scholarly journals Anatomical landmarks of the external branch of the superior laryngeal nerve

2019 ◽  
Vol 12 (4) ◽  
pp. 161-177
Author(s):  
Viktor Y. Malyuga ◽  
Aleksandr A. Kuprin
Keyword(s):  
Thyroid Cartilage ◽  
Oblique Line ◽  
Superior Laryngeal Nerve ◽  
Laryngeal Nerve ◽  
Constrictor Muscle ◽  
External Branch ◽  
Close Proximity ◽  
Inferior Pharyngeal Constrictor ◽  
Line Type

Background. The external branch of the superior laryngeal nerve innervates a cricothyroid muscle, which provides tension in vocal cords and formation of high-frequency sounds. When the nerve is damaged during surgery, patients may notice hoarseness, inability to utter high pitched sounds, “rapid fatigue” of the voice, and dysphagia. According to literature, paresis of an external branch of the superior laryngeal nerve reaches up to 58% after thyroid surgery. Aim: to identify permanent landmarks and topographic variations of the external branch of the superior laryngeal nerve. Materials and methods. The study is based on the autopsy material (21 complexes organs of the neck) and on identification of variations of 40 external branches of the superior laryngeal nerve. We identified two permanent landmarks that are located at the minimum distance from nerve and we made metrical calculations relative to them: oblique line of thyroid cartilage and tendinous arch of the inferior pharyngeal constrictor muscle. Results. The piercing point of the nerve is always located at the inferior pharyngeal constrictor muscle without protruding beyond the oblique line of thyroid cartilage superiorly and tendinous arch of the inferior pharyngeal constrictor muscle anteriorly. The nerve had the parallel direction in 92.8% of cases (angel less than 30 degrees) relative to the oblique line and in 85.7% cases it was in close proximity to this line (at distance up to 4 mm). The proposed topographic classification of the location of the external branch of the superior laryngeal nerve is based on localization of the piercing point of the nerve relative to the length of the oblique line of thyroid cartilage and the risk of nerve damage. In 14.2% of cases, the piercing point was in the front third of the line (type I), and in 50% it was in the middle third of this line (type II). These variations of the external branch of the superior laryngeal nerve was in close proximity to the upper pole of the thyroid gland, which could have lead to its damage during surgery. In type III and IV (35.8%) – the piercing point in the muscle was located as far as possible from the upper pole of the thyroid gland and the greater part of the nerve was covered with the fibers of inferior pharyngeal constrictor muscle. Conclusion. We identified the main orienteers for the search and proposed anatomical classification of the location of the external branch on the superior laryngeal nerve.

scholarly journals VIRIATION OF THE EXTERNAL BRANCH OF THE SUPERIOR LARYNGEAL NERVE

2019 ◽  
Vol 21 (1) ◽  
pp. 84-88
Author(s):  
V Y Malyuga ◽  
A A Kuprin
Keyword(s):  
Thyroid Gland ◽  
Thyroid Cartilage ◽  
Oblique Line ◽  
Superior Laryngeal Nerve ◽  
Laryngeal Nerve ◽  
Type I ◽  
Constrictor Muscle ◽  
Point Of Entry ◽  
External Branch ◽  
Inferior Pharyngeal Constrictor

Till now, there is no universal clinical classification about variations of the external branch of the superior laryngeal nerve despite the multiple classifications that was proposed. The aim of this research is identification and systematization of topographic types of the external branch of the superior laryngeal nerve. The study is based on the autopsy material (21 complexes organs of the neck) and on identification of variations of 40 external branches of the superior laryngeal nerve. We identify two permanent landmark that are located at the minimum distance from nerve and on which we made metrical calculations: oblique line of thyroid cartilage, tendinous arch of the inferior pharyngeal constrictor muscle. The “entry” point of the nerve is always located on the inferior pharyngeal constrictor muscle,and not protruding beyond the oblique line of thyroid cartilage superiorly and tendinous arch of the inferior pharyngeal constrictor muscle anteriorly. The proposed topographic classification of the location of the external branch of the superior laryngeal nerve is based on localization of point of pierced of the nerve relating to the length of the oblique line of thyroid cartilage. In 64.2% of cases, the external branch of the superior laryngeal nerve was in close proximity to the upper pole of the thyroid gland, which could lead to its damage during surgery (type I and II). In type III and IV (35.8%) - the point of "entry" in the muscle was located as far as possible from the upper pole of the thyroid gland, and most of the nerve was covered by the fibers of the inferior pharyngeal constrictor muscle.

scholarly journals Improving classification of the external branch of the superior laryngeal nerve with neural monitoring: a research appraisal and narrative review

