Extralaryngeal Branching Research Articles

The relation of recurrent laryngeal nerve to inferior thyroid artery and extralaryngeal nerve branching may increase the risk of vocal cord paralysis in thyroidectomy

PurposeThe anatomical variations of the recurrent laryngeal nerve (RLN) are common during thyroidectomy. We aimed to evaluate the risk of RLN paralysis in case of its anatomical variations, retrospectively.MethodsThe patients with primary thyroidectomy between January 2016 and December 2019 were enrolled. The effect of age, gender, surgical intervention, neuromonitorisation type, central neck dissection, postoperative diagnosis, neck side, extralaryngeal branching, non-RLN, relation of RLN to inferior thyroid artery (ITA), grade of Zuckerkandl tubercle on vocal cord paralysis (VCP) were investigated.ResultsThis study enrolled 1070 neck sides. The extralaryngeal branching rate was 35.5%. 45.9% of RLNs were anterior and 44.5% were posterior to the ITA, and 9.6% were crossing between the branches of the ITA. The rate of total VCP was 4.8% (transient:4.5%, permanent: 0.3%). The rates of total and transient VCP were significantly higher in extralaryngeal branching nerves compared to nonbranching nerves (6.8% vs. 3.6%, p = 0.018; 6.8% vs. 3.2%, p = 0.006, respectively). Total VCP rates were 7.2%, 2.5%, and 2.9% in case of the RLN crossing anterior, posterior and between the branches of ITA, respectively (p = 0.003). The difference was also significant regarding the transient VCP rates (p = 0.004). Anterior crossing pattern increased the total and transient VCP rates 2.8 and 2.9 times, respectively.ConclusionRLN crossing ITA anteriorly and RLN branching are frequent anatomical variations increasing the risk of VCP in thyroidectomy that cannot be predicted preoperatively. This study is the first one reporting that the relationship between RLN and ITA increased the risk of VCP.

Comprehensive review of laryngeal nerve

The laryngeal nerve plays a crucial role in vital functions of the larynx, such as breathing, phonation, and airway protection. This review explores its intricate origination, extracranial pathways, anatomical variations, and functions. Emerging from the vagus nerve, it descends through the jugular foramen, exhibiting distinct pathways on each side of the body. Understanding these pathways is vital in surgery to prevent complications. Anatomical variations, including the non-recurrent laryngeal nerve and extralaryngeal branching, pose challenges during thyroid surgery. Surgeons must be vigilant, as failure to recognize these variations can lead to nerve injuries. Meticulous preoperative evaluation and surgical expertise are essential. The superior laryngeal nerve triggers protective reflexes like the cough reflex, safeguarding the respiratory tract. The recurrent laryngeal nerve controls crucial laryngeal muscles for phonation and respiration. Understanding these functions is paramount, especially for surgeons, ensuring optimal patient outcomes. In conclusion, this review underscores the laryngeal nerve's complexity and the need for in-depth knowledge, particularly in surgery. Ongoing research and medical advancements are crucial for refining techniques and enhancing patient care. Acknowledging these complexities empowers medical surgeons contributing to safer and more effective surgeries.

An Exposition on Surgical Experiences in Identification, Exposure, and Injuries of Recurrent Laryngeal Nerve (RLN) During Thyroid Operations: Gleanings, Narrative, and the Reflections.

Identifying and preserving the recurrent laryngeal nerve (RLN) is of paramount importance during thyroid surgeries. Iatrogenic injuries to RLN (RLNI) are considered one of the most serious and feared complications of thyroidectomies. Surgically, there are four routes/approaches (lateral, inferior, superior, and medial) for localizing and identifying the RLN. This study aims to estimate the incidence of RLNI in the context of various approaches taken intra-operatively for nerve localization and identification. This retrospective analytical study included 54 cases of thyroidectomies operated for various benign and malignant thyroid disorders in a tertiary care center from January 2018 to December 2020. Intraoperative search, identification, and dissection of the nerve were done with superior, inferior, medial, and lateral approaches. The chi-square test and exact test were used to analyze the data and p-value < 0.05 was considered significant. Pre- and post-operative recurrent laryngeal nerve evaluation was done with 90 degrees Hopkins laryngoscope. Overall in this series, the incidence of post-thyroidectomy RLNI was 3.7% and 3.7% for permanent and temporary nerve insults, respectively. Non-recurrent RLN on the right side was identified in one case and extra-laryngeal branching of RLN was identified in two cases. There was no statistically significant difference (p = 0.929) between the different approaches taken and the incidence of RLNI. The type of surgery and pathology also expressed no statistically significant relevance with the incidence of RLNI (p = 0.463 and p = 0.277, respectively). Adoption of a particular surgical approach to localize and identify RLN during thyroid surgery carries no statistically significant difference between RLNI and approaches taken. Meticulous handling and dissection of the tissue in the correct surgical plane are crucial determinants in preventing RLNIs.

