Introduction
While endoscopic thyroid surgery development a significant surgical approaches variants number for performing interventions have been developed. Thus, video-assisted and "fully" endoscopic techniques were proposed because of the greatest interest. The main position among endoscopic approaches today is occupied by accesses outside the thyroid gland projection (extra-projection, extracervical). According to various estimates nearly 50 surgical approaches variants have been proposed. In them the introduction of trocars (techniques with gas mixture insufflation to maintain the working cavity volume) or the execution of section (techniques without gas insufflation to maintain once) is carried out in various anatomical areas. It is necessary to distinguish the axillary area, the paraareolar area, the area of the anterior chest wall as the most frequently used anatomical areas for surgery access [1, 2, 3, 4]. Transoral approaches and approaches involving the retroauricular region are began popularity [5, 6, 7]. At the same time, with all the variety of surgical procedures, the most important issue is to ensure a high level of safety during the thyroid gland endoscopic operations.
It’s necessary to mention that in all thyroid operation cases the methodological and technical approaches on our opinion should be performed like: anatomical space, surgeon work space, potentional surgeon work space, safety surgeon work space. But it should be mentioned that one of the great hindrances for deployment the thyroid surgery endoscopic techniques is the difficulty of work space forming and limitation. But at the same time the thyroid surgery endoscopic techniques require the appropriate enough for revision and manipulation surgical access [4, 8, 9]. Thus, it is necessary to develop appropriate work safety spacing forming techniques for such surgical thyroid endoscopic interventions.
The study aim — to develop optimal principles for the safe working space formation in the performing various endoscopic operations stages on the thyroid gland on the basis of experimental and primary clinical experience.
Materials and methods
The endoscopic thyroid surgery through extracervical accesses in 15 experimental interventions and 11 operations in patients with benign thyroid diseases were performed. The surgical interventions amplitude in all cases corresponded to hemithiroidectomy. The axillary region served as one of the access areas (or the only area) in all cases.
Experimental interventions were performed on 15 unfixed corpses (9 male and 6 female). 8 left-sided and 7 right-sided interventions with gas mixture insufflation were performed to maintain the working cavity volume. For their implementation, 3 types of surgical access were used — isolated axillary, axillary-mammary and original axillary-retroauricular (Russian Federation patent for invention No. 2500355 "Method of endovideosurgical access to the thyroid lobe"). With each of the accesses, 5 operations were performed. The cadavers whose operations were performed from the axillary access had an average height of 169.8 cm (from 158 to 182 cm), weight — 67.2 kg (from 58 to 79 kg). The average body mass index (BMI) was 23.2 kg/m2. The cadavers underwent operations by means of axillary-mammary access were characterized by an average height of 173.6 cm (from 157 to 186 cm), an average weight of 66.8 kg (from 53 to 81 kg), and an average BMI of 22.0 kg/m2. The cadavers selected for operations from the axillary-retroauricular approach had an average height of 174.8 cm (from 161 to 183 cm), an average weight of 70.2 kg (from 59 to 84 kg), and an average BMI of 22.9 kg/m2.
In the presented work clinical part 11 operations were performed by "gas-free" axillary endoscopic access, all in the volume of hemithiroidectomy. The working cavity volume was maintained by using a specialized retractor during such operations. The choice of hemithiroidectomy as the scope of surgical intervention (both in the experiment and in the clinic) was associated with the technical limitations of the used surgical access types. Such surgical intervention type do not allow for an adequate anatomical structures examination from the side opposite to the instruments insertion side. The only "gas-free" technique using at the stage of primary clinical experience accumulation was performed to minimize the risk of complications associated with gas insufflation into the working cavity. It should be noted that this risk may increase with an increase in the duration of the intervention, which can be observed in the new surgery method assimilation process..
The criteria for inclusion of patients for endoscopic surgery were as follows: age from 18 years and more; presence of a benign nodular formation (formations) thyroid gland with a diameter of up to 6.0 cm when localized in one lobe; ultrasound picture in the range of TIRADS 2-3; Morphological picture of the Bethesda II or Bethesda IV biopsy material; thyroid volume not exceeding 70 ml; voluntary consent of the patient to the operation and participation in the study.
