Details on the age and sex of patients are listed in Table 2. The basic information of patients including age and sex was reported in 9 articles (n=203, 96.2%). The average age reported in 9 articles ranged from 24.0 to 54.9 years old, with a weighted average of 35.6 years old. The amount of female patients is 179 cases (88.2%).
The review of perioperative outcomes were presented in Table 3. The location of incision is reported in 10 articles (n=211, 100%) and 9 authors (n=203, 96.2%) chose the oral vestibular area of the lower lip. The mean operative time, available in 10 studies, ranged from 60.4 to 265.4 minutes, with a weighted average of 119.9 minutes. Mean volume of intraoperative blood loss, reported in 7 articles (n=188, 89.1%), ranged from 11.1 to 97.0 mL, with a weighted average of 35.5 mL. Ninety-eight patients (46.4%) underwent single thyroidectomy. Details of pathologic diagnosis were presented in 9 articles (n=203, 96.2%). Overall, 22 patients were diagnosed with papillary carcinoma (10.4%) and the other 189 patients harbored benign lesions (89.6%). The average hospital stay days was reported in 8 articles (n=157, 74.4%), which ranged from 1.2 to 8.2 days, with a weighted average of 4.0 days. Two articles8,15 reported 4 cases (1.9%) converted to open surgery. The main reasons for conversion were technique and bleeding complications.
The postoperative complications are listed in Table 4. The most common complications in transoral thyoidectomy are hypoparathyroidism, RLN injury, mental nerve palsy, and wound infection. Temporary hypoparathyroidism was reported in 4 articles11,14,15 and the overall incidence was 7.1%. Nine temporary RLN injuries were presented in 5 articles8,9,11,12,14 and the overall incidence was 4.3%. Only 1 case of permanent RLN injury occurred in this review. Mental nerve palsy was reported in 2 articles8,10 and the overall incidence was 4.3%. Two patients incurred wound infections. Other complications, including skin ecchymosis, emphysema, hematoma, skin pierced, and skin burn were reported in this review.
Thyroidectomy is one of the most common procedures performed in general surgery. Because of the advancement in surgical technique, the modifications, modernization, and development of the instruments including intraoperative neuromonitoring, and the assistance of optical magnifying devices,18,19 thyroidectomy is considered a safe procedure. Aside from the known complications including RLN palsy and hypoparathyroidism, the visible scar mark in the neck after conventional open thyroidectomy may lead to unpleasant consequence for the patients. Various approaches to endoscopic thyroidectomy2,20,21 have been developed in recent years, which can avoid the visible scar in anterior neck postsurgically. However, some surgeons think that these approaches do not comply with the ideology of minimally invasive surgery due to extensive dissection from a remote site. Since the natural orifice transluminal endoscopic surgery concept emerged in modern surgery, TOTE gained rapid development in recent years, requiring a shorter dissection tunnel compared with other approaches.
Several different approaches were invented during the development of transoral thyroid surgery including vestibular approach, sublingual access, and the combination of both. However, the sublingual access can bring structural and operative damage to the floor of the mouth. So the sublingual access is avoided and discontinued. Transoral vestibular approach is feasible and allows easy accessibility to the thyroid area. Meanwhile TOTE has less trauma, quicker postoperative wound healing and a lack of visible residual surgical scars. However, with this approach, surgeon requires an in depth knowledge in the anatomic structure of the operative area as the dissection is performed in the cranio-caudal direction which differs from open thyroidectomy.
Even though transoral thyroid surgery has left its infantile state, not all patients diagnosed with thyroid disease meet the criteria of this procedure. At present, the inclusion criteria are as follows: (1) benign tumor, such as single or multinodular goiter; (2) follicular neoplasm; (3) Graves’ disease; (4) thyroid papillary carcinoma without any evidence of metastasis.9,11,12 However, the most important criteria is that the patient is keen to pursue an optimal cosmetic result. Exclusion criteria comprised of patients who were as follows: (1) unfit for surgery; (2) had previous surgery or radiation in the area of neck; (3) evidence of tracheal/esophageal invasion or metastasis; (4) infected lesions like oral ulcers.10–12,14,17
A prolonged surgical time was noted in TOTE compared with open surgery. In the present study, the mean operative time ranged from 60.4 to 265.4 minutes, with a weighted average of 119.9 minutes. Intraoperative time for thyroid surgery is not less as extra time is needed to create the working space or port insertion. However, Cunchuan Wang10 reported that the average surgical time was 60.4 minutes which was much shorter than other authors. Lee22 believed that the learning curve should stabilize after 20 procedures. Therefore, the surgical time should be considered as an improbable factor. In this review, 22 patients were diagnosed with papillary carcinoma (10.4%), and the other 189 patients harbored benign lesions (89.6%). The central node of patients with papillary carcinoma was dissected in all articles. Four cases (1.9%) in this review were converted to open surgery because of technique and bleeding complications.
Hypoparathyroidism and RLN injury were the most common complications in thyroid surgery. The overall incidence of temporary hypoparathyroidism in this study was 7.1%. Fewins et al23 reported that the incidence rate of hypoparathyroidism in thyroid surgery was 6.9% to 46%. The overall incidence of temporary RLN injury was 4.3%. However, in conventional open thyroidectomy, the rates of transient and permanent RLN injury in the literature ranged from 2.11% to 11.8% and from 0.2% to 5.9%,24 respectively. Meanwhile, mental nerve palsy was reported in 2 articles8,10 published in 2011 and 2014 with an overall incidence of 4.3%. The mental foramen is most commonly located below and between the mandibular premolar, however the 2 lateral incisions were made in the vestibule near the premolars. Therefore, the mental nerve palsy may also occur in TOTE. So care must be taken to identify and avoid this nerve injury while making the lateral incisions. Concern for the infection occurrence arises due to the presence of the clean-contaminated wounds in transoral thyroid surgery. Therefore, in this study the patients who underwent this procedure were given prophylactic antibiotics to prevent wound infection due to clean-contamination wounds.
Conclusions based on the review of 10 articles with 211 cases suggest that TOTE is feasible and safe in selected patients. However, some pending questions about this procedure still remains which includes learning curve, long-term outcomes etc., which should be demonstrated. Therefore, specifically designed prospective randomized trials including standardization of outcome measures need to be performed to evaluate TOTE further.
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Keywords:Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.
transoral thyroidectomy; thyroid surgery; vestibular