Gland Surgery ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 2847-2860
Author(s):  
Yishen Zhao ◽  
Zihan Zhao ◽  
Daqi Zhang ◽  
Yujia Han ◽  
Gianlorenzo Dionigi ◽  
...  
Keyword(s):  
Superior Laryngeal Nerve ◽  
Laryngeal Nerve ◽  
Narrative Review ◽  
External Branch ◽  
Neural Monitoring

scholarly journals Protection of the external branch of the superior laryngeal nerve in Transoral endoscopic thyroidectomy vestibular approach (TOETVA): an observational study

2021 ◽  
Author(s):  
Zhen Wu ◽  
Jugao Fang ◽  
Hongzhi Ma ◽  
Xiao Chen ◽  
Qi Zhong ◽  
...  
Keyword(s):  
Contractile Activity ◽  
Endoscopic Thyroidectomy ◽  
Thyroid Cartilage ◽  
Superior Laryngeal Nerve ◽  
Laryngeal Nerve ◽  
External Branch ◽  
Protective Strategies ◽  
The Right ◽  
Intraoperative Nerve Monitoring ◽  
Vestibular Approach

Abstract Background: Avoiding injury of the external branch of the superior laryngeal nerve（EBSLN） is one of the major challenges during thyroid surgery, especially in transoral endoscopic thyroidectomy vestibular approach (TOETVA). This study aimed to investigate the protective strategies of the EBSLN during TOETVA. Methods: In order to protect the EBSLN during TOETVA, we adopted the method of identification the nerve by anatomy and localization. The method of anatomy involves the dissection of EBSLN by complete transection of the sternothyroid muscle in the attachment of the thyroid cartilage. The method of localization involves nerve stimulation localization, which produces cricothyroid contractile activity through intraoperative nerve monitoring stimulation (IONM). Concurrently, patients were evaluated preoperatively and at 1 and 3 weeks postoperatively in an individual prospective cohort study using a stroboscopic laryngoscope and the voice handicap index-10 (VHI-10). The VHI-10 score was used to evaluate voice changes. Results: We retrospectively analyzed patients with papillary thyroid cancer (PTC) who underwent TOETVA in the thyroid center of the Beijing Tongren hospital between February 2018 and June 2020. Patients with recurrent laryngeal nerve（RLN）damage were excluded. Sixty patients were enrolled in this study, of which four underwent total thyroidectomy. Intraoperatively, 56 EBSLNs were located (56/64, 87.50%). Among these, the left EBSLN was identified in 20/25(80.00%) and the right EBSLN was identified in 36/39 (92.31%) cases. One week postoperatively, a blinded stroboscopic laryngoscope examination showed that no patient had paresis of the EBSLN. However, the VHI-10 score was significantly higher than the preoperative value (10.58 ± 4.54 vs. 3.00 ± 1.54, p＜0.01). At three weeks postoperatively, the overall score was still different from that preoperatively (4.83 ± 3.34 vs. 3.00 ± 1.54, p＜0.01); however, the vast majority of patients returned to their preoperative status. Conclusion: In TOETVA, the EBSLN can be well exposed by transection of the sternothyroid muscle, and combined with IONM, the protection of the function of the EBSLN can be guaranteed. Simultaneously, we observed that TOETVA could cause a short-term voice handicap in patients, with such changes generally returning to normal within three weeks.

The Anatomical and Clinical Significance of the Superior Laryngeal Nerve

2021 ◽  
pp. 019459982198962
Author(s):  
Kai-ning Lu ◽  
Jin-wang Ding ◽  
Yu Zhang ◽  
Jing-jing Shi ◽  
Li Zhou ◽  
...  
Keyword(s):  
Thyroid Cartilage ◽  
Superior Laryngeal Nerve ◽  
Laryngeal Nerve ◽  
Entry Point ◽  
Horizontal Line ◽  
Lower Edge ◽  
External Branch ◽  
Starting Point ◽  
Human Cadavers ◽  
Medical University

