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.

Viscera of the neck

The thyroid gland is a symmetrical H-shaped endocrine structure in the lower neck. It consists of two lobes, each extending from the oblique line of the thyroid cartilage above to the sixth tracheal ring below – united by a median isthmus covered by the anterior jugular veins. The small, (usually) paired and inconsistent parathyroid glands lie behind the lobes of the thyroid gland. They measure 6mm by 4mm by 2mm and are ordinarily four in number – two superior and two inferior. They are involved in the careful regulation of the body’s calcium levels. Both superior and inferior glands are ordinarily supplied by the inferior thyroid artery. Drainage is into the venous plexus on the anterior surface of the thyroid.

Endovascular treatment of massive hemorrhage arising from inferior thyroid artery after fine needle aspiration of thyroid: a case report

Background Fine needle aspiration (FNA) of the thyroid gland is an effective and safe method for evaluating thyroid nodules; catastrophic complications following FNA of thyroid are rare. Massive hematomas with active bleeding leading to airway compromise are extremely rare complications of FNA, with only a few reported cases in literature. Case presentation An 80 year-old man presented to the emergency room with severe respiratory distress, four hours after undergoing thyroid FNA for the evaluation of a thyroid nodule. An axial neck computed tomography (CT) revealed a large hematoma in the retropharyngeal space that caused anterior deviation of the trachea, with extravasation of contrast media suggesting active bleeding within the hematoma. Right subclavian angiography identified active bleeding from the right inferior thyroid artery (ITA). Transcatheter arterial embolization (TAE) was successfully performed with n-Butyl cyanoacrylate (NBCA). Follow-up CT done three weeks after the procedure revealed a low-density lesion in the retropharyngeal space, indicating an old hematoma. The patient recovered well and was discharged 6 weeks later. Conclusion Massive hemorrhage arising from the ITA is a rare but possible complication following FNA, which can potentially be fatal. Appropriate preventive measures should be taken while performing FNA, especially in patients on long-term anticoagulant drugs, and prompt intervention is mandatory for patients with acute hematoma after FNA.

Anatomical Variation of Recurrent Laryngeal Nerve with Inferior Thyroid Artery: A Cross Sectional Study in Bangladeshi People

Background: Recurrent laryngeal nerve is varied anatomically with inferior thyroid artery. Objective: The purpose of the present study was to observe the anatomical variation of recurrent laryngeal nerve with inferior thyroid artery among Bangladeshi people. Methodology: This comparative cross-sectional study was conducted in the Department of Otolaryngology and Head-Neck surgery at Sylhet MAG Osmani Medical College Hospital, Sylhet, Bangladesh from January 2004 to December 2004 for a period of one (01) year. Patients whose recurrent laryngeal nerve was identified during thyroidectomy due to various pathological conditions of thyroid gland were selected as group I. Again, the dead body which were undergone dissection were designated as group II. All the patients whose recurrent laryngeal nerve and inferior thyroid artery were identified during total, near total, sub-total, hemithyroidectomised or lobectomised were included in this study. Result: A total number of 32 patients were recruited for this study. On the left side nerve was found anteriorly in 2(10.53%), in between in 4(21.05%) and posteriorly in 13(68.42%). On the right side-nerve was found anteriorly in 7(30.43%), in between in 6(26.09%) and posteriorly in 10(43.48%). In this series nerve was seen posterior relation more than other two relations and anterior relation more on right side whereas posterior relation on left side, anterior relation more than in between relation on right side but reverse on left side. In group II On the left side nerve was found anteriorly in 2(6.25%), in between in 6(18.75%) and posteriorly in 24(75%). On the right side-nerve was found anteriorly in 8(25%), in between in 9(28.12%), and posteriorly in 10(46.88%). Conclusion: In conclusion each recurrent laryngeal nerve lies posterior to the inferior thyroid artery in the majority of the occasions whereas the nerve lies anterior to the branches of the inferior thyroid artery less commonly except right side of both study group. Journal of Science Foundation, January 2020;18(1):7-12

Clinical impacts of the Sudanese anatomical variations in a relation of the recurrent laryngeal nerve to the inferior thyroid artery

Background: Until recently, the knowledge of the anatomical variations in the relationship between the recurrent laryngeal nerve (RLN) and the inferior thyroid artery (ITA) combined with visual intraoperative RLN identification are essential for the protection of these life-important structures during surgical exposure and the mobilization of thyroid and parathyroid glands. This leads to the proper treatment of patients and improvement of the surgical techniques.Aim: To describe anatomical variations in the relationship of the recurrent laryngeal nerve to the inferior thyroid artery in the Sudanese population.Patients and methods: Following ethical committee approval, an observational descriptive prospective cross-sectional study in the period between March 2019 and February 2020, for anatomical variations in the relation of the recurrent laryngeal nerve to the inferior thyroid artery in seventy-two cervical sides of thirty-six well-dissected embalmed Sudanese cadavers. The RLN was investigated in three positions: posterior to the ITA main trunk, anterior to the ITA main trunk and between the ITA branches. Then, the results were analyzed according to the gender, age and dissection side.Results: We found that the anatomical variations were more frequent in males (97.2%) than females (2.8%). The age of these variations ranged between 31–45 years which represents (61.1%). On the right side of the neck, the commonest position of the RLN is posterior to the ITA (63.9%) followed by in decreasing order of frequency, the RLNs run between the ITA branches (30.6%) and anterior to the ITA (5.6%). On the left side of the neck, the commonest position of the RLN is posterior to the ITA (69.4%). It passed between the ITA branches in (30.6%) of specimens. There was no anterior location of the RLN to the ITA. Variations in a relationship of the RLN to the ITA on one side is significantly different from the opposite side.Conclusions: Although the risk of potential damage to the RLN during surgical neck procedures involving the thyroid gland and parathyroid glands is well recognized, pre-operative detailed surgeon’s knowledge for these frequent anatomical variations and the usage of the ITA as an anatomical landmark for intraoperative RLN recognition is important. This will lead to a reduction of iatrogenic RLN injury prevalence. Future studies are recommended to compare the findings on this cadaveric study with a larger sample size in the long-term period.

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.