Revision and Reoperative Thyroid Surgery Treatment & Management

In cases of primary unilateral thyroid surgery, “exploring” the nonoperative side is not recommended. This operative exploration is generally not helpful because ultrasonography is widely performed when surgery is being considered for thyroid disease. Palpation is less accurate than ultrasonography. When a single lobe and isthmus have already been removed, the morbidity of a completion thyroidectomy can be minimized when the contralateral lobe has not been explored via palpation.

Some authors prefer to perform completion thyroidectomy through a lateral approach. This approach calls for lateral retraction of the carotid sheath and transection of the omohyoid muscle to reach the lateral aspect of the gland through a virgin tissue plane. ^[15] Reoperation of the ipsilateral lobe for removal of the subtotal thyroidectomy stump or for the excision of paratracheal lymph nodes calls for meticulous dissection of the remaining scar tissue to identify the recurrent laryngeal nerve. Intraoperative neural monitoring of the recurrent laryngeal nerve may be helpful in this setting.

Completion thyroidectomy

The use of elective completion thyroidectomy has been controversial in the management of well-differentiated thyroid carcinoma. ^[16] Justifications for performing elective completion thyroid surgery for patients with DTC include the following:

1. enhanced clinical response to radioactive iodine,

2. accurate thyroglobulin monitoring, and

3. removal of multifocal tumors in the contralateral lobe. ^[17]

Once the need for reoperation is established, the reoperation should be performed at intervals from the original surgery that decrease the risk of surgical complications. This subject is also controversial. Some authors state that the completion thyroidectomy should optimally be performed within 7 days; other authors say that 6 weeks to 3 months after the initial operation is the optimal time. ^[18]

Another group showed that transient recurrent laryngeal nerve palsy occurred more frequently in patients who underwent completion thyroidectomy within 8 days to 3 months of the initial surgical procedure rather than in patients in whom completion thyroidectomy was performed either within 7 days of the primary operation or after a minimum of 3 months. They conclude that completion thyroidectomy should be performed either within 7 days of the primary operation or after a minimum of 3 months. ^[19] However, other authors state that the timing of reoperation has no impact on the development of complications. ^{[20, 21]}

Reoperative central lymph node dissection for thyroid cancer

Papillary thyroid carcinoma (PTC) is the most common histological type of malignancy that originates from the thyroid and, thus, the most frequent type of cancer that requires reoperation. These tumors are generally slow growing, but they frequently metastasize to the regional lymph nodes. ^{[17, 22, 23, 24]} Recurrence in the cervical lymph nodes develops in 5.4-13% of patients after initial surgery. ^[25] The presence of nodal metastasis correlates with the persistence and recurrence of tumor. Although routine elective neck dissection is not indicated for all patients with PTC, clinically positive lymph nodes should be systematically cleared at initial surgery. Central lymph node dissection (level VI) should be performed for all recurrent, well-differentiated thyroid carcinomas.

Central neck dissection requires removal of all nodal tissue between the trachea and the carotid sheath and from the thoracic inlet to the hyoid bone. The superior mediastinum is cleared by removing nodes down to the innominate vein, usually in conjunction with cervical thymectomy. Pretracheal nodal tissue is also removed from the midline.

The literature on surgical technique for thyroid bed recurrence is scant. However, Palme et al recommend wide field exposure by horizontally sectioning all of the ipsilateral or bilateral strap muscles and blunt dissection to separate the tissue from the cricoid and tracheal cartilages. ^[26] This is done in a superomedial to inferolateral direction along the course of the recurrent laryngeal nerve to identify the recurrent laryngeal nerves and parathyroid glands in all cases. Once the recurrent nerve has been identified, sharp dissection may be safely used in the removal of the disease.

The use of surgical loupes and a headlight may be of benefit in the identification of critical structures and aid in safe disease removal ^[26]

Meticulous localization of the parathyroids should be accomplished. Intraoperative confirmation of identified parathyroid tissue as well as differentiation from lymph node and soft tissue metastasis can be accomplished by performing small biopsies and frozen sections. Any structure that is suggestive of being a parathyroid gland should be considered as such until proven otherwise.

If a parathyroid cannot be preserved or is inadvertently removed, it should be diced into small pieces and immediately transplanted into the sternocleidomastoid muscle.

Intraoperative neural monitoring (IONM) techniques have been routinely used by many surgeons in an attempt to provide functional assessment of the RLN during surgery. Although no substitute for detailed knowledge of anatomy exists, the use of IONM can be valuable in maintaining the functional integrity of the RLN, particularly in reoperative thyroid surgery, where the location of the RLN is less constant.

