Recent technologic advances have engendered alternative and innovative approaches to thyroid surgery aimed at reducing cosmetic sequelae. Minimally invasive techniques via small anterior cervical incisions hidden in natural skin creases and remote access approaches that eliminate anterior neck incisions entirely have emerged as viable options for patients who regard cosmesis as a priority. The safe application of these techniques to both benign and malignant thyroid disease has been evaluated.
Key points
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Two divergent paradigms have developed for reducing the cosmetic burden of thyroid surgery: minimally invasive anterior cervical approaches and remote access approaches.
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Minimally invasive cervical approaches use small incisions on the anterior neck for direct access to the thyroid compartment and require limited dissection to remove the thyroid gland.
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Remote access approaches use well-hidden incisions but should not be considered minimally invasive, given the increased extent of dissection required and the resultant prolonged recovery compared with that of minimally invasive anterior cervical approaches.
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These alternative approaches have been applied to small, low-risk, well-differentiated thyroid cancers with promising and oncologically appropriate results. Careful patient selection and comprehensive preoperative counseling is essential.
Introduction
Conventional thyroidectomy techniques, although appropriate in some cases, yield a conspicuous anterior cervical scar that may be difficult to camouflage. Patient-driven motivations to decrease the cosmetic impact of thyroid procedures have generated procedures that aim to minimize the visible scar and improve postoperative recovery. Two distinct pathways have emerged from these efforts. One track created minimally invasive anterior cervical approaches that strive to decrease the incisional length and extent of dissection while providing direct and anatomically familiar access to the thyroid gland. The other developed remote access techniques that approach the thyroid gland from extracervical vantage points using endoscopic and robotic assistance, consequently removing the thyroidectomy scar from the visible neck. For the appropriate patients, these are viable techniques that accomplish both the surgical and cosmetic goals. The role of these procedures in treating malignant thyroid disease has been recently evaluated.
Introduction
Conventional thyroidectomy techniques, although appropriate in some cases, yield a conspicuous anterior cervical scar that may be difficult to camouflage. Patient-driven motivations to decrease the cosmetic impact of thyroid procedures have generated procedures that aim to minimize the visible scar and improve postoperative recovery. Two distinct pathways have emerged from these efforts. One track created minimally invasive anterior cervical approaches that strive to decrease the incisional length and extent of dissection while providing direct and anatomically familiar access to the thyroid gland. The other developed remote access techniques that approach the thyroid gland from extracervical vantage points using endoscopic and robotic assistance, consequently removing the thyroidectomy scar from the visible neck. For the appropriate patients, these are viable techniques that accomplish both the surgical and cosmetic goals. The role of these procedures in treating malignant thyroid disease has been recently evaluated.
Background and history
In the late 1800s, Emil Theodor Kocher revolutionized the field of thyroid surgery, transforming the thyroidectomy from a perilous operation with sometimes dire consequences to a validated and accepted procedure. For more than a century, his traditional method, which involved a large 7- to 10-cm transverse cervical incision, elevation of subplatysmal flaps, and routine postoperative drainage and inpatient care, was routinely performed. The development and widespread utilization of endoscopic and minimally invasive techniques in other surgical fields provoked interest in their application to neck surgery. In 1996, Gagner described the first endoscopic cervical surgery, using multiple ports and CO 2 insufflation to perform a subtotal parathyroidectomy. Although the cosmetic outcome was ostensibly excellent, the procedure took 5 hours, produced mild hypercarbia and significant subcutaneous emphysema, and necessitated a 4-day inpatient admission. This experience, while demonstrating issues that would need to be overcome before these techniques could be widely used, elicited the attention of patients and surgeons to the possibility of alternative approaches to the thyroid compartment.
