Recurrent laryngeal nerve and voice preservation: routine identification and appropriate assessment �C two important steps in thyroid surgery

INTRODUCTION

The aims of this study were to assess and compare vocal cord functions before and after thyroid surgery after intra-operative identification of recurrent laryngeal nerve.

PATIENTS AND METHODS

Recurrent laryngeal nerve (RLN) is seen intra-operatively in all cases undergoing thyroid surgeries. Vocal cord functions including any voice change were evaluated by indirect laryngoscopy (I/L) and direct laryngoscopy (D/L) before and after surgery.

RESULTS

Prospective study on 100 patients over 18 months with a total of 146 nerves at risk (NAR). Majority were women (n = 86) with mean age of 37.48 years (range, 13–60 years). RLN was seen in all patients and 19 patients complained of some change in quality of their voice after surgery. Evaluation by I/L and D/L at 6 weeks showed recurrent laryngeal nerve palsy (RLNP) in nine (47.36%) and five (26%) of these 19 patients respectively. Analysed according to total NAR, the incidence of voice change and temporary RLN palsy (I/L and D/L) at 6 weeks was still less at 13.01%, 6.16% and 3.42%, respectively. Voice change improved in all cases at 3 months with no RLNP palsy by I/L or D/L. All these 19 patients had undergone difficult or extensive surgery for malignancy, large gland, extratyhroidal spread or fibrosis.

CONCLUSIONS

Despite identification and preservation of RLN, patients can develop postoperative voice change and RLNP although all voice change cannot be attributed to damaged RLN. Proper assessment of vocal cord functions by I/L and D/L laryngoscopy is required to rule out injuries to these nerves. Risk of damage is higher in patients undergoing more difficult surgery.     

Recurrent laryngeal nerve palsy after thyroidectomy with routine identification of the recurrent laryngeal nerve

BACKGROUND: The aim of this study was to assess the risk of recurrent laryngeal nerve palsy (RLNP) after thyroidectomy with routine identification of the recurrent laryngeal nerve (RLN) during the operation. METHODS: The present study was confined to 521 patients, 348 total lobectomies and 178 total thyroidectomies, treated by the same surgeon. Temporary and permanent RLNP rates were analyzed for patient groups with stratification of primary operation for benign thyroid disease, thyroid cancer, Graves' disease, and reoperation. Measurement of the RLNP rate was based on the number of nerves at risk. Twenty-six RLNs in 20 thyroid cancer patients with intentional sacrifice were excluded from analysis. RESULTS: Forty RLNs (40 patients) developed postoperative RLNP. Complete recovery of RLN function was documented for 35 of the 37 patients (94.6%) whose RLN integrity had been ensured intraoperatively. Recovery from temporary RLNP ranged from 3 days to 4 months (mean, 30.7 days). Overall incidence of temporary and permanent RLNP was 5.1% and 0.9%, respectively. The rates of temporary/permanent RLNP were 4.0/0.2%, 2.0/0.7%, 12.0/1.1%, and 10.8/8.1% for groups classified according to benign thyroid disease, thyroid cancer, Graves' disease, and reoperation, respectively. CONCLUSIONS: Operations for thyroid cancer, Graves' disease, and recurrent goiter demonstrated significantly higher RLNP rates. Invasion of RLN was identified in 19.4% of patients with thyroid cancer. Postoperatively, the RLN recovered in most of the patients without documented nerve damage during the operation. Total lobectomy with routine RLN identification is recommended as a basic procedure in thyroid operations.     

The use of readily available equipment in a simple method for intraoperative monitoring of recurrent laryngeal nerve function during thyroid surgery: initial experience with more than 300 cases

