Beijing Bohaikangyuan Medical Devices Co., Ltd.
Beijing Bohaikangyuan Medical Devices Co., Ltd.

Tips for Complete Laparoscopic Lymph Node Dissection for Thyroid Cancer

The incidence rate of thyroid cancer is increasing year by year, of which 90% are papillary carcinoma. Even for micro papillary carcinoma, the incidence of lymph node metastasis in central area (Area VI) can reach about 50%. Lobectomy and routine dissection of lymph nodes in Area VI are widely accepted. With the development of economy and the improvement of living standards, oncoplastic thyroid surgery (OTS) for thyroid cancer, that is, to cure thyroid cancer and obtain the maximum cosmetic effect at the same time, is the common long cherished wish of thyroid surgery and patients. Therefore, endoscopic thyroid surgery emerges as the times require. After more than 20 years of clinical application, the concept and surgical skills of endoscopic thyroid surgery have been improved. Lobectomy and selective neck lymph node dissection are safe and feasible. Due to the limitation of operation space and the shielding of sternal handle and clavicle, endoscopic neck lymph node dissection is difficult and demanding, which has its strict surgical indications and contraindications. On the basis of conventional dissection of the central area, I have carried out selective Lymph node dissection in the lateral cervical region. At present, some experience has been accumulated in cleaning areas Ⅱ, Ⅲ, Ⅳ, and Ⅴ B. The related problems of complete endoscopic neck lymph node dissection will be discussed in combination with the literature.

1. Establishment and maintenance of operation space

A good operating space is the first step to a successful operation. Normally, the doctor will report the method of establishing the operating space under complete endoscopy. The first choice for beginners is the thoraco mammary approach. The whole areola approach has better cosmetic effect. The oral approach is suitable for special people, which is a real scarless OTS on the body surface. For unmarried women, especially patients with small areola or large breasts, the incision of the right operation hole can be moved up by 5 mm to leave the areola for easy operation. The thoracic mammary approach is the first choice for the cleaning of the lateral cervical area. The lateral boundary of the space on the sweeping side must be free to the lateral edge of sternocleidomastoid muscle (SCM). After the completion of thyroidectomy and central area dissection, the cervical lymph nodes can be cleaned, and the trocar direction of the cleaned side can be readjusted (opposite to the direction of 1 / 3 in the clavicle).

It is recommended to select a special visual puncture stripper (Patent No.: ZL201410177508.9) to establish the operation space under direct vision, so as to ensure the correct level and reduce bleeding. Holding the suction device in the left hand can absorb and remove water vapor and smoke while maintaining the space; Properly opening the exhaust holes of bilateral operation holes trocar can promote the timely discharge of smoke in the space. The mixed space maintenance method with high flow and low pressure is used to maintain the space, so as to ensure the clarity of the operating field. Two retractors can be used to pull SCM or banded muscle laterally during neck lateral area cleaning. If necessary, the third retractor or minilap can be placed to cooperate with the lens to obtain a good operation field.

2. Central lymph node dissection

The scope of lymph node dissection in the central area under endoscopy is the same as that of open surgery. In principle, the lymph nodes in the central area include the lymph nodes in front of the larynx, trachea, and bilateral paratracheal. For beginners, it is recommended to choose unilateral operation. When cleaning the left side, the tissue near the trachea on the right side, that is, the thyroid on the right, the innominate artery, the tissue between the common carotid artery and the trachea, and in front of the right recurrent laryngeal nerve (RLN), should be cleaned routinely. The right central area should be cleaned, and the tissue next to the left trachea, that is, between the left thyroid, trachea and left RLN, should also be cleaned. Because the ascending position of the right RLN is shallow and runs through the right central lymph node and adipose tissue space, the right central lymph node is divided into two groups before and after RLN. The difficulty of cleaning the right side under endoscope is increased significantly. Therefore, beginners should start with cleaning on the left. RLN is an important marker of lymph node dissection in the central region, and routine whole course exposure is recommended. During the cleaning of the central area, two pull hooks must be placed at the same time. If two retractors enter from the same side, one will pull and the other will push, that is, the lower retractor pulls the banded muscle to the outside, and the upper retractor pushes the trachea to the opposite side. If the retractor is inserted from both sides, the trachea and banded muscle are pulled from both sides, and the position and force direction of the retractor are reasonably adjusted to achieve the best exposure, so as to open the surgical field and make the operation more convenient and clear. Insufficient use of banded muscle cleaning will affect the ideal exposure of traction.

