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Keywords:

  • intraoperative monitoring;
  • recurrent laryngeal nerve;
  • recurrent laryngeal nerve palsy;
  • thyroidectomy;
  • vocal cord paralysis

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Risk factors for RLNP in thyroid surgery
  5. Intraoperative visualization and dissection of the RLN
  6. The role of IONM
  7. Perioperative evaluation of RLN function
  8. Conclusions
  9. References

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.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Risk factors for RLNP in thyroid surgery
  5. Intraoperative visualization and dissection of the RLN
  6. The role of IONM
  7. Perioperative evaluation of RLN function
  8. Conclusions
  9. References

Recurrent laryngeal nerve palsy (RLNP) is a long recognized and potentially catastrophic complication of thyroid surgery. Damage to a recurrent laryngeal nerve (RLN) with resultant paralysis of the sole abducting muscle (posterior cricoarytenoid) of the vocal cords can cause symptoms ranging from almost undetectable hoarseness in unilateral lesions to stridor and acute airway obstruction in bilateral damage.[1-3] RLNP following thyroid surgery is one of the leading reasons for medico-legal litigation against surgeons.[4]

Post-operative RLNP is a rare complication of thyroid surgery in expert hands. Over the years, surgical strategy has advanced from non-visualization and avoidance of the RLN to the modern surgical technique of capsular dissection and direct visualization of the RLN.[5] Permanent post-operative RLNP occurs in approximately 0.3–3% of cases[2, 6-9] and transient palsies in 3–8% of cases.[1, 2, 7, 9, 10] Rates of RLNP are most accurately described in terms of ‘nerves at risk’ (NAR) and are dependent on the type of surgery and nature of disease.[11]

We analysed our data from the Monash University/Alfred Hospital Endocrine Surgery Unit between January 2007 and October 2011. A total of 2422 thyroid resection procedures were included, with a total of 3736 NAR (Table 1).

Table 1. Thyroid procedures January 2007–October 2011
OperationBenignCancerTotal operationsNAR
  1. Operation: procedure performed. Benign: number procedures benign diagnosis. Cancer: number procedures cancer diagnosis. Total operations: total procedures including benign and cancer diagnosis. Nerves at risk (NAR): number recurrent laryngeal nerves at risk in given procedure.

Hemithyroidectomy86314310061006
Total thyroidectomy101927812972594
Re-operative unilateral thyroidectomy975102102
Re-operative bilateral thyroidectomy1341734
Totals199342924223736

Pre- and post-operative RLN evaluation was performed via fibre-optic nasoendoscopy (FNE) in the majority of cases. Fifty-three RLNP occurred during this period, consisting of 6 permanent and 47 temporary palsies. Overall, post-thyroid surgery RLNP incidence is 0.16% and 1.25% for permanent and transient RLNP, respectively. Of the 53 RLNP in this series, there were two cases of bilateral involvement, both transient. No patient required tracheostomy.

We present an analysis of the literature and our own data to provide an update on RLN injury in thyroid surgery. In particular, we look at potential risk factors for RLN injury, including re-operative surgery, malignancy, extent of surgery, surgeon experience, side of surgery, retrosternal goitre and pathology. We also examine the current gold standard of capsular dissection, intraoperative visualization and dissection of the RLN, as well as the role of adjuncts such as intraoperative neuromonitoring (IONM).

Risk factors for RLNP in thyroid surgery

  1. Top of page
  2. Abstract
  3. Introduction
  4. Risk factors for RLNP in thyroid surgery
  5. Intraoperative visualization and dissection of the RLN
  6. The role of IONM
  7. Perioperative evaluation of RLN function
  8. Conclusions
  9. References

There are considerable data identifying specific patients and procedures with higher risk of RLNP in thyroid surgery.