HYPOTHESIS: An inexpensive and widely applicable technique to monitor recurrent laryngeal nerve (RLN) function during thyroid surgery can be safely implemented. DESIGN: Consecutive sample. SETTING: Single-surgeon academic practice. PATIENTS: Three hundred sixty-three consecutive patients undergoing surgery for thyroid disease in the 18 months from November 1, 1999, to May 31, 2001. INTERVENTIONS: Anesthetic management using laryngeal mask airway and spontaneous ventilation, combined with electrical RLN stimulation and fiberoptic video laryngoscopy to confirm vocal cord response. MAIN OUTCOME MEASURES: Vocal cord response to RLN stimulation, intraoperative anatomic findings, postoperative voice quality, and anesthetic complications. RESULTS: We used the laryngeal mask airway-based technique in 327 cases. Visualization of vocal cords was maintained throughout the surgery in 310 cases (95%). In 10 cases (3%), the branch of the RLN carrying vocal cord function could not be identified until electrical testing was performed. A single inadvertent RLN palsy was seen in 1 of the 17 cases in which vocal cord visualization was lost during the procedure (0.03% overall). Upper airway obstruction occurred in 16 (5%) of 327 attempted procedures, requiring tracheal intubation in 3 (1%). No further complications regarding airway management were seen. Pneumothorax was observed in 5 cases (2%), each of which resolved without chest tube placement. CONCLUSIONS: This technique can be applied to thyroid surgery as a safe means of managing the airway. It is associated with an ability to test RLN function at will in more than 95% of cases using readily available equipment.     

Functional Laryngeal Results after Thyroidectomy and Extensive Recurrent Laryngeal Nerve Dissection without Neuromonitoring

Summary BACKGROUND: Permanent recurrent laryngeal nerve palsy (RLNP) is a major complication after thyroid surgery. Therefore methods are mandatory which reduce this complication. One strategy is the identification and dissection of the recurrent laryngeal nerve (RLN) in all patients as an inflexible rule. It is an ongoing discussion whether RLN neuromonitoring is helpful. METHODS: We prospectively investigated 624 surgical patients with 1076 nerves at risk (NAR) after hemithyroidectomy or total thyroidectomy because of a benign thyroid pathology (BT). In all patients, extensive nerve dissection was performed. Electrophysiological neuromonitoring was not used. All patients were investigated both pre- and postoperatively for regular laryngeal function, using indirect laryngoscopy and videostroboscopy. RESULTS: 2.4 % temporary and 0.3 % permanent RLNPs were documented respectively. CONCLUSIONS: Reviewing the literature, the total rates of (temporary and permanent) RLNPs are identical or lower in studies performing RLN dissection compared to those where no RLN dissection had been performed. Performing RLN dissection reduced the rate of permanent RLNPs. However, our results do not imply that neuromonitoring decreases the rate of permanent RLNP, since studies that included neuromonitoring did not reveal better data. Our observations also suggest that besides indirect laryngoscopy, videostroboscopy should be performed in all patients with no evidently normal bilateral laryngeal function and no normal voice quality. Failing this, the rate of false positive or negative identification of RLNP is likely to increase.     

Risk factors of paralysis and functional outcome after recurrent laryngeal nerve monitoring in thyroid surgery

BACKGROUND: Recurrent laryngeal nerve monitoring (RLNM) has been suspected to reduce postoperative RLN paralysis (RLNP). However, functional outcome of RLNM in comparison with no nerve identification and visual nerve identification only has not been analyzed. METHODS: Analysis of 16,448 consecutive multi-institutional operations resulted in 29,998 nerves at risk. Three groups of different RLN treatment were compared: group 1, no RLN identification; group 2, visual RLN identification; and group 3, visual RLN identification and electromyographic monitoring. RLNM was performed with a bipolar needle electrode that was placed through the cricothyroid ligament into the vocal muscle. RESULTS: Risk factors for permanent RLNP were recurrent benign and malignant goiter (odds ratios, [ORs]), 4.7, and 6.7, respectively), primary surgery in thyroid malignancy (OR, 2.0), lobectomy (OR, 1.8), no nerve identification (OR, 1.4), low or medium volume hospital (OR, 1.3), and low volume surgeons (OR, 1.2). CONCLUSIONS: Based on these data, visual nerve identification was identified to be the gold standard of RLN treatment in thyroid surgery. RLNM is a promising tool for nerve identification and protection in extended thyroid resection procedures. However, because of the overall low frequency of RLNP, no statistical difference compared with visual nerve identification only was reached in the setting of this study.     

NERVE STIMULATION IN THYROID SURGERY: IS IT REALLY USEFUL?