The criteria for patients non-inclusion were: the presence of contraindications to routine surgical treatment or to general anesthesia; suspicion of a malignant nature of the neoplasm; BMI exceeding 35 kg/m2; the presence of thyroiditis or diffuse toxic goiter; multiple endocrine neoplasia syndrome; the presence of concomitant diseases of the parathyroid glands; previous operations and / or radiation in the neck.
The patients excluding criteria from the study were: identification of the patient during the preoperative examination or intraoperative disease affecting the scope and nature of surgery; failure to follow the recommendations of the attending physician in the postoperative period; refusal to undergo a control examination.
Before the surgery all patients underwent a comprehensive examination, on the basis of which the main preoperative indicators were recorded (Table 1).
Table 1. Preoperative parameters in patients who underwent endoscopic hemithyroidectomy
|
Parameter |
Value |
|
Male / Female, n |
2 (18.2%)/9 (81.8%) |
|
Age, years |
38.9±10.3 |
|
BMI, kg/m2 |
26.2±7.1 |
|
Right-side / Left-side nodular formation (based on ultrasound examination data ), n |
4 (36.4%)/7 (63.6%) |
|
Average node size (based on ultrasound examination data), sm |
4.3±1.2 |
|
Average thyroid volume (based on ultrasound examination data), sm |
53.5±10.8 |
|
Bethesda II / Bethesda IV (based on biopsy data), n |
7 (63.6%)/4 (36.4%) |
Note. BMI — Body Mass Index.
In all cases, the patients had an euthyroid condition. Surgical interventions for suspected nodular colloidal goiter (Bethesda II) were performed with a large node size and / or its rapid growth. The maximum size of the nodular formation was 5.7 cm.
Operational technique. All operations, both experimental and clinical, regardless of the used surgical access type, were performed in 5 stages: skin access, creation of the primary manipulation cavity, access to the thyroid lobe, hemithiroidectomy, specimen extraction and wound closure of access. The thyroid lobe selection and removal was performed in accordance with the original manipulation algorithm (Russia Federation patent for invention No. 2511461 "Method of endovideosurgical hemithiroidectomy). The actions sequence on performing all stages of endoscopic thyroid surgery was considered in detail in one of the previous publications [10], so in this paper we would like to focus on the description of the features of the formation of the working space.
At the stage of skin access, for further working space creation it is necessary to correctly determine the trocars introduction points (for operations with gas insufflation) or the location and length of the incision in the axillary region (for "gas-free" access). Places for the introduction of axillary trocars should be selected at the most upper and lower points of the axillary cavity, along the posterior edge of the pectoralis major muscle. The incision of the skin and subcutaneous tissue with" gas-free " access should also be carried out along the posterior edge of the pectoralis major muscle, its length should be at least 5 cm to ensure sufficient working space width and endoscopic instruments triangulation.
When creating a primary manipulation cavity, it is necessary to ensure that the tissue dissection is carried out in the correct layer and a sufficient cavity width and height. It is safe to dissect the fiber in the layer between the thoracic fascia upper leaf and the pectoralis major muscle, which should be identified as the cavity bottom (Fig. 1). It should be noted that the "way" to the thyroid gland was formed through the muscle fascial sheath and the pectoralis major muscle anterior surface was the reference point. Sufficient width and height, of the formed tunnel to the thyroid gland are important conditions for further safe manipulations during organ isolation, as they contribute to the creation of the necessary volume of the working cavity (Fig. 2). The principal condition at this stage is the formed cavity direction. The tunnel to the thyroid gland should be led diagonally from the axillary region to the projection of the thyroid gland, above the clavicle. With the horizontal direction of dissection (to the upper part of the sternum), which may seem easier during the operation, in the future there will be an exit to the lower pole of the thyroid gland, and not to its lateral surface, which will significantly complicate the performance of hemithiroidectomy. During operations with gas insufflation, safety is also ensured by the low pressure level of the gas mixture (6—8 mm Hg), which prevents its spread through the cellular spaces and into the mediastinum. During operations from the" gas-free " access, timely replacement of the retractor blade holding the upper wall of the manipulation cavity is necessary, in accordance with the gradual increase in the depth of the wound and the required length of the blade.
