Radiofrequency Ablation: A Novel Treatment Option for Neck Recurrence in Medullary Thyroid Carcinoma

Background: Medullary thyroid carcinoma (MTC) is an aggressive cancer with cervical lymph node metastases typically found at presentation. The recurrence rate after resection is high (~ 50%)(1), and patients often need multiple surgeries. Radiofrequency ablation (RFA) has been used in treatment of recurrent thyroid cancer when surgery is contraindicated or declined by patients in both Asia and Europe (2). We present the first case of an MTC recurrence treated successfully with RFA in North America. Clinical Case: A 43-year-old female with sporadic metastatic MTC, status post total thyroidectomy and multiple neck surgeries, presented with elevated calcitonin level of 630 pg/mL (normal: < 10 pg/mL). Neck ultrasound showed left tracheoesophageal groove mass, measuring 12 mm X 12 mm X 17 mm, consistent with metastatic MTC on cytopathology with calcitonin washout of 16590 pg/mL (normal: < 10 pg/mL). She had no dysphagia, shortness of breath or hoarseness of voice. Computed tomography (CT) scan of chest confirmed presence of mass, in proximity with left recurrent laryngeal nerve. Serial imaging showed rapid enlargement, with concern for impending aerodigestive tract invasion. Surgical intervention had a high risk of vocal cord paralysis due to the lesion’s location. A multidisciplinary tumor board agreed that thermal ablation aimed at shrinking the mass, as a bridge to systemic therapy, would be the best option. RFA was performed as an outpatient with conscious sedation, after informed consent and observing standard aseptic techniques. Under continuous ultrasound guidance, D5W was injected into left tracheoesophageal groove behind the mass and a continuous infusion of D5W at 15 mL/hr was maintained to protect the nerve from thermal injury. Using a trans-isthmic approach, an 18 G monopolar RFA probe with 5 mm active tip was advanced into the malignant mass and ablation was performed with 35 W power until the entire mass was hyperechoic. Vocal response was monitored throughout the procedure and voice remained normal after RFA. A neck ultrasound at her 6 months follow-up showed ablated lesion measuring 7 mm X 11 mm X 10 mm, representing a 68.6% reduction in volume. Repeat CT scan thorax showed disappearance of mass in left neck region. Conclusion: RFA is a minimally invasive and effective treatment for recurrent cervical MTC lesions, and a viable alternative to surgery, as shown in our case. Future studies should focus on long term follow-up and comparison with surgery with regards to safety and efficacy. References: 1.Skoura E. Depicting medullary thyroid cancer recurrence: the past and the future of nuclear medicine imaging. Int J Endocrinol Metab. 2013;11(4):e8156. 2.Garberoglio R, Aliberti C, Appetecchia M, Attard M, Boccuzzi G, Boraso F, et al. Radiofrequency ablation for thyroid nodules: which indications? The first Italian opinion statement. J Ultrasound. 2015;18(4):423-30.

Comprehensive Comparison of Right and Left Recurrent Laryngeal Nerves in the Tracheoesophageal Groove

Objective A left-sided cervical approach to esophageal mobilization is considered safer given the perceived oblique path and more lateral orientation of the right recurrent laryngeal nerve (RLN) in the tracheoesophageal groove. Given the risk of recurrent laryngeal nerve, the current study investigated if there are differences in right and left RLN location in the tracheoesophageal groove. Methods Right and left RLNs were carefully exposed in human cadavers. Comparison of location was determined at tracheal rings 2, 4, and 6 using 3 parameters: depth of the RLN from the anterior margin of the tracheal ring, lateral distance of the RLN from the posterior margin of the tracheal ring, and distance of the RLN to the anterior midline trachea following the curvature of the trachea. Statistical analysis was used to determine differences between the right and left sides. Results Compared with the right RLN, the left RLN was slightly over 1 mm deeper at the second tracheal ring. Despite this trend, there was no significant difference in RLN location between individual sides or as an aggregate for any of the 3 parameters at tracheal rings 2, 4, or 6. Conclusions Careful characterization of RLN location precludes avoiding hoarseness, aphonia, and vocal cord paralysis. Counter to common surgical perception and educational beliefs, this study demonstrated that right and left RLN anatomical courses do not significantly differ along the trachea. Therefore, ensnarement on either side during a blind mobilization of the cervical esophagus is equally likely to occur.