Re-operative surgery

Patients undergoing secondary or re-operative thyroid operations are at increased risk of RLN injury. It is estimated that the risk of permanent RLNP is 2–30% for re-operative procedures.[4, 12-16] In re-operative surgery, anatomical planes are distorted due to scarring from the primary procedure, resulting in difficult RLN identification and increased nerve traction.[14] Disease and/or scarring may encase the nerve, resulting in difficulty in dissection and placing the nerve at greater risk.[17] It is reported that re-operative surgery for both benign and malignant disease is associated with increased risk.[13, 14, 17] The Jatzko et al. study reported secondary operations for recurrent benign goitre having an incidence of post-operative RLNP approaching 8% compared with almost zero for primary surgery. This study went on to report rates as high as 30% in re-operative procedures where the nerve was unable to be identified intraoperatively.[18] The large prospective trial of Thomusch et al. reported a relative risk of 3.1 for RLNP in secondary compared with primary benign goitre surgery.[14] The study of Lo et al. is in keeping with this evidence, but is expansive in analysing data from all histopathological diagnosis. This study reports a 4% incidence of RLNP for re-operative thyroid surgery compared with less than 1% for primary procedures.[7] The higher risk of RLNP is generally accepted in the context of disease.[19, 20] Our unit's experience is in keeping with the literature. A statistically significant increase in permanent RLNP occurred in re-operative procedures compared with primary surgery, with rates of 0.74% and 0.13%, respectively (P = 0.01). Similarly, transient RLNP rates were 4.41% in re-operative surgery versus 1.13% for primary surgery (P = 0.02).

Cancer surgery

Surgery for thyroid cancer places the RLN at greater risk of intraoperative damage, often due to tumour invasion of the surrounding soft tissue and at times the nerve itself. It is reported that the nerve is invaded in up to 20% of cases.[16] Dralle et al. reported permanent RLNP in 1.52% of patients undergoing primary thyroid cancer surgery compared with less than 0.5% (P < 0.001) in benign disease. The RLNP rates are even greater in secondary malignancy surgery, approaching 6%.[13] The prospective study of Lo et al. also reports statistically significant rates of RLNP in surgery for malignant disease (5.26%) as opposed to benign disease (0.7%, P = 0.01). These findings are supported in several other smaller studies, with reported rates for RLNP in thyroid cancer operations ranging from 2% to 50%.[1, 6, 7, 13, 21]

Our data confirm increased incidence of temporary and permanent RLNP in cancer versus benign disease surgery. The incidence of permanent and transient RLNP in thyroid cancer surgery was 0.28% and 1.82%, respectively. In thyroid operations performed for benign disease, permanent RLNP occurred in 0.13%, with transient palsy in 1.12%. The increased incidence of transient RLNP in surgery for thyroid cancer is statistically significant compared with benign disease (P = 0.0001). However, the observed trend of increased permanent RLNP in thyroid cancer surgery (0.28% versus 0.13%), and benign disease was not statistically significant (P = 0.08). This is likely due to the very small event rate in this group.

Extent of surgery

The extent of thyroid surgery has been investigated, and it is generally accepted that extended resections carry higher risk of RLNP.[22] Erbil et al., in a retrospective study analysing 3250 patients, reported a 12.6 times greater risk (P = 0.01) of RLNP in patients undergoing extended thyroidectomy (lobectomy or total thyroidectomy) compared with conservative surgery (sub-total resection) for thyroid carcinoma and malignancy.[1] These findings are supported by the Dralle et al. study, where the risk of permanent RLNP was significantly higher in those undergoing lobectomy versus subtotal resection (1.34% and 0.68%, respectively).[13]

Favourable long-term survival and low reoccurrence rates have been demonstrated in total thyroidectomy and near-total thyroidectomy for thyroid carcinoma, with less extensive/sub-total resections not advocated.[23, 24] Near-total thyroidectomy (defined by leaving less than 1 g of thyroid tissue adjacent to the RLN at the ligament of Berry on one side) has been shown to have low instances of RLNP and hypoparathyroidism and is commonly and safely practised in many centres.[25, 26]