These alternative approaches developed along 2 avenues: minimally invasive and remote access approaches ( Table 1 ). Along the minimally invasive anterior cervical pathway, both minimally invasive video-assisted thyroidectomy (MIVAT) and minimally invasive nonendoscopic thyroidectomy (MINET) were cultivated. These approaches camouflage incisions that are significantly smaller than those of a conventional thyroidectomy in natural neck creases and reduce the extent of dissection, obviating postoperative drainage and reducing postoperative pain. Not only is the cosmetic impact reduced but also outpatient surgery becomes feasible with these techniques. The other pathway pursued remote access approaches that primarily emerged in Asian practices, tailored to a population at increased risk of hypertrophic scarring and highly cognizant of postoperative cosmesis. Although not completely scarless, these techniques eliminate any scar from the visible neck by accessing the thyroid compartment by way of a more distant but concealed site. Consequently, more extensive dissection is required and anatomic structures not otherwise encountered during a traditional thyroidectomy are placed at risk of injury. Additionally, some techniques require postoperative drainage and hospital admission.
| Approach | Incision Site | Technique |
|---|---|---|
| Minimally invasive anterior cervical | Anterior neck |
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| Remote access | Chest or breast |
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| Axillary |
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| Combined |
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| Postauricular |
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As with Gagner group’s initial endoscopic experience, early efforts with these alternative approaches used endoscopic visualization and were contingent on CO 2 insufflation to maintain an adequate operative pocket. Given the previously mentioned drawbacks associated with CO 2 insufflation, gasless techniques were explored. The minimally invasive anterior cervical approaches use blunt retraction of soft tissue and some remote access techniques use percutaneous suspension techniques or specialized retractors to render CO 2 insufflation unnecessary to maintain the operative space. Although these modifications were conducive to performing cosmetically conscious thyroid surgery, concerns remained regarding the ability to perform oncologically sound surgeries with these alternative approaches.
Advantages and disadvantages of alternative approaches
Long-term morbidity and mortality after traditional thyroid surgery are rare and may potentially be even lower in minimally invasive video-assisted anterior cervical approaches. When performed by experienced surgeons, MIVAT and MINET techniques can lead to shorter operative times, less blood loss, less postoperative pain, and improved cosmetic outcomes compared with conventional thyroid surgery, while still providing an anatomically familiar route of access. Bilateral resection can also be performed without necessitating an additional scar.
Although minimally invasive, MIVAT and MINET generate a small but visible anterior neck scar. An assistant to operate the endoscope is also necessary in the MIVAT technique. Not all patients who require thyroid surgery are appropriate for MINET and MIVAT, because the minimally invasive approach may be difficult or even unsafe in instances of large goiters, substernal or retropharyngeal extension, or thyroiditis. Furthermore, patients with thyroid malignancies need to be carefully considered to provide the most oncologically appropriate surgery for their disease.
Remote access procedures provide an attractive alternative for individuals who find any visible cervical scar an unacceptable outcome. The various access sites and more extensive dissection required make it difficult to directly compare the degree of postoperative pain or length of recovery for this group as a whole to traditional thyroid surgery. The increased dissection and unconventional anatomic view of the thyroid compartment may also affect surgical times, although this is highly dependent on surgeon experience and technique. The increased medical resource expenditure associated with remote access surgery versus traditional thyroid surgery has been demonstrated.
There is concern over obtaining enough exposure and visualization in these alternative approaches to adequately remove thyroid tissue and, if indicated, perform a nodal dissection in cases of malignancies to ensure a reliable oncological outcome. To address these concerns, the suitability of both minimally invasive and some remote access techniques in treating thyroid cancers has been evaluated.
Approaches
Minimally Invasive Anterior Cervical
Minimally invasive video-assisted thyroidectomy
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Prior to surgery, a 15- to 20-mm cervical incision is marked in a low natural skin crease with the patient awake and upright to ensure a vertically favorable position in the neck.
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The incision is carried through the platysma until the sternohyoid and sternothyroid muscles are encountered.
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No subplatysmal flaps are elevated.
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The strap muscles are separated vertically in the midline, bluntly dissected off the anterior and lateral aspect of the thyroid gland, and retracted laterally.