Now, taking the right side as an example, this article expounds on the specific steps of endoscopic lymph node dissection in the central area through the thoraco mammary approach. After lobectomy, lift the thymus and disconnect it with an ultrasonic knife right in front of the trachea. Pay attention to the effective coagulation of the lowest blood vessel of the thyroid to prevent bleeding. Remove the thymus in front of the trachea and clean the lymph nodes in front of the trachea and first separate the anterior 2 / 3 tissue of the medial trachea. However, in the operation of transoral approach, due to the field of vision from top to bottom, there is no need to remove the thymus, and the steps of cleaning the central area can be cleaned from outside to inside. Adjust the position of the right lower retractor, expose the right common carotid artery and innominate artery, disconnect them from bottom to top with an ultrasonic knife in front of them until the level of the lower edge of the thyroid cartilage, and pay attention to 2 to 3 inferior thyroid veins. It is suggested that minilap be used routinely to preserve the upper pole of thymus in order to preserve some lower parathyroid glands and their blood supply. Then, the lymph nodes of the tracheoesophageal sulcus can be cleaned. RLN can be located and exposed from the low position and cleaned from bottom to top. Our suggestion is to start with the exposed RLN, expose the RLN from top to bottom with a small right angle bend, and then expose the RLN from top to bottom in combination with the whole process and first clean the lymphoid adipose tissue in front of the RLN. Pay attention to pad a yarn on the exposed RLN surface to prevent thermal damage to the ultrasonic knife; Disconnect the blood vessels in front of and near RLN one by one with an ultrasonic knife. When cleaning to the lower boundary, lift up the cleaned lymphoid adipose tissue as much as possible to overcome the obstruction of clavicular bone and sternal notch, and routinely remove part of the thymus to clean the posterior lymph nodes.

When cleaning the posterior lymph nodes of the right RLN, make rational use of the advantages of the retractor and carefully separate the RLN from the posterior tissue. The RLN is pulled to the outside, and the posterior medial tissue is lifted to remove the posterior group of lymph nodes on the premise of ensuring the safety of RLN. Do not pull excessively upward and medial to avoid damaging the cervical sympathetic nerve and esophagus.

The difficulty of endoscopic lymph node dissection is to ensure the functional integrity of RLN and the in situ preservation of the parathyroid gland while cleaning the central lymph nodes. With the wide application of high-definition endoscopy, it is easier to find RLN and parathyroid gland in OTS than in open surgery. For conditional units, it is recommended to routinely use i intraoperative neuromonitoring(IONM). Routine use of IONM in OTS can significantly shorten the learning curve and reduce the permanent injury of RLN. In particular, continuous nerve monitoring is applied during operation, because it can make immediate feedback and alarm for traction, separation, clamp, and other operations, so that the operator can correct actions in time, and change bad operation habits, which can greatly improve the safety of OTS. However, when placing continuous monitoring electrodes, the vagus nerve must be exposed first. In addition, the operation space under endoscopy is small and the operation instruments are limited. Therefore, it will take some time. The application of multifunctional separating forceps with detection function can realize real-time detection, which is convenient and safe, and can replace continuous nerve monitoring during operation.

On the one hand, the application of nano carbon in OTS can improve the thoroughness of lymph node dissection; On the other hand, according to the principle of negative development of parathyroid gland, it can improve the possibility of in situ preservation of parathyroid gland and reduce the incidence of permanent hypoparathyroidism. Although some scholars advocate that the inferior parathyroid gland should be mainly autologous transplantation, we suggest that the parathyroid gland should be retained in situ as much as possible during the operation, and the parathyroid gland with affected blood supply, which cannot be retained or accidentally cut should be immediately implanted in the healthy side SCM. Pay attention to the blood supply of the parathyroid gland retained in situ. If there is congestion, it is recommended to puncture the capsule of the parathyroid gland with a No. 7 needle at multiple points.

3. Cervical lymph node dissection (selective dissection of Ⅱ, Ⅲ, Ⅳ and part Ⅴ b)

The classic "L" incision significantly will affect the appearance of cervical lymph node dissection in open surgery. Especially for patients with scar constitution, it will affect the appearance and function of the neck and seriously affect the quality of life. Although there has been a practice of low arc incision in recent years, the scar of 6 to 8 cm in the neck is still difficult to avoid. OTS via transthoracic approach can complete selective cleaning and achieve the effect of beauty while curing diseases.

