Thyroidectomy is commonly performed through a transcervical approach, a technique first described by Theodor Billroth in the late 19th century. , Since that early description, technological advancement and its application have seen a remarkable evolution in thyroidectomy techniques over the past 20 years. The endoscope was first utilized for parathyroidectomy by Gagner and then by Hüscher et al. for the thyroid lobectomy. , Several endoscopic techniques have since been described employing axillary, breast-axillary and transoral approaches. With the advent of robotic surgery and its application to the head and neck, interest has grown in employing this minimally invasive technology to endocrine surgery. The impetus for this has been avoiding a visible cervical scar, an inevitable component of the traditional approach. This has also been influenced by a societal emphasis on physical appearance.
The first robotic-assisted thyroidectomy was performed by Chung and colleagues via a transaxillary approach in 2007. This adopted a previously described endoscopic approach but afforded advantages of increased range of motion and eye-hand coordination. Since then, new approaches have been developed including a breast-axillary, retroauricular/facelift, and more recently a transoral technique. Although scar avoidance is the premise behind these approaches, the robotic surgeon needs to balance this with adequate exposure which continues to drive critics opposed to these techniques.
The American Thyroid Association (ATA) has recognized the role robotic surgery plays in thyroidectomy and published a position statement in 2016. Several important considerations were proposed, including patient selection, surgeon experience, cost, and technical challenges. Surgeon experience above all is the single most important factor in successful robotic-assisted thyroid surgery. Surgeons performing both high-volume traditional thyroid procedures as well as head and neck robotic procedures are best equipped to perform this surgery. Nuances such as appropriate patient selection, exposure requirements, and degree of technical difficulty only come through experience. Robotic-assisted thyroid surgery represents the next iteration in robotic head and neck surgery and is a safe technique for select patients performed by high volume head and neck institutions.
Indications and contraindications
There is a lack of consensus among surgeons performing robotic-assisted thyroidectomy as to its contraindications and this is reflected in the absence of established criteria in the literature. Patient factors such as fitness for general anesthesia (GA) and previous surgery or radiation therapy are contraindications that are agreed upon among most experienced surgeons. Furthermore, patient body mass index (BMI) needs to be taken into account for access purposes. Inconsistency, however, exists in other key criteria, including thyroid size, nodule/tumor size, thyroid pathology, and extent of disease. Thyroid size criteria varies considerably among authors. Some specify maximum allowable thyroid diameter, whereas others focus on total thyroid volume or dominant nodule size. Razavi and Russell reviewed the literature and proposed a 10-cm total thyroid diameter limit for robotic-assisted thyroidectomy. Furthermore, they felt that a total tumor or dominant nodule size of greater than 6 cm in indeterminate or benign pathology was a contraindication to robotic-assisted thyroidectomy.
There is some agreement that preoperative pathology needs careful consideration when proposing robot-assisted thyroidectomy. Well differentiated thyroid carcinoma greater than 2 cm in size is a relative contraindication to a robot-assisted technique. , Extrathyroidal extension (ECE), especially gross tracheal or esophageal invasion as well as patients with preoperative recurrent laryngeal nerve (RLN) palsy, should be considered for conventional surgery. Unless performed in high-volume centers, patients with poorly differentiated thyroid cancer or lymph node metastasis should also have traditional thyroid surgery.
Benign pathology including Hashimoto thyroiditis, Graves disease, and multinodular goiters, although not absolute contraindications to robotic-assisted thyroidectomy, need special consideration. Kang et al. considered poorly controlled and severe Graves disease as a contraindication to a robotic-assisted thyroidectomy. Bilateral thyroid disease is another special consideration, especially depending on the robotic approach used. Table 48.1 summarizes the key contraindications and special considerations for robotic-assisted thyroidectomy.
A thorough head and neck history and examination should be performed routinely in any patient considered for robotic thyroid surgery. The history should focus on previous head and neck surgery and radiation therapy to the neck or upper mediastinum. Cervical/thoracic spine abnormalities or a history of spinal surgery should be established, as this impacts access. A history of breast or axillary surgery should also be asked when considering a transaxillary approach. As with any thyroid history, symptoms and signs of hyper/hypothyroidism, voice change, airway symptoms, and a family history of thyroid cancer should be determined.
The physical examination (PE) should concentrate on patient factors which may limit robotic surgical access. For transoral robotic thyroidectomy (TORT) this may include poor neck extension, limited mouth opening or trismus, and retrognathia. Poor dental hygiene with abscess is a contraindication to TORT. The presence of axillary or retroauricular scars may exclude these approaches for thyroidectomy. The other key element to the PE is assessment of the extent of thyroid disease. This includes palpation of the thyroid to assess goiter size, retro/substernal extension, or in the setting of thyroid cancer whether this is locoregionally advanced. A large firm fixed mass may indicate significant extranodal extension (ENE). Palpation for central and lateral neck disease also provides vital information for staging purposes but importantly in most institutions necessitates a neck dissection through a cervical incision, thus abolishing any benefit from robotic thyroidectomy. The PE should be completed with a dedicated voice assessment and laryngoscopy to evaluate vocal cord function. Vocal cord paralysis may indicate locally invasive thyroid cancer or in the setting of benign disease confirm a relative contraindication to robotic surgery.
