Here, we present a protocol to describe the methodology for the transoral endoscopic thyroidectomy vestibular approach in detail.
The manuscript describes the transoral endoscopic thyroidectomy vestibular approach (TOETVA) for thyroid lobectomy. The patient is placed in the supine position with extension and fixation of the neck. One 20 mm transverse incision and two 5 mm incisions are made through the mucosa of the oral vestibule for camera and instrument placement after disinfection of the skin and oral cavity. The workspace is established and maintained by the skin suspension device, which is made of unabsorbable string (3-0) and rubber bands, and the CO2 insufflation pressure. Lobectomy using a medial-to-lateral technique and prophylactic ipsilateral central neck dissection is performed simultaneously on patients with papillary thyroid cancer (PTC). The specimen is extracted through the 20 mm incision. The parathyroid gland is immediately searched for in the specimen and auto-transplanted to the left brachioradialis. A drainage tube is inserted through the retractor hole into the bed of the thyroid gland, and absorbable sutures are used to close the mucosal incisions in the oral vestibule and the linea alba cervicalis. Prophylactics administered intravenously are recommended for the first 24 h after surgery, and oral antibiotics are used for 7 days postoperatively.
Conventional open thyroidectomy has been safely performed using a cervical incision for more than 100 years1. Although most patients have efficient scar healing and the cosmetic effect is generally acceptable, a permanent scar on the neck always draws immediate attention from common observers2. Nearly 20% of post-thyroidectomy patients experience self-awareness, and more than 10% consider further treatments to remove the scar3. Moreover, a negative impact of the cervical incision on health-related quality of life (HRQOL) has also been reported4. Varied remote-access approaches for thyroid surgery, such as axillobreast, transaxillary, retroauricular, and subclavian approaches, have been developed to avoid a visible neck scar5,6,7,8 by moving the cutaneous incision to less conspicuous locations.9 However, these approaches require wide-flap dissection to access the thyroid gland and still leave cutaneous scars at the incision sites10.
Since 2008, techniques for natural orifice transluminal endoscopic surgery for transoral thyroid surgery have been developed. These can be performed via the oral vestibular approach or the sublingual approach. The former is more popular because it is associated with fewer complications. In 2016, Anuwong published the first case series of 60 patients undergoing the transoral endoscopic thyroidectomy vestibular approach (TOETVA) and identified an excellent prognosis11. In comparison with the remote-access methods, TOETVA is considered truly minimally invasive because the area of the flap dissection is similar to conventional open thyroidectomy, and it does not leave any scars on the body10.
TOETVA, a revolutionary endoscopic method, meets women's cosmetic needs and allows easy access to the bilateral thyroid and central compartment12. It is distinguished by the complete exposure and dissection of the central lymph nodes, which is beneficial in treating differentiated thyroid cancer with cN1a10,13,14,15. However, because of the limited operating space, dealing with large tumors in the upper pole of the thyroid gland is relatively challenging. The current study describes the step-by-step procedures of TOETVA.
The study was approved by the medical ethics committee of West China Hospital, Sichuan University (2018[457]), and written informed consent was obtained from all subjects.
1. Preoperative preparation
2. Surgical preparation
Figure 1: A schematic of the operating room layout. Please click here to view a larger version of this figure.
3. Designing the incisions and establishing the working space (Figure 2)
Figure 2: Positioning of the patient and the laparoscopic ports. The center one is the camera port. Arm I and Arm II are for instrument placement. Please click here to view a larger version of this figure.
Figure 3: The traction suspension device. The arrow points at the traction suspension device. The suspension device is made of unabsorbable string (3-0) and rubber bands. Please click here to view a larger version of this figure.
4. Thyroid lobectomy
5. Central lymph node dissection
6. Removal of the specimen and closure
7. Parathyroid gland autotransplantation
We set up a routine clinical pathway for patients with TOETVA at the center. Laryngoscopy and a thyroid ultrasound are carried out on each patient before the operation. Parathyroid hormone (PTH), thyroid function, 25-dihydroxy vitamin D (25-OH-VD), and serum calcium are routinely measured before the operation, and all of them except for thyroid function are remeasured 1 day after the surgery. In our hospital, Foley catheters are routinely used for patients who will have a TOETVA surgery of more than 3 h. The Foley catheter is also removed at 1 day after the surgery. Every patient is given 4 g of calcium gluconate through an intravenous drip after the surgery, and another 2 g is provided on the first day postoperatively. Oral calcium is not for routine use unless the patient has symptoms like numbness or tetany. Patients who have vitamin D deficiency are asked to take vitamin D supplementation after the surgery. Patients are discharged on the second postoperative day after removing the closed-suction drain unless there is a major adverse event like bleeding, hypocalcemia, or hoarseness. Patients are asked to take oral antibiotics for 5-7 days after the surgery.