High risk of true extralaryngeal branch of recurrent laryngeal nerves during thyroid surgery.

High risk of true extralaryngeal branch of recurrent laryngeal nerves during thyroid surgery.

Branching Patterns of Recurrent Laryngeal Nerve in Thyroidectomy Patients

Background: Historically, the Recurrent laryngeal nerve (RLN) has been considered to branch after it enters the larynx, but numerous studies have demonstrated that it often branches before. The wide variability of this extra laryngeal branching (ELB) has significant implications for the risk of iatrogenic injury. Accurate knowledge of anatomical variations of the recurrent laryngeal nerve (RLN) provides information to prevent inadvertent intraoperative injury.Objectives: Our study aimed to assess extra laryngeal branching of recurrent laryngeal nerve to find out branching patterns of RLN and to study whether there is any correlation between right and left side branching of RLN.Materials and Methods: This was a retrospective analysis conducted on patients of Thyroid surgeries that is total and Near-total thyroidectomies. This cross-sectional study was conducted in Hayatabad Medical Complex Peshawar from 1st Jan 2014 till 31st Dec 2020, with total of 269 patients. We excluded hemi thyroidectomies and recurrent cases.Results: The prevalence of single branching RLN was found to be 29.3% with 79 out of 269 patients. The branching pattern was found not statistically significant with age and gender. Surgeons need to pay special attention to the branching pattern of RLN so as to preserve it during surgery.Conclusion: The anatomy of the RLN is highly variable, and ELB is likely to have been underreported in intraoperative studies. Because of its high likelihood, the possibility of ELB needs to be assessed in patients to prevent iatrogenic injury and long-term postoperative complications.Key Words: Total thyroidectomy, Recurrent laryngeal nerve.Extralaryngeal branching.

Surgical treatment of unilateral laryngeal paralysis by selective reinnervation in thyroid surgery

State of the problem: One of the complications in thyroid surgery is a lesion of RLN which can be bilateral with a violation of respiratory function of the larynx and unilateral, in which the first priority is a violation of vocal function of the larynx. The most effective treatment for paralysis of the larynx is the method of laryngeal reinnervation, which can be non-selective, which is usually used in unilateral laryngeal paralysis and promotes reinnervation of both abductors and laryngeal adductors. Selective reinnervation is selectively focuses on the reinnervation of individual target muscles, so it is more often used in bilateral laryngeal paralysis. But despite this, it was used in unilateral laryngeal paralysis during surgery on the thyroid gland during intentional resection of the anterior branch of RLN with partial invasion of its tumour process. Aim: evaluation of the results of surgical treatment unilateral laryngeal paralysis by the method selective reinnervation in thyroidectomy. Materials and Methods: clinical case results of patient A. 15 years old with papillary thyroid cancer and metastases to regional lymph nodes of the neck (T4aN1M0) with absence disorders of laryngeal motility before surgery were analyzed. Examination of the larynx and voice examination were performed before surgery, 2-3 days and 6,12 months after surgery. Changes of laryngoscopic images and evaluation of the Indicators: maximum pho- nation time, fundamental frequency, noise to harmonic ratio, Jitter (loc), Shimmer (loc), Voice Handicap Index-30 (VHI-30), completed version of Jacobcon B. Results: Considering extralaryngeal bifurcation of the recurrent laryngeal nerve (RLN) and invasion of the tumor into the adductive branch of RLN on the left, its dissection was performed and end-to-end neuroanastomosis was formed, completed is selective laryngeal reinnervation. In the immediate postoperative period, patients complained of voice disorders. Study of voice parameters corresponded to severe voice disorders. Partial resumption of the mobility of the larynx and voice function was after 6 months. The signs of the laryngoscopic picture and the spectral analysis of the voice corresponded to the indicators before the operation after 12 months Сonclusions 1. Primary selective reinnervation of the larynx can be used to treat unilateral laryngeal paralysis under the following conditions: extralaryngeal branching of the recurrent laryngeal nerve (bifurcation), lesion of only one of its branches, which will provide sufficient coaxiality to perform anastomosis "end-to-end" and preservation electrical integrity of another branch. 2. This method allows you to restore the motility of the denervated vocal folds and the main indicators of the voice. 3. Given only one clinical case of treatment of unilateral laryngeal paralysis by selective reinnervation, this technique needs further study and refinement.