Thyroid ultrasound (US) is mandatory prior to consideration of any surgical procedure on the thyroid. Specifically for robotic thyroid surgery it defines total thyroid diameter and volume along with nodule size and characteristics. In well trained hands it can also be useful in defining ENE or central/lateral neck lymphadenopathy. In conjunction with fine needle aspiration (FNA), the information gathered from US helps to plan the correct thyroid surgery for patients and more importantly assists in defining patients eligible for a robotic approach.
Although not mandatory, cross-sectional including computed tomography (CT) or magnetic resonance imaging (MRI) of the neck may be useful in large goiters, especially with sub/retrosternal extension. The extent of gross ENE can also be defined; however, these are situations in which robotic thyroidectomy is contraindicated. Posteriorly based lymphadenopathy may also be evaluated. Routinely, CT and MRI do not tend to add any further information that US does not already provide and so has a limited role in the preoperative workup of potential robotic thyroidectomy candidates. US is the most important modality for thyroid workup, and cross-sectional imaging techniques should be reserved for situations where US expertise is not available.
Fine needle aspiration
The role of FNA is no different in robotic thyroid surgery from conventional surgery. It may assist the surgeon in counseling patients for surgery, in particular, the extent of surgery planned. The ATA guidelines on thyroid nodules and differentiated thyroid cancer best summarizes the role of FNA in thyroid nodule evaluation and treatment.
Thyroid function testing, especially thyrotropin (TSH), should be performed in all patients with a thyroid nodule being evaluated for surgery as recommend by the ATA. Free T3 and T4 is also important prior to surgery to assess secretory activity of the thyroid. Graves disease robotic thyroidectomy is best performed by experienced robotic thyroidectomy surgeons.
The patient is positioned supine with neck slightly extended and the ipsilateral arm raised and fixed to ensure the shortest distance between the axilla and anterior neck. GA is performed using an endotracheal tube, secured superiorly.
A vertical skin incision is made in the axilla approximating 8 cm. A flap is elevated under direct vision subcutaneously from the axilla to the anterior neck, with dissection over the anterior surface of the pectoralis muscle and clavicle and continuing in the subplatysmal plane. The medial border of the SCM is exposed and then dissection is continued between the clavicular and sternal heads of the SCM deep to the strap muscles to identify the thyroid lobe. At this point an external retractor is inserted through the incision as a lifting device to assist in maintaining operative field exposure. An optional, additional skin incision less than 1 cm is made on the medial aspect of the anterior chest wall, superior and medial to the nipple. This is used for the fourth robotic arm. The other three arms are placed through the axillary incision with a dual channel endoscope centrally and a Maryland dissector and harmonic shears placed laterally. A ProGrasp™ forceps (Intuitive Surgical Inc., Sunnyvale, CA) is placed in the anterior chest wall arm. The dissection of the thyroid proceeds analogous to conventional thyroid surgery. The superior pole is retracted inferiorly and medially by the ProGrasp to allow for exposure of the superior pole vessels. All vessel ligation is performed by the harmonic shears. The inferior and lateral aspect of the gland is released. Care is taken to identify and preserve the RLN and parathyroid glands. Lastly, the gland is dissected off the trachea and Berry’s ligament divided. The specimen is delivered back through the axillary incision. At the end of the procedure, careful hemostasis is obtained and a suction drain placed in a separate incision below the axillary skin incision. The axillary incision is closed with resorbable sutures.
Routinely, patients are sent to the general ward immediately postoperatively. As a suction drain is used, most patients are discharged on postoperative day (POD) 2. If drain output is minimal, discharge occasionally occurs on POD 1. Patients are commenced on a soft diet postoperatively and they are discharged home with this diet. Simple analgesia including paracetamol and ibuprofen are used for postoperative pain. Rarely opiate analgesia is required.
The major complication related to this approach is traction injury to the brachial plexus. Although rare, care must be taken to ensure the ipsilateral arm is not over extended. Kang et al. reported on 338 consecutive patients who underwent transaxillary robotic thyroidectomy with a transient ipsilateral arm paralysis rate of 1%. Paresthesia to the neck skin is common in this approach. The accessory nerve is also at risk in the level V neck during flap dissection.
Advantages and limitations
The transaxillary approach provides the best access to the ipsilateral thyroid, central, and lower lateral neck of all three robotic-assisted approaches. An external retractor for the strap muscles can be used to provide necessary retraction to free all robotic arms. Its main limitations are superior neck access along with the contralateral thyroid and neck. Often, bilateral approaches are required for bilateral disease.
The retroauricular robotic thyroidectomy can be performed using da Vinci Si, Xi, or single port (SP) platforms. The room setup is similar to that described for TORT; however, the patient cart should be at the contralateral side of the incised neck ( Fig. 48.1 ). GA similarly is performed using an endotracheal tube, secured contralateral to the operative side. The patient is placed in the supine position without neck extension and the head rotated away from the operative side.