BACKGROUND: Monitoring of the recurrent laryngeal nerve (RLN) has been claimed in some studies to reduce rates of nerve injury during thyroid surgery compared with anatomical dissection and visual identification of the RLN alone, whereas other studies have found no benefit. Continuous monitoring with endotracheal electrodes is expensive whereas discontinuous monitoring by laryngeal palpation with nerve stimulation is a simple and inexpensive technique. This study aimed to assess the value of nerve stimulation with laryngeal palpation as a means of identifying and assessing the function of the RLN and external branch of the superior laryngeal nerve (EBSLN) during thyroid surgery. METHODS: This was a prospective case series comprising 50 consecutive patients undergoing total thyroidectomy providing 100 RLN and 100 EBSLN for examination. All patients underwent preoperative and postoperative vocal cord and voice assessment by an independent ear, nose and throat surgeon, laryngeal examination at extubation and all were asked to complete a postoperative dysphagia score sheet. Dysphagia scores in the study group were compared with a control group (n = 20) undergoing total thyroidectomy without nerve stimulation. RESULTS: One hundred of 100 (100%) RLN were located without the use of the nerve stimulator. A negative twitch response occurred in seven (7%) RLN stimulated (two bilateral, three unilateral). Postoperative testing, however, only showed one true unilateral RLN palsy postoperatively (1%), which recovered in 7 weeks giving six false-positive and one true-positive results. Eighty-six of 100 (86%) EBSLN were located without the nerve stimulator. Thirteen of 100 (13%) EBSLN could not be identified and 1 of 100 (1%) was located with the use of the nerve stimulator. Fourteen per cent of EBSLN showed no cricothyroid twitch on EBSLN stimulation. Postoperative vocal function in these patients was normal. There were no instances of equipment malfunction. Dysphagia scores did not differ significantly between the study and control groups. CONCLUSION: Use of a nerve stimulator did not aid in anatomical dissection of the RLN and was useful in identifying only one EBSLN. Discontinuous nerve monitoring by stimulation during total thyroidectomy confers no obvious benefit for the experienced surgeon in nerve identification, functional testing or injury prevention.     

Modification of the Surgical Strategy for the Dissection of the Recurrent Laryngeal Nerve Using Continuous Intraoperative Nerve Monitoring

Background

The aim of this study was to describe first experiences and changes in management using continuous intraoperative neuromonitoring (C-IONM) in thyroid and parathyroid surgery.

Method

Retrospective analysis of patients who underwent surgery with C-IONM since 2012. Surgical maneuvers were modified when electrophysiologic events occurred. Patients with persistent loss of signal (LOS) underwent postoperative laryngoscopy.

Results

One hundred and one patients (of 1586 neck surgeries) were included and 19 had events: In 13 these were temporary (resolved before end of surgery) and led to intraoperative modifications in surgical approach; in all cases traction was released, and in 8, recurrent laryngeal nerve (RLN) approach was changed [superior approach (2), inferior approach (2), both (4)]. Six patients had persistent LOS (5.9%, present at end of procedure), with RLN palsy (RLNP) on postoperative day 1: In three, LOS occurred at electrode placement on the vagus nerve, leading to distal placement of the electrode allowing ipsilateral dissection under continuous monitoring; all three had complete recovery at 6 months. In the three other patients, LOS occurred on the RLN: one probable thermal, one traction lesion and one accidental section of the anterior RLN branch. The RLN recovered within 6 months in two patients, and in the third, RLNP persisted after 6 months (1/101 = 1%).

Conclusion

C-IONM provides real-time evaluation of the RLN function, allowing for adaptation of surgical maneuvers to prevent RLNP. It seems particularly useful in difficult cases like redo neck surgery, invasive thyroid cancer and intrathoracic or large goiter. Care should be given at electrode placement on the vagus nerve.

     

Voice quality after recurrent laryngeal nerve resection and immediate reconstruction

Objective To evaluate clinician perception of voice quality, patient self-reported psychosocial impact of dysphonia, and glottic closure in patients who have undergone resection of the recurrent laryngeal nerve (RLN) and immediate operative reconstruction during thyroid surgery. Study Design Prospective observational study. Setting Single tertiary care hospital. Subjects and Methods Nine patients underwent immediate operative reconstruction of the RLN by the senior author from 2002 to present. Outcome measures included (1) perceptual voice ratings assessed using the GRBAS (Grade, Roughness, Breathiness, Asthenia, Strain) scale, (2) psychosocial impact of dysphonia assessed using the Voice Handicap Index (VHI), and (3) assessment of glottic closure from laryngeal videostroboscopy. Results The RLN was reconstructed with primary anastomosis (4), free nerve graft (3), or vagus-RLN anastomosis (2). Seven patients had voice samples and videostroboscopy examinations obtained at a minimum of 9 months from surgery. Six were judged to have slight disturbance of voice based on overall Grade scoring (G = 1). Five rated their voice as normal or mild on the VHI instrument (score range 8-29). Laryngeal analysis revealed the immobile vocal fold in the median, physiologic phonating position with preserved bulk, recovered tension, and glottic closure during phonation. Three patients less than 9 months from surgery had an expected severe self-reported rating of dysphonia. Conclusion Primary anastomosis, free nerve grafting, and vagus-RLN anastomosis are viable options for RLN reconstruction. Patients who undergo resection and immediate reconstruction of the RLN are able to regain self-perceived functional voices.     