Non-Recurrent Laryngeal Nerve - A Surgical Challenge

Both the cases discussed here had right sided NRLN, out of which one had associated aberrant right subclavian artery. None had iatrogenic nerve palsy. Dissection was difficult as during the routine procedure of dissection, the nerve was not found in its usual route and was found that the right laryngeal nerve was not recurrent and originated directly from the vagus nerve. The non-recurrent laryngeal nerve (NRLN) is a rare embryologically derived variant of the recurrent laryngeal nerve and is found in 0.25 to 0.99% of patients who undergo thyroid surgery. On the right side, NRLN is found in 0.3% to 0.8% of patients and it is extremely rare on the left (0.004%).[1-2] The right NRLN is found to be associated with an aberrant right subclavian artery (86.7%) In experienced hands, meticulous dissection in the region of the tracheoesophageal groove will result in identification of RLN. In any case, if the nerve is not seen / found longitudinally along the tracheoesophageal groove, then dissecting transversely along the fascial spaces between the carotid sheath and the larynx, will allow identification of the presence of NRLN. Recurrent laryngeal nerve is a branch of the vagus nerve that is associated with both motor function and sensation of the larynx. It supplies all the intrinsic muscles of the larynx except the cricothyroid muscles. The non-recurrent laryngeal nerve (NRLN) is a rare embryologically derived variant of the recurrent laryngeal nerve and occurs in 0.25 to 0.99% of patients who undergo thyroid surgery and was first reported by Steadman in 1823.[3] on the right side, NRLN is found in 0.3% to 0.8% of patients and on the left side, it is extremely rare (0.004%).[1-2] The right NRLN is found to be associated with an aberrant right subclavian artery (86.7%).[1],[4] The NRLN is usually an unexpected surgical discovery, specifically during thyroidectomy. Hence, adequate anatomic knowledge of the normal course and variations/types of NRLN, and careful dissection during surgery is necessary to prevent iatrogenic injury to the nerve. We are reporting two cases of NRLN, which were identified while performing total thyroidectomy in patients diagnosed with papillary ca thyroid.

Tracheoesophageal groove: a reliable landmark

<p class="abstract"><strong>Background:</strong> Galen first described the recurrent laryngeal nerve (RLN) as a nerve that descended from the brain to the heart, then reversed the course and ascended to the larynx and caused the vocal cords to move. Tracheoesophageal groove is useful for identifying the RLN. In the present study we studied the course of RLN in tracheoesophageal groove and its anatomical position, in patients undergoing thyroid surgery.</p><p class="abstract"><strong>Methods:</strong> The study was conducted in the Department of ENT and Head and Neck Surgery, SMGS Hospital, for a period of two years, on the patients who underwent thyroid surgeries. Tracheoesophageal groove was considered first landmark to identify RLN position and only after meticulous dissection in the groove, the nerve could be identified. The nerve was carefully dissected and its position evaluated in relation with trachea and esophagus. </p><p class="abstract"><strong>Results:</strong> Trajectory of the nerves studied in the patients was mostly in the tracheoesophageal groove (TEG), seen in 113 (69.75%) nerves. 16.05% of the nerves were seen in the posterior half of the trachea while 4.94% of the nerves were seen to travel from TEG to anterior half of trachea and 1.85% from TEG to posterior half of trachea. 6.17% of nerves travelled from oesophagus to the TEG.</p><p class="abstract"><strong>Conclusions:</strong> A uniform dissection procedure should be followed and the recurrent laryngeal nerve must be first looked for in the TEG, which serves as important landmark and later any deviation must be considered.</p><p class="abstract"> </p>

