Cervical approach for retro-sternal goiter reaching the arch of aorta


 Background: Although the retrosternal goiters are characterized by the protrusion of at least 50% of the thyroid tissue below the level of the thoracic inlet, their definite definition is still controversial. Total thyroidectomy for retrosternal goiter has a great challenge and mostly requires an experienced thyroid surgeon. Excision could be possible through a cervical incision in most cases, though Sternotomy remains an option. Patients and Methods: We report fourteen patients who presented to our academic medical center between 2016 and 2019 with large thyroid goiters and retrosternal extension proven by computerized tomography scan of the neck, presented in both Mansoura University Oncology Center, Egypt and East Jeddah Hospital, Saudi Arabia from 2016 to 2019. Results: Fourteen cases with retrosternal goiter been undergone total thyroidectomy through a cervical incision without the need for median sternotomy, although the thoracic surgeon was stand-by in three cases. Six patients were found to have a malignancy in the post-operative histopathological assessment.CONCLUSION: Surgical procedures for most all retrosternal goiters can be completed successfully using a cervical approach; however, a sternotomy is required in a small number of such patients.


Introduction
Substernal goiter refers to the descend of a portion of thyroid mass into the thoracic cavity. Those goiters are usually enlarged and presented clinically with symptoms associated with the close proximity of the substernal part of the gland to the surrounding visceral and vascular tissues. (1,2). We present fourteen patients diagnosed with a retrosternal goiter who underwent total thyroidectomy using a cervical approach. Six of the patients were discovered to have a malignancy on histopathological assessment these malignancies included: papillary thyroid cancer, follicular thyroid cancer, chondrosarcoma, and non-Hodgkin lymphoma.

Patients & Methods
A retrospective review was undertaken of all patients with underlying retrosternal goiter who had undergone total thyroidectomy through a cervical incision at the general surgery department at East Jeddah General Hospital and Mansoura University Oncology Center.
Retro-sternal goiter was diagnosed using both neck ultrasound and CT neck with IV contrast. All patients underwent thyroid function test and US-guided ne-needle aspiration cytology from the prominent suspicious nodule; A Thoracic surgeon was stand-by in three cases for the possible need for sternotomy incision. All cases were pre-operatively evaluated and cleared by the anesthesia team and were consented for the surgery.

Results
Fourteen cases with retrosternal goiter been undergone total thyroidectomy through a cervical incision without the need for median sternotomy; although the thoracic surgeon was stand-by in three cases.
All patients were women except for four male patients, with a median age of 55.5 years (range, 34 -78 years). Retro-sternal goiter has been con rmed with both US neck and enhanced computerized tomography (CT) neck with a median size of the prominent enlarged nodule of 5.8 x 3.5 cm, accompanied by a retro-sternal extension down to aortic arch (Level-II) causing tracheal narrowing and deviation to the contralateral side in all cases.
All patients were euthyroid except one case showed sub-clinical hypothyroidism. US-guided FNA has been done for four cases from the most suspicious thyroid nodule and revealed benign nding (DC-II) (According to the Bethesda system reporting for cytology). For the fth case, US-guided FNA was done from the suspicious right cervical lymph node which came back as non-conclusive and an excisional biopsy had to be performed and con rmed papillary thyroid carcinoma.
Endotracheal intubation after anesthetic induction using a bro-optic laryngoscope for two cases. Total thyroidectomy has been done successfully through the cervical incision in all cases. In the fth case, we extended the incision to form half apron for lateral neck dissection.
Complete visualization of recurrent laryngeal nerve on both sides has been done.
All cases did not experience any intra-operative or post-operative complications, except one case showed a temporary post-operative hypocalcemia which was recovered in two weeks. Histopathological assessment of the excised specimens for all cases showed multifocal papillary carcinoma in 3 cases, with the need for radioactive iodine ablation for two of them. On outpatient follow-up, all patients showed satisfactory outcomes with concomitance to their replacement therapies.
Patient characteristics are summarized in Table one and two representative cases are described below:

Case Study 1
This case pertains to a 69-year-old lad, who was admitted to the orthopedic surgical ward for a traumatic fracture right femur neck after falling down at home. She is known to have rheumatoid arthritis and noncompliant on her medications, with an inability to fully extend her very short neck.
On preoperative preparation, the anesthesia team noticed enlarged and engorged neck veins over the anterior chest wall with no other symptoms of respiratory compromise. The orthopedic surgery was postponed as instructed by the Anaethesia team and we received a consultation for the assessment of this patient.
Laboratory exams including thyroid function tests were within normal limits. CT chest with IV contrast was done and revealed; left thyroid lobe measured 8 x 4 x 4 cm with central necrosis and extension down to the level of the aortic arch, while the right lobe measured 3 x 7 x 4 cm, extending from the level of vocal cords down to the right paratracheal area at the level of T6, with noticed moderate luminal tracheal narrowing with deviation to the right side ( Figure 1).
After written consent, the patient was admitted for surgery, which was done under general anesthesia with endotracheal intubation via exible ber optic bronchoscope.
With thoracic surgeon, standby for the possible need for sternotomy. Surgery was started with cervical incision and management has been done to deliver both lobes and get a clear visualization of right and left recurrent laryngeal nerves and all parathyroid glands (Figures 2).
Removal of the thyroid gland was done through a cervical incision without the need for sternotomy ( Figure 3).
The patient was shifted to the surgical ward after successful extubation. The patient passed the postoperative period safely and was discharged from surgery side in a good condition. In the same admission, the patient went for her orthopedic surgery for xation.
Histopathological examination of the excised thyroid gland revealed multifocal papillary thyroid carcinoma (3 foci each less than 0.5 cm) in background of multinodular goiter with hyperplastic nodules.
Thyroid hormone replacement therapy started immediately on the next day of surgery (1.7 x kg body weight). The patient is following in the general surgery clinic. Neck U/S showed multiple nodules in both thyroid lobes, with multiple bilateral cervical modules, the largest seen in the right cervical side measures 4.3 x 3 cm. CT scan of the neck with IV contrast con rmed the multiple nodules in the right cervical region as a chain down to the retrocaval, anterior and upper mediastinal region (Figure 4).
This patient This patient is a 42-year-old woman, who presented to the outpatient clinic with a complaint of progressive swelling of the right-sided of her neck; she reported no other associated symptoms. Upon examination; a palpable large right cervical lymph node masse at level II & III about 4 x 4 cm with stretching of the nearby sternomastoid was noticed. While the thyroid gland was normal in its size and site.
Neck U/S showed multiple nodules in both thyroid lobes, with multiple bilateral cervical modules, the largest seen in the right cervical side measures 4.3 x 3 cm. CT scan of the neck with IV contrast con rmed the multiple nodules in the right cervical region as a chain down to the retrocaval, anterior and upper mediastinal region (Figure 4).
As a result, Total thyroidectomy with central and right lateral neck dissection was planned, and after the patient's consent and clearance from the anesthesia side, surgery has been undergone through a cervical half apron incision, starting with the delivery of the retro-sternal enlarged central compartment lymph nodes successfully through the performed incision without the need for the sternotomy after blunt dissection of the mass from the aortic arch ( Figure 5).
Followed by delivery of each lobe after complete visualization of the recurrent laryngeal nerve on each side, especially the right recurrent laryngeal nerve ( Figure 6) which was encroached by the tumor mass along its whole cervical length before the complete excision has been completed.
Finalizing the procedure by lateral neck dissection for the lymph nodes at level II, III and IV, and all the specimens (Figure 7) were sent for the pathologist.
The patient has passed the post-operative period uneventfully apart from temporary hypocalcemia to which oral calcium carbonate was administered, and was discharged on post-operative day 3 The histopathological assessment of the excised specimen showed multifocal papillary Carcinoma < 1 cm with a lymphocytic thyroiditis in the background. In addition to the metastasis to the amalgamated lymph nodes at the levels II, III, IV and VI.
On follow-up at the outpatient clinic, the patient was satis ed with the outcome and she was referred for radio-iodine ablation.