Fig. 1. Creation of the primary manipulation cavity by dissection of adipose tissue in the layer between the superficial sheet of the f. pectoralis and the m. pectoralis major.
Fig. 2. The volume of the primary manipulation cavity is formed, dissection of adipose tissue is carried out to the lateral edges of the origins of the right m. sternocleidomastoideus.
When performing an operation using an axillary-retroauricular approach the trajectory of the retroauricular trocar insertion intersects with the projection of the external jugular vein. To prevent the vein damage it is necessary to use one of the special techniques: preoperative ultrasound vein marking, dissection of subcutaneous tissue from the side of the manipulation cavity along the sternocleidomastoid muscle before identifying the vein, introduction of a trocar in the muscle layer of the sternocleidomastoid muscle without entering the subcutaneous tissue, introduction of a trocar with a close-focus endoscope instead of a stiletto to examine the passable layers.
At the all thyroid lobe accessing stage, the working space formation continues by creating a window between the sternocleidomastoid muscle pedicles without crossing the muscle fibers (Fig. 3). To minimize the vascular structures damage risk, the pedicles separation should be made as close as possible to the medial pedicles posterolateral surface. Stitching the sternocleidomastoid muscle medial pedicle to the working cavity upper wall during operations with gas insufflation is required to perform two sutures covering the pedicle from the outside to prevent bleeding from the muscle and reduce pressure on it. In operations without gas mixture insufflation it is necessary to make the retractor blade length and width reasonable choice which is inserted into the interdigital space for avoiding damage to the anatomical formations if the blade size is too large.
Fig. 3. Creating a window between the origins of the m. sternocleidomastoideus for subsequent access to the lateral surface of the right lobe of the thyroid gland.
After creating a window between the sternocleidomastoid muscle pedicles, the pretracheal muscles (sternocleidomastoid, sternocleidomastoid, scapulocleidomastoid) become available for further manipulation which are partially dissected. The pretracheal muscles dissection should be performed on half of their width from the side of the removed lobe of the thyroid gland, which will contribute to the best conditions for layered wound healing in the future and reduce the likelihood of the formation of fluid accumulations. A pretracheal muscles wider dissection although they do not have functional significance, does not make sense and does not improve the conditions for the subsequent allocation of the lobe during the hemithiroidectomy.
During the thyroid lobe direct isolation before tissue dissection in the area of the main vessels and the recurrent laryngeal nerve, it is necessary to ensure the necessary mobility of the lobe, which is achieved by initially isolating it first in the upper pole area (Fig. 4a), and then the lower pole (Fig. 4b). This isolation allows to achieve the necessary removed lobe mobility during its traction within the working cavity after gripping the clamp, which improves the conditions for examining structures in the recurrent laryngeal nerve and tracheoesophageal furrow localization area. The moment of the end of tissue dissection during the actual hemithiroidectomy is the exit to the anterior trachea surface, which actually simultaneously completes the formation of the working cavity. At this stage the thyroid gland lobe in the isthmus area is cut off using ultrasound scissors with a safe distance (at least 2—3 mm) from the trachea to prevent thermal damage to the latter.
Fig. 4. Mobilization of the upper (a) and lower (b) poles of the right lobe of the thyroid gland.
Results
The experimental interventions results analysis showed that the average time of operations with isolated axillary access was 147.7±19.6 minutes, interventions with axillary-mammary access — 108.3±12.1 minutes, operations with axillary-retroauricular access-113.5±14.2 minutes. Confident identification of both parathyroid glands on the operation side was achieved in all 15 cases. The recurrent laryngeal nerve was identified during hemityroidectomy during 3 out of 5 operations with isolated axillary access, 4 out of 5 operations with axillary — mammary access and axillary-retroauricular access.
In the clinical studied groups the main intraoperative and postoperative indicators (Table 2).
