Laryngeal approach to the recurrent laryngeal nerve involved by thyroid cancer at the ligament of Berry

Intraoperative Management of the Recurrent Laryngeal Nerve Transected or Invaded by Thyroid Cancer

Thyroid cancer often invades the recurrent laryngeal nerve (RLN), causing vocal cord paralysis. In such patients, the invaded portion of the RLN usually needs to be resected through curative surgery. We attempt to preserve the nerve by performing sharp dissection in such cases. During nerve dissection, an intraoperative nerve monitoring system helps identify the course of the RLN in the fibrous tissue around the tumor or even within the tumor, and also helps evaluate the nerve integrity. Because of extensive dissection, the preserved RLN may become much thinner than its original thickness. We refer to this procedure as "partial layer resection" of the RLN. In our cases, although the dissected RLNs became thinner, we found that vocal cord function recovered in most patients. If the RLN is fully involved by thyroid cancer or response of the vocal cord against electric stimulation to the RLN is lost, we resect the portion of the RLN together with the tumor and repair it using one of the reconstruction techniques. When a unilateral RLN is resected, the vocal cord on that side is paralyzed. Symptoms include hoarseness, mis-swallowing, and short phonation. RLN reconstruction using one of the reconstruction techniques leads to the recovery of phonatory and swallowing function, although the normal motion of the vocal cord on the side of the anastomosis is not restored. We used direct anastomosis, free nerve grafting, ansa cervicalis-RLN anastomosis, and vagus-RLN anastomosis to reconstruct the RLN. Thyroid cancer often invades the RLN near the Berry's ligament. In such patients, surgeons might assume that reconstruction of the RLN may not be possible because the peripheral stump of the RLN cannot be observed. However, if we divide the inferior pharyngeal constrictor muscles along the lateral edge of the thyroid cartilage, the peripheral RLN can be identified, and nerve reconstruction can be performed. We refer to this procedure as "laryngeal approach".In summary, of the patients with thyroid cancer who required resection of the RLN, RLN reconstruction led to the recovery of phonatory function. We suggest that all thyroid surgeons familiarize themselves with these reconstruction techniques.

Optimal Management of the Unilateral Recurrent Laryngeal Nerve Involvement in Patients with Thyroid Cancer

Simple Summary

Recurrent laryngeal nerve (RLN) is the second most common structure invaded by primary or metastatic thyroid cancer. However, little is known about the optimal procedure for maintaining vocal function in patients with unilateral RLN involvement in thyroid cancer. This study aimed to evaluate various parameters of vocal function to establish the optimal management of thyroid cancer patients with unilateral RLN involvement. Based on our findings, we propose that for optimal management of unilateral RLN involvement in thyroid cancer, first, sharp dissection should be performed, and if this is impossible, a simultaneous RLN reconstruction procedure should be adopted whenever possible. These findings may help improve management of RLN involvement in patients with thyroid cancer and ensure vocal function preservation.

Abstract

We aimed to determine the optimal management of recurrent laryngeal nerve (RLN) involvement in thyroid cancer. We enrolled 80 patients with unilateral RLN involvement in thyroid cancer between 2000 and 2016. Eleven patients with preoperatively functional vocal folds (VFs) underwent sharp tumor resection to preserve the RLN (shaving group). Thirty-three patients underwent RLN reconstruction with RLN resection (reconstruction group). We divided the reconstruction group into two subgroups based on preoperative VF mobility (normal-reconstruction and paralyzed-reconstruction subgroups). In the cases where RLN reconstruction was difficult, phonosurgeries including arytenoid adduction (AA), with or without thyroplasty type I, or nerve muscle pedicle implantation with AA were performed later (phonosurgery group). We evaluated and compared vocal function among the evaluated periods and different groups. Postoperative vocal function in the shaving and normal-reconstruction subgroups was favorable. There were no significant differences between the two groups. In the paralyzed-reconstruction and phonosurgery groups, postoperative vocal function was significantly improved, and vocal function in the paralyzed-reconstruction subgroup was significantly better than that in the phonosurgery group. For optimal management of unilateral RLN involvement in thyroid cancer, first, sharp dissection should be performed, and if this is impossible, a simultaneous RLN reconstruction procedure should be adopted whenever possible.

Novel surgical methods for reconstruction of the recurrent laryngeal nerve: Microscope-guided partial layer resection and intralaryngeal reconstruction of the recurrent laryngeal nerve

BACKGROUND

The optimal strategy for surgical management of papillary thyroid carcinoma invasion of the recurrent laryngeal nerve remains controversial. Our aim was to evaluate the efficacy of 2 surgical methods and provide detailed descriptions of microscope-guided partial layer resection and intralaryngeal reconstruction of the recurrent laryngeal nerve.

