Fig. 2.1
Different approaches to minimally invasive and remote access parathyroid surgery
Mini-open Parathyroidectomy
The open, focused parathyroidectomy has gained widespread acceptance as having statistically equivalent outcomes to traditional bilateral exploration. For a well-localized parathyroid adenoma, a focused approach can be performed through an incision of 2.5 cm with a success rate of 96 %.
One key to a successful focused parathyroidectomy is accurate preoperative localization. Patients with primary HPT and a concordant preoperative MIBI and US very likely have a single adenoma at that location (96 %). In contrast, those who have no parathyroid localized on MIBI and US have a 30 % chance of having multigland disease and usually require bilateral exploration.
An anterior mini-open parathyroidectomy is performed through a small skin crease incision in the central, inferior neck between the strap muscles and is well suited for exploring the lower parathyroid glands which tend to be more anterior. The lateral, or so-called back-door, approach is better for upper parathyroid adenomas which tend to be located posteriorly. In this approach the space between the strap muscles and sternocleidomastoid muscle is entered to expose the plane behind the thyroid. The disadvantage is the potential for a larger incision or bilateral incisions if the contralateral side needs to be explored.
Mini-open parathyroidectomy has an equivalent cure rate to the traditional bilateral exploration with shorter operative times and shorter hospital stays. Mini-open parathyroidectomy has also been shown to decrease the overall cost per procedure compared to traditional exploration. Its success depends on good preoperative imaging and ioPTH monitoring, which may not be universally available.
Radioguided Parathyroidectomy
Intraoperative radioguided localization, with sestamibi technetium-99m (TC-99m) can be used to aid the standard mini-open parathyroidectomy. In this technique, the patient is injected with a TC-99m radiotracer 1–2 h prior to surgery. The radiotracer collects preferentially in the mitochondria of enlarged parathyroid glands and can therefore be identified using a handheld gamma probe. The surgeon uses a gamma probe to explore the operative field, looking for counts greater than background.
Reports on the utility of radioguided parathyroidectomy have been mixed with localization rates between 40 and 100 %. Some of this variability may be due to the learning curve associated with this technology. Advocates suggest that using the gamma probe helps select the location of the skin incision and allows for identification of ectopic parathyroid tumors. Drawbacks may include the increased cost of the technology, its learning curve, and its lack of substantiated benefit.
Videoscopic Parathyroidectomy
Videoscopic parathyroidectomy has gained considerable attention over the last decade. The potential advantages of videoscopic techniques include the magnification provided by the optics, improved cosmesis, and reduced postoperative pain. Gagner et al. performed the first videoscopic parathyroidectomy in 1996. The procedure took almost 5 h to perform, and the patient developed hypercarbia and subcutaneous emphysema from his eyelids to his scrotum that took 3 days to resolve. Since Gagner’s initial description, videoscopic parathyroidectomy has continued to evolve and currently can be divided into two subgroups, EMIP and MIVAP, depending on how the operating space in the neck is maintained.
Endoscopic Minimally Invasive Parathyroidectomy
Henry et al. described endoscopic minimally invasive parathyroidectomy (EMIP) using a lateral approach in 1999. One 12-mm and two 2.5-mm trocars are inserted at the anterior border of the sternocleidomastoid muscle. The plane between the strap muscles and the carotid is bluntly dissected and carbon dioxide (CO2) insufflation is used to maintain the working space. The posterior surface of the thyroid is approached and the parathyroid adenoma is dissected free using 2-mm endoscopic instruments. A modified approach was report by Ikeda et al. in 2002.
Several large series comparing EMIP to open parathyroidectomy demonstrate equivalent cure rates with minimal morbidity. EMIP is generally reserved for single-gland disease with adequate preoperative localization. The major advantage of EMIP is the improved lighting and view provided by the endoscope and the limited size of incision regardless of the patient’s body habitus. The major drawbacks are the cost of endoscopy, increased operative time, and possible gas insufflation complications such as hypercarbia, subcutaneous emphysema, and gas embolism.
Minimally Invasive Video-Assisted Parathyroidectomy
MIVAP differs from EMIP in that it does not require gas insufflation. MIVAP was first described by Miccoli et al. in 1998. In MIVAP, a small transverse skin incision is made 1 cm above the sternal notch. The strap muscles are separated. A 5-mm, 30° scope is inserted through the incision, and dissection is done using specially designed open instruments and external retractors, but under a videoscopic view. The operation is similar to mini-open parathyroidectomy, except special instruments and a videoscope are used, which allows the operation to be performed through a 1.5-cm instead of a 2.5-cm incision.
As with endoscopic MIP, MIVAP can be performed with high cure rates and minimal morbidity. The videoscope provides improved lighting and a magnified view. Because of the anterior central approach, it can be used to perform a bilateral exploration. One major drawback is the need for two experienced assistants, one to maintain external retraction and the other to handle the scope. Large parathyroid adenomas, large goiters, prior neck operations, lack of preoperative localization, and suspicion of hyperplasia are relative contraindications to MIVAP.
Remote Access Parathyroidectomy
Remote access parathyroidectomy developed as an extension of endoscopic parathyroidectomy by moving the trocar sites and incisions away from the anterior neck to achieve better cosmetic results. In 2000, Ikeda and Takami reported on six patients who underwent successful parathyroidectomy via an axillary approach and four patients that underwent exploration via an anterior chest approach. Although the operative time was long (180 min for a unilateral axillary approach), all the operations were successful with no significant morbidity. Small series by Landry et al. and Foley et al. also suggested successful outcomes can be achieved via the transaxillary approach but that it is associated with longer operative times and increased costs. In 2011, Karakas et al. described successful transoral parathyroidectomy in two patients.