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喉返神经损伤引起的声带麻痹是甲状腺手术常见的严重并发症之一,以单侧多见,造成不同程度的声音嘶哑、误吸和呛咳等症状,影响病人的生活质量。传统的治疗方法如声带注射术、甲状软骨成形术和杓状软骨内收术等虽能改善发音,但这种声音缺乏音调、音量的调节功能,且远期疗效不满意。声带麻痹的最佳治疗方法是通过神经修复手术恢复麻痹喉的生理性功能。手术方法包括:喉返神经探查减压术、喉返神经端端吻合术、颈袢喉返神经吻合术、游离神经移植术、神经肌蒂埋植术或神经植入术、舌下神经转位术及喉神经修复联合声带内移术等。早期减压效果最佳,颈袢喉返神经吻合等神经修复术也能有效地恢复喉的发音功能。损伤病程长者宜采用神经修复联合声带内移手术。喉神经修复术式的选择应根据病程、神经损伤的部位、程度、类型而定。     

外科手术治疗甲状腺手术所致喉返神经损伤

目的探讨外科手术治疗喉返神经(RLN)损伤的疗效。方法回顾性分析38年来外科手术治疗的57例甲状腺手术所致RLN损伤的原因、部位、类型及其疗效。结果57例中共损伤RLN 61支(其中双侧神经损伤4例)。右侧RLN损伤27支,左侧34支。造成RLN损伤的手术:甲状腺叶全切除26例次(42.6%),甲状腺叶次全切除术30例次(49.2%),腺瘤或囊肿摘除术5例次(8.2%)。损伤部位位于RLN入喉处下方2cm以内者49支(80.3%),其他部位12支(19.7%)。RLN横断性损伤者23支(37.7%),缝扎或瘢痕压迫者38支(62.3%)。术后51例(89.5%)获1年以上随访,发音恢复正常或明显好转者49例,占96.1%;声音好转者2例,占3.9%。42例46支神经接受间(直)接镜喉镜检查,其中声带活动恢复正常的26侧(支)(56.5%),部分恢复活动的8侧(支)(17.4%),未恢复活动的12侧(支)(26.1%)。4例双侧RLN损伤者均于出院前拔除气管导管。全组患者发音及声带活动的恢复与修复手术时间及手术方式均无明显关系。结论绝大部分甲状腺手术所致RLN损伤发生在其入喉处附近,外科手术是RLN损伤确切有效的治疗方法。     

Recurrent laryngeal nerve injury in thyroid surgery: a review

Recurrent laryngeal nerve palsy (RLNP) is an important and potentially catastrophic complication of thyroid surgery. Permanent RLNP occurs in 0.3–3% of cases, with transient palsies in 5–8%. A literature review and analysis of recent data regarding RLNP in thyroid surgery was performed, with particular focus on the identification of high‐risk patients, the role of intraoperative identification and dissection of the nerve, and the role of intraoperative neuromonitoring (IONM) and optimal perioperative nerve assessment. In conjunction with the review, data from the Monash University/Alfred Hospital Endocrine Surgery Unit between January 2007 and October 2011 were retrospectively analysed, including 3736 consecutive nerves at risk (NAR). The current literature and our data confirm that patients undergoing re‐operative thyroid surgery and thyroid surgery for malignancies are at increased risk of RLNP. Intraoperative visualization and capsular dissection of the RLN remain the gold standard for intraoperative care during thyroid surgery for reducing RLNP risk. IONM should not be used as the sole mechanism for identifying and preserving the nerve, although it can be used to aid in the identification and dissection of the nerve, and may aid in nerve protection in high‐risk cases including cancer surgery and re‐operative surgery.     