Evaluating intramuscular neural distribution in the cricopharyngeus muscle for injecting botulinum toxin

ObjectivesThe objective of this study was to determine the area in the cricopharyngeus muscle (CPM) where botulinum neurotoxin (BoNT) can be injected safely and effectively by evaluating neural distribution in the CPM. MethodsEleven specimens of the CPM were gathered from human cadavers. The anatomical relationship between the posterior cricoarytenoid muscle (PCAM) and the CPM was evaluated. Myelinated nerve fibers in the CPM were stained using modified Sihler's method. The CPM was classified into five zones according to the area accessible within the CPM via transcutaneous and transluminal approaches for BoNT injection as follows: i) lateral area including upper area (zone 1) and lower area (zone 2); ii) posterolateral area including upper area (zone 3) and lower area (zone 4); and iii) posterior area (zone 5). Neural distribution originating from the pharyngeal plexus and the extralaryngeal branches of recurrent laryngeal nerve (EBRLN) within each classified zone in stained specimens was determined. ResultsSix specimens (12 lateral areas, 12 posterolateral areas, and 6 posterior areas) were suitable for evaluating neural distribution within the CPM. Zone 1 was adjacent to the PCAM the most in all specimens. Nerve endings originating from the EBRLN were observed on four sides of zone 2 (33.3%, 4/12 sides) in three specimens (3/6, 50%). Neural distribution originating from the pharyngeal plexus was found on ten sides (83.3%, 10/12 sides) of zone 3 in five specimens (83.3%, 5/6 specimens) and on nine sides (75.0%, 9/12 sides) of zone 4 in five specimens (83.3%, 5/6 specimens). ConclusionThe posterolateral area (zone 3 and zone 4) is thought to be the most suitable area for alleviating the spasticity of CPM with a minimum dose of BoNT.

Anatomy and motor function of extra-laryngeal branching patterns of the recurrent laryngeal nerve; an electrophysiological study of 1001 nerves at risk

Introduction Safe thyroid surgery depends on a deep knowledge of human neck anatomy, including the recurrent laryngeal nerve (RLN). Anatomic variations such as extra-laryngeal terminal branching (ETB) are common. Patients and methods We studied the ETB pattern of 1001 RLNs at risk in 596 patients. We identified and exposed the location of division points on the cervical part of bifid RLN. The function of nerve branches was assessed through intraoperative nerve monitoring (IONM). Results Bifid RLNs was identified in 39.6% of patients. The nerve-based prevalence of ETB was 28.5%. The prevalence of ETB for the right and left RLN was 21.8% and 35.5%, respectively (p < 0.001). The location of the division point was found in the middle, distal, and proximal segments in 48.8%, 33.3%, and 18% of bifid RLNs, respectively. Electrophysiological monitoring revealed motor functions in all anterior and in 7% of posterior branches. The rate of injury was 0.4%, and 1.1% in single trunk and bifid nerves, respectively (p = 0.360), and 3.9% in nerves with proximal branching (p = 0.084). Conclusions The ETB prevalence is high and showing division points in different cervical segments of the RLN. All anterior branches and some posterior branches contain motor fibers. Knowledge and awareness of these anatomic and functional variations are mandatory for every thyroid surgeon to avoid misidentification and misinterpretation of human RLN anatomy.

Is craniocaudal dissection of recurrent laryngeal nerve safer than lateral approach: a prospective randomized study comparing both techniques by using continuous intraoperative nerve monitoring.