METHODS

This retrospective study enrolled 85 patients with papillary thyroid carcinoma who underwent initial surgical excision for invasion of the recurrent laryngeal nerve. Twenty-seven patients (28 recurrent laryngeal nerve sites) underwent partial layer resection, and 11 patients (11 recurrent laryngeal nerve sites) underwent intralaryngeal reconstruction of the recurrent laryngeal nerve. The remaining patients underwent either only resection or resection with immediate reconstruction of the recurrent laryngeal nerve. Pre and postoperative phonetic function and rates of locoregional recurrence were extracted from medical charts for analysis.

RESULTS

Isolated locoregional recurrence specific to the aerodigestive tract was identified in 1 patient (3.7%) in the partial layer resection group and 1 patient (9.1%) in the intralaryngeal reconstruction group. Seventy-five percent of patients in the partial layer resection group recovered or had preserved vocal cord function, and the mean maximum phonation time of the patients with postoperative complete vocal cord palsy was 15.3 seconds. The mean maximum phonation time of the patients, excluding 4 patients with permanent stoma in the intralaryngeal reconstruction group, was 22.3 seconds. The mean maximum phonation time of either group was longer than that of patients with recurrent laryngeal nerve resection only and comparable with that of patients with recurrent laryngeal nerve resection and immediate reconstruction.

CONCLUSION

Patients who underwent either partial layer resection or intralaryngeal reconstruction had low rates of locoregional recurrence specific to the aerodigestive tract and good postoperative functional outcomes.

International neuromonitoring study group guidelines 2018: Part II: Optimal recurrent laryngeal nerve management for invasive thyroid cancer-incorporation of surgical, laryngeal, and neural electrophysiologic data

The purpose of this publication was to inform surgeons as to the modern state-of-the-art evidence-based guidelines for management of the recurrent laryngeal nerve invaded by malignancy through blending the domains of 1) surgical intraoperative information, 2) preoperative glottic function, and 3) intraoperative real-time electrophysiologic information. These guidelines generated by the International Neural Monitoring Study Group (INMSG) are envisioned to assist the clinical decision-making process involved in recurrent laryngeal nerve management during thyroid surgery by incorporating the important information domains of not only gross surgical findings but also intraoperative recurrent laryngeal nerve functional status and preoperative laryngoscopy findings. These guidelines are presented mainly through algorithmic workflow diagrams for convenience and the ease of application. These guidelines are published in conjunction with the INMSG Guidelines Part I: Staging Bilateral Thyroid Surgery With Monitoring Loss of Signal. Level of Evidence: 5 Laryngoscope, 128:S18-S27, 2018.

Surgical Methods and Experiences of Surgeons did not Significantly Affect the Recovery in Phonation Following Reconstruction of the Recurrent Laryngeal Nerve

BACKGROUND

We reported phonatory recovery in the majority of 88 patients after recurrent laryngeal nerve (RLN) reconstruction. Here we analyzed factors that might influence the recovery, in a larger patient series.

METHODS

At Kuma Hospital, 449 patients (354 females and 95 males) underwent RLN reconstruction with direct anastomosis, ansa cervicalis-to-RLN anastomosis, free nerve grafting, or vagus-to-RLN anastomosis; 47.4 % had vocal cord paralysis (VCP) preoperatively. Maximum phonation time (MPT) and mean airflow rate during phonation (MFR) were measured 1 year post surgery. Forty patients whose unilateral RLNs were resected and not reconstructed and 1257 normal subjects served as controls.

RESULTS

Compared to the VCP patients, the RLN reconstruction patients had significantly longer MPTs 1 year after surgery, nearing the normal values. The MFR results were similar but less clear. Detailed analyses of 228 female patients with reconstruction for whom data were available revealed that none of the following factors significantly affected phonatory recovery: age, preoperative VCP, method of reconstruction, site of distal anastomosis, use of magnifier, thickness of suture thread, and experience of surgeon. Of these 228 patients, 24 (10.5 %) had MPTs <9 s 1 year after surgery, indicating insufficient recovery in phonation. This insufficiency was also not associated with the factors mentioned above.

CONCLUSIONS

Approximately 90 % of patients who needed resection of the RLN achieved phonatory recovery following RLN reconstruction. The recovery was not associated with gender, age, preoperative VCP, surgical method of reconstruction, or experience of the surgeon. Performing reconstruction during thyroid surgery is essential whenever the RLN is resected.