The approach and steps of endoscopic cervical lymph node dissection are different from those of traditional open dissection. According to the approach of endoscopic dissection, the author's center is applied to open cervical lymph node dissection, which is safe and feasible, and also in line with the tumor free principle of intrathecal metastasis of thyroid papillary carcinoma. The lymph nodes in the lateral cervical region are cleaned under endoscopy. The SCM intermuscular approach between the clavicular head and the thoracic head is selected to clean the lymph nodes in areas III and IV. First, use the separating forceps to find the potential gap between the clavicular head and the thoracic head, and use the ultrasonic knife and electric hook alternately to free from bottom to top, down to the clavicle and up to below the bifurcation of the carotid artery. Reasonably use the special retractor to pull the thoracic bone and clavicular bone to both sides to expose the scapulohyoid muscle. In order to facilitate operation, it can be disconnected with an ultrasonic knife. Open the carotid sheath, separate the lymphoid adipose tissue along the surface of the internal jugular vein, gradually pull the internal jugular vein inward to expose the vagus nerve, and clean the tissue behind the internal jugular vein. The difficulty of cleaning the lateral cervical area lies in the cleaning of the venous angle in area IV. Firstly, clean the tissue at the junction of zone III and IV, then lift it to the head, lean to the outside and above, and expose the thoracic duct or lymphatic duct at the corner of the vein. The communicating lymphatic vessels between the neck trunk of the thoracic duct and the subclavian trunk should be clamped with Hemolock as far as possible to prevent postoperative lymphatic leakage; The communicating lymphatic vessels between the neck trunk of the thoracic duct and the subclavian trunk should be clamped with hemolock as far as possible to prevent postoperative lymphatic leakage; Then expose the transverse cervical vessels, C3 and C4 nerve roots, and clean the lymph nodes in areas Ⅳ, Ⅲ and part Ⅴ B from inside to outside and from bottom to top. When cleaning, it should not be deep to avoid causing damage to deep phrenic nerve and brachial plexus; Reasonably use energy instruments to avoid damaging the supraclavicular nerve and transverse cervical nerve; When cleaning some lymph nodes in area Ⅴ B, pay attention to the protection of external jugular vein and accessory nerve.

When continuing to clean up the lymph nodes in areas II and III, SCM and banded intermuscular approach are used to separate them from the internal jugular vein upward and medial. Pay attention to the protection of facial vein, expose the posterior abdomen of digastric muscle and clean it from inside to outside. Pay attention to expose the accessory nerve and clean the lymph nodes in area IIA. If the transfer is relatively limited or the transfer of area IIA is not clear, area IIB may not be cleaned routine. So far, selective cervical lymph node dissection has been completed.

It is also feasible to clean area IIB under endoscope. Use minilap or suture to pull the accessory nerve. Pull the accessory nerve upward and laterally, and clean the lymph nodes in area IIB with electric hook or ultrasonic knife. During lymph node dissection in area II, pay attention to protect the facial vein and disconnect the branches of internal jugular vein to prevent internal jugular vein from tearing and bleeding. When exposing the accessory nerve, pay attention to the accompanying vein. In case of bleeding, do not blindly stop bleeding to avoid damaging the accessory nerve.

Cervical lymph node dissection often encounters bleeding caused by internal jugular vein injury. The main cause of bleeding is the rupture of internal jugular vein when dealing with the branches of internal jugular vein, including muscle reflux vein, lymph node reflux vein and facial vein. If the breach is too large, in addition to the large amount of bleeding, there  will be a risk of gas embolism. In case of bleeding, carbon dioxide injection should be stopped immediately, and the bleeding should be controlled with non-invasive grasping forceps to rely on the retractor to maintain the space. Endoscopic repair of internal jugular vein is relatively difficult. At this time, reasonably use the suction device to find the bleeding site and deal with it according to different conditions. Most of them can be coagulated and closed with ultrasonic scalpel, and then clamped with Hemolock. If the internal jugular vein is thin, especially before the facial vein converges, it can be coagulated and closed directly with an ultrasonic scalpel, then ligated or clamped with Hemolock. For blood vessels with a diameter greater than 6 mm, it is recommended to suture or ligate directly. If possible, 5-0 Prolene can be used for suture, and ultrasonic scalpel should not be used. If the bleeding cannot be stopped under endoscopy, switch to open surgery or increase small incision in the neck.

To sum up, under the condition of strictly mastering the indications, it is safe and feasible to complete the selective cleaning of the central area and lateral cervical area under endoscopy. However, due to the narrow operation space and high requirements for the operator, the operator must have rich experience in open thyroid cancer surgery and skilled endoscopy technology. With the application of new instruments and technologies such as IONM and nano carbon negative parathyroid development, OTS will be popularized and applied to meet the needs of some patients. If there are all kinds of accidents during the operation, including differences from the preoperative evaluation, those who cannot complete the operation or radical cure, should be transferred to open operation in time to ensure safety.