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Under visualization with a 5-mm 30° laparoscope, the avascular space between the inferior constrictor muscle and the medial aspect of the superior pole is bluntly dissected, isolating the superior vascular pedicle.
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The superior pole vessels are divided close to the thyroid capsule with Harmonic ACE shears, ACE23P (Ethicon Endo-Surgery, Cincinnati, Ohio) ( Fig. 1 ). Care is taken to identify and preserve the superior parathyroid gland.
Fig. 1
Bundle ligation of the superior vascular pedicle with an advanced energy device during MIVAT.
( From Terris DJ, Seybt MW. Modifications of Miccoli minimally invasive thyroidectomy for the low-volume surgeon. Am J Otolaryngol 2011;32:395; with permission.)
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The middle thyroid vein is then isolated and divided, allowing mobilization of the inferior pole. The inferior pole vessels are divided, with care taken to identify and preserve the inferior parathyroid gland.
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The lobe is exteriorized with gentle traction using hemostat clamps placed directly on the gland, especially the superior pole. Once delivered externally, the lobe is retracted medially and ventrally and the recurrent laryngeal nerve (RLN) identified ( Fig. 2 ).
Fig. 2
Identification of the RLN ( arrow ) is facilitated by the magnified endoscopic view available during an MIVAT.
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The nerve is carefully traced until it courses under the inferior constrictor muscle.
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If only a lobectomy is performed, the isthmus is divided and the lobe delivered from the field. If a total thyroidectomy is indicated, the contralateral lobe is removed in a similar manner.
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The surgical field is irrigated with saline and Surgicel (Ethicon, Somerville, New Jersey) is placed into the thyroid bed.
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The strap muscles are reapproximated in the midline with a single 3-0 Vicryl suture (Ethicon) in a figure-of-8 configuration. This single fixation point decreases the risk of postoperative airway obstruction by allowing any fluid accumulation to egress from the thyroid compartment.
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The subcutaneous tissues are closed with buried interrupted 4-0 Vicryl sutures, the superficial skin layer reapproximated with tissue adhesive and a single ¼ inch Steri-Strip (3M, St. Paul, Minnesota) is placed over the incision ( Fig. 3 ). The procedure is performed on an outpatient basis without postoperative drainage.
Fig. 3
The MIVAT incision is closed with tissue adhesive and a ¼ inch sterile strip.
Patient selection
Initially considered for only small-volume benign lesions, patient selection criteria have expanded to include nodule size as large as 35 mm, estimated thyroid volume less than 25 cm 3 , absence of thyroiditis, and no history of previous neck surgery or irradiaton. Some investigators have reported criteria that include thyroiditis, cytologically indeterminate nodules, and low- and even intermediate-risk differentiated thyroid cancers (DTCs), according to American Thyroid Association staging, that are less than 20 mm. Reported contraindications have included nodules larger than 35 mm, estimated thyroid volume greater than 25 cm 3 , severe thyroiditis, malignancies larger than 20 mm, and the presence or suspicion of nodal metastases.
An early multi-institutional trial that included 336 patients demonstrated a mean operative time of 69.4 minutes for a hemithyroidectomy and 87.4 minutes for total thyroidectomy with MIVAT. Complications included hemorrhage in 0.9% of cases, temporary RLN weakness in 2.1% of cases, permanent RLN weakness in 0.3% of cases, a temporary hypocalcemia rate of 2.7%, permanent hypocalcemia in 0.6% of patients, and a conversion rate of 4.5%. This safety profile was corroborated in a large North American study of 228 patients. Terris and Seybt described several important modifications (detailed previously) designed to aid with MIVAT procedures as well as any anterior cervical approach. An important limitation is the obligate need for 2 surgical assistants: 1 to maintain the operative field with retractors and 1 to maneuver the endoscope.
The oncologic soundness of MIVAT thyroid cancers has been evaluated. Miccoli and colleagues described a series in which 33 patients with biopsy-proven low-risk (T1) papillary carcinomas were randomized to either MIVAT or conventional total thyroidectomy. To measure the completeness of resection, serum thyroglobulin levels and iodine 131 uptake scans were obtained 1 month postoperatively, with no significant difference found between the 2 groups. Although there were 3 cases of transient RLN palsy and 1 case of permanent hypoparathyroidism, there was no significant difference in the frequency of these complications between the 2 groups.