Conclusion
In summary, MIP, especially mini-open parathyroidectomy, is available in most high-volume endocrine surgery centers and is associated with high success rates and minimal morbidity. It has become a costandard with traditional bilateral four-gland exploration for treating patients with primary HPT. The mini-open technique, with a 2.5-cm neck incision, is the most commonly performed parathyroid procedure. Endoscopic parathyroidectomy and MIVAP are performed at fewer centers, but also have excellent outcomes. Remote access parathyroidectomy appears safe and may have cosmetic advantages, but requires more extensive dissection and is more expensive. Successful MIP and remote access parathyroidectomy depends on accurate preoperative localization studies and intraoperative adjuncts such as ioPTH monitoring. Table 2.1 summarizes the advantages and drawbacks to the various approaches.
Table 2.1
Benefits and drawback to various approaches to parathyroidectomy and thyroidectomy
Approach | Incision length | Benefit | Drawback |
|---|---|---|---|
Parathyroidectomy | |||
Traditional | 4–5 cm | Excellent exposure to both sides of thyroid. Gold standard with cure rates in excess of 95 % | Relatively long incision. Bilateral exploration is often unnecessary |
Mini-open “focused” parathyroidectomy | 2–3 cm | Shorter incision. Able to explore both sides with aid of retraction. Reduced operative times and costs | Can be difficult in obese patients. Relies on adequate preoperative localization and ioPTH which may not be available |
Radioguided parathyroidectomy | 2–3 cm | Helps focus skin incision. May help localize ectopic adenomas | Difficult to learn. May increase patient costs |
Totally endoscopic parathyroidectomy | (a) 5 mm ×3 (anterior approach) | Improved magnification and lighting with the endoscope. Shortest incision | Gas insufflation can cause subcutaneous emphysema, air embolism, hypercapnea. Increased cost and operative time |
(b)1.2 cm, 2.5 mm x2 (lateral approach) | |||
Minimally invasive video-assisted parathyroidectomy (MIVAP) | 1.5 cm | Improved magnification and lighting with videoscope. No need for insufflation. Easy to convert to bilateral operation | Requires two experienced assistants to maintain exposure |
Axillary approach to parathyroidectomy | 4.5–6 cm | No neck scar | More extensive dissection. Increased operative times and cost. Difficult learning curve |
Transoral approach to parathyroidectomy | 1.5 cm | No neck scar | Concerns for infection. Minimal reported experience |
Thyroidectomy | |||
Standard open thyroidectomy | 4–6 cm | Excellent exposure. Able to perform neck bilateral exploration and lymph node dissection | Relatively long scar in the neck |
Mini-open thyroidectomy | 2.5 cm | Easy to learn. Easy to convert to bilateral thyroidectomy | Limited to thyroid lobes <7 cm. Lateral approach only for thyroid lobectomy |
Completely endoscopic thyroidectomy | |||
Anterior approach | 5 mm ×4 | Short neck incisions and quicker return to normal activity. Magnified view | Limited to selected patients. Longer operative time. Insufflation may cause complications (hypercarbia, subcutaneous emphysema) |
Lateral approach | 10 mm ×1; 2.5 mm ×2 | Short neck incisions and quicker return to normal activity. Magnified view | Limited to selected patients. Only hemithyroidectomy. Insufflation may cause complications |
Minimally invasive video-assisted thyroidectomy (MIVAT) | 1.5 cm | Use open instruments. Easy to learn. Less pain and better cosmetic outcomes | Requires two experienced assistants to maintain exposure |
Remote access thyroidectomy – infraclavicular approach | 3 cm; 5 mm ×2 | No scar in the neck | More extensive dissection. Risk of subcutaneous hemorrhage |
Remote access thyroidectomy – axillary approach | 3–6 cm | No scar in the neck. Ipsilateral central neck dissection possible | More extensive dissection. Longer operative time. More expensive. Difficult to dissect contralateral thyroid lobe |
Remote access thyroidectomy – breast approach | 15 mm ×1; 12 mm ×1; 5 mm ×1 | No scar in the neck | More extensive dissection. Scar in the breast |
Remote access thyroidectomy –axillo-bilateral breast approach | 2.5 cm areolar; 10 mm ×2 axillary | Improved angles of dissection between instruments and thyroid | More extensive dissection. Scar in the breast |
Remote access thyroidectomy – bilateral axillo-breast approach | 12 mm ×2 in each areolar; 5 mm × 2 in each axilla | Improved angles of dissection between instruments and thyroid. Bilateral dissection easy | More extensive dissection. Scar in the breast |
Transoral thyroidectomy | 2.5 cm in the floor of the mouth | No neck scar | Very limited data on the utility and complications of this procedure |
Robotic facelift thyroidectomy | N/A | No neck scar. Supine position | Greater auricular nerve at risk |
Minimally Invasive and Remote Access Thyroid Surgery
Background
Traditional thyroid surgery was developed by Theodor Kocher at the beginning of twentieth century and was performed through an 8–10 cm collar incision. Currently open thyroidectomies are routinely performed through an incision that is 4–6 cm. Minimally invasive thyroidectomy (MIT) strives to minimize the length of incision in the neck, sometimes with the help of an endoscope. MIT encompasses a diverse set of procedures including (1) completely endoscopic thyroidectomy with CO2 insufflation, (2) minimally invasive video-assisted thyroidectomy (MIVAT) without gas insufflation, and (3) mini-open thyroidectomy. All three approaches can be performed using an anterior (between the strap muscles) or lateral (between strap muscles and the sternocleidomastoid muscle) approach. Remote access thyroidectomy moves the incision from the neck to the chest, breast, axilla, upper back of the neck, or the mouth, but it is not truly minimally invasive surgery because of the additional surgical dissection required from the remote site. Figure 2.2 shows the various approaches of MIT and remote access thyroidectomy.
