Robotic and Extracervical Approaches to the Thyroid and Parathyroid Glands

Introduction

Advances in surgical technology have enabled surgeons to develop multiple minimally invasive and remote access approaches to the thyroid gland.

In the early 2000s, Miccoli introduced the minimally invasive endoscopic thyroidectomy (MIVAT) using a small cervical incision, which initially gained significant interest in the United States.

Following that, remote-access approaches were attempted using endoscopes through small incisions placed on the anterior chest, breast, or axilla, or combinations of these sites.

It was believed that such extra-cervical, “scar-less in the neck” approaches would be desirable for many patients interested in cosmetic outcomes, specifically young patients and patients with a history of keloid or hypertrophic scars.

However, initial experience proved that endoscopic remote-access thyroidectomy was limited by two-dimensional visualization and rigid instruments.

The surgical robot technology was then introduced to thyroid surgery through the work of Chang and colleagues, who pioneered a gasless transaxillary approach, and the work of Terris and colleagues, who described the facelift (or retroauricular) approach. The robot system provided three-dimensional visualization and multi-articulated endoscopic arms, which proved ideal for the limited workspace of the neck.

Development of multiple remote-access thyroid surgery techniques prompted the American Thyroid Association (ATA) to issue a statement on this topic in 2016.

In this statement, the authors acknowledged that remote-access thyroid surgery has a role in selected circumstances when done by surgeons performing high volume thyroid surgery. Adherence to strict selection criteria was recommended to help ensure safe outcomes.

At the time of publication of this ATA statement, the four most commonly utilized remote-access approaches to thyroidectomy in the United States were: the endoscopic breast approach, the endoscopic and robotic bilateral axillo-breast approach (BABA), the endoscopic and robotic transaxillary approach, and the endoscopic and robotic facelift (retroauricular) approach.

In recent years, there has been a trend moving away from the robotic facelift approach in favor of transaxillary and transoral approaches, as was noted in a U.S. multi-institutional study. In that study, robotic facelift approach operative time was significantly longer than the other two remote-access approaches.

The transoral endoscopic thyroidectomy vestibular approach (TOETVA) was introduced to clinical practice by Anuwong, and this technique has been adapted to include modifications such as transoral endoscopic parathyroidectomy vestibular approach (TOEPVA), transoral robotic thyroidectomy vestibular approach (TORTVA), and transoral robotic parathyroidectomy vestibular approach (TORPVA; see Chapter 33 , Transoral Thyroidectomy).

Some suggested advantages proposed by the proponents of TOETVA include shorter distance from the incision to the thyroid or parathyroid gland, thus decreasing the amount of dissection needed to create a sufficient working space, and reducing the operative time.

TOETVA also provides a midline, symmetrical view of the anatomic landmarks. It is performed with standard, reusable laparoscopic instruments, which may reduce cost compared with robotic-assisted techniques. The healing of oral mucosa occurs quickly and the incisions are usually not visible within weeks after surgery. However, the procedure continues to evolve. Recently submental incision was described to facilitate the extraction of the thyroid gland.

A recent publication attempted to establish a basic framework necessary for a safe and responsible implementation of transoral techniques that may also be applicable to the evaluation and potential integration of other technologies or techniques. The authors suggested a list of requirements that a surgeon must meet before considering this approach:

• High-volume thyroid practice

• Competence with necessary instrumentation

• For robotic cases, surgeons must be facile and credentialed in robotic surgery

The authors also stressed the importance of institutional support, surgeon and team education, and preparation and outcomes recording.

Patient Selection, Indications, and Contraindications

For the two most commonly performed robotic thyroidectomy techniques in the United States—the robotic-assisted gasless transaxillary and retroauricular approaches—an “ideal” patient is typically a young female, who have a small or average body mass index (BMI) less than 30 kg/m ² .

However, our group has demonstrated that robotic transaxillary thyroidectomy can be safely done in North American patients with BMI above 40 kg/m ² , and other groups have shown that robotic retroauricular approach can be safely done for patients who are obese, but with a BMI less than 40kg/m ² .

Like other remote-access approaches, these techniques may be considered especially in patients meeting such criteria with a history of keloid or hypertrophic scar formation.

Moreover, patients selected for the trans-axillary approach should also be free from any anatomic or pathologic contraindications to the required procedural positioning, such as rotator cuff pathology or cervical spine stenosis.

As previously stated, obese patients may undergo these procedures safely by experienced. Due to the learning curve of 25 to 40 cases associated with these procedures, conservative patient selection is recommended for surgeons new to these techniques.

Thyroid tumor characteristics and surgeons operative experience should also weigh in when selecting patients for robotic-assisted approaches. Although we suggest partial thyroidectomy as the procedure for surgeons new to the robotic-assisted techniques, several studies have reported that robotic-assisted total thyroidectomy and neck dissection are equivalent in oncologic outcomes and safety to open technique, when performed by surgeons who are experienced with both thyroid surgery and neck dissection as well as robotic techniques. This has allowed for the expansion of clinical pathology successfully treated by robotic-assisted procedures.

For patients with parathyroid pathology, this approach should only be offered to those with a well-localized parathyroid adenoma preoperatively on imaging studies. Patients with higher possibility of multi gland disease should not be offered this approach.

Absolute clinical contraindications to robotic-assited thyroidectomy ( Table 32.1 ) include large substernal or retropharyngeal goiters, thyroid tumor size ≥ 4 cm (≥T3) or any suspicious gross invasion, and medullary thyroid cancer. Relative clinical contraindications have previously included nodules greater than 5 cm, large goiters with volumes greater than 40 ml, known well differentiated thyroid cancer between 2-4 cm (T2), Hashimoto's thyroiditis, and Grave's disease, as well as obesity, a history of previous neck surgery or radiation.

The indications for TOETVA include the following: thyroid diameter no more than 10 cm and dominant nodule size no more than 6 cm, when benign or indeterminate (Bethesda II, III, IV), and no more than 2 cm when Bethesda V, suspicious for malignancy or confirmed well-differentiated thyroid cancer. Contraindications include history of head and neck surgery—including mandibular surgery, history of head/neck/upper mediastinum irradiation, patients unfit for general anesthesia, evidence of acute clinical hyperthyroidism, preoperative recurrent laryngeal nerve (RLN) palsy, lymph node metastasis, extrathyroidal extension, such as tracheal or esophageal invasion, presence of oral abscesses, and evidence of substernal thyroidal extension. Relative contraindications include chronic lymphocytic (Hashimoto’s) thyroiditis and an elevated BMI, due to the potential increased friability of the thyroid and greater difficulty with elevating skin flaps, respectively. These cases would warrant more extensive patient and surgeon preparation. Table 32.2 summarizes indications and contraindications for TOETVA.

Surgical Technique