All 6 patients completed transvestibule endoscopic thyroidectomy successfully, with no conversion to open surgery; among them, 5 patients underwent partial thyroidectomy and 1 patient underwent unilateral subtotal thyroidectomy. The mean operation time was 122 minutes (100 to 150 min). The average blood loss during surgery was 30 mL (10 to 40 mL). The pathologic diagnosis coincided with the preoperative diagnosis, which was 1 case of thyroid adenoma and 5 cases of thyroid goiters. The mean length of hospital stay was 8.2 days (8 to 10 d). No severe complications such as nerve damage or parathyroid injury were reported. One patient had a postoperative wound infection, but recovered thoroughly after symptomatic treatment. No local recurrence was reported during the follow-up of 3 to 13 months, and patients were satisfied with the cosmetic outcome (Fig. 3).
The Surgical Approach
Previous surgical manners of endoscopic thyroid surgeries included the supraclavicular approach, minimally invasive video-assisted thyroidectomy by anterior cervical incision, the subclavicular approach, the transaxillary approach, the areola and cleavage approach, the axillo-breast approa approach, and the fully areola approach.3 However, each of the above surgical approaches result in considerable scars on the skin surface that may bring about consequent psychological burden on patients. It is for the first time in 2009 that Wilhelm and Metzig4 conducted the first transoral thyriodectomy successfully and realized an absolute scarless effect. The transoral approach follows the anatomic characteristics of embryonic thyroid and achieved authentic minimal invasiveness and is also in line with NOTES principles.5 Nevertheless, the transoral approach of endoscopic thyriodectomy allows only a small incision of about 5 mm. Besides, this approach poses potential threats for damage of the sublingual gland, the submaxillary gland, the deep lingual vessels, etc. Moreover, small incisions also constrain the tumor size. Three of the 8 cases reported by Wilhelm were converted to open surgery due to difficult retrieval of specimens from the incision. On the basis of this approach, Wang et al6 ameliorated it and designed a thoroughly transvestibule approach for Chinese people, who are generally characterized by a flat mandible and mental region and a strong repair ability of the oral mucosa. Unlike the transoral approach, the transvestibule approach moves the observation port to vestibule and consequently lowers the risk of damaging important structures surrounding the transoral channel and increases the safety of the surgery. In conclusion, this operational manner widened indications of NOTES for thyroid diseases owing to its convenience in handling bilateral lesions and feasibility with relatively large lesions (Fig. 4).
Characteristics of Transvestibule Endoscopic Thyroidectomy
We have performed 6 transvestibule endoscopic thyroidectomies on patients with benign tumors of thyroid since September 2013, and summarized several features of NOTES for thyroid by the transvestibule approach. (1) Absolute scarless results are realized with incisions located in the buccal cavity. (2) Clear vision of anatomic structures is obtained with magnification of lens and angled tip of endoscopy.7 (3) Easy recognition of recurrent laryngeal nerves under endoscopy resulted in less injury of recurrent laryngeal nerves compared with open surgery. (4) Correct distinction of loose membranous structures in the deep surface of the superficial fascia under endoscopy helps surgeons loosen and separate at this anatomic level to establish operating space under the platysma, which can effectively ensure the postoperative anterior “flat” look.8 (5) Effective hemostasis: the harmonic scalpel can not only stanch bleeding during thyroid vascular dissection, but can also cut the thyroid gland directly. This instrument can facilitate surgeons to control bleeding effectively and allow the surgery to be performed without interruption, thereby reducing blood loss significantly.9 (6) The perspective is the same as with open surgery from the cephalic to the foot side. (7) Proper pressure for postoperative bandage can be achieved easily for surgical areas located outside the mandibular. (8) Good outcomes: this surgery method is safe and feasible with better recovery and fewer complications.
Choice of Patients
To lower the conversion rate, patients should be selected strictly according to surgeons’ technique and availability of devices to avoid unnecessary conversion due to improper patient selection, for example, a large tumor size, malignant lesions, intraoperative bleeding, etc. Because this is our first attempt to use the NOTES technique on thyroid surgery, we selected patients with unilateral solitary benign thyroid nodules in this group. In 2005, the Chinese Medical Association of Surgery, Laparoscopic and Endoscopic Surgery drafted surgical indications for endoscopic thyroid surgery as follows: (1) thyroid adenoma, (2) thyroid cyst, (3) nodular goiter (single or multiple, tumor diameter <5 cm), (4) solitary toxic nodules, and (5) low-grade malignant thyroid carcinoma. Surgical indications suggested by Wilhelm and Metzig10 for NOTES of thyroid: thyroid volume <30 mL; diameter of solitary nodule <2 cm. In our study, the eligibility criteria were as follows: (1) patients who comply with conventional endoscopic thyroid surgical indications; (2) patients without hyperthyroidism or parathyroid diseases; (3) tumor with the maximum diameter <5 cm (for cystic lesions >5 cm, apply suction first11; (4) I or II degree thyroid enlargement due to primary or secondary hyperthyroidism; (5) good mobility under palpation, clear boundary without significant adhesion with the surrounding benign tissue; (6) no history of neck surgery.
To enable the smooth implementation of the operation, and to minimize the occurrence of postoperative complications, attention should be paid perioperatively. (1) Prevent infection: this approach has altered the incision of thyroid surgery from type I to type II with the absence of drainage; therefore, the chance of effusion and postoperative wound infection could be increased, to prevent infection; perioperative antibiotics should be administrated. In our group, 1 patient had postoperative wound infection, but was cured after timely treatment with antibiotics and supportive treatments. (2) Protect the mental nerve: the chin hole, where mental nerves and blood vessels pass through (Fig. 5), is located beneath the gingival sulcus between the first and the second premolar on each side of the buccal cavity, and so the incision should be made between the 2 first premolars. It is beneficial for the preservation of the mental nerve function. (3) Identify the anatomic level: place the first trocar adjacent to the anterior muscle fascia and dissect as close to the muscle as possible. Identify the gap under the deep fascia, and dissect bluntly with a good grasp of the anatomic plane to make sure that it is not too shallow to avoid flap necrosis in the neck or too deep to cause muscular damage. (4) Proper use of the ultrasonic scalpel: good manipulation of the harmonic scalpel is vital: the longer the heating, the greater the thermal damage. Therefore, when dealing with tissues adjacent to the recurrent laryngeal nerve, use it intermittently with the distance >5 mm.12 Continuous usage of the harmonic scalpel should be avoided; the head temperature should be lowered by cleaning the ultrasonic head frequently to avoid damage to nerves, glands, and other tissues13; when performing in the area of the recurrent laryngeal nerve, blunt dissection is wiser.
Problems and Prospects
Transvestibule endoscopic thyroidectomy as a new minimally invasive surgical approach brings vitality to the industry of minimally invasive surgery on thyroid14; however, we still face many problems awaiting urgent solutions such as the operational difficulty,15 the long operative time due to the narrow operative space, large areas of soft tissue tear, leakage of small thyroid lesions, potential metal nerve damage, and consequent malfunction of expression muscles. Besides, whether this endoscopic surgical manner could apply to thyroid malignancies without violating tumor principles still requires careful considerations. However, we believe that with the development and the improvement of endoscopic surgical techniques and instruments, surgical indications for NOTES on thyroid will increase gradually; postoperative complications will be further reduced, and its development will lead to a new era of minimally invasive thyroid surgery.
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Keywords:Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.
thyroid surgery; transvestibule; endoscopy