Surgeon experience

There is a small group of studies investigating surgeon's experience as a risk factor for RLNP. Sosa et al. concluded that surgeons with a caseload of greater than 100 thyroid operations per year are at a significantly reduced risk of complications and have shorter inpatient hospital stays. It was observed that the experienced surgeons were performing a far greater proportion of ‘complex’ procedures (malignancy and re-operative surgery). It is postulated that the true effect of surgeon experience may be somewhat diluted by lower caseload hospitals/surgeons referring more complex cases to specialist centres.[27] Dralle et al. reported RLNP rates of 0.72% for surgeons performing greater than 45 NAR procedures per year compared with 1.06% in those with less than 45 NAR per year (P = 0.003), with both groups having similar surgery types and pathology.[13] These findings are, however, refuted in other studies, where no difference in RLNP incidence is seen when a supervised trainee performs the operation.[14, 28-30] These data demonstrate that surgical trainees can safely perform thyroidectomy under supervision, and suggest that inexperienced surgeons with no specialty training may have increased RLNP incidence. There is evidence suggesting that surgeon training has a greater bearing on morbidity rates than caseload, with surgeons having undergone thyroid-specific specialty training based on provincial areas (with reduced caseload) being found to have similar RLNP rates as those surgeons based in metropolitan endocrine surgery units with similar training.[31]

Left versus right side

There are differences in the anatomy of the right and left RLN. The left has a longer course, curving around ligamentum arteriosum at the aortic arch and travels in the tracheo-oesophageal groove. The right nerve rears around the subclavian artery and, as a consequence, is normally anterolateral to the tracheo-oesophageal groove.[8] Despite these differences, few studies report individual rates for right and left RLN palsy. The Dionigi et al. study reported no dominance of RLNP side[32] and is supported by other studies.[7, 22] There have been some reports implying the right nerve being injured more regularly.[33]

Overall data confirm no difference in the laterality of nerve injured. Within our series, excluding the two cases of bilateral damage, of the remaining 51 RLNP, 24 involved the left RLN (1.37% of 1742 NAR) and 27 the right RLN (1.35% of 1990 NAR). There is no statistically significant difference in the laterality of RLNP (P = 1.0).

Retrosternal goitre

Evidence regarding increased RLNP in primary retrosternal goitre extension is scarce. It has been suggested that these patients may have increased RLNP.[13] However, evidence from a large case series shows no increased risk of RLNP.[34] It is well established that secondary surgery for retrosternal goitre carries increased risk.[7, 33] Within our data, 204 NAR were exposed in surgery for retrosternal goitre, with one temporary and zero permanent RLNP. Given this small incidence, it was deemed impossible to draw conclusions from our data.

Graves' disease

Historically, it has been suggested that surgery for Graves' disease carries increased RLNP risk; this is, however, refuted in several studies, including ours where no significant difference in RLNP is seen between any specific benign histological diagnoses.[1, 11, 13]

Intraoperative visualization and dissection of the RLN

  1. Top of page
  2. Abstract
  3. Introduction
  4. Risk factors for RLNP in thyroid surgery
  5. Intraoperative visualization and dissection of the RLN
  6. The role of IONM
  7. Perioperative evaluation of RLN function
  8. Conclusions
  9. References

In the early 1900s, Lahey of Boston (1938) and Riddell of London (1956) revolutionized thyroid surgery by advocating routine identification and dissection of the RLN.[35] This method was not initially endorsed, with early studies disputing the effect of routine identification in protecting the RLN.[36] There is now strong evidence advocating routine intraoperative identification of the RLN.[5, 37, 38] The Jatzko et al. review incorporating 12 000 thyroid resections revealed RLNP rates of 1.2% in cases where the nerve was identified versus 7.2% where it was not (P ≤ 0.001).[18] The study of Hermann et al. including 27 000 NAR reported permanent RLNP rates of 0.4% where the nerve was identified, as opposed to 1.1% where it was not (P ≤ 0.001).[39] More contemporary studies are in keeping with this finding.[1, 9, 13, 14, 39] Dralle et al., in the large multi-centre, multivariate study analysing close to 30 000 NAR, definitively identified visual RLN identification and dissection as the gold standard for RLN protection when comparing no nerve identification, visual identification only and visual identification plus IONM.[13]