The prevalence of occult lymph node metastasis in DTC in the central compartment has been reported at 50% to 60%. Debate continues regarding the benefit of elective neck dissection in low-risk DTC patients. Some investigators argue a possible survival benefit and reduced risk of nodal recurrence whereas others argue the potential risk to the RLN and parathyroid glands outweigh the benefits. Neidich and Steward retrospectively assessed outcomes in cases of total or completion thyroidectomy and elective central neck dissection by MIVAT. Dissection of prelaryngeal, pretracheal, and either unilateral or bilateral paratracheal nodal basins was performed with a mean yield of 5.2 lymph nodes per patient; 11 of 28 patients harbored central compartment lymph nodes positive for metastases on pathology. The majority of the final pathology was consistent with papillary thyroid cancer; the remaining diagnoses included follicular and medullary carcinoma. Fifteen patients underwent radioiodine ablation. No recurrences were recorded during a median follow-up period of 14 months; 91% of the patients had low or undetectable thyroglobulin levels, defined as less than 1 ng/mL, and the remaining 2 patients had levels less than 1.5 ng/mL. No instances of permanent hypocalcemia or RLN palsy occurred. The reported rate of conversion to open surgery is rare but has been described for reasons, including early surgeon experience, difficult dissection, excessive bleeding, and preoperatively understaged cancer, where local tumor infiltration or metastatic lymph nodes were identified intraoperatively. Thus, the possibility of extension to a conventional incision must be discussed with patients preoperatively.
Promising oncologic outcomes, as evidenced by postoperative serum thyroglobulin levels and radioiodine scintigraphy results comparable to those obtained after conventional thyroidectomies, support the viability of MIVAT for low-risk DTC.
Minimally invasive nonendoscopic thyroidectomy
Almost concurrently with the development of MIVAT, groups in South Korea and the United States reported a minimally invasive nonendoscopic thyroidectomy (MINET) approach. This technique also strived to minimize incisional size and dissection extent compared with conventional thyroidectomy but without the addition of endoscopic instrumentation.
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Prior to surgery, a 3- to 5-cm cervical incision is marked in a low natural skin crease with the patient awake and upright to ensure a vertically favorable position in the neck.
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Dissection is performed in a similar fashion to that of the MIVAT approach .
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Without endoscopic magnification, positioning of retractors in a favorable vector maintains optimal exposure via the slightly longer incision through which both thyroidectomy and central neck dissection may be performed.
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Closure is identical to the MIVAT technique and the patient is managed on an outpatient basis without postoperative drainage.
MINET has been demonstrated to be a safe and effective procedure in appropriately selected individuals. A retrospective comparison of patients undergoing MINET versus conventional thyroidectomy demonstrated MINET cases having a shorter operative time, less blood loss, a briefer hospital stay, decreased drain utilization, and less postoperative pain, with no significant difference in complication rates. Limitations of MINET include inability to remove some large nodules or substernal goiters, in which case conventional thyroidectomy may be more appropriate. Oncologically, there is concern for the potential of missing positive lymph nodes, either in the contralateral tracheoesophageal groove due to inadequate visualization or in the lateral lymph node compartments if involved.
In the same retrospective study, central neck dissection was performed in more than 80% of the patients with malignancy in both the MINET and conventional thyroidectomy groups. There was no significant difference in either the number of central neck nodes dissected per patient or the number of positive lymph nodes identified per patient. In a prospective nonrandomized study by Cavicchi and colleagues, MINET was performed on patients with papillary thyroid carcinoma; postoperative iodine 131 uptake was found to range from 0% to 2.13%. A completion thyroidectomy for malignancy on final pathology was also performed in 1 patient through the same incision. The cosmetic result was regarded as excellent in all patients. Selection criteria were similar to those for MIVAT.
