HOW THYROID RFA IS PERFORMED

Radiofrequency thermal ablation is an outpatient operation that is performed under ultrasound guidance, without the need to make surgical incisions, by means of a needle-electrode that overheats the nodular tissue and reduces the volume of benign thyroid nodules by at least 80%. The reduction of the volume of the lump is generally sufficient to make the compression symptoms disappear and obtain excellent aesthetic results. RFA also improves the quality of life (Health Related Quality of Life, HRQoL) (1, 2).

Radiofrequency thermal ablation is indicated for the treatment of solid or partially cystic benign nodules of the thyroid gland, autonomously functioning thyroid adenomas, toxic or pretoxic. Malignant micropapillary tumors (microPTC) or lymph node metastases that are not responsive to radioiodine or candidates for surgery are also thermally ablated (3).

Before surgery, it is necessary to determine the nature of the thyroid nodule by ultrasound-guided fine needle aspiration or by needle biopsy.

The best results are obtained on benign nodules with a volume <30 ml, oval-shaped and with a colloid-cystic spongiform echo structure, or in cystic or partially cystic benign nodules. There is evidence that in non-metastatic T1 N0 M0 primary papillary cancers thermal ablation technology obtains the same results as more aggressive open surgery.

The most used technique is monopolar radiofrequency. During minimally invasive, ultrasound-guided thermal ablation surgery, the patient is part of a circuit that includes a radiofrequency generator, a needle-electrode and two dispersion plates positioned on the patient’s legs (Fig 1).

The electrode needle is introduced into the nodule under ultrasound guidance. The high frequency electromagnetic waves emitted by the electrode overheat the nodule inducing necrosis of the treated tissue, which will be replaced over time by fibrous-scar tissue. This leads to a significant reduction in the volume of the thyroid nodule. A saline cooling system controls the temperature at the needle tip during treatment to avoid the charring process.

The operation takes place on an outpatient basis, without the need for general anesthesia with intubation. The patient is placed on the operating table in a supine position, with the head hyperextended.

The surgeon, with the help of the surgical room nurse, performs ultrasound-guided local pericapsular anesthesia with 2% lidocaine (short action) and 10% bupivacaine (protracted action). The anesthetist cannulates a vein and sedates the patient with 3-5 mg midazolam followed by pumped propofol for infusion. Oxygenation is maintained by means of “goggles” connected to an oxygen cylinder. Vital signs, including respiration, ECG, partial pressure of oxygen, blood pressure are monitored by the anesthetist for the duration of the operation. Sedation is necessary to facilitate maneuvers and to reduce the spontaneous acts of swallowing. Sedation causes unconsciousness and even anterograde amnesia. The patient loses all memory of the surgery and does not complain of any intraoperative pain while maintaining a certain reactivity.

The procedure, including set-up times, has a variable duration of about 60-90 minutes. It can be repeated on particularly bulky nodules or in cases of recurrence. At the end of the operation, steroid and pain-relieving therapy is administered via the venous route. After RFA surgery, the patient awakens promptly but is kept under observation in the recovery room for 1-2 hours. Finally, before discharge, the patient undergoes a thyroid ultrasound examination.

Risks or side effects with proper technique, are of minimal relevance. They include sense of discomfort in the neck, skin bruising, no bleeding, no abscesses or infections are observed provided that the whole procedure is performed in a sterile field.

The only very rare relevant side effect is dysphonia (hoarse voice). In rare cases transient hoarseness occurs, due to overheating of the recurrent laryngeal nerve. The infusion of cold glucose solution + 2 ° C dissecting the inferior laryngeal nerve from thyroid nodule minimizes the risk.

At the time of discharge, some drugs are prescribed to patients: corticosteroids in various doses and durations to reduce post-operative edema and eliminate the risk of late colliquation of the treated mass, to be taken orally at breakfast. A pump inhibitor to achieve gastroprotection is administered for the duration of the corticosteroid treatment.

The equivalence of surgical therapy and thermo-ablative therapy is demonstrated. The advantages of ultrasound-guided radiofrequency over traditional “open” surgery are: absence of scars, organ preservation and normal function of the thyroid after thermal ablation, no need to take any therapy, minimal side effects, no need of deep general anesthesia, absence of postoperative drainage tubes, no need of hospitalization, much faster recovery, minimized aggression, improvement of the quality of life.