Intraoperative identification and capsular dissection are crucial in the preservation of the RLN. The final 2 cm of extralaryngeal RLN where it is covered by the tubercle of Zuckerkandl and fascial layers is a common anatomical site of injury.[5, 40, 41] In this position, the RLN is covered anterolaterally by a vascular fascial layer containing tertiary branches of the inferior thyroid artery, and medially/posteriorly sits on the true Berry's ligament. Dissection of the RLN from these two capsular layers is potentially the site of greatest traction on the nerve, with sound anatomical understanding and careful dissection important in preserving the RLN.[41] Possible mechanisms of injury include transection, clamping, ligation, traction, thermal injury (diathermy) and ischaemia.[42, 43] Snyder et al. examined the mechanisms of RLN injury and concluded that injury was more likely to occur in visually intact nerves rather than accidental transection (which accounts for approximately 0.3% of RLNP). It was concluded that the majority of such injuries occur under traction, in the setting of an anatomical variant such as extralaryngeal bifurcation, medial or anterior displacement of the nerve, bifurcation of the nerve at the inferior thyroid artery and non-recurrence. It was found that by far the most common and troublesome variant was extralaryngeal bifurcation of the RLN and subsequent traction injury.[44, 45] The prospective trial of Sancho et al. noted extralaryngeal branching of the RLN in 37.4% of nerves, with a mean branching distance from the larynx of 21.5 mm. Transient vocal cord dysfunction was twice as common in extralaryngeal-branched nerves (15.8% versus 8.1%, P = 0.022).[46] The incidence and importance of this variant is confirmed in other studies.[8, 47] We have recently demonstrated that the anterior branch of an extralaryngeal bifurcated RLN carries the motor fibres for all intrinsic laryngeal muscles.[8] If unnoticed, this may lead to a posterior branched limb of the nerve being considered the nerve in its entirety, placing the anterior limb of the nerve at risk of injury.[44, 46, 48]

The role of IONM

  1. Top of page
  2. Abstract
  3. Introduction
  4. Risk factors for RLNP in thyroid surgery
  5. Intraoperative visualization and dissection of the RLN
  6. The role of IONM
  7. Perioperative evaluation of RLN function
  8. Conclusions
  9. References

In recent times, the use of IONM as an adjunct to RLN visual identification and dissection has been safely applied and its efficacy was analysed in reducing rates of RLNP in thyroid surgery.[4, 13, 39] The large multi-centre, prospective trial of Thomusch et al. reported significantly lower rates of permanent and temporary RLNP in sub-total resection for benign goitre using IONM and visual identification compared with visualization alone.[22] There is, however, little support within the literature advocating the use of IONM to reduce RLNP incidence. Several studies show a small reduction in RLNP incidence using IONM, but fail to exhibit statistical significance when compared with direct visualization alone.[6, 12, 13, 17, 49-54] The one published randomized control trial comparing IONM versus identification alone in bilateral thyroid surgery concluded that IONM reduced rates of transient but not permanent palsies.[55] The recent meta-analysis by Higgins et al. analysed data from the 1 randomized control trial, 7 comparative trials and 34 case series, including a total of 64 699 NAR. No statistically significant difference in transient (2.74% IONM versus 2.49% identification only; odds ratio (OR): 0.93, 95% confidence interval (CI): 0.76–1.12) or permanent RLNP (0.75% IONM versus 0.58% identification only; OR: 0.50, 95% CI: 0.15–1.75) was reported.[56]

There are some instances where evidence for IONM use is stronger, suggesting that it can aid in the identification of the nerve, correlating with decreased complication rates.[12, 49, 55, 57] The large International Intraoperative Monitoring Study Group strongly advocate the use of IONM, applying its use to aid in the initial identification, dissection and prognostication of post-operative function.[58] Dralle et al. identified that surgeons undertaking a ‘low volume’ of thyroid surgery benefitted from IONM in reducing RLNP rates when compared with ‘high volume’ counterparts.[35] The support for IONM appears stronger when used in ‘high-risk’ procedures. This is particularly apparent in re-operative thyroid procedures and malignancy surgery. In these instances, a trend for slightly reduced RLNP rates is observed, although not to statistically significant levels in all instances.[12, 13, 17, 45, 59] The Yarbrough et al. study exclusively analysed re-operative thyroid procedures and showed no difference in RLNP rates between monitored and unmonitored groups.[17] There is some evidence suggesting that IONM may reduce palsy rates in Hashimoto's and Graves' disease.[13]