PS02.088: COMPARATIVE STUDY OF CT AND PATHOLOGICAL DIAGNOSIS TOWARD MEDIASTINAL LYMPH NODE METASTASIS IN ESOPHAGEAL CARCINOMA

Background To investigate the diagnostic criteria of mediastinal lymph node metastasis (MLNM) in special site, which were less than 1cm, in esophageal carcinoma (EC) by comparing the lymph node size measured by CT and obtained by postoperative pathological examination. Methods A total of 305 EC patients were selected, scanned the location, short diameter, and number of MLNs one week before surgery, and then compared with their pathological findings. Results the ROC curve analysis revealed that the best short diameters of MLNM in the thoracic cavity, supraclavicular fossa (located among the clavicle, sternocleidomastoid, and omohyoid muscle), tracheoesophageal groove that can be diagnosed by CT were 8mm, 5mm, and 6mm, respectively; compared with those with the short diameter as 10mm, the sensitivity was increased significantly, the specificity and accuracy were little changed, while the Youden's index was increased significantly. Conclusion It is reasonable to reduce the CT diagnostic criteria of the short diameter of positive lymph nodes in some special site such as supraclavicular fossa and tracheoesophageal groove. Disclosure All authors have declared no conflicts of interest.

The Reliability of the Tracheoesophageal Groove and the Ligament of Berry as Landmarks for Identifying the Recurrent Laryngeal Nerve: A Cadaveric Study and Meta-Analysis

Purpose. The aim of this meta-analysis was to provide a comprehensive evidence-based assessment, supplemented by cadaveric dissections, of the value of using the Ligament of Berry and Tracheoesophageal Groove as anatomical landmarks for identifying the Recurrent Laryngeal Nerve.Methods. Seven major databases were searched to identify studies for inclusion. Eligibility was judged by two reviewers. Suitable studies were identified and extracted. MetaXL was used for analysis. All pooled prevalence rates were calculated using a random effects model. Heterogeneity among included studies was assessed using the Chi2test and theI2statistic.Results. Sixteen studies (n=2,470 nerves), including original cadaveric data, were analyzed for the BL/RLN relationship. The RLN was most often located superficial to the BL with a pooled prevalence estimate of 78.2% of nerves, followed by deep to the BL in 14.8%. Twenty-three studies (n=5,970 nerves) examined the RLN/TEG relationship. The RLN was located inside the TEG in 63.7% (95% CI: 55.3–77.7) of sides.Conclusions. Both the BL and TEG are landmarks that can help surgeons provide patients with complication-free procedures. Our analysis showed that the BL is a more consistent anatomical landmark than the TEG, but it is necessary to use both to prevent iatrogenic RLN injuries during thyroidectomies.

The Identification of Recurrent Laryngeal Nerve by Injection of Blue Dye into the Inferior Thyroid Artery in Elusive Locations

Introduction. Thyroidectomy creates a potential risk for all parathyroid glands and the recurrent laryngeal nerve (RLN). The identification and dissection of the RLN is the gold standard for preserving its function. In some cases, it may be quite difficult to identify the nerve localization. In such elusive locations, we aimed to identify RLNs using peroperative injection of a blue dye into the inferior thyroid artery.Materials and Methods. This study included 10 selected patients whose RLN identification had been difficult peroperatively during the period from April 2008 to June 2009. When the RLNs became elusive in location, the branches of the inferior thyroid artery (ITA) on the capsule of the thyroid lobe were isolated, and then 0.5 mL isosulphan blue dye was injected into the artery.Results. RLN was carefully dissected in the tracheoesophageal groove. RLN was clearly visualized, in all patients. All RLNs were identified along their course in the dyed surrounding tissue. No RLN palsy was encountered.Conclusion. The injection of blue dye into the ITA branches can be used as an alternate method in case of difficulty in identification of RLNs.