Radioguided revision thyroid surgery

Radioguidance with a variety of radionucleotides has demonstrated use in reoperative thyroid surgery, both in the management of residual thyroid tissue and in locoregional recurrence. ^[27] Thyroid remnant and recurrent or persistent DTC that is iodine positive is amenable to¹³¹ I radioguided surgery. Salvatori et al, in their series of 10 patients, were able to locate and remove the foci of disease using¹³¹ I guided surgery with high sensitivity and specificity. ^[28]

For DTC recurrence that is iodine negative, sestamibi scanning has been successfully used for radioguided surgery. ^[29] In their series of 58 patients with iodine-negative locoregional recurrent DTC, Rubello et al found that technetium-99m–sestamibi-guided radiosurgery was helpful in locating tumors intraoperatively, especially when those tumors were located in fibrotic tissue or behind blood vessels. ^[30] Although the feasibility of radioguided surgery has been established, the benefit in terms of disease recurrence and survival has yet to be proven. However, radioguidance may decrease morbidity of reoperative surgery.

Lateral neck dissection

Papillary thyroid cancer often presents with lateral neck lymph node metastasis. Large retrospective studies have consistently failed to identify lymph node metastasis as an important prognostic factor in papillary thyroid cancer. Even if present, they rarely progressed to or even indicated an increased risk of death. Thus, prophylactic lymph node dissection is not warranted routinely for DTC because no clear survival benefit is evident and this surgery is not without complications. Elective neck dissection is recommended for all patients with medullary thyroid cancer, a rarer disease with an aggressive biology. ^{[31, 32]}

The accepted standard of care stated by the American Thyroid Association is as follows: "A modified radical neck dissection is usually indicated for patients with clinically palpable extensive ipsilateral cervical adenopathy.” Similarly, a consensus statement by the American Association of Clinical Endocrinologists and the American Association of Endocrine Surgeons advises that "surgeons should remove all enlarged lymph nodes in the central and lateral neck areas. Prophylactic lateral neck dissection is not recommended.”

Recurrent cervical lymph node metastases have been identified in 30-40% of patients. ^[2] Roh et al analyzed 22 patients who underwent lateral and central neck dissections for lateral cervical recurrence of PTC. ^[33] They found that pathologic examination of the removed nodes showed a high incidence (86%) of positive central nodes in patients with lateral neck node recurrence. They hypothesized that patients with recurrent tumors in the lateral neck may also have clinically or subclinically positive nodes in the central compartment of the neck, if these nodes were not removed during the initial operation.

Preoperatively, direct laryngoscopy or video stroboscopy should always be performed to assess and document vocal cord function and prior RLN damage.

The rate of complications among patients who undergo completion thyroidectomy is higher than among those patients without prior thyroid surgery. Scarring and inflammation in the thyroid bed make dissection and identification of important structures in these cases more difficult. In the largest study of its kind, Lefevre et al evaluated postoperative morbidity in 685 patients operated on over a 14-year period in a single center. ^[34] They found an 8.9% rate of transient complication and a 3.8% rate of permanent complications in patients undergoing completion thyroid surgery.

The incidence of recurrent laryngeal nerve (RLN) injury and transient and permanent hypoparathyroidism after reoperative thyroid surgery has, in the past, been reported to be higher than that of primary thyroid surgery. ^{[35, 36]} More recent studies report that the incidence of transient RLN injury and permanent RLN injury is 1.5-5% and 0-5.6%, respectively. ^{[18, 37, 38, 39]} Transient hypoparathyroidism occurs in 8-15% of patients. ^{[35, 32, 36, 37]} Permanent hypoparathyroidism is less common and is seen in up to 3% of patients who undergo completion thyroidectomy. ^{[37, 38, 39, 40]} In comparison, in an unoperated neck, the risk for RLN injury is less than 1%, and the risk for permanent hypoparathyroidism is 1-2%. ^{[41, 42]}

Reoperative surgery for recurrent or persistent thyroid cancer presents several challenges to the surgeon. In this setting, the surgeon may encounter significant difficulty in the identification and preservation of important anatomic structures because of scarring and disturbance of the normal anatomic relationships from prior treatment. The use of intraoperative neurological monitoring, meticulous surgical dissection, and identification of the recurrent laryngeal nerve and parathyroid glands are key to decreasing the potential for complications in these patients.