Discussion
Substernal goiter (SSG) is clinically and/or radiologically de ned as thyroid tissue extension below the sternal fork when the patient is in a supine position. (3) Two entities can be distinguished in SSG: cervico-thoracic goiter (CTG) and intrathoracic goiter (ITG), the former shows exclusively thyroid vascularization; while the ITG featuring with the development of ectopic thoracic thyroid tissue, without continuity with the cervical tissue. In addition to being rare (< 1% of goiters), it shows speci cally thoracic vascularization (internal thoracic artery, aorta, etc.) (4), and thus comes within the eld of thoracic surgery, with speci c approaches. (5) Thoracic extension in CTG is progressive into regions of lower anatomic resistance behind and anterior to the supra-aortic vessels. Anterior extension is the most familiar at about 75% of CTGs. (4) It shows a rapidly compressive manifestations, hindered in its inferior development by the brachiocephalic artery. CTGs with posterior development may be quite large, without clinical impact or symptoms, because there is a large space behind the brachiocephalic artery. (4) The retrosternal goiter shows a slowly progressive growth course, that leads to its presentation in the fth or sixth decade of life.(6) In some series of patients with retrosternal goiters, acute problems occur with an incidence of between 5-11%. (7,8) The diagnosis of RG is mainly based upon history, clinical examinations, and imaging ndings (7). Computed tomography (CT) of the neck is the examination of choice for assessment of the extent of the goiter and compression effects on adjacent anatomical structures (9). Magnetic resonance imaging (MRI) adds a little additional information to that obtained with CT and is not routinely used (10).
The papillary thyroid carcinoma is the most common histopathologic subtypes, which may be detected in the retrosternal goiter, with overall malignancy rate between 0-20%. (11,12) Thyroidectomy should be performed in all patients with retrosternal goiter, when there are no medical contraindications for the surgery. The recommendation was based on the increased risk of thyroid cancer and later respiratory problems. (1) Preoperative FNA is an excellent tool for the evaluation of patients with a solitary, cervical thyroid nodule, but its value is still debatable in patients with multiple nodules and substernal goiters. (13,14).
The collar incision is the standard access for retrosternal goiter, except for around 2% who may need for either manubriotomy, sternotomy or thoracotomy. (1) Most RGs can be totally removed through a cervical approach, while a partial or total sternotomy should be performed only in a minority of patients, ranging between 1-11% (1).
When performing a thyroidectomy for a retrosternal goiter, an experience with a speci c interest in thyroid surgery is needed. (1) Although most retrosternal goiter can be safely resected through a cervical incision, the combined cervical-thoracic approach has been reported to be necessary in up to 2% of cases. (11,12,15). An agreement has been reached that sternotomy is not to the routine recommendations, as a collar incision is su cient in most situations. (1) In conclusion: Thyroidectomy should be performed in all patients with retrosternal goiter who do not have medical comorbidity excluding them from surgery.
The majority of retrosternal goiter could be totally resected through a cervical incision avoiding the morbidities of additional thoracic approach. An attempt to remove the goiter through the cervical incision should always be made, using all the available techniques.
Thyroidectomy for a retrosternal goiter should be carried out by a skillful surgical team that is familiar with its unique pitfalls. The need for thoracic surgeons may only be required in a few selected cases.

Declarations
Ethics approval and consent to participate: Case study-1, CT neck with IV contrast.

Figure 3
Case study-1, total excision of the thyroid gland.

Figure 4
Case study-2, CT neck with IV contrast.

Figure 5
Case study-2, delivery of the enlarged lymph node.

Figure 6
Case study-2, identi cation of right recurrent laryngeal nerve.