At the center, TOETVA was performed on 32 patients with papillary thyroid cancer (PTC), and another 97 patients had traditional open surgery from November 2021 to April 2022 (Table 1). In the TOETVA group, the IONM showed the neural signal of all the patients to be in good condition during the operation. There was no case of postoperative hoarseness. Regardless of hypocalcemic symptoms, any decrease in the serum PTH level below the normal limit (normal range = 1.6-6.9 pmol/L) was defined as postoperative hypoparathyroidism, and a lack of recovery of the serum PTH level to the normal range more than 6 months postoperatively was defined as permanent hypoparathyroidism. If the reduction lasted less than 6 months, it was designated as transient. In the entire group, 12.5% (4/32) of the patients had transient hypoparathyroidism, and 0% had permanent hypoparathyroidism.
The mean age and gender composition of the patients differed between the two groups (p < 0.05). Younger female patients were more likely to choose TOETVA. The operation time of the TOETVA was longer than that of open surgery (p < 0.05). As no significant differences in the number of harvested lymph nodes were found between the two groups (p > 0.05), the dissection range of central lymph nodes of TOETVA could be consistent with that of open surgery. In terms of the metastatic lymph nodes, the ratio of extrathyroidal extension and tumor size differed between the two groups (p < 0.05), meaning the characteristics of the tumors differed between the two groups. No significant differences in postoperative PTH and postoperative calcium were found between the two groups (p > 0.05). The two surgical techniques had identical effects on parathyroid function (Table 1).
Parameters | TOETVA (N=32) | Open surgery (N=97) | P* | ||
Mean age, years (range) | 34.00 (32.00-39.00) | 44.00 (35.00-51.00) | 0.000 | ||
Sex | 0.007 | ||||
Female | 31 | 73 | |||
Male | 1 | 24 | |||
Preoperative PTH (pmol/L) | 5.04 ± 0.24 | 5.41 ± 0.20 | 0.228 | ||
Preoperative Calcium (mmol/L) | 2.28 ± 0.01 | 2.31 ± 0.01 | 0.205 | ||
Surgical extent | 0.790 | ||||
Left | 11 | 37 | |||
Right | 21 | 60 | |||
Extrathyroidal extension | 11 | 12 | 0.005 | ||
Tumor size (cm) | 0.80 (0.6-1.00) | 1.75 (1.20-2.32) | 0.000 | ||
Operation time (min) | 190.03 ± 5.39 | 102.00 ± 13.25 | 0.000 | ||
Postoperative PTH (pmol/L) | 2.78 ± 0.17 | 2.78 ± 0.01 | 0.962 | ||
Postoperative Calcium (mmol/L) | 2.21 ± 0.25 | 2.24 ± 0.12 | 0.282 | ||
No. of harvested lymph nodes | 8.75 (5.00-12.70) | 8.00 (6.00-11.25) | 0.110 | ||
No. of metastatic lymph nodes | 0.75 (0-2.40) | 1.75 (0-2.50) | 0.002 |
Table 1: Baseline characteristics and results of the 32 cases of TOETVA and the 97 cases of open surgery. The median is presented for continuous variables with non-normal distribution. The mean ± standard deviation is presented for continuous variables with normal distribution. Differences in continuous variables between the groups were examined using a nonparametric test or the Student's t-test. The Fisher's exact test or Pearson's chi-squared test were used to examine the differences in categorical variables between the groups. A P value of < 0.05 was considered statistically significant. Abbreviations: PTH = parathyroid hormone.
TOETVA is characterized by the full exposure and dissection of the central lymph nodes, which is significantly advantageous in the treatment of differentiated thyroid carcinoma with cN1a10,13,14,15. However, it should be noted that due to the limited operating space, it is relatively difficult to deal with the big tumors located in the upper pole of the thyroid gland. The surgical indications and contraindications should be strictly followed to ensure the safe development of the operation. After completely dislocating the upper pole of the thyroid, the RLN is identified and further separated under direct visualization and monitored by IONM during the operation. When the RLN is in the vicinity of a hemorrhage, using an electrotome or an ultrasonic scalpel for hemostasis without figuring out the anatomy of the RLN and the surrounding conditions should be avoided, as this may result in accidental damage to the RLN. Wiping the blood with gauze strips can help to identify the anatomical relationship between the bleeding point and the RLN and, thus, stop the bleeding.
