Revision and Reoperative Thyroid Surgery 

Updated: Dec 19, 2016
Author: Ron Mitzner, MD; Chief Editor: Arlen D Meyers, MD, MBA 

Overview

Problem

Revision or reoperative thyroid surgery is often technically challenging because of anatomic changes following primary surgery.

Presentation

Most thyroid cancers are differentiated, slow-growing, easily treatable tumors with an excellent prognosis after surgical resection and targeted medical therapy. Approximately one third of patients with differentiated thyroid cancer (DTC) have tumor recurrence; most are diagnosed within 10 years of treatment.[1, 2, 3] Locoregional recurrences may arise in the central or lateral neck, thyroid remnant, mediastinum, or, rarely, in the trachea or the muscle overlying the thyroid bed. The mortality from locally recurrent disease in the low-risk group (according to the Age, Metastases, Extent, and Size [AMES] prognostic index) with DTC is 4%. However, patients who are male and older than age 45 years experience a mortality rate of 27% once DTC recurs.[4]

Clinical or radiologic evidence of locally recurrent DTC is generally treated with surgical removal of the focus of disease and postoperative iodine-131 (131 I).

Indications

Reoperative thyroid surgery may be performed under a number of circumstances. A patient may have had a previous thyroid lobectomy and require a completion thyroidectomy for differentiated thyroid cancer (DTC). Recurrence of thyroid cancer may require reexploration of the thyroid bed or cervical lymph node dissection, including the central compartment (level VI). Additionally, occurrence of cancer in the thyroid remnant after operation for benign thyroid diseases or symptomatic disease in a partially removed nodular or multinodular goiter may also require reoperation.[5]

Relevant Anatomy

Normal anatomy

The thyroid is a highly vascular gland in the neck that overlies the proximal trachea and thyroid cartilage. It is composed of right and left lateral lobes joined at their medial aspects by an isthmus (see image below). In approximately 50% of patients, an appendage to the gland (termed the pyramidal lobe) courses cephalad from the isthmus. The strap muscles overlie the thyroid lobes.

Thyroid gland, anterior and lateral views. Thyroid gland, anterior and lateral views.

The arterial blood supply to the gland is composed of the superior thyroid artery and the inferior thyroid artery, branches of the external carotid artery and the thyrocervical trunk, respectively (see the first image below). Approximately 3% of individuals also have a thyroid ima artery that supplies the gland. The thyroid is attached to the trachea by the ligament of Berry. The recurrent laryngeal nerves (RLN) are in close proximity to the thyroid as they course from the tracheoesophageal groove to the cricothyroid membrane. The tubercle of Zuckerkandl is an important landmark of the RLN.[6] The parathyroid glands lie in close proximity to the thyroid, usually as paired structures adjacent to the upper and lower poles of the thyroid gland (see the second image below).

Distribution of thyroid arteries with associated l Distribution of thyroid arteries with associated laryngeal nerve, anterior view.
Axial CT scan of a patient with a thyroid lesion p Axial CT scan of a patient with a thyroid lesion prior to thyroidectomy.

Anatomical changes following thyroidectomy

Changes in cervical anatomy may take place following thyroidectomy. The carotid sheath is an important landmark in thyroid surgery. It provides the lateral boundary of dissection and is an important landmark when initially identifying the RLN.[7] Realizing that the great vessels of the neck may medialize following thyroidectomy and may be directly adjacent to the trachea (see the image below) is important. Scarring and fibrosis from prior surgery may cause increased difficulty in identifying and dissecting important structures. When reoperating the area of the ipsilateral thyroid remnant, the recurrent laryngeal nerve is often difficult to identify and dissect because it is buried in scar tissue. The tracheoesophageal groove itself may be scarred and distorted.

Axial CT scan of a patient one year after total th Axial CT scan of a patient one year after total thyroidectomy. The great vessels of the neck are significantly medialized.

For more information about the relevant anatomy, see Thyroid Anatomy.

 

Workup

Approach

Approach to Recurrent Differentiated Thyroid Cancer

During the postoperative period, the clinician should be aware of the signs of residual or recurrent thyroid cancer. Persistently elevated thyroglobulin after surgery and/or focal radioiodine avidity suggests residual tumor burden or residual functioning thyroid tissue. When thyroglobulin is elevated due to tumor burden, it may be due to residual primary tumor, locoregional disease, nodal, or distant metastases. Suspicious lesions found on physical examination, radiologic examination, or radioiodine scan should have a biopsy performed on them by ultrasound-guided fine-needle aspiration (FNA). Alternative strategies must be used for surveillance and treatment when radioiodine avidity is lost or when thyroglobulin is not a valid tumor marker.