PurposeThis study was performed to compare the real-time electromyographic (EMG) changes and the rate of recurrent laryngeal nerve (RLN) injury in craniocaudal and lateral approaches for RLN during thyroidectomy.MethodsOne hundred twelve and 86 patients were prospectively randomized to receive lateral (group 1) or craniocaudal (group 2) approach to RLN, respectively, under continuous intraoperative nerve monitoring.ResultsLoss of signal (LOS) occurred in 7 (2.0%) of 356 nerves at risk (NAR). LOS was significantly associated with repeated adverse EMG changes and presence of RLN entrapment at the ligament of Berry (LOB), which was accompanied by other clinicopathological or anatomical features, such as tubercle of Zuckerkandl (TZ), extralaryngeal branching, hyperthyroidism, autoimmune thyroid disease (ATD), or thyroid lobe volume of >29 cm3 (P = 0.001 and P = 0.030, respectively). The rate of repeated adverse EMG changes and LOS in the NARs with LOB entrapment accompanied by other clinicopathological and anatomical features was higher in group 1 vs. group 2 (11.1% vs. 2.2%, respectively and 9.7% vs. 0%, respectively; P = 0.070). The total rate of vocal cord palsy (VCP) was significantly higher in group 1 than in group 2 (P = 0.005). The rate of permanent VCP showed no significant difference between the 2 groups.ConclusionThe craniocaudal approach to the RLN is safer than the lateral approach in the RLNs with entrapment at the LOB accompanied by other features, such as TZ, extralaryngeal branching, hyperthyroidism, ATD, or high thyroid lobe volume.

Recurrent Laryngeal Nerve Injury Near the Nerve Entry Point in Total Endoscopic Thyroidectomy: A Retrospective Cohort Study.

BackgroundRecurrent laryngeal nerve injury (RLNI) still occurs in total endoscopic thyroidectomy (TET) by using intraoperative neuromonitoring (IONM). As the region where most injuries occur, more attention should be paid to RLNI near the nerve entry point (NEP) in TET.Materials and MethodsThis cohort study collected retrospectively data from 415 patients who underwent TET between February 2012 and December 2019. The functions of the recurrent laryngeal nerve (RLN) in TET were recorded by IONM. The patients with RLNI near the NEP were followed up by laryngoscopies. The demographic and clinical characteristics, the mechanisms of RLNI, and the outcomes of RLNI were recorded and analyzed.ResultsThere were a total of 444 at-risk nerves in 405 patients were analyzed. The incidence of RLNI near the NEP was 7.9%. RLNs with extralaryngeal branches were more likely to be injured near the NEP (P = 0.037). The incidences of different types of RLNI, in order of frequency, were 68.8% for thermal injury (n = 22), 28.1% for traction/compression injury (n = 9), and 3.1% for transverse injury (n = 1). A total of 93.8% (n = 30) of RLNI patients had complete recovery of vocal cord activity function.ConclusionThe extralaryngeal branch was a risk factor for RLNI near the NEP in TET. Thermal injury caused by an ultrasonic scalpel was the most common cause of RLNI near the NEP. Most RLNIs near the NEP would eventually recover.

Extralaryngeal branching of the recurrent laryngeal nerve. Autopsy case series

Background. The thesis «thyroid surgery is the surgery of the recurrent laryngeal nerve», which was defined in the XX ­century, remains relevant to this day. Thus, despite the use of modern scientific and technological achievements, vocal cord paresis is diagnosed on average in 9.8% patients after thyroid and parathyroid surgery.According to many authors, the main problem which a surgeon encounters is a difficult and sometimes individual anatomy of the recurrent laryngeal nerve. For example, in one study authors identified 28 variants of relationships between the ­recurrent laryngeal nerve and the inferior thyroid artery. In a recent meta-analysis, it was noted that the frequency of extralaryngeal branching remains underestimated and reaches 73% of cases. Anatomical variants of the recurrent laryngeal nerve or its thin branches, which have not been noticed in time, can lead to inevitable consequences — to nerve injury and a laryngeal dysfunctions, and if anatomical features are not detected on both sides — to a tragedy.Aim. The aim of this study is to determine anatomical variants of the extralaryngeal branches of the recurrent laryngeal nerve and their frequency in autopsy case series.Materials and methods. 46 (100%) recurrent laryngeal nerves were dissected in 23 cadavers. Their path was traced, their relationships with the inferior thyroid artery were determined, and the extralaryngeal branches of the recurrent laryngeal nerve were identified.Results. Few extralaryngeal branches of the recurrent laryngeal nerve were identified during dissection: tracheoesophageal branches, laryngeal branches, aberrant branches. Tracheoesophageal branches were determined in all cadavers. In 37 (80.4%) cases the recurrent laryngeal nerve had got two or more extralaryngeal laryngeal branches. In 6 (13.0%) cases aberrant branches were presented.The inferior thyroid artery was detected in 42 (91.3%) cases. The vessel was in close location with the recurrent laryngeal nerve, forming a neuro-arterial chiasm. In 39.1% of cases the recurrent laryngeal nerve was located between the branches of the inferior thyroid artery, in 39.1% of cases — deeper than the artery, and in 10.9% of cases — more superficial than the artery.Conclusion. The variable anatomical configuration of the recurrent laryngeal nerve inevitably causes difficulties during intraoperative nerve dissection. Tardy identification of these anatomical features can lead to the injury of nerves or its branches, which determines the amount of postoperative vocal cord paresis.

