Operative indications

The inclusion criteria and the main contraindications for MIVAT are summarized in Table 1-1. The main limiting factor is the size of both the nodule and the thyroid gland, as measured by preoperative ultrasonography. In geographic areas with endemic goiter, the gland volume can vary considerably compared with the nodule volume. Thus, if the gland was not adequately imaged before attempting MIVAT, there is increased risk for conversion to open thyroidectomy. Ultrasonography also may be useful to exclude thyroiditis, which can increase the difficulty of the dissection. If thyroiditis is suspected by ultrasonography, then serum autoantibodies should be determined. In general, thyroiditis by itself should not be an indication for MIVAT.

Table 1-1 Indications and Contraindications for MIVAT

Indications	Contraindications
Benign disease*	Recurrent disease
Low risk papillary carcinoma Graves disease	Locally advanced and/or metastatic carcinoma Short neck in an obese patient

^* Thyroid volume less than 25 mL and nodule diameter less than 3 cm.

One of the most controversial operative indications for MIVAT is malignancy. Although low-risk papillary carcinoma (characterized by female sex, age <30 years, absence of distant metastasis, no extrathyroidal extension, and tumor dimension <2 cm) generally has been thought to be amenable to MIVAT, a careful evaluation for possible lymph node involvement in the neck has to be done in the thyroid cancer patient who is considered for this procedure. Great caution should be taken with disease metastatic to lymph nodes or with extracapsular invasion. In these cases, MIVAT may not allow for complete lymphadenectomy or for adequate excision of a mass infiltrating into the trachea or esophagus and therefore is not advisable. Accurate preoperative ultrasonography is paramount for the proper selection of a patient with thyroid cancer who may undergo MIVAT.

Preoperative evaluation, testing, and preparation

All patients should be rendered euthyroid before the procedure. Preoperative preparation of the patient with thyrotoxicosis is critical to avoid perioperative thyroid storm. During the informed consent process, the possibility of conversion to open surgery should be explained to the patient, particularly if the diagnosis is cancer. It is our opinion that in addition to neck ultrasonography, preoperative laryngoscopy should be performed in all patients undergoing thyroid surgery to identify asymptomatic vocal cord hypokinesia or palsy.

Patient positioning

The operation is performed with the patient under general anesthesia; alternatively, a deep bilateral cervical block may be used. The patient is placed supine without neck hyperextension (Fig. 1-1). After aseptic preparation, the skin is protected with a transparent adhesive film (e.g., Tegaderm, 3M, St. Paul, Minn.) and then draped. The surgeon stands on the patient’s right, the first assistant is opposite the surgeon on the left, the second assistant is at the head of the table, the camera operator is on the patient’s left and caudal to the first assistant, and the scrub technician is on the right and caudal to the surgeon (Fig. 1-2). Two monitors, one facing the surgeon and the other facing the first assistant, are optimum. The basic instrumentation used for MIVAT is shown in Figure 1-3. Other helpful instruments include a suction dissector, thin ear forceps, vascular clip applier, and straight scissors.

FIGURE 1-1 Patient positioning on the operating table for MIVAT. The neck is not extended.

FIGURE 1-2 Operating team setup for MIVAT.

FIGURE 1-3 Basic instrument tray for MIVAT, including large double-ended retractor, Army-Navy-type (a); small double-ended retractor (length 12 cm) (b); forward-oblique endoscope, 30-degree viewing angle, diameter 5 mm, length 30 cm (c); aspirating spatula (d); dissecting spatula (e); ultrasonic scalpel (f); endoscopic scissors (g); endoscopic forceps (h); and insulated monopolar electrocautery tip (i).

Operative technique

Preparation of the Operative Space

A 1.5-cm horizontal skin incision is performed 2 cm above the sternal notch. Subcutaneous fat and platysma are carefully dissected to minimize bleeding. During this step of the procedure, the use of the insulated electrocautery blade (see Fig. 1-3) is preferred to avoid damage to the skin and the superficial planes. Two small retractors are used to expose the deep cervical fascia, which is incised in the vertical midline in a bloodless plane for 2 to 3 cm (Fig. 1-4). The thyroid lobe is then bluntly dissected from the strap muscles using small spatulas (see Fig. 1-3) and gentle retraction. When the thyroid lobe is almost completely dissected from the strap muscles, larger double-ended retractors (Army-Navy type; see Fig. 1-3) can be inserted to maintain the operative space during the endoscopic portion of the procedure (Fig. 1-5). A 30-degree, 5-mm (or 7-mm) endoscope is then introduced through the skin incision to commence the endoscopic portion of the procedure (Fig. 1-6).