Remote Access Endoscopic
Chest/Breast approaches
In 2000, Ohgami and colleagues described a series of CO 2 insufflation–assisted endoscopic hemithyroidectomies, which were considered the first truly remote access thyroidectomy procedures. Access was achieved through incisions at the parasternal border of 1 breast and along the superior margins of both areolas. Using a low insufflation pressure of 6 mm Hg, endoscopic dissection was conducted superiorly and superficially to the strap muscles to expose and remove the thyroid lobe.
Since that initial description, several variations of the anterior chest and breast approach have been described, including isolated anterior chest wall approaches as well as bilateral and unilateral transareolar approaches. Recent studies reported indications, including unilateral benign lesions up to 3 cm that required removal to relieve compressive symptoms or cosmetic deformity and lesions positive for papillary carcinoma on cytology measuring less than 2 cm; patients must also not have suspicious or positive lymphadenopathy or a prior history of neck surgery or irradiation. There is potential need to convert to a conventional approach should a central or lateral neck dissection be warranted ; however, in an early series, subtotal thyroidectomy and pretracheal and bilateral paratracheal lymph node dissections were performed without conversion to the conventional approach on patients with malignant tumors ranging from 1.0 to 2.3 cm.
Although these approaches eliminate scars on the visible neck, they generate incisions on the anterior chest that are prone to hypertrophic scarring, and on the breast, which may be an unappealing consideration for North American patients. Additionally, these approaches have a narrow operative field, with restricted range of movement of the rigid endoscopic equipment. These limitations prompted the development of other remote access techniques.
Axillary approaches
Ikeda and colleagues described the endoscopic axillary approach, the first remote access alternative to the anterior chest and breast approach. In this technique, the patient is positioned supine on an operating table with the arm ipsilateral to the dissection elevated to expose the axilla. An axillary incision is made and dissection advances along the pectoralis major muscle until the platysma is encountered. Trocars are placed though the incision and CO 2 insufflation applied to maintain visualization of the operative field. Under endoscopic visualization, dissection continues between the anterior border of the sternocleidomastoid muscle (SCM) and the strap muscles until the thyroid lobe is encountered. The strap muscles are divided.
Although the cosmetic impact is less conspicuous compared with conventional surgery, this approach takes significantly longer to perform than a conventional open thyroidectomy. The narrow operative field, reliance on rigid endoscopic instruments, and potential morbidity related to CO 2 insufflation are obvious limitations. Gasless remote access techniques that do not require a closed operative pocket and CO 2 insufflation were developed to overcome these drawbacks. Later modifications of this approach involved dissection between the sternal and clavicular heads of the SCM rather than between the SCM and the sternohyoid muscles.
This gasless technique has been described for thyroidectomy and central compartment node dissection of low-risk papillary thyroid carcinoma without need for open conversion. In 1 series of 410 malignant cases, no recurrences were observed in a follow-up range of 10 to 18 months, and thyroglobulin levels were less than 1 ng/mL in more than 90% of the cases; 71 patients underwent radioiodine ablation with subsequent iodine 131 scans, which showed no uptake. The investigators cited the advantage of approaching the thyroid bed between the SCM heads and dissecting along the anterior surface of the carotid sheath, allowing complete dissection of the ipsilateral central neck compartment, including both the prelaryngeal and paraesophageal lymph nodal packets. Another report described successful unilateral lobectomy and isthmusectomy with central compartment dissection for papillary thyroid microcarcinoma using this approach.
Several hybrid approaches, combining axillary and areolar incisions, were also developed. These techniques include the axillo-bilateral breast approach (ABBA) and the bilateral axillo-breast approach (BABA). These approaches exploit the cosmetic benefit of the axillary approaches while providing additional anterior chest working ports without producing a transverse parasternal scar ( Fig. 4 ). Despite their cosmetic appeal, these approaches have been associated with several complications not typically associated with traditional thyroid surgery, including transient neuropraxia of the brachial plexus and pneumothorax.
