IJ, Lee BC, Lee GH. New endoscopic thyroidectomy via a unilateral axillo-breast approach with gas insufflation: preliminary report. Head Neck. 2013;35(4):471–476. doi: 10.1002/hed.22984. [DOI] [PubMed] [Google Scholar]
- 18.Witzel K, von Rahden BHA, Kaminski C, Stein HJ. Transoral access for endoscopic thyroid resection. Surg Endosc. 2008;22(8):1871–1875. doi: 10.1007/s00464-007-9734-6. [DOI] [PubMed] [Google Scholar]
- 19.Benhidjeb T, Wilhelm T, Harlaar J, Kleinrensink GJ, Schneider TAJ, Stark M. Natural orifice surgery on thyroid gland: totally transoral video-assisted thyroidectomy (TOVAT): report of first experimental results of a new surgical method. Surg Endosc. 2009;23(5):1119–1120. doi: 10.1007/s00464-009-0347-0. [DOI] [PubMed] [Google Scholar]
- 20.Benhidjeb T, Witzel K, Stark M, Mann O. Transoral thyroid and parathyroid surgery: still experimental! Surg Endosc. 2011;25(7):2411–2413. doi: 10.1007/s00464-010-1530-z. [DOI] [PubMed] [Google Scholar]
- 21.Lee HY, You JY, Woo SU, et al. Transoral periosteal thyroidectomy: cadaver to human. Surg Endosc. 2015;29(4):898–904. doi: 10.1007/s00464-014-3749-6. [DOI] [PubMed] [Google Scholar]
- 22.Deroide G, Honigman I, Berthe A, et al. Trans oral endoscopic thyroidectomy (TOETVA): first French experience in 90 patients. J Visc Surg. 2021;158(2):103–110. doi: 10.1016/j.jviscsurg.2021.02.001. [DOI] [PubMed] [Google Scholar]
- 23.Sun H, Zheng H, Wang X, Zeng Q, Wang P, Wang Y. Comparison of transoral endoscopic thyroidectomy vestibular approach, total endoscopic thyroidectomy via areola approach, and conventional open thyroidectomy: a retrospective analysis of safety, trauma, and feasibility of central neck dissection in the treatment of papillary thyroid carcinoma. Surg Endosc. 2020;34(1):268–274. doi: 10.1007/s00464-019-06762-6. [DOI] [PubMed] [Google Scholar]
- 24.Nguyen HX, Nguyen HX, Nguyen TTP, Van Le Q (2021) Transoral endoscopic thyroidectomy by vestibular approach in Viet Nam: surgical outcomes and long-term follow-up. Surg Endosc. Published online October 7. 10.1007/s00464-021-08759-6 [DOI] [PubMed]
- 25.Hong YT, Ahn JH, Kim JH, Yi JW, Hong KH. Bi-institutional experience of transoral endoscopic thyroidectomy: challenges and outcomes. Head Neck. 2020;42(8):2115–2122. doi: 10.1002/hed.26153. [DOI] [PubMed] [Google Scholar]
- 26.Bhattacharyya N, Fried MP. Assessment of the morbidity and complications of total thyroidectomy. Arch Otolaryngol Head Neck Surg. 2002;128(4):389–392. doi: 10.1001/archotol.128.4.389. [DOI] [PubMed] [Google Scholar]
- 27.Kakava K, Tournis S, Papadakis G, et al. Postsurgical hypoparathyroidism: a systematic review. Vivo Athens Greece. 2016;30(3):171–179. [PubMed] [Google Scholar]
- 28.Bergamaschi R, Becouarn G, Ronceray J, Arnaud JP. Morbidity of thyroid surgery. Am J Surg. 1998;176(1):71–75. doi: 10.1016/s0002-9610(98)00099-3. [DOI] [PubMed] [Google Scholar]
- 29.Kalyoncu D, Gönüllü D, Gedik ML, et al. Analysis of the factors that have an effect on hypocalcemia following thyroidectomy. Turk J SurgeryUlusal Cerrahi Derg. 2013;29(4):171–176. doi: 10.5152/UCD.2013.2438. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.Del Rio P, Rossini M, Montana CM, et al. Postoperative hypocalcemia: analysis of factors influencing early hypocalcemia development following thyroid surgery. BMC Surg. 2019;18(1):25. doi: 10.1186/s12893-019-0483-y. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 31.Del Rio P, Rossini M, Montana CM, et al. Postoperative hypocalcemia: analysis of factors influencing early hypocalcemia development following thyroid surgery. BMC Surg. 2019;18(1):25. doi: 10.1186/s12893-019-0483-y. [DOI] [PMC free article] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
All data underlying the results are available as part of the article, and no additional source data are required. All data sources described in this study are directed at the corresponding author.