Экcтраларингеальные варианты возвратного гортанного нерва. Серия наблюдений на аутопсийном материале

Background. The thesis «thyroid surgery is the surgery of the recurrent laryngeal nerve», which was defined in the XX ­century, remains relevant to this day. Thus, despite the use of modern scientific and technological achievements, vocal cord paresis is diagnosed on average in 9.8% patients after thyroid and parathyroid surgery. According to many authors, the main problem which a surgeon encounters is a difficult and sometimes individual anatomy of the recurrent laryngeal nerve. For example, in one study authors identified 28 variants of relationships between the ­recurrent laryngeal nerve and the inferior thyroid artery. In a recent meta-analysis, it was noted that the frequency of extralaryngeal branching remains underestimated and reaches 73% of cases. Anatomical variants of the recurrent laryngeal nerve or its thin branches, which have not been noticed in time, can lead to inevitable consequences — to nerve injury and a laryngeal dysfunctions, and if anatomical features are not detected on both sides — to a tragedy. Aim. The aim of this study is to determine anatomical variants of the extralaryngeal branches of the recurrent laryngeal nerve and their frequency in autopsy case series. Materials and methods. 46 (100%) recurrent laryngeal nerves were dissected in 23 cadavers. Their path was traced, their relationships with the inferior thyroid artery were determined, and the extralaryngeal branches of the recurrent laryngeal nerve were identified. Results. Few extralaryngeal branches of the recurrent laryngeal nerve were identified during dissection: tracheoesophageal branches, laryngeal branches, aberrant branches. Tracheoesophageal branches were determined in all cadavers. In 37 (80.4%) cases the recurrent laryngeal nerve had got two or more extralaryngeal laryngeal branches. In 6 (13.0%) cases aberrant branches were presented. The inferior thyroid artery was detected in 42 (91.3%) cases. The vessel was in close location with the recurrent laryngeal nerve, forming a neuro-arterial chiasm. In 39.1% of cases the recurrent laryngeal nerve was located between the branches of the inferior thyroid artery, in 39.1% of cases — deeper than the artery, and in 10.9% of cases — more superficial than the artery. Conclusion. The variable anatomical configuration of the recurrent laryngeal nerve inevitably causes difficulties during intraoperative nerve dissection. Tardy identification of these anatomical features can lead to the injury of nerves or its branches, which determines the amount of postoperative vocal cord paresis.

The Most Common Anatomical Variation of Recurrent Laryngeal Nerve: Extralaryngeal Branching.

Objective:Extralaryngeal branching of recurrent laryngeal nerve (RLN) is frequent. In various studies, detection rate of extralaryngeal nerve branching was increased by intraoperative neuromonitorization (IONM). Our aim was evaluation of the relationship between the features of extralaryngeal branching of RLN and other anatomic variations in thyroidectomy patients under the guidance of IONM.Methods:Patients underwent thyroidectomy using IONM between January 2016 and December 2019 and whose RLNs were fully explored till the nerve’s entry point to the larynx, were enrolled to the study. Extralaryngeal branching of RLN was accepted as branching of the nerve at a ≥5 mm distance from its laryngeal entry point and having its all branches entering the larynx. Entrapment of RLN at the region of ligament of Berry (BL) by a vascular structure or posterior BL and relationship between RLN and inferior thyroid artery (ITA) was evaluated.Results:Out of 696 patients meeting the inclusion criteria, 1127 neck sides (536F and 160M) were evaluated. Mean age was 49.1±13.4 (range; 18–89). Nerve branching ratio was 35.3% and was higher in females than males (38.2%vs.25.8%, p<0.0001, respectively). Extralaryngeal branching of RLN was detected in 398 (35.3%) out of 1127 nerves. A total of 368 (92.5%) RLNs had two, 27 (6.8%) nerves had three, and 3 (0.7%) had multiple branches. RLN crossed anterior to and between branches of ITA more frequently in branching nerves than non-branching nerves (47.7 vs. 44.4% and 12.8% vs. 7.6%, respectively) but crossed posterior to ITA less frequently in branching nerves (38.5% vs. 48%, respectively, p=0.001). Entrapment of RLN at the region of BL was higher in branched nerves (25.9% vs. 17.5%, respectively, p=0.001). Entrapment of RLN wasmore frequent at the right side than left side both in branching (31.5% vs.19.4%, respectively, p=0.008) and non-branching nerves (20.6% vs. 14.4%, respectively).Conclusion:Extralaryngeal branching of RLN is not rare and mostly divided into two branches. Branching ratio is higher in females than males. In branching nerves, rate of crossing anterior to and between branches of ITA was higher, in non-branching nerves, rate of crossing posterior to ITA was higher. In branching nerves, possibility of entrapment of RLN at the region of BL was higher. Both in branching and non-branching nerves, entrapment of RLN at the region of BL was higher at the right side. Extralaryngeal branching, relationship between RLN and ITA, and entrapment of RLN at the region of BL are frequently seen and variable anatomic variations and cannot be foreseen preoperatively. Most of the extralaryngeal branches and their relationship with other variations can be detected by finding RLN at the level of ITA and following RLN until its entry point to the larynx.

