A small (1.5–2 cm), midline skin incision is made between the cricoid cartilage and the sternal notch (Fig. 17.2). The skin incision in MIVAP is often placed higher than in conventional parathyroidectomy. Precise placement of the incision may also be impacted by the location of the apparent adenoma on preoperative imaging.

After the skin incision is carried through the subcutaneous tissues and platysma muscle, the linea alba, between the strap muscles, is opened as widely as possible. When initially developed, MIVAP utilized a short period of CO₂ insufflation to facilitate dissection of the thyroid lobe from the strap muscles. The use of gas insufflation has now been completely abandoned. The thyroid lobe is separated from the overlying strap muscles by means of small conventional retractors (Farabeuf retractors), which are also used to maintain the operative space. Following this, the thyroid lobe is medially retracted, while the strap muscles are retracted laterally. At this point, the endoscope (5 mm – 30°) and the dedicated small surgical instruments (2 mm in diameter) are introduced through the incision (Fig. 17.3). The endoscope is maintained in position with two hands by the assistant. The absence of a trocar allows the position of the endoscope to be precisely changed, thus constantly providing optimal visualization of the operative site. This represents an important advantage of the video-assisted procedure over purely endoscopic techniques. In MIVAP, the endoscope is usually angled upwards, oriented toward the head of the patient. The angle of the endoscope can be changed to expose and explore the upper mediastinum when required.

Critical to obtaining exposure is the complete release of the thyroid gland from the strap muscles. This allows the view necessary to fully explore the likely sites of the parathyroid glands. Inadequate dissection and rotation of the thyroid gland medially can lead to difficulty identifying an adenoma.

After unfurling the thyroid gland from the tracheoesophageal groove, the recurrent laryngeal nerve can be identified, usually in close proximity to the inferior thyroid artery. Following this, a targeted exploration is carried out, almost exclusively with blunt dissection, to identify the abnormal gland. The magnification of the endoscope permits, in most cases, the nerve and the parathyroid glands to be easily recognized. This is particularly true if the principles of blunt and bloodless dissection are respected.

After being identified (Fig. 17.4a), the pathologic parathyroid gland is bluntly dissected under endoscopic vision, using dedicated spatulas and spatula-shaped aspirator (Karl STORZ, Tuttlingen, Germany) (Fig. 17.4b). The pedicle of the adenoma is usually clipped with titanium clips or ligated with conventional ligature. After dividing the pedicle, the adenoma is extracted through the skin incision (Figs. 17.5 and 17.6). IO-PTH assay should confirm the removal of all pathologic tissue. After assuring adequate hemostasis, the strap muscles are sutured along the midline. The skin is closed by means of a subcuticular running suture or with a skin sealant. No drain is placed.

In case of suspicion of multiglandular disease (whether because of inadequate IO-PTH decrease, 2-gland enlargement recognized during unilateral exploration, or if no localization is provided by preoperative imaging studies), bilateral parathyroid exploration can be accomplished using the same video-assisted technique through the single, central skin incision.

A number of retrospective series have reported on the outcome and the medium-term results of MIVAP. The largest of these series, from the Miccoli group, assessed 350 cases of MIVAP after a 6-year experience. They reported a cure rate of 98.3 %. After an average follow-up of 35.1 months, persistent disease was evident in four cases. In regard to complications, the authors reported a 2.7 % rate of transient hypocalcemia, 0.8 % rate of definitive nerve palsy, and a 0.3 % rate of postoperative bleeding. Other studies have uniformly shown similar excellent cure and complication rates.

With appropriate patient selection and adequate surgeon experience, the need to convert to conventional BNE is usually infrequent, even in an endemic goiter region. The need to convert to an open approach or BNE is usually related to difficulty identifying the diseased gland(s), challenging dissection because of a large goiter or adenoma, thyroiditis or previous surgery, suspicion of thyroid malignancy, suspicion of multiglandular disease, or an ectopically located adenoma.

Studies have shown favorable benefits of MIVAP compared to BNE and open minimally invasive parathyroidectomy. One prospective, randomized trial compared MIVAP with BNE, in terms of operative time, postoperative pain, complications, cosmetic result, and costs. The results showed a significant decrease in operative time, postoperative pain, and postoperative inactivity period with MIVAP. Patient satisfaction with the cosmetic outcome was significantly superior in the group of patients who underwent MIVAP. Despite the need for two assistants (a frequently cited concern with MIVAP), no significant differences in terms of overall costs were found between the two procedures. Several studies comparing open minimal invasive parathyroidectomy with MIVAP have shown that the two approaches have similar results with regard to cure and morbidity rates and operative time. MIVAP appears to offer improved cosmesis, significantly better postoperative physical functioning, and perhaps shorter postoperative hospital stays.