Benign parathyroid cyst causing vocal fold paralysis: a case report and review of the literature

BACKGROUND: Parathyroid cysts are uncommon, frequently asymptomatic lesions of the neck and superior mediastinum. Symptomatic parathyroid cysts are very rare, with roughly only 200 cases reported in the literature. Of these, only nine cases have been reported with recurrent laryngeal nerve (RLN) paralysis METHODS: We report a case of a 49-year-old man initially seen with a 6-month history of worsening hoarseness. Physical examination revealed a palpable 3-cm, firm, smooth, nontender mass of the right thyroid lobe. Fiberoscopic laryngoscopy showed right vocal cord immobility consistent with RLN paralysis. After CT and fine-needle aspiration of the mass, the patient underwent a right thyroid lobectomy. During surgery, the recurrent laryngeal nerve was found to be stretched and adherent to a right inferior lobe mass. RESULTS: Histologic analysis of the surgical specimen revealed a benign parathyroid adenomatous cyst. Postoperatively, the patient's voice improved markedly. This case represents an extremely rare return of function of the RLN after cyst removal. CONCLUSION: Parathyroid cysts should be included in the differential diagnosis for vocal fold paralysis.     

甲状腺手术所致喉返神经损伤的手术治疗

目的探讨甲状腺手术所致喉返神经(RLN)损伤的处理。方法回顾性分析1970至2001年治疗的50例甲状腺手术所致RLN损伤患者的损伤原因、部位、类型、手术治疗方法、随访结果等。结果50例患者共损伤RLN54条(其中双侧神经损伤4例)。损伤部位位于RLN入喉处下方2cm以内者45例支(83．3％),其他部位6例支(11．3％),部位不明3例支(5．4％)。横断性损伤19例支(35．2％),缝扎或瘢痕压迫35例支(64．8％)。54例支神经均经手术修复,4例双侧RLN损伤者同时行气管切开术。术后44例(88．O％)患者获1．5年以上随访,发音恢复正常或明显好转者42例(95．5％);声音好转者2例(4．5％)。35例患者39支神经接受间(直)接喉镜检查,其中声带活动恢复正常的21条(53．8％),部分恢复活动的7条(17．9％),未恢复活动的11条(28．3％)。本组患者发音及声带活动的恢复与修复手术时间及手术方式均无明显关系。结论甲状腺手术所致RLN损伤绝大部分为发生在RLN入喉处附近的机械性损伤,手术可解除病因。RLN损伤一经诊断应尽早行再次手术。     

THYROID SURGERY AND VOICE‐RELATED OUTCOMES

Background : Vocal dysfunction in patients with thyroid pathology has been poorly documented, and dysfunction after thyroid surgery is generally reported in terms of recurrent laryngeal nerve or external laryngeal nerve palsy. But voice dysfunction is more complex than simply nerve integrity. The present study reports the incidence of dysphonia in patients presenting for thyroid surgery, and relates postoperative changes in vocal function to recurrent and external laryngeal nerve function, and the surgical handling of the strap muscles. Methods : Fifty patients were assessed by Visipitch before and after thyroidectomy. Following surgery the patients filled out a questionnaire. Results : Overall 26 of 44 patients had no subjective postoperative voice change, while 10 reported subjective deterioration and eight reported subjective improvement in voicing. Postoperative objective assessment of these patients found that 17 were the same, eight refused to come for testing because they felt their voice had not changed, 13 were better and six were worse. Following surgery two patients (4.5%) had temporary recurrent laryngeal nerve palsies (2.5% of nerves at risk), and four patients (10%) suffered external laryngeal nerve palsies. Division of strap muscles was not detrimental to voicing. Six patients were lost to follow‐up. Fifteen patients (34%) presented with vocal abnormalities, six (40%) of whom improved postoperatively. Conclusions : Patients may have voicing abnormalities before thyroid surgery is performed. Surgery may improve or worsen the voice irrespective of the pre‐operative voice status.     