Anatomical, Functional, and Dynamic Evidences Obtained by Intraoperative Neuromonitoring Improving the Standards of Thyroidectomy.

The use of intraoperative neuromonitoring (IONM) is getting more common in thyroidectomy. The data obtained by the usage of IONM regarding the laryngeal nerves’ anatomy and function have provided important contributions for improving the standards of the thyroidectomy. These evidences obtained through IONM increase the rate of detection and visual identification of recurrent laryngeal nerve (RLN) as well as the detection rate of extralaryngeal branches which are the most common anatomic variations of RLN. IONM helps early identification and preservation of the non-recurrent laryngeal nerve. Crucial knowledge has been acquired regarding the complex innervation pattern of the larynx. Extralaryngeal branches of the RLN may contribute to the motor innervation of the cricothyroid muscle (CTM). Anterior branch of the extralaryngeal branching RLN has always motor function and gives motor branches both to the abductor and adductor muscles. In addition, up to 18% of posterior branches may have adductor and/or abductor motor fibers. In 70–80% of cases, external branch of superior laryngeal nerve (EBSLN) provides motor innervation to the anterior 1/3 of the thyroarytenoid muscle which is the main adductor of the vocal cord through the human communicating nerve. Furthermore, approximately 1/3 of the cases, EBSLN may contribute to the innervation of posterior cricoarytenoid muscle which is the main abductor of ipsilateral vocal cord. RLN and/or EBSLN together with pharyngeal plexus usually contribute to the motor innervation of cricopharyngeal muscle that is the main component of upper esophageal sphincter. Traction trauma is the most common reason of RLN injuries and constitutes of 67–93% of cases. More than 50% of EBSLN injuries are caused by nerve transection. A specific point of injury on RLN can be detected in Type 1 (segmental) injury, however, Type 2 (global) injury is the loss of signal (LOS) throughout ipsilateral vagus-RLN axis and there is no electrophysiologically detectable point of injury. Vocal cord paralysis (VCP) develops in 70–80% of cases when LOS persists or incomplete recovery of signal occurs after waiting for 20 min. In case of complete recovery of signal, VCP is not expected. VCP is temporary in patients with incomplete recovery of signal and permanent VCP is not anticipated. Visual changes may be seen in only 15% of RLN injuries, on the other hand, IONM detects 100% of RLN injuries. IONM can prevent bilateral VCP. Continuous IONM (C-IONM) is a method in which functional integrity of vagus-RLN axis is evaluated in real time and C-IONM is superior to intermittent IONM (I-IONM). During upper pole dissection, IONM makes significant contributions to the visual and functional identification of EBSLN. Routine use of IONM may minimalize the risk of nerve injury. Reduction of amplitude more than 50% on CTM is related with poor voice outcome.

ЗАКОНОМЕРНОСТИ АНАТОМИИ И ТОПОГРАФИИ ГОРТАННЫХ НЕРВОВ У ВЗРОСЛОГО ЧЕЛОВЕКА ПО ДАННЫМ ЛИТЕРАТУРЫ

Establishing the morphological regularities of laryngeal nerves of the human is extremely important in surgical and oncological practice. During surgical intervenrions on the thyroid gland, damage of the superior and inferior laryngeal nerves can occur — the second most common complication after hypoparathyroidism. Based on the studied literature data on anatomy and topography of the laryngeal nerves in an adult, a number of the morphological features have been identified. The article describes the morphometric parameters of the laryngeal nerves and their branches. Also, the article describes variants of the localisation of the internal branch of the superior laryngeal nerve relatively to the superior laryngeal artery, a number of classifications based on the localisation of the external branch of the superior laryngeal nerve relatively to the superior thyroid artery and the inferior laryngeal constrictor, variants for the inferior laryngeal nerve passage in tracheoesophageal groove, its location in relation to the trunk and branches of the inferior thyroid artery, Berry's ligament, Zuckerkandl's tubercle and also such anatomical features of the inferior laryngeal nerve as its extralaryngeal branching and cases of non-recurrent laryngeal nerve. These topographic and anatomical features of the laryngeal nerves that should be taken into account for the identification of the nerves during surgery, and also allows them to be considered prerequisites for an increased risk of iatrogenic trauma.

Anatomical Variations of the Recurrent Laryngeal Nerve and Implications for Injury Prevention during Surgical Procedures of the Neck.

Accurate knowledge of anatomical variations of the recurrent laryngeal nerve (RLN) provides information to prevent inadvertent intraoperative injury and ultimately guide best clinical and surgical practices. The present study aims to assess the potential anatomical variability of RLN pertaining to its course, branching pattern, and relationship to the inferior thyroid artery, which makes it vulnerable during surgical procedures of the neck. Fifty-five formalin-fixed cadavers were carefully dissected and examined, with the course of the RLN carefully evaluated and documented bilaterally. Our findings indicate that extra-laryngeal branches coming off the RLN on both the right and left side innervate the esophagus, trachea, and mainly intrinsic laryngeal muscles. On the right side, 89.1% of the cadavers demonstrated 2–5 extra-laryngeal branches. On the left, 74.6% of the cadavers demonstrated 2–3 extra-laryngeal branches. In relation to the inferior thyroid artery (ITA), 67.9% of right RLNs were located anteriorly, while 32.1% were located posteriorly. On the other hand, 32.1% of left RLNs were anterior to the ITA, while 67.9% were related posteriorly. On both sides, 3–5% of RLN crossed in between the branches of the ITA. Anatomical consideration of the variations in the course, branching pattern, and relationship of the RLNs is essential to minimize complications associated with surgical procedures of the neck, especially thyroidectomy and anterior cervical discectomy and fusion (ACDF) surgery. The information gained in this study emphasizes the need to preferentially utilize left-sided approaches for ACDF surgery whenever possible.

Selective reinnervation for correction of unilateral paralysis of larynx in thyroidal surgery

Objective. To estimate the possibility of performance of selective reinnervation of larynx in its abductionaal unilateral paralysis in thyroidal surgery.&#x0D; Маterials and methods. There were analyzed the results of selective laryngeal reinnervation in 2 patients, suffering thyroidal cancer. Visual inspection of the larynx was conducted (fibrolaryngoscopy with archiving of the data) in preoperative and postoperative periods, аs well as in 2, 4, 6, 12, 18 and 24 mo postoperatively, spectral vocal analysis, estimation of vocal quality in accordance to the VHI-30 sсale reporting, using questionnaires ЕАТ-10 for determination of the dysphagia degree.&#x0D; Results. Selective reinnervation was performed in 2 patients with extralaryngeal branching of nervus recurrence: in one - the postponed selective reinnervation of larynx (аutoplasty of the adduction branch of nervus recurrence) for correction of its postoperative abductional paralysis, and in the second - primary selective laryngeal reinnervation (аnastomosis of the adductional branch of nervus recurrence in the “end-to-end” style). In the first patient the tone and stretching of the paralyzed vocal cord free edge was registered in 15 mo after reinnervation, the coordinated move signs - in 2 yrs. In a second patient the restoration of tone and mobility of a vocal cord was registered in 4 mo after reinnervation. In both patients the main indices of the voice spectral analysis and of the self-estimation in accordance to the VHI-30 and ЕАТ-10 scales were restored up to normal values.&#x0D; Conclusion. Selective reinnervation of larynx may be applied not for correction of respiratory disorders due to its bilateral paralysis only, but for restoration of a vocal function and elimination of aspiration symptoms in a case of unilateral paralysis of larynx as well.

A Cadaveric Study of Occurrence of Extralaryngeal Branches of the Recurrent Laryngeal Nerve with Reference to its Importance in Thyroid Surgery

Introduction&#x0D; Recurrent Laryngeal Nerve Palsy (RLNP) is the most common complication of thyroid surgery. Patients complain of hoarseness of voice and sometimes variable amount of respiratory distress due to palsy of recurrent laryngeal nerve (RLN), extra laryngeal branches of which are often ligated along with Inferior Thyroid Artery (ITA) during thyroidectomy. So prevalence and variable pattern of extra laryngeal nerve branches (ELNB) of RLN should be known to the thyroid surgeon to avoid post operative complications.&#x0D; Materials and Methods &#x0D; Dissection was carried on the neck of properly embalmed 25 adult cadavers including both sexes in the dissection hall to study extra laryngeal nerve branches (ELNB) of 50 RLN specimens.&#x0D; Results&#x0D; Out of 50 RLN, 13 nerves (26%) have ELNBs. Only in 4 cadavers (16%) they are bilateral. In 9 cases RLN branches were surrounding either single trunk of ITA or branches of the artery. In rest of the 4 cases ELNBs were passing entirely either in front or behind the ITA&#x0D; Conclusion&#x0D; The gold standard for preservation of the RLN during thyroid surgery is still visual anatomical identification. Proper dissection and anatomical identification of the RLN and all its branches is very important prior to the clamping of the ITA and all its branches.

Bilateral patterns and motor function of the extralaryngeal branching of the recurrent laryngeal nerve.

To evaluate the bilateral patterns and motor function of the extralaryngeal branches (ELB) of the recurrent laryngeal nerve(RLN). This study included 500 consecutive patients who underwent total thyroidectomy. Intraoperative nerve monitoring (IONM) was used in 230 patients. Demographic data, indications for surgery, the bilateral patterns of ELB of the RLN, electromyographic activity of the ELB, distance between the branching point to the entrance into the larynx, and the rate of postoperative morbidity were analyzed. The overall rate of ELB was 27.6% (276/1000). A single trunk of the RLN on both sides was found in 269 (54%) patients, whereas ELB on both sides was observed in 45 (9%) patients. The rates of ELB on the left and right sides were 26.6 and 28.6%, respectively. Of the 89 branched nerves which were dissected using IONM, an evoked motor response was present in 100% of the anterior branches and 5.6% of the posterior branches. The mean branching distance of the RLN was significantly greater in female patients than in male patients on the left side (p = 0.031). The patterns of ELB showed no significant difference in male and female patients. The rates of postoperative transient and permanent hypoparathyroidism and unilateral RLN palsy were 21.6 and 2.8%, and 3.2 and 0.8%, respectively. The rate of RLN palsy was higher in branched nerves compared to those with a single trunk (0.75 vs 0.3%; p = 0.2). Unilateral ELB of the RLN might be observed in approximately 1/4 of the patients, while bilateral branching is rare. A few number of posterior branches of the RLN can have motor function. The RLN's with ELB might have a higher risk of injury compared to those with a single trunk.

Extralaryngeal division of the recurrent laryngeal nerve: A common and asymmetric anatomical variant.

Recognition of extralaryngeal branching of the recurrent laryngeal nerve is crucial because prevention of vocal cord paralysis requires preservation of all branches of the recurrent laryngeal nerve. We assessed the prevalence of extralaryngeal branching of the recurrent laryngeal nerve and the median branching distance from the point of bifurcation to the entry point of the nerve into the larynx. Prospective operative data on recurrent laryngeal nerve branching were collected from 94 patients who underwent thyroid or parathyroid surgery between September 2011 and May 2012. A total of 161 recurrent laryngeal nerves were examined (82 right, 79 left). Overall, 77 (47.8%) of 161 recurrent laryngeal nerves were bifurcated before entering the larynx. There were 36 (43.9%) branching nerves on the right and 41 (51.9%) branching nerves on the left, and there was no significant difference between the sides in terms of branching (p=0.471). Among 67 patients who underwent bilateral exploration, 28.4% were found to have bilateral branching, 40.3% had unilateral branching, and the remaining 31.3% had no branching. The median branching distance was 15 mm (5-60mm). Extralaryngeal division of recurrent laryngeal nerve is a common and asymmetric anatomical variant. These variations can be easily recognized if the recurrent laryngeal nerve is identified at the level of the inferior thyroid artery and then dissected totally to the entry point of the larynx. Inadvertent division of a branch may lead to vocal cord palsy postoperatively, even when the surgeon believes the integrity of the nerve has been preserved.