Recurrent Laryngeal Nerve Liberations and Reconstructions: A Single Institution Experience

Background

Recurrent laryngeal nerve (RLN) palsy rates vary from 0.5 to 10 %, even 20 % in thyroid cancer surgery. The aim of this paper was to present our experience with RLN liberations and reconstructions after various mechanisms of injury.

Methods

Patients were treated in our institution from year 2000 to 2015. First group (27 patients) had large benign goiters, locally advanced thyroid/parathyroid carcinomas, or incomplete previous surgery of malignant thyroid disease. Second group (5 patients) had reoperations due to RLN paralysis on laryngoscopy. Liberations and reconstructions of injured RLNs were performed.

Results

Surgical exploration of central compartment enabled identification of the RLN injury mechanism. Liberations were performed in 11 patients, 2 months to 16 years after RLN injury, by removing misplaced ligations. Immediate or delayed (18 months to 23 years) RLN reconstructions were performed in 21 patients, by direct suture or ansa cervicalis-to-RLN anastomosis (ARA). RLN liberation provided complete voice recovery within 3 weeks in all patients. Patients with direct sutures had better phonation 1 month after reconstruction. Improved phonation was observed 2–6 months after ARA in 43 % of patients.

Conclusions

Vocal cords do not regain normal movement once being paralyzed after RLN transection, but they restore tension during phonation by reconstruction. Nerve liberation is a useful method which enables patients with RLN paresis/paralysis a significant improvement in phonation, even complete voice recovery. Reinnervation of vocal cords, using one of the mentioned techniques, should be a standard in thyroid and parathyroid surgery, with aim to improve quality of patient’s life.

The differential diagnosis of central compartment radioactive iodine uptake after thyroidectomy: anatomic and surgical considerations

OBJECTIVE

Foci of increased radioactive iodine (RAI) uptake in the thyroid bed following total thyroidectomy (TT) indicate residual thyroid tissue that may be benign or malignant. The use of postoperative RAI therapy in the form of remnant ablation, adjuvant therapy, or therapeutic intervention is often followed by a posttherapy scan. Our objective is to improve the clinician's understanding of the anatomic complexity of this region and to enhance the interpretation of postoperative scans.

METHODS

We conducted a comprehensive review of the literature evaluating RAI uptake in the central compartment following thyroid cancer treatment and literature related to anatomic nuances associated with this region. Thirty-eight articles were selected.

RESULTS

Through extensive surgical experience and a literature review, we identified the 5 most important anatomic considerations for clinicians to understand in the interpretation of foci of increased RAI uptake in the thyroid bed on a diagnostic scan: 1) residual benign thyroid tissue at the level of the posterior thyroid ligament, 2) residual benign thyroid tissue at the superior portion of the pyramidal lobe and/or superior poles of the lateral thyroid lobes, 3) residual benign thyroid tissue that was left attached to a parathyroid gland in order to preserve its vascularity, 4) ectopic benign thyroid tissue, and 5) malignant thyroid tissue that has metastasized to central compartment nodes or invaded visceral structures.

CONCLUSION

By correlating anatomic description, medical illustrations, surgical photos, and scans, we have attempted to clarify the reasons for foci of increased uptake following TT to improve the clinician's understanding of the anatomic complexity of this region.

Outcome of vocal cord function after partial layer resection of the recurrent laryngeal nerve in patients with invasive papillary thyroid cancer

BACKGROUND

The recurrent laryngeal nerve (RLN) may be involved by thyroid cancer even in patients with functioning vocal cords preoperatively. In such cases, we try to preserve the nerve with sharp dissection. As a result of the dissection, the nerve may become thinner than its original thickness. Here we call this operative procedure "partial layer resection of the RLN," if the thickness of the preserved nerve is less than half of its original size. However, there is no report on postoperative vocal cord function after this procedure.

METHODS

We report on 4,585 patients with papillary thyroid cancer who underwent their initial surgery in Kuma Hospital. Among them, 18 patients underwent "partial layer resection of the RLN." We also performed histologic examinations on the RLNs resected because of cancer invasion in 3 other patients.

RESULTS

Postoperatively, 2 patients had functioning vocal cords, 13 had transient vocal cord paralysis, and the remaining 3 had permanent paralysis. Thus, 83% (15/18) of the present patients who underwent partial layer resection of the RLN had functioning vocal cords 1 year after surgery. In patients with transient paralysis, the phonation efficiency index (PEI) 1 year after operation recovered to normal range from the low PEI immediately after operation. Histologic examinations of resected RLN revealed that 78-82% of the cross-section of the nerve is composed of perineural connective tissue surrounding the nerve fibers.

CONCLUSION

An unexpectedly high proportion (83%) of the patients who underwent partial layer resection of the RLN achieved functioning vocal cords and nearly normal phonation postoperatively.