Anatomical Variations of Recurrent Laryngeal Nerve: The Danger in Thyroid Surgery

Objective: To describe the anatomic relationship of the recurrent laryngeal nerve and the inferior thyroid artery in adult cadavers in the Philippines and to compare the proportions of these anatomic relationships with those reported in the foreign literature. Methods: Study design: Descriptive, cross-sectional Setting: University of the Philippines College of Medicine Anatomy Laboratory Subjects: Fifty-four (54) preserved cadavers (108 sides) dissected within a period from June 2008 to Aug 2010. The anatomy and position of both the right and the left recurrent laryngeal nerves (RLN) and inferior thyroid arteries (ITA) were noted. The RLN was further classified into 2 variations: non-branching or branching prior to insertion at the cricothyroid joint, under the inferior constrictor muscle. The ITA was also classified into non-branching and branching. The results were compared to two foreign studies using a Z-test for two proportions. Results: Fifty four (54) cadavers (108) sides were dissected. Among the cadavers, both the recurrent laryngeal nerves and inferior thyroid arteries had a maximum of two branches although both the RLNs and ITAs for both the right and left sides were mostly non-branching. The right side of one cadaver was noted to have both a branching RLN and a branching ITA. There were no non-recurrent laryngeal nerves seen among the 54 cadavers. For both left and right sides, the RLN was mostly dorsal to the ITA. Branching RLNs was mostly dorsal to a non-branching ITAs. Most of the non-branching RLNs were dorsal to the ITAs. Non-branching RLNs were usually dorsal to the ITA. The local patterns of the course of the RLN in relation to the ITA approximates those of Chinese where there is predominance of the RLN dorsal to the ITA but differs from those of Brazilians where the RLN is usually between ITA branches. Conclusion: There are multiple anatomical variations with regards to the relationship of the RLN and the ITA. The anatomic variation among Asians may be different from Brazilians. The surgeon’s knowledge of the possible various configurations of the RLN and ITA should be able to help in identification and preservation of the RLN and prevention of complications in thyroid surgery. Keywords: recurrent laryngeal nerve, inferior thyroid artery, thyroid surgery, Filipino cadavers, anatomical variations

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WITHDRAWN: Non-recurrent laryngeal nerve in thyroid surgery: Frequency, anatomical variations according to a new classification and surgery consideration

American Journal of Otolaryngology ◽

10.1016/j.amjoto.2019.03.006 ◽

2019 ◽

Author(s):

Quang Van Le ◽

Quoc Ngo Duy ◽

Quy Xuan Ngo

Keyword(s):

Recurrent Laryngeal Nerve ◽

Thyroid Surgery ◽

Anatomical Variations ◽

Laryngeal Nerve ◽

New Classification

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Thyroid tubercle of Zuckerkandl: anatomical and surgical experience from 79 thyroidectomies

The Journal of Laryngology & Otology ◽

10.1017/s0022215108004003 ◽

2008 ◽

Vol 123 (7) ◽

pp. 768-771 ◽

Cited By ~ 18

Author(s):

C Page ◽

P Cuvelier ◽

A Biet ◽

P Boute ◽

M Laude ◽

...

Keyword(s):

Thyroid Gland ◽

Recurrent Laryngeal Nerve ◽

Thyroid Surgery ◽

Anatomical Variation ◽

Lateral Lobe ◽

Anatomical Variations ◽

Anatomical Landmark ◽

Laryngeal Nerve ◽

Surgical Experience ◽

The Right

AbstractObjective:To highlight a poorly known anatomical variation of the lateral lobe of the thyroid gland, which can be useful in identifying the recurrent laryngeal nerve during thyroid surgery.Materials and methods:We performed a three-year prospective study of 79 thyroid surgery patients. Great attention was paid to anatomical variations of the thyroid gland (i.e. the presence or absence of a distinct tubercle of Zuckerkandl), the recurrent laryngeal nerve and the location of the parathyroid glands.Results:A total of 71 right lobectomies and 74 left lobectomies were performed. Five tubercles of Zuckerkandl were identified (7.04 per cent of cases) and were useful in detecting the recurrent laryngeal nerve (but only on the right side).Conclusion:The tubercle of Zuckerkandl is a poorly known and variable anatomical feature of the thyroid gland which may not, in fact, be so rare. It arises for embryological reasons, and it can be a reliable anatomical landmark for identifying the recurrent laryngeal nerve during thyroid surgery. It should be included in the Nomina Anatomica as the ‘processus posterior glandulae thyroideae’ described by Zuckerkandl.