Following the report in 201611, transoral thyroid surgery has started to be adopted around the world13,18,19,20. According to one meta-analysis21 and five published systematic reviews22,23,24,25,26, TOETVA is safe and feasible in treating thyroid diseases. TOETVA, as a new endoscopic approach, satisfies the esthetic requirement because of the absence of a skin incision. Furthermore, it provides easy access to the bilateral central area and thyroid12. Surprisingly, most patients who underwent TOETVA in the center were female. A higher incidence of PTC and higher esthetic requirements in women may have contributed to this result.
The most common complications of thyroidectomy are RLN injury and hypoparathyroidism27. A meta-analysis of 10 articles involving 1,677 patients showed no significant difference in transient RLN injury, transient hypoparathyroidism, and transient hypocalcemia between TOETVA and non-transoral endoscopic thyroidectomy (NTET)28. The IONM showed that the neural signal of all the patients did not fade or disappear during the operation. The better view of the RLN and parathyroid gland provided by the endoscopic magnification might explain the result29,30.
Additional complications associated with TOETVA are surgical site infection and mental nerve injury, which can result in lip and/or chin numbness10. TOETVA is considered a clean-contaminated surgery because diverse bacterial flora, including anaerobic bacteria and gram-positive aerobic, colonize the mucosa of the oral cavity31. However, one meta-analysis showed no significant difference in the occurrence of wound infection between TOETVA and NTET28. The prophylactic measures, including prophylactic antibiotics, sterilization, and drainage, may contribute to this result32,33,34,35. In our center, the patients are asked to take oral antibiotics for 7 days after surgery, while other centers use oral antibiotics for different durations after surgery2,20,22. Further studies are needed to determine the standard antibiotic duration and dosage after TOETVA.
Tumor prognosis is the most important problem in cancer surgery. It is generally believed that lymph node metastasis is associated with tumor prognosis and higher mortality36,37. One meta-analysis reported that the central lymph node dissection rates of the TOETVA group and NTET group were comparable28. However, the follow-up duration of other remote access endoscopic methods is longer than that of TOETVA27. Building up a prospectively large-scale cohort, with procedures such as the bilateral axillo-breast approach (BABA) and transaxillary methods23,24,25, will be necessary to check the tumor prognosis.
TOETVA is an innovation in the concept of thyroid surgery. With the aim of ensuring the quality of surgery and curing diseases, it achieves the characteristic of minimal invasiveness and embodies the treatment concept of natural orifice transluminal endoscopic surgery (NOTES). TOETVA has the advantage of a top-down perspective and can be used to thoroughly dissect the central lymph nodes, which may play an essential role in improving the radical effect and long-term prognosis of endoscopic thyroid cancer surgery.
The authors have nothing to disclose.
We thank all the patients who participated in this study for their cooperation. This research was supported by the project fund of the Science and Technology Department of Sichuan Province. (Grant No. 2021YFS0103).
Allis Grasping Forceps,310 mm x 5 mm | AESCULAP | PO111R | |
Button Electrode Tip | AESCULAP | GK385R | |
Ceramic Electrode | AESCULAP | GK384R | |
Complete Trocar | AESCULAP | EJ751R | |
Endoscope | Olympus | WA53005A | |
IONM | Medtronic | NIM-3.0 | |
Light Transmitting Bundle | Olympus | WA03310A | |
Maryland Dissecting Forceps, 310 mm x 5 mm | AESCULAP | PO102R | |
Monopolar Handle (5 mm diameter, 33 cm working length) | AESCULAP | GK372R | |
Pneumoperitoneum tube,4 m | STRYKE | 620-240-223 | |
Pyramidal Tip Obturator | AESCULAP | EJ755R | |
Reusable Monopolar Cable | AESCULAP | GK245 | |
Scissors | AESCULAP | P0004R | |
Suction irrigation tube | AESCULAP | PG027R | |
Super Righting Needle Holder, 5 mm | AESCULAP | PL414R | |
Veress | TianSong | E2014.6 |