The use of IONM is yet to be universally supported by thyroid surgeons, with a recent survey reporting regular usage rates of approximately 20–40%.[60] There is though a definite trend that surgeons will be more inclined to use IONM in ‘high-risk’ operations, which may significantly alter the interpretation of results, particularly in retrospective and non-randomized trials.[6, 12, 60]

Various studies have looked at the validity of IONM in accurately detecting RLNP intraoperatively. Most studies conclude that IONM can be reliably used to predict normal cord function where nerve signal is intact and therefore has a high negative predictive value, on the order of 92–100%.[4, 14, 61] This is particularly the case when the identified nerve responds to less than 0.5 mA of stimulation.[62] Conversely, little information is gained when the IONM signal is lost/absent. The outcomes for these patients are extremely variable, with extremely poor positive predictive value (reported ranges from 10% to 70%). Intraoperative loss of signal may indicate nerve injury or incorrect electrode placement/equipment failure; it is therefore strongly suggested that IONM not be used as the sole method of RLN identification and preservation.[4, 14, 55, 57, 61, 63]

There is a lack of high-level evidence (i.e. level A, randomized control trials) to elucidate the true RLN sparing effect of IONM. This is partly due to the rarity of RLNP in specialized institutions and additionally due to the reluctance of many centres to participate in randomization.[13, 56] Because of the rarity of RLNP, it is calculated that to achieve significant study power, recruitment of over 40 000 patients to each arm of randomized study focusing on thyroid cancer would be required to unveil a true effect, and over 9 million patients if examining benign disease.[12, 13, 58] Another suggested limitation in interpreting studies is the lack of a standardized approach to IONM set-up and use.[13] Chiang et al. constructed a standardized ‘four step’ IONM set-up procedure which when adhered to significantly reduced IONM signal loss, confirming the importance of diligent equipment set-up.[4] Other studies have investigated nerve stimulation with concurrent posterior cricoarytenoid palpation, reporting encouraging results in predicting RLNP.[64] This is, however, refuted as having an unsatisfactorily high false-negative rate and is yet to be confirmed as a useful adjunct.[63]

Data from the Monash University/Alfred Hospital Endocrine Surgery Unit in using IONM were analysed. Within the specified time frame and including all histological diagnoses, a total of 2861 NAR were exposed when using IONM, compared with 875 NAR without. Temporary RLNP occurred in 1.43% of NAR when using IONM, compared with 0.68% without. The difference in these RLNP rates is not statistically significant (P = 0.054). Permanent RLNP occurred in 0.10% and 0.34% of NAR for groups using IONM versus without IONM, respectively. The difference in these rates also failed to reach statistical significance (P = 0.14). We suspect that these results may be influenced by selection bias, with a tendency to use IONM in more difficult cases. Our experience with IONM is in keeping with the literature, with no significant difference in RLNP rates when comparing thyroid surgery with the use of IONM versus without IONM.

Perioperative evaluation of RLN function

  1. Top of page
  2. Abstract
  3. Introduction
  4. Risk factors for RLNP in thyroid surgery
  5. Intraoperative visualization and dissection of the RLN
  6. The role of IONM
  7. Perioperative evaluation of RLN function
  8. Conclusions
  9. References

RLN assessment is inadequate in the majority of large studies to accurately detect and report RLNP.[7, 65] Preoperative assessment of RLN function is becoming more commonly advocated to allow greater accuracy in post-surgery reporting.[43] Randolph and Kamani recently reported 70% of all invasive thyroid disease and 0.3% of benign disease having preoperative defective vocal cord opposition.[64] Other studies reported one-third of all patients will have some degree of preoperative vocal cord hypomobility on examination.[66, 67] In instances of preoperative cord deficit being caused by benign goitre, it is reported that 89% will recover full function after surgery.[68] Pre-intubation laryngoscopy and subsequent assessment has revealed that vocal fold injury can occur in approximately 30% of endotracheal intubations and 4% of post-operative RLNP are attributable to intubation injury.[69] Accurate preoperative assessment and consideration of other causes of dysfunction including hyperaemia related to gastro-oesophageal reflux, Reinke's oedema and chronic laryngitis is crucial to reporting true surgical RLNP rates.[66, 70] It is widely accepted that clinical evaluation of voice function is an unacceptable means of identifying RLNP, particularly in unilateral lesions that commonly remain asymptomatic.[32, 71]