Thyroid surgery and voice-related outcomes

BACKGROUND: Vocal dysfunction in patients with thyroid pathology has been poorly documented, and dysfunction after thyroid surgery is generally reported in terms of recurrent laryngeal nerve or external laryngeal nerve palsy. But voice dysfunction is more complex than simply nerve integrity. The present study reports the incidence of dysphonia in patients presenting for thyroid surgery, and relates postoperative changes in vocal function to recurrent and external laryngeal nerve function, and the surgical handling of the strap muscles. METHODS: Fifty patients were assessed by Visipitch before and after thyroidectomy. Following surgery the patients filled out a questionnaire. RESULTS: Overall 26 of 44 patients had no subjective postoperative voice change, while 10 reported subjective deterioration and eight reported subjective improvement in voicing. Postoperative objective assessment of these patients found that 17 were the same, eight refused to come for testing because they felt their voice had not changed, 13 were better and six were worse. Following surgery two patients (4.5%) had temporary recurrent laryngeal nerve palsies (2.5% of nerves at risk), and four patients (10%) suffered external laryngeal nerve palsies. Division of strap muscles was not detrimental to voicing. Six patients were lost to follow-up. Fifteen patients (34%) presented with vocal abnormalities, six (40%) of whom improved postoperatively. CONCLUSIONS: Patients may have voicing abnormalities before thyroid surgery is performed. Surgery may improve or worsen the voice irrespective of the pre-operative voice status.     

Validity of intra-operative neuromonitoring signals in thyroid surgery

Background Although intra-operative neuromonitoring (IONM) is widely used in thyroid surgery, the validity of the received IONM signals are still unknown.Method Prospective collection of data forms in 29 hospitals from 8,534 patients with 15,403 nerves at risk, who underwent surgery for benign and malignant goitre disorders between August 1999 and January 2001. IONM was performed by indirect stimulation via the vagal nerve and by direct recurrent laryngeal nerve (RLN) stimulation in 12,486 cases. IONM signals were compared with early (<14 days) and late (6 months) postoperative vocal cord function findings.Results The transient and permanent RLN palsy rate was 2.8% and 0.7%, respectively. Monitoring of the RLN function was significantly more reliable via the indirect IONM stimulation route than via the direct IONM stimulation route (specificity P<0.05). IONM by indirect stimulation via the vagal nerve reliably excluded postoperative, permanent, vocal cord palsy (specificity 97.6%, negative predictive value 99.6%). However, a changed IONM was insufficient to predict permanent RLN palsy (sensitivity 45.9%, positive predictive value 11.6%). IONM was not associated with increased general morbidity.Conclusions For intra-operative neuromonitoring, indirect stimulation of the RLN is superior to direct stimulation. An intact acoustic IONM signal is highly predictive of intact postoperative RLN function. When the IONM signal is abnormal or absent, a one-stage extensive thyroid resection should be performed only if the surgeon is absolutely convinced that the first RLN is not harmed or a total thyroidectomy is mandatory.     

Results of Intraoperative Neuromonitoring in Thyroid Surgery and Preoperative Vocal Cord Paralysis

Background

Systematic studies of intermittent intraoperative neuromonitoring (IONM) have shown that IONM enhances recurrent laryngeal nerve (RLN) identification via functional assessment, but does not significantly reduce rates of vocal cord (VC) paralysis (VCP). The reliability of functional nerve assessment depends on the preoperative integrity of VC mobility. The present study was therefore performed to analyze the validity of IONM in patients with pre-existing VC paralysis.

Methods

Of 8,128 patients, 285 (3.5 %) with preoperative VCP underwent thyroid surgery using standardized IONM of the RLN and vagus nerves (VNs). VC function was assessed by pre- and postoperative direct videolaryngoscopy. Quantitative parameters of IONM in patients with VCP were compared with IONM in patients with intact VC function. Clinical symptoms and surgical outcomes of patients with pre-existing VCP were analyzed.

Results

A total of 244 patients revealed negative, and 41 revealed positive IONM on the side of the VCP. VCP with positive IONM revealed significantly lower amplitudes of VN and RLN than intact VN (p = 0.010) and RLN (p = 0.011). Symptoms of patients with VCP included hoarseness (25 %), dyspnea (29 %), stridor (13 %), and dysphagia (13 %); 13 % were asymptomatic. New VCP occurred in five patients, ten needed tracheostomy for various reasons, and one patient died.

Conclusions

Patients with pre-existing VCP revealed significantly reduced amplitude of ipsilateral VN and RLN, indicating retained nerve conductivity despite VC immobility. Preoperative laryngoscopy is therefore indispensable for reliable IONM and risk assessment, even in patients without voice abnormalities.     