After thyroidectomy and radioiodine remnant ablation, several methods are used to follow patients with differentiated thyroid cancer, including serum thyroglobulin levels, ultrasonography of the neck, iodine-131 (131 I) whole body scintigraphy (WBS), and scintigraphy with nonspecific tracers such as technetium-99 m (99m Tc) tetrofosmin, or sestamibi.

Laboratory Studies

Serum thyroglobulin levels

Serum thyroglobulin (Tg) level measurement is the most-used method of early detection and monitoring for recurrent thyroid cancer. Serum Tg levels principally integrate the following 3 variables:

  • The mass of thyroid tissue present (benign or neoplastic)

  • The degree of thyrotropin (TSH) receptor stimulation

  • The tumor's intrinsic ability to synthesize and secrete Tg

Serum Tg levels are part of the preoperative evaluation. When TSH is low (on levothyroxine [LT4] therapy), basal serum Tg may be undetectable and recombinant human thyrotropin (rhTSH) administration may be needed to increase serum Tg into the measurable range. The Tg fold response to rhTSH is an index of the tumor's sensitivity to TSH and is calculated by dividing the rhTSH-stimulated Tg level by the basal Tg level. Normal thyroid remnant and differentiated thyroid cancer (DTC) display a greater (>10-fold) serum Tg response to TSH stimulation compared with less well-differentiated tumors (< 3-fold).

Imaging Studies

Ultrasonography

Ultrasonography is important in the preoperative assessment of patients with thyroid cancer. This technique allows for the detection of cervical lymph node and soft tissue metastasis that is not evident on physical examination.[8] Lesions as small as 4 mm have been reported to be detectable via ultrasonography. This becomes especially helpful in reoperative planning and determination of the need for further neck dissection. Ultrasonography has been shown to be a sensitive technique that can be used to monitor patients for recurrent thyroid carcinoma in the thyroid bed after total thyroidectomy. One potential diagnostic pitfall is the misdiagnosis of normal residual thyroid or parathyroid gland tissue as recurrent tumor.[9] Preoperative high-resolution ultrasound mapping improves the detection and assessment of lymph node metastasis in those patients with persistent or recurrent papillary thyroid cancer (PTC).[10, 11] The authors find preoperative high-resolution neck ultrasoundmappingandmarkinghelpful when it is used prior to reoperative thyroid cases.

Positron emission tomography with 2-(F-18)-fluoro-2-deoxy-D-glucose/CT scanning

Positron emission tomography with 2-(F-18)-fluoro-2-deoxy-D-glucose/CT scanning (PET-FDG/CT) can provide precise anatomic localization of recurrent or metastatic thyroid carcinoma (which leads to improved diagnostic accuracy) and can guide therapeutic management. Two thirds of recurrences or metastases of differentiated thyroid cancer store iodine.[12, 13] Most metastases that are131 I negative demonstrate FDG uptake, which represents rapid tumor growth and poor differentiation, whereas most of the131 I–positive metastases are PET-FDG negative.[12] The sensitivity for detecting131 I-negative metastases with PET-FDG can be increased by elevated thyroid-stimulating hormone (TSH) after withdrawal of thyroid hormone therapy or after intramuscular injection of recombinant TSH.

Iodine-131 whole-body scintigraphy

131 I is the radionucleotide with the highest specificity for DTC. However, only about two thirds of metastases from DTC accumulate iodine.[14] Therefore, in addition to131 I whole-body scintigraphy (WBS), other nonspecific tracers (eg,99m Tc tetrofosmin WBS,99m Tc sestamibi WBS, or PET-FDG) are needed to detect iodine-negative recurrences or metastases.[14]

The combination of131 I-WBS and FDG-PET increases the detection rate to more than 90-95% of cases.

Other imaging modalities

When determining the extent of metastasis in recurrent disease, CT scans and MRI may be valuable in delineating the location and extent of tissue invasion.

Other Tests

Fine-needle aspiration

The sensitivity of ultrasound-guided fine-needle aspiration (FNA) for diagnosing recurrent carcinoma in the thyroid bed after total thyroidectomy was 100% with a specificity of 85.7%.[9]

 

Treatment

Surgical Therapy

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.

Preoperative Details

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

Complications

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]

Outcome and Prognosis

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.