The assessment of RLN function may be performed in a variety of ways, the most commonly used methods include indirect laryngoscopy, FNE and videostroboscopy. The large systematic review of Jeannon et al. reported significant differences in RLNP reporting when comparing assessment modalities and advocated FNE to be considered the ‘gold standard’ in diagnosing perioperative RLNP, owing to superior visualization, being generally well tolerated and widely available.[2] FNE also permits the observer to electronically record images, with retrospective analysis allowing diagnosis of subtle palsies.[71]

Dionigi et al. evaluated the optimal time for post-operative nasolaryngoscopy to accurately determine RLN dysfunction. Following surgery patients were examined with FNE in post-operative recovery (day 0), the day following surgery (day 1) and again at 2 weeks following surgery (day 14). RLNP was identified in 6.4%, 6.7% and 4.8%, respectively for these time intervals. The difference between day 0 and day 1 examination failed to reach statistical significance; however, RLNP detection on day 14 was significantly reduced compared with examination on post-operative day 0 or day 1. It is therefore concluded that FNE assessment on day 0 or day 1 post-thyroidectomy is the recommended time frame to detect the majority of RLNP, including those mild lesions that require follow-up but would not be detected on outpatient follow-up 2 weeks following surgery.[32] With this in mind, and due to practicality and patient comfort, it is suggested that FNE examination on day 1 post-thyroid surgery be adopted as a common practice. FNE pre- and post-thyroid surgery is a useful audit tool, allowing immediate feedback and therefore potentially enhancing surgical technique, which may lead to better patient outcomes in the longer term.

There is considerable evidence that partial lesions commence the healing process within the first few days post-operatively, with normal nerve function present within a few weeks.[32, 72] There is, however, considerable conjecture regarding the definition of ‘transient’ palsy. It is thought that two-thirds of transient palsies will recover within 4 weeks.[46] Dionigi et al. reported that 89% of all partial palsies were resolved within 12 months.[32] Several groups support diagnosis of permanent RLNP after 12 months of serial examination with ongoing dysfunction.[7, 32, 56, 63] However, Streuer et al. reported RLN function restitution up to 2 years following intraoperative injury.[9]

Conclusions

  1. Top of page
  2. Abstract
  3. Introduction
  4. Risk factors for RLNP in thyroid surgery
  5. Intraoperative visualization and dissection of the RLN
  6. The role of IONM
  7. Perioperative evaluation of RLN function
  8. Conclusions
  9. References

The literature and our data confirm that patients undergoing re-operative thyroid surgery and thyroid surgery for cancer are at increased risk of RLNP. There is no significant difference in laterality of nerve injured or in rates between histological diagnoses. The literature suggests that extended resection and possibly low surgeon caseload are also risk factors. Pre- and post-operative laryngoscopy (optimally via FNE) is advocated for RLN assessment. Intraoperative visualization and capsular dissection of the RLN is the gold standard for intraoperative care during thyroid surgery for reducing risk of RLNP. Abnormal traction forces leading to RLNP are frequently the result of RLN anatomical variants, including extralaryngeal branching of the nerve. The benefit of IONM in aiming to reduce RLNP for routine thyroid surgery is not well defined. 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 reduce risk of injury in ‘high-risk’ cases including malignancy and re-operative surgery. If using IONM, a standardized approach is recommended to reduce equipment-related error. In the post-operative period, FNE assessment within 24 h of surgery is advocated. Any post-operative RLNP requires ongoing serial examination. It is reasonable to diagnose permanent palsy following 12 months of RLN dysfunction.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Risk factors for RLNP in thyroid surgery
  5. Intraoperative visualization and dissection of the RLN
  6. The role of IONM
  7. Perioperative evaluation of RLN function
  8. Conclusions
  9. References