Table. 2. The results of operations in patients who underwent endoscopic hemithyroidectomy
|
Parameter |
Value |
|
Average surgery time, min. |
173.4±62.7 |
|
The average creating surgery access stage time, min. |
118.3±49.5 |
|
The recurrent laryngeal nerve identification, n |
8 (72.7) |
|
Both parathyroid glands identification, n |
10 (90.9) |
|
Complications, n |
|
|
perforation of the skin in the clavicle area, n |
1 (9.1) |
|
plexitis of the brachial plexus, n |
5 (45.5) |
|
Duration of parenteral anesthesia, day |
2.2±0.6 |
|
Average duration of postoperative wound drainage, days. |
3.6±0.5 |
|
Average amount of drainage discharge, ml |
207.5±58.2 |
|
Duration of hospitalization, day |
6.7±1.4 |
The obtained data analysis showed the average time of surgical intervention significantly exceeded the average duration of experimental operations, approaching 3 hours. This is explained by the stage of mastering the technique in clinical practice. But the expected average duration of operations to decrease as accumulating practical experience. It should be noted that the creating operational access stages (the first three stages of the operation) were the longest, taking up 68.2% of the total intervention time.
Identification of both parathyroid glands and the recurrent laryngeal nerve on the surgery side during the actual hemithiroidectomy was achieved in the majority of cases.
In the presented observations severe specific complications, such as postoperative hypoparathyroidism and impaired mobility of the vocal cords were not mentioned. There were also no cases of postoperative seroma in the tunnel projection formed from the axillary region towards the thyroid gland. The recorded complications were represented by 1 case (9.1%) of skin perforation in the clavicle area on the surgery side, which was obtained during the creation of a subfascial tunnel for access to the thyroid gland due to excessive fiber dissection. In 5 patients (45.5%) in the immediate postoperative period, the phenomena of the brachial plexus plexitis on the side of the intervention were noted, which were manifested by paresthesia and partial loss of skin sensitivity in the distal parts of the upper limb. The phenomena of plexitis in all cases were completely resolved within the first day after the operation, independently or with medical support. The development of plexitis is because of the prolonged upper limb forced position on the operation side during the intervention. Also expected a significant reduction in the frequency of plexitis development as practical experience is accumulated and the duration of operations is reduced. In our experience, the upper limb on the side of the operation was fixed on the holder in the "pioneer greeting" position. An alternative option is to simply move the limb to an angle of 90°, but this position limits the space for manipulating the instruments, which can lead to the development of more severe complications during tissue dissection. It should also be noted that the appearance of plexites is not associated with the peculiarities of the operational technique of operations and the creation of a working space for manipulations. This complication also cannot be caused by the pressure of the instruments during tissue dissection, since during the intervention there is no significant and prolonged pressure of the instruments on the plexus zone and the projection of the nerves.
The average patients hospitalization duration was close to 7 days, was associated with the need for a postoperative wound long drainage of the through a counterperture in the axillary region in order to prevent the development of fluid accumulations. Also it was connected with desire of extending the observation of patients in hospital conditions at the stage of the method implementation in clinical practice. According to the postoperative morphological study, nodular colloidal goiter was detected in 8 cases (72.7%), thyroid adenoma — in 3 cases (27.3%), which was generally consistent with the preoperative data. After the scar formation a in the axillary region patients were interviewed for a subjective aesthetic assessment of the operation outcome of the. According to the 5-patient scale, 9 patients (81.8%) regarded the aesthetic result as excellent, and 2 patients (18.2%) — as good. The number of basic principles that contribute to the formation of a safe working space in the process of performing endoscopic operations on the thyroid gland from accesses that include the axillary region are based on the experience gained, the results of experimental operations and interventions carried out in the clinic:
— Trocar insertion points or skin incision points exact determination;
— Working cavity of sufficient width and volume creating;
— The correct choice of the tissue dissection direction in forming a tunnel to the thyroid gland;
— Maintaining a gas mixture low pressure during operations from gas insufflated access points;
— The retractor length and width correct selection at various stages of operations from access points without gas insufflation;
— Accounting for the projection of large neck vessels during trocar insertion and tissue dissection;
— Muscle structures careful isolation for prevention bleeding from them;
— Ensuring sufficient mobility of the removed thyroid lobe before the recurrent laryngeal nerve and parathyroid glands identification;
Keeping a distance from important anatomical structures during the electrosurgical instruments using to prevent thermal injury.
Results discussion
Endoscopic thyroid surgery is an intervention in a potential workspace. The workspace creation is associated with a certain complications development risk. Thus usage the number of techniques and principles that increase the level of security during the formation of the workspace should be considered useful and absolutely justified.
The obtained experimental and clinical experience, during which the proposed principles of safe working space creation were developed and implemented, allowed to avoid the development of severe complications in patients, especially associated with postoperative hypoparathyroidism and damage to the recurrent laryngeal nerve. All recorded complications should be classified as "small" and not compromising the applied method. For example, damage to the skin in the clavicle area was associated with technical errors, and plexitis of the brachial plexus — with the forced prolonged position of the upper limb during surgery, which is typical for most endoscopic surgical accesses to the thyroid gland, but can be overcome by reducing the intervention time after the completion of the stage of its full development.
A number of other authors also offer some ideas of the operational equipment specificity during the working space creatioT during endoscopic thyroid surgery, offering various solutions. For example, L. Y. Zhang et al. [11] suggest using a combined gas-liquid mixture when creating a workspace. When comparing the results of endoscopic operations on the thyroid gland by means of thoracic access in the group with the use of the proposed mixture and in the group without its use, the authors found that the proposed method allowed for a statistically significant reduction in the duration of the stage of working space creatingin the absence of differences in other indicators. [12] in 30 cases, when performing a BABA (bilateral axillo-breast approach) operation, the method of "single biaxillary tunneling" was used, including limiting blunt tissue dissection with the passage of fiber "in one stroke". It was noted that this approach can significantly reduce the time spent on the formation of the working space, reduce the frequency of hemorrhages in the subcutaneous tissues and could be used by inexperienced surgeons. It should be noted that the method proposed in this article is contrary to most of the known methods in terms of the risk of injury to anatomical structures due to the lack of methodical step-by-step dissection.
In the literature, there are references about choosing of a layer to create a workspace and a tunnel to the thyroid gland. Y. H. Tan et al. [13] performing endoscopic operations on the thyroid gland proposed to form a working space between the superficial fascia anterior and posterior leaves of the breast from the bilateral areolar access. This technique was implemented in 85 patients with benign thyroid diseases with good results and without significant complications.
In a number of studies usage of additional lifting systems is proposed to improve the quality of the formed working cavity. Y. J. Lyu et al. [14] supplemented the thoracic endoscopic access with gas mixture insufflation by introducing an additional curved lift of their own design through a point puncture in the neck. This technique use of allowed to increase the working space height by an average of 1 cm and reduce the time spent on the stage of lobectomy and central lymph node dissection in comparison with operations during which the lift was not used (46.7±4.7 minutes versus 50.7±4.9 minutes.; p<0.01). At the same time, the total duration of operations averaged 78.1±6.6 minutes and 80.4±7.0 minutes. accordingly (p=0.069). K. Shimizu et al. [15] note that currently in Japan, the working space during endoscopic thyroid surgery is formed in 81.5% of cases when using the" gas-free " technique. In this case both retractors inserted into the wound and additional lifting systems are used, in the sticks form lift the skin in the area of the front neck surface.
For transoral access various options for operational approaches are also proposed, including in the formation of the workspace. They can consist both in changing the spatial arrangement of the instruments [16], and in using single endoscopic access systems with hydrodissection to expand the created working space [17].
It should be noted that in accordance with our own results and data from literature sources, the question of the correct and safe formation of the working space during endoscopic thyroid surgery should be considered one of those topics that requires active discussion and close attention. We hope that the above principles of creating a safe working space will help reduce the risk of complications during endoscopic thyroid surgery and will be useful for surgeons performing minimally invasive operations in thyroid surgery.
Conclusion
The the complications risk of endoscopic thyroid surgery reducing continues to be one of the main aims in minimally invasive endocrine surgery. The proposed principles of working space formation will significantly increase the level of safety during endoscopic operations on the thyroid gland from the access points, including the axillary region, in the process of further wider technique application in practice.
The participation of the authors:
Concept and design of the study — I.A. Kurganov, S.I. Emelyanov, M.Sh. Mamistvalov, D.Yu. Bogdanov
Data collection and processing — I.A. Kurganov, S.I. Emelyanov, M.Sh. Mamistvalov, D.V. Lukyanchenko, O.A. Agafonov
Statistical processing of the data — I.A. Kurganov
Text writing — I.A. Kurganov, M.Sh. Mamistvalov
Editing — S.I. Emelyanov
The authors declare no conflicts of interest.