endosergЭндокринная хирургияEndocrine Surgery2306-35132310-3965Типография «Печатных дел Мастер»10.14341/serg12706endoserg-12706Research ArticleОригинальное исследованиеOriginal studyЭкcтраларингеальные варианты возвратного гортанного нерва. Серия наблюдений на аутопсийном материалеExtralaryngeal branching of the recurrent laryngeal nerve. Autopsy case serieshttps://orcid.org/0000-0001-5810-2999КупринАлександр АлександровичKuprinAleksandr A.

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fishbig04@mail.ruhttps://orcid.org/0000-0001-8757-3415МалюгаВиктор ЮрьевичMalyugaViktor Y.

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t.britvin@gmail.comhttps://orcid.org/0000-0002-3576-4815АбуладзеИван ОтариевичAbuladzeIvan O.

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abuladze.ivan@mail.ruМосковский областной научно-исследовательский клинический институт им. М.Ф. Владимирского; ГБУЗ Городская клиническая больница им. А.К. ЕрамишанцеваРоссияMoscow Regional Research and Clinical Institute (MONIKI); A.K. Eramishanzeva city clinical hospitalRussian FederationМосковский областной научно-исследовательский клинический институт им. М.Ф. ВладимирскогоРоссияMoscow Regional Research and Clinical Institute (MONIKI)Russian FederationМедицинский институт ФГАОУ ВО «Российский университет дружбы народов» Минздрава РоссииРоссияMedical Institute Peoples’ Friendship University of RussiaRussian Federation202026092021144418Copyright © Куприн А.А., Малюга В.Ю., Бритвин Т.А., Абуладзе И.О., 20212021Куприн А.А., Малюга В.Ю., Бритвин Т.А., Абуладзе И.О.Kuprin A.A., Malyuga V.Y., Britvin T.A., Abuladze I.O.Данная работа распространяется под лицензией Creative Commons Attribution 4.0.This work is licensed under a Creative Commons Attribution 4.0 License.https://www.surg-endojournals.ru/jour/article/view/12706Обоснование

Обоснование. Тезис «хирургия щитовидной железы — это хирургия возвратного гортанного нерва», сформированный еще в ХХ в., сохраняет свою актуальность и по сей день. Так, несмотря на использование современных научных и технологических достижений, парезы гортани диагностируются в среднем у 9,8% пациентов после операций на щитовидной и околощитовидных железах.

По мнению многих авторов, основная проблема, с которой сталкивается хирург, — это сложная, а порой и индивидуальная анатомия возвратного гортанного нерва. Например, в одном из исследований выделено 28 вариантов синтопического расположения возвратного гортанного нерва и нижней щитовидной артерии. В недавнем метаанализе отмечено, что частота экстраларингеальных ветвлений нерва остается недооцененной и достигает 73% случаев. Повреждение же незамеченного вовремя возвратного гортанного нерва или отдельных его ветвей приведет к неизбежным последствиям — нарушению функции гортани, а при невыявлении анатомических особенностей с двух сторон — к катастрофе.

Цель

Цель. Определение экстраларингеальных вариантов строения возвратного гортанного нерва и их частоты встречаемости в серии аутопсийных наблюдений.

Материалы и методы

Материалы и методы. В 23 трупных органокомплексах шеи выявлено 46 (100%) возвратных гортанных нервов. Прослежен их ход, определено взаимоотношение с нижней щитовидной артерией, выделены экстраларингеальные ветви возвратного гортанного нерва.

Результаты

Результаты. В ходе диссекции выявлены следующие экстраларингеальные ветви возвратного гортанного нерва: трахеопищеводные, гортанные, аберрантные (дополнительные). Трахеопищеводные ветви определялись во всех препаратах. В 37 (80,4%) наблюдениях возвратный гортанный нерв имел две и более эксраларигеальные гортаные ветви. В 6 (13,0%) случаях присутствовали дополнительные аберрантные ветви.

Нижняя щитовидная артерия выявлена в 42 (91,3%) наблюдениях. Сосуд находился в тесном контакте с возвратным гортанным нервом, образуя нервно-артериальный перекрест. При этом в 39,1% случаев возвратный гортанный нерв располагался между ветвями нижней щитовидной артерии, еще в 39,1% наблюдений — глубже артерии, а в 10,9% препаратов — поверхностнее артерии.

Заключение

Заключение. Таким образом, многообразие топографо-анатомической картины возвратного гортанного нерва неизбежно создает сложности при интраоперационном выделении нерва. В свою очередь, несвоевременное выявление особенностей анатомического строения нерва может привести к повреждению структуры или его отдельных ветвей, что и определяет число послеоперационных парезов гортани.

Background

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

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

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

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

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.