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Morphology and Functional Anatomy of the Recurrent Laryngeal Nerve with Extralaryngeal Terminal Bifurcation

Anatomy Research International ◽

10.1155/2016/9503170 ◽

2016 ◽

Vol 2016 ◽

pp. 1-5 ◽

Cited By ~ 1

Author(s):

Fuat Cetin ◽

Emin Gürleyik ◽

Sami Dogan

Keyword(s):

Motor Activity ◽

Recurrent Laryngeal Nerve ◽

Bifurcation Point ◽

Thyroid Surgery ◽

Functional Anatomy ◽

Anatomical Variations ◽

Laryngeal Nerve ◽

Main Trunk ◽

Anterior Branch ◽

Intraoperative Nerve Monitoring

Anatomical variations of the recurrent laryngeal nerve (RLN), such as an extralaryngeal terminal bifurcation (ETB), threaten the safety of thyroid surgery. Besides the morphology of the nerve branches, intraoperative evaluation of their functional anatomy may be useful to preserve motor activity. We exposed 67 RLNs in 36 patients. The main trunk, bifurcation point, and terminal branches of bifid nerves were macroscopically determined and exposed during thyroid surgery. The functional anatomy of the nerve branches was evaluated by intraoperative nerve monitoring (IONM). Forty-six RLNs with an ETB were intraoperatively exposed. The bifurcation point was located along the prearterial, arterial, and postarterial segments in 11%, 39%, and 50% of bifid RLNs, respectively. Motor activity was determined in all anterior branches. The functional anatomy of terminal branches detected motor activity in 4 (8.7%) posterior branches of 46 bifid RLNs. The motor activity in posterior branches created a wave amplitude at 25–69% of that in the corresponding anterior branches. The functional anatomy of bifid RLNs demonstrated that anterior branches always contained motor fibres while posterior branches seldom contained motor fibres. The motor activity of the posterior branch was weaker than that of the anterior branch. IONM may help to differentiate between motor and sensory functions of nerve branches. The morphology and functional anatomy of all nerve branches must be preserved to ensure a safer surgery.

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Non-recurrent laryngeal nerve related to thyroid surgery: report of three cases

The Journal of Laryngology & Otology ◽

10.1017/s0022215107008389 ◽

2007 ◽

Vol 122 (7) ◽

pp. 757-761 ◽

Cited By ~ 17

Author(s):

C Page ◽

P Monet ◽

J Peltier ◽

B Bonnaire ◽

V Strunski

Keyword(s):

Recurrent Laryngeal Nerve ◽

Subclavian Artery ◽

Thyroid Surgery ◽

Anatomical Variation ◽

Anatomical Variations ◽

Laryngeal Nerve ◽

Frequency Of Occurrence ◽

Laryngeal Nerves ◽

Recurrent Laryngeal Nerves ◽

The Right

AbstractPurpose of the study:We aimed to highlight a rare anatomical variation involving the recurrent laryngeal nerve, and to emphasise its implications for thyroid surgery.Materials and methods:Over a period of 13 years, 993 patients underwent thyroid surgery; 1557 recurrent laryngeal nerves (887 on the right side) were exposed.Results:Three non-recurrent laryngeal nerves were found on the right side, associated with a retro-oesophageal subclavian artery. One case was suspected before surgery.Discussion:Several variations in the path and branches of the recurrent laryngeal nerve have been reported in the literature. The frequency of occurrence of a non-recurrent laryngeal nerve is about 1 per cent, for patients undergoing thyroid surgery. Other surgically relevant anatomical variations of the recurrent laryngeal nerve include associations with the inferior thyroid artery and the presence of nerve branches.Conclusion:The recurrent laryngeal nerve must be carefully dissected and totally exposed during thyroid surgery in order to best preserve its function. Moreover, the thyroid surgeon must be aware of the existence of anatomical variations, which are not as rare as one may think.

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