Recurrent Laryngeal Nerve Identification and Assessment during Thyroid Surgery: Laryngeal Palpation

Electrical identification and monitoring of the recurrent laryngeal nerve (RLN) has been proposed as an adjunct to standard visual identification of the nerve during thyroid and parathyroid surgery. This study was undertaken to assess laryngeal palpation as an intraoperative technique for identifying and assessing the RLN during surgery and to investigate the relation between laryngeal palpation and associated laryngeal electromyographic (EMG) activity. The postcricoid region of the larynx during surgery was palpated through the posterior hypopharyngeal wall to sense posterior cricoarytenoid muscle contraction in response to ipsilateral RLN stimulation (i.e., the laryngeal twitch response.) Laryngeal palpation was performed in a series of 449 consecutive thyroid and parathyroid surgeries with 586 RLNs at risk. All patients underwent preoperative and postoperative laryngoscopy to assess vocal cord mobility. In a subset of patients, laryngeal palpation and simultaneous laryngeal EMG recordings were compared during intraoperative RLN stimulation. In this series, there was no permanent RLN paralysis. There was one case of temporary RLN paralysis secondary to neural stretch that resolved 6 weeks postoperatively (temporary paralysis rate: 0.2% of patients, 0.2% of nerves at risk). Intraoperative laryngeal palpation of the laryngeal twitch response reliably correlated with normal postoperative vocal cord function. Loss of the laryngeal twitch response occurred in the single case of temporary paralysis in the setting of an anatomically intact nerve. Laryngeal palpation correlated well with simultaneous laryngeal EMG activity. There were no palpation-induced laryngeal injuries or laryngeal edema. There were also no RLN injuries due to repetitive neural stimulation. Intraoperative laryngeal palpation during RLN stimulation is a safe, reliable method for neural monitoring that can assist in RLN identification and assessment during thyroid and parathyroid surgery. Most importantly, it provides important prognostic information regarding ipsilateral vocal cord function at the completion of the initial side of the thyroid or parathyroid surgery. Intraoperative laryngeal palpation allows the surgeon to stage contralateral surgery if RLN damage is diagnosed, thereby avoiding the potential for bilateral vocal cord paralysis. We believe that laryngeal palpation is useful as an adjunct to formal EMG monitoring during thyroid and parathyroid surgery.     

Voice and vocal self-assessment after thyroidectomy

BACKGROUND: Voice alterations after thyroidectomy can be found even with preserved function of laryngeal nerves. The purpose of this study was to evaluate voice before and after thyroid surgery and the role of orotracheal intubation on voice changes. METHODS: We conducted a prospective nonrandomized study of patients who underwent thyroid surgery and compared the results with a control group of patients who underwent breast surgery. Subjects underwent a videolaryngoscopic exam, a subjective and an objective voice analysis and a Voice Handicap Index (VHI) questionnaire before and after surgery. RESULTS: A total of 100 patients who underwent thyroidectomy and 30 who underwent breast surgery were studied. Both groups were similar in demographic, clinical, and surgical variables. Postoperative videolaryngoscopy showed larynx alterations in 28% of the thyroidectomized patients, without significant alterations in the control group. There were subjective voice changes in 29.7% of the patients without vocal fold immobility after thyroid surgery and no statistically significant changes after breast surgery. Acoustic analysis showed significant increased values in the voice turbulence index (VTI) parameter in both groups, although higher in the thyroid one. In the VHI assessment, voice complaints were more frequently registered in the thyroid group rather than in the control group. CONCLUSIONS: Voice alterations are frequent after thyroidectomy even with preserved vocal fold mobility. Such alterations were more frequently detected in that group than in patients who underwent breast surgery. Orotracheal intubation is just one of the multiple factors involved.     

喉返神经隧道解剖法结合神经监测在腔镜甲状腺手术中的应用

目的:探讨喉返神经隧道解剖法结合神经监测在腔镜甲状腺手术中的应用价值。方法:回顾分析2014年11月至2018年12月施行的141例腔镜甲状腺手术,术中均采用喉返神经隧道解剖法结合神经监测技术。其中甲状腺良性结节93例,甲状腺恶性肿瘤48例;行单侧腺叶切除术52例,单侧甲状腺癌根治术44例,双侧甲状腺癌根治术4例,41例部分切除术。结果:140例手术顺利完成,1例因喉返神经横断伤转开放手术行神经对端吻合;术后9例(9/141,6.38%)暂时性神经麻痹,无永久性声音嘶哑患者。结论:腔镜甲状腺手术中采用喉返神经隧道解剖法结合神经监测技术可快速定位喉返神经,降低手术难度,提高手术安全性,利于腔镜甲状腺手术更好地在基层医院推广普及。