хирургия щитовидной железыхирургия околощитовидных железвозвратный гортанный нервэкстраларингеальные варианты возвратного гортанного нервапарез гортаниthyroid surgeryparathyroid surgeryrecurrent laryngeal nerveextralaryngeal branchingvocal cord palsyReferencesBallester A, Gould F, Bond L. Maturation of the Coordination Between Respiration and Deglutition with and Without Recurrent Laryngeal Nerve Lesion in an Animal Model. Dysphagia. 2018;33(5):627-635. doi: https://doi.org/10.1007/s00455-018-9881-z.Ballester A, Gould F, Bond L. Maturation of the Coordination Between Respiration and Deglutition with and Without Recurrent Laryngeal Nerve Lesion in an Animal Model. Dysphagia. 2018;33(5):627-635. doi: https://doi.org/10.1007/s00455-018-9881-z.Fisahn C, Yilmaz E, Iwanaga J, et al. Avoiding the Esophageal Branches of the Recurrent Laryngeal Nerve During Retractor Placement: Precluding Postoperative Dysphagia During Anterior Approaches to the Cervical Spine. Global Spine J. 2019;9(4):383-387. doi: https://doi.org/10.1177/2192568218810198.Fisahn C, Yilmaz E, Iwanaga J, et al. Avoiding the Esophageal Branches of the Recurrent Laryngeal Nerve During Retractor Placement: Precluding Postoperative Dysphagia During Anterior Approaches to the Cervical Spine. Global Spine J. 2019;9(4):383-387. doi: https://doi.org/10.1177/2192568218810198.Решетов И.В., Полунин Г.В., Ананичук А.В., и др. Возможности восстановления функции гортани: современный подход // Вестник оториноларингологии. — 2017. — Т. 82. — №6. — С. 18-23.Reshetov I, Polunin G, Ananichuk A, et al. The possibilities for the restoration of the laryngeal function: The current state-of-the-Art. Vestnik otorinolaringologii. 2017;82(6):18-23 (In Russ.). doi: https://doi.org/10.17116/otorino201782618-23.Folk D, Wahba B, Sasaki CT. Is the external branch of the superior laryngeal nerve dispensable in thyroid surgery? Thyroid. 2016;26(1):169-173. doi: https://doi.org/10.1089/thy.2015.0457.Folk D, Wahba B, Sasaki CT. Is the external branch of the superior laryngeal nerve dispensable in thyroid surgery? Thyroid. 2016;26(1):169-173. doi: https://doi.org/10.1089/thy.2015.0457.Henry BM, Pękala PA, Sanna B, et al. The Anastomoses of the Recurrent Laryngeal Nerve in the Larynx: A Meta-Analysis and Systematic Review. J Voice. 2017;31(4):495-503. doi: https://doi.org/10.1016/j.jvoice.2016.11.004.Henry BM, Pękala PA, Sanna B, et al. The Anastomoses of the Recurrent Laryngeal Nerve in the Larynx: A Meta-Analysis and Systematic Review. J Voice. 2017;31(4):495-503. doi: https://doi.org/10.1016/j.jvoice.2016.11.004.Hydman J, Mattsson P. Collateral reinnervation by the superior laryngeal nerve after recurrent laryngeal nerve injury. Muscle Nerve. 2008;38(4):1280-1289. doi: https://doi.org/10.1002/mus.21124.Hydman J, Mattsson P. Collateral reinnervation by the superior laryngeal nerve after recurrent laryngeal nerve injury. Muscle Nerve. 2008;38(4):1280-1289. doi: https://doi.org/10.1002/mus.21124.Martin-Oviedo C, Maranillo E, Lowy-Benoliel A, et al. Functional role of human laryngeal nerve connections. Laryngoscope. 2011;121(11):2338-2343. doi: https://doi.org/10.1002/lary.22340.Martin-Oviedo C, Maranillo E, Lowy-Benoliel A, et al. Functional role of human laryngeal nerve connections. Laryngoscope. 2011;121(11):2338-2343. doi: https://doi.org/10.1002/lary.22340.Naidu L, Lazarus L, Partab P, et al. Laryngeal nerve «anastomoses». Folia Morphol (Warsz). 2014;73(1):30-36. doi: https://doi.org/10.5603/FM.2014.0005Naidu L, Lazarus L, Partab P, et al. Laryngeal nerve «anastomoses». Folia Morphol (Warsz). 2014;73(1):30-36. doi: https://doi.org/10.5603/FM.2014.0005Sañudo J-R, Maranillo E, León X, et al. An anatomical study of anastomoses between the laryngeal nerves. Laryngoscope. 1999;109(6):983-987. doi: https://doi.org/10.1097/00005537-199906000-00026.Sañudo J-R, Maranillo E, León X, et al. An anatomical study of anastomoses between the laryngeal nerves. Laryngoscope. 1999;109(6):983-987. doi: https://doi.org/10.1097/00005537-199906000-00026.Wu CW, Lee KD. Recurrent Laryngeal Nerve (RLN) Injury in Thyroid Surgery: Lessons Learned from the Intraoperative Neural Monitoring (IONM). International Journal of Head and Neck Science. 2017;1(1):19-26. doi: https://doi.org/10.6696/IJHNS.2017.0101.04.Wu CW, Lee KD. Recurrent Laryngeal Nerve (RLN) Injury in Thyroid Surgery: Lessons Learned from the Intraoperative Neural Monitoring (IONM). International Journal of Head and Neck Science. 2017;1(1):19-26. doi: https://doi.org/10.6696/IJHNS.2017.0101.04.Schneider R, Randolph G, Dionigi G, et al. Prospective study of vocal fold function after loss of the neuromonitoring signal in thyroid surgery: The International Neural Monitoring Study Group’s POLT study. Laryngoscope. 2016;126(5):1260-1266. doi: https://doi.org/10.1002/lary.25807.Schneider R, Randolph G, Dionigi G, et al. Prospective study of vocal fold function after loss of the neuromonitoring signal in thyroid surgery: The International Neural Monitoring Study Group’s POLT study. Laryngoscope. 2016;126(5):1260-1266. doi: https://doi.org/10.1002/lary.25807.Cetin F, Gürleyik E, Dogan S. Morphology and Functional Anatomy of the Recurrent Laryngeal Nerve with Extralaryngeal Terminal Bifurcation. Anat Res Int. 2016;2016:9503170. doi: https://doi.org/10.1155/2016/9503170.Cetin F, Gürleyik E, Dogan S. Morphology and Functional Anatomy of the Recurrent Laryngeal Nerve with Extralaryngeal Terminal Bifurcation. Anat Res Int. 2016;2016:9503170. doi: https://doi.org/10.1155/2016/9503170.Chandrasekhar SS, Randolph GW, Seidman MD, et al. Clinical practice guideline: improving voice outcomes after thyroid surgery. Otolaryngol Head Neck Surg. 2013;148(6 Suppl):S1-S37. doi:10.1177/0194599813487301.Chandrasekhar SS, Randolph GW, Seidman MD, et al. Clinical practice guideline: improving voice outcomes after thyroid surgery. Otolaryngol Head Neck Surg. 2013;148(6 Suppl):S1-S37. doi:10.1177/0194599813487301.Zhuang P, Nemcek S, Surender K, et al. Differentiating arytenoid dislocation and recurrent laryngeal nerve paralysis by arytenoid movement in laryngoscopic video. Otolaryngol Head Neck Surg. 2013;149(3):451-456. doi: https://doi.org/10.1177/0194599813491222.Zhuang P, Nemcek S, Surender K, et al. Differentiating arytenoid dislocation and recurrent laryngeal nerve paralysis by arytenoid movement in laryngoscopic video. Otolaryngol Head Neck Surg. 2013;149(3):451-456. doi: https://doi.org/10.1177/0194599813491222.Xin J, Liu X, Sun H, et al. A laryngoscopy-based classification system for perioperative abnormal vocal cord movement in thyroid surgery. J Int Med Res. 2014;42(4):1029-1037 doi: https://doi.org/10.1177/0300060514535367.Xin J, Liu X, Sun H, et al. A laryngoscopy-based classification system for perioperative abnormal vocal cord movement in thyroid surgery. J Int Med Res. 2014;42(4):1029-1037 doi: https://doi.org/10.1177/0300060514535367.Дайхес Н.А., Кокорина В.Э., Нажмудинов И.И., и др; Национальная медицинская ассоциация оториноларингологов. Клинические рекомендации «Парезы и параличи гортани». М.; 2014.Dajhes NA, Kokorina VJe, Nazhmudinov II, et al; Nacional’naja medicinskaja associacija otorinolaringologov. Klinicheskie rekomendacii. Parezy i paralichi gortani. Moscow; 2014. (In Russ.).Varaldo E, Ansaldo GL, Mascherini M, et al. Neurological complications in thyroid surgery: a surgical point of view on laryngeal nerves. Front Endocrinol (Lausanne). 2014;5:108. doi: https://doi.org/10.3389/fendo.2014.00108.Varaldo E, Ansaldo GL, Mascherini M, et al. Neurological complications in thyroid surgery: a surgical point of view on laryngeal nerves. Front Endocrinol (Lausanne). 2014;5:108. doi: https://doi.org/10.3389/fendo.2014.00108.Estrela F, Záquia Leão H, Pereira Jotz G. Anatomic relation between the external branch of the superior laryngeal nerve and the thyroid gland. