Keywords

1 Background

The bilateral axillo-breast approach (BABA) is currently one of the most popular endoscopic thyroidectomy techniques in the world [1]. Since the first endoscopic parathyroidectomy was reported in 1996 [2], the development of minimally invasive thyroidectomy has been fueled by the need to eliminate neck scars [3, 4]. Currently, there are two main models of endoscopic approach to thyroidectomy [2]. The first involves techniques that reduce the scar length, making it less obviously visible, and include the popular minimally invasive video-assisted thyroidectomy described by Miccoli, as well as approaches made through an endoscopic lateral incision, lateral mini-incision, or postauricular incision [2]. The second model is extracervical endoscopic thyroidectomy, developed for scarless neck surgery. This includes the transaxillary approach [5], the axillo-breast approach, the anterior chest/breast approach, the bilateral breast approach, and the transoral endoscopic approach. Conceived as a modification of the axillo-bilateral breast approach by Shimazu et al. [6], the BABA was developed in 2007 by Choe et al. [7]. The initial experiences with BABA endoscopic thyroidectomy (BABA-ET) recorded satisfactory cosmetic outcomes but were associated with many technical challenges and safety concerns: with the use of straight rigid instruments without articulations and a two-dimensional camera view within the limitations of a narrow working space, the operation proved difficult to perform and the learning curve was longer than that of traditional surgical treatment [8]. Thus, BABA-ET could be applied to a small subset of patients only [3, 4]. With introduction of the da Vinci robotic system (Intuitive Surgical, Inc., Sunnyvale, CA, USA), hand tremor filtration, multi-articulated endo-wrist function, fine motion scaling, and three-dimensional magnification were used to overcome many technical disadvantages of BABA-ET, and the indications for BABA robotic thyroidectomy (BABA-RT) could be largely extended [9].

2 Indications and Patient Selection

A large body of evidence supports that BABA-RT can now be safely and effectively applied to the management of benign and malignant thyroid conditions [9,10,11].

BABA-RT currently has the following indications:

  • low-risk differentiated thyroid carcinoma <4 cm in diameter

  • minimal invasion of anterior thyroid capsule or strap muscle [11]

  • benign thyroid nodule or follicular neoplasm <8 cm in diameter

  • Graves’ disease (recommended for <100 mL in volume),

  • suspicious lateral neck metastasis limited to levels IIa, III, IV, and Vb (modified radical neck dissection can be safely accomplished by BABA-RT [11])

Absolute contraindications to BABA-RT include huge substernal goiter, thyroid malignancies that are likely to recur (e.g., medullary, undifferentiated, or poorly differentiated thyroid carcinoma), distant metastasis, extrathyroidal invasion to larynx, trachea, esophagus, or recurrent laryngeal nerve (RLN) and prior irradiation to the neck or breast.

Relative contraindications are:

  • Large-sized thyroid nodules >8 cm in diameter

  • Thyroid malignancy laid posteriorly around the ligament of Berry and the RLN (unpredictable risk of RLN involvement)

  • Patient with breast malignancy

BABA does not involve the breast parenchyma in the subcutaneous dissection, so previous breast surgery (modified radical mastectomy, breast-conserving surgery or breast augmentation) is not contraindicated. Previous thyroid or parathyroid surgery or cervical spine surgery is not contraindicated.

Candidates for BABA-RT should be carefully selected on the basis of thyroid pathology and patient factors [1, 12]. Although there is no age limit for BABA-RT, most surgeons operate on patients <70 years of age [13]. BABA-RT can be safely conducted on both sexes, though male sex has been an independent factor predicting difficult surgery [14]. Obesity is generally considered a relative contraindication [15].

3 Procedure

BABA-RT uses a midline approach to the thyroid, which provides a 3D symmetrical view of both thyroid lobes with optimal visualization and dissection of vital structures, and enables large operative angles between the instruments that can prevent instrument crowding or fighting. The thyroid dissection method in BABA is similar to that of open thyroidectomy, so the operation process is familiar to surgeons. The learning curve of BABA-RT is about 40 cases [16].

The robotic platforms used are da Vinci S, Si or Xi (Intuitive, USA), with the following EndoWrist instruments: graspers (Maryland bipolar and ProGrasp forceps) and electrocautery hook. The patient is positioned supine on the operating table, with the armpits opened slightly to aid axillary incisions, and the neck extended by placing a pillow under the patient’s shoulders. The operative field is prepped and draped as a large area including the neck and the patient’s chest. The robot location is at the patient’s shoulder for the da Vinci S, Si, while the da Vinci Xi system can be placed on either side. The ventilator is usually positioned at the patient’s feet or right side of the patient. Guidelines are drawn with a marker along the landmarks of the anterior chest and the neck: midline, thyroid cartilage, cricoid cartilage, anterior border of the sternocleidomastoid muscle, the clavicles, suprasternal notch, four incisions, trajectory lines from the port site to the neck, and the working spaces (Fig. 10.1) [4].

Fig. 10.1
A drawing of the upper half of a human body demonstrates the markings along the neck and the chest. The labels are area 1 and 8 millimeters on the right, 8 millimeters and area 2 on the left, and 12 millimeters camera and 8 millimeters at the bottom.

Guidelines and port sites. Dissection should start in Area 2 and proceed to Area 1. Thyroid cartilage (*), cricoid cartilage (x). Modified from Choi et al. [4] with permission of Springer Nature

Full size image

Epinephrine-mixed saline solution (1:200,000) is injected in the working space under the platysma muscles in the neck and anterior chest, forming a saline pocket in the subplatysmal layer, which can reduce bleeding in the flap and make the dissection easier.

Two 8-mm incisions are made in both axillae and blunt dissection is performed to elevate the flap using straight mosquito hemostats and a vascular tunneler. The ports are then inserted through the incisions. Two ports should be inserted to meet in the middle. The working space is insufflated with CO2 at 6 mmHg through the left axillary port. This pressure solved the earlier problems of hypercarbia, tachycardia, respiratory acidosis, subcutaneous emphysema, and air embolism with >10 mmHg of CO2 [17].

Sharp dissection is started in Area 1 of the anterior chest with the harmonic shear and, once completed, two incisions are made at the superomedial margin of the areolae; the flap is now extended to Area 2, up to the cricoid cartilage (Fig.10.1).

In the da Vinci S and Si systems, the robot column is aligned with the camera port of the right breast, while the da Vinci Xi system is placed in the middle. The robotic arms are docked to each 8-mm port and the camera is inserted through the 12-mm right breast port. A monopolar electrocautery or ultrasonic shear is inserted through the left breast port. Graspers are inserted through both axillary ports and further flap dissection is performed.

The midline between the strap muscles is divided from the suprasternal notch to the thyroid cartilage to expose the thyroid gland and the trachea. To help visualize the midline, the assistant may palpate the thyroid cartilage while inside it is marked with electrocautery. After dividing the midline, the isthmus is divided with the harmonic shear. Isthmectomy helps to retract the thyroid gland more easily.

The thyroid gland is retracted medially with ProGrasp forceps, and the right side of the strap muscles is retracted laterally using Maryland forceps. The strap muscles are thoroughly dissected off the thyroid capsule and lateral dissection is performed down to the common carotid artery. The thyroid lobe can be effectively retracted by manipulating the third and fourth robot arms, gradually pulling and switching their mutual positions.

While dissecting the lower pole, large vessels such as the inferior thyroid vein and the thyroid ima artery are ligated with bipolar electrocautery or ultrasonic shears, but only after the RLN has been identified. When lateral dissection is complete, the inferior thyroid artery and inferior parathyroid gland (PT) can be seen.

The RLN is found between the common carotid artery and trachea (tracheoesophageal groove). Once identified, the RLN can be confirmed using a nerve monitor. The inferior PT, which should be carefully preserved, sits around the lower pole of the gland, over the RLN.

Dissection is continued to the upper part near the point of RLN entry into the larynx under the cricopharyngeal muscle. The nerve may divide into a couple of branches along its course from the level of the inferior thyroid artery to the larynx. The ligament of Berry is the most frequent site of nerve injuries. A cotton ball is used to protect the nerve from thermal and mechanical damage.

Drawing the upper third of the strap muscles laterally with the Maryland forceps, the ultrasonic shears is used to dissect the vessels of the upper pole. Here, an anteromedial approach is recommended to avoid injury to the superior laryngeal nerve. Care must be taken to preserve the superior PT, as it is usually located under the RLN.

After thyroid lobectomy is completed, the specimen wrapped in the endobag is pulled out through the left axillary port. If the left axillary incision is not wide enough to extract the specimen, it can be extended posteriorly along the axillary crease.

After meticulous hemostasis, the strap muscles are approximated with a continuous running suture. Optionally, a Jackson-Pratt drain can be placed into the operative fields through the right or left axillary incision.

The skin incisions are closed with a subcuticular absorbable suture and the incision is dressed. The anterior chest is compressed with a Robo-Bra to reduce emphysema, postoperative bleeding and pain.

4 Outcomes and Cost

The main purpose of robotic thyroidectomy is to achieve better patient satisfaction with cosmetic outcomes. BABA-RT consistently recorded better cosmetic satisfaction than open thyroidectomy (OT) [15, 17,18,19].

In the literature, the operating time of BABA-RT was 1.3–2.4 times longer than that of OT [16, 18, 20,21,22], which may increase medical expenses. In remote access robotic thyroidectomy flap dissection can be a time-limiting procedure. However, the time required for flap dissection and robot docking gradually decreases with the experience of the surgical team [16, 20].

Studies investigating postoperative pain suggest that BABA-RT caused similar or less pain to patients than OT [19, 21, 23]. Prospective observational studies reported that about 40% of patients experienced transient paresthesia of the anterior chest after BABA-RT, which normalized within 3 months [24].

Drain output [25, 26] and hospital stay (mean, 3 to 5 days) [11, 18, 20, 21, 23, 25, 27] were found to be similar between BABA-RT and OT.

No significant difference was observed between BABA-RT and OT in the rates of transient and permanent RLN injuries [11, 18,19,20,21,22,23, 25, 27, 28].

In most studies examining BABA-RT, hypoparathyroidism was defined by hypocalcemic symptoms and low parathyroid hormone level (<15 pg/dL), and it was permanent when symptoms continued for more than 6 months [19, 23, 29]. The rates of permanent hypoparathyroidism were comparable between BABA-RT and OT [11, 18, 19, 21,22,23, 25, 27,28,29,30].

The reported rates of postoperative bleeding and hematoma after BABA-RT was 0–0.9%, not significantly different from OT [11, 18,19,20,21,22,23, 25, 27, 29].

Current evidence supports that BABA-RT is comparable to OT in terms of completeness of surgical resection [28]. Central neck dissection can be performed down to the common carotid artery and distal innominate artery, although there are mixed results in the literature in terms of the lymph node yield of BABA-RT compared to OT [19]. No significant difference was observed in the absolute level of stimulated thyroglobulin between BABA-RT and OT [20, 22, 23, 25, 27,28,29]. No difference in the uptake on whole-body scan after radioactive iodine (RAI) therapy, number of RAI sessions, and the RAI dose between BABA-RT and OT [28].

The evidence on locoregional recurrence and disease-specific survival after BABA-RT is limited. In a study that compared BABA-RT and OT for 2–4 cm papillary thyroid carcinoma, no recurrence was observed in both groups in a median follow-up of 40.2 months [22].

BABA-RT is comparable to OT in terms of complications and is safe and feasible when performed by experienced surgeons and on carefully selected patients concerned about neck scarring.

Robotic surgery is more expensive than open or endoscopic surgery, with the cost of BABA-RT recorded at 2.5–6.2 times higher than OT [18, 23, 25]. With robotic systems and procedures evolving, it is likely that more cost-effective ways will be found to provide safe and complete surgery that offers improved quality of life.