Objective This study summarizes the anatomical features of the superior laryngeal nerve in Chinese to enable the rapid location of the superior laryngeal nerve during an operation. Study Design Retrospective analysis of anatomical data. Setting Hangzhou First People’s Hospital Affiliated to Nanjing Medical University. Methods A total of 71 embalmed human cadavers (132 heminecks) were examined over 3 months. The length and diameter of the internal and external branches of the superior laryngeal nerve and their relationships with different landmarks were recorded. Results The total length of the internal branch of the superior laryngeal nerve was 23.4 ± 6.9 mm. The length of the external branch of the superior laryngeal nerve was 47.7 ± 11.0 mm. Considering the midpoint of the lower edge of the thyroid cartilage as the starting point and using that edge as a horizontal line, when the entry point is above that line, the external branch of the superior laryngeal nerve can be found within 41.1 mm and at an angle of 57.2°. When the entry point is below the lower edge of the thyroid cartilage, the external branch of the superior laryngeal nerve can be found within 34.0 mm and at an angle of 36.5°. Conclusion The superior laryngeal nerve in Chinese people has distinct anatomical characteristics. This article provides a new method of quickly locating the external branch of the superior laryngeal nerve during the operation, which can reduce the probability of damaging the external branch of the superior laryngeal nerve.

scholarly journals Cernea's classification of the External Branch of the Superior Laryngeal Nerve during Microscopic Thyroidectomy at Gandaki Medical College, Pokhara

2021 ◽  
Vol 14 (2) ◽  
pp. 133-136
Author(s):  
Tulika Dubey ◽  
Brihaspati Sigdel ◽  
Rajendra Nepali ◽  
Neeraj KC
Keyword(s):  
Superior Laryngeal Nerve ◽  
Neck Surgery ◽  
Laryngeal Nerve ◽  
Type I ◽  
Medical College ◽  
Risk Of Injury ◽  
External Branch ◽  
The Right ◽  
Dissection Technique

Background: Preservation of the external branch of the superior laryngeal nerve (EBSLN) during thyroidectomy is important because its injury may lead to frequent occurrence of vocal fatigue and the inability to perform phonation. The objective of the study was to identify and classify the nerve as per Cernea's classification using operating microscope during thyroidectomy Method: Between January 2017 to December 2019, we evaluated 50 patients for the position of external branch of superior laryngeal nerve, who underwent microscopic thyroid surgeries in the department of ENT- head and neck surgery at Gandaki Medical College. Results: In our study, we dissected a total 59 superior poles of thyroid from 50 patients and identified the nerve in all the cases. Of the total superior poles, 36 (61.01%) had type IIa EBSLN among which 24 was on the right side and 12 on the left followed by 19 (32.20%) patients with type IIb EBSLN among which 8 on right and 11 on left side. There were only 4 poles (6.77%) of type I with 3 on the right and 1 on the left side. Conclusion: The EBSLN can be very efficaciously identified during a microscope assisted thyroidectomy. Cernea type 2a and 2b EBSLNs are in position to be at high risk of injury during ligation of the superior vascular pedicle, which can be avoided by prompt identification through a microscope and a meticulous extra capsular dissection technique.

The Identification, Preservation and Classification of the External Branch of the Superior Laryngeal Nerve in Thyroidectomy

2017 ◽  
Vol 41 (10) ◽  
pp. 2521-2529 ◽  
Author(s):  
Kun Wang ◽  
Huilan Cai ◽  
Deguang Kong ◽  
Qiuxia Cui ◽  
Dan Zhang ◽  
...  
Keyword(s):  
Superior Laryngeal Nerve ◽  
Laryngeal Nerve ◽  
External Branch

Anatomical variations of the external branch of the superior laryngeal nerve in relation to the inferior constrictor muscle: cadaveric dissection study

2012 ◽  
Vol 126 (9) ◽  
pp. 907-912 ◽  
Author(s):  
U Patnaik ◽  
A Nilakantan ◽  
T Shrivastava
Keyword(s):  
Superior Laryngeal Nerve ◽  
Anatomical Variations ◽  
Laryngeal Nerve ◽  
Rational Approach ◽  
Cadaveric Dissection ◽  
Constrictor Muscle ◽  
External Branch ◽  
Type 3

AbstractObjectives:To determine anatomical variations in the external branch of the superior laryngeal nerve in relation to the inferior constrictor muscle, and to propose a rational approach for the preservation of the nerve in thyroid surgery based on anatomical principles.Method:A cadaveric dissection study of the anatomy of the external branch of the superior laryngeal nerve in relation to the inferior constrictor muscle was conducted. Twenty-nine formalin-fixed cadavers of both sexes (age 50–70 years), with normal necks, were examined.Results:In relation to the Friedman classification, three anatomical variations of the external branch of the superior laryngeal nerve were found. Type 1 variation was found in 57.1 per cent of cases, type 2 in 26.8 per cent and type 3 in 16 per cent.Conclusion:The prevalence of type 3 variation of the external branch of the superior laryngeal nerve suggests that the nerve will not be encountered in a certain percentage of individuals as it lies under the cover of the inferior constrictor. Therefore, there is no justification for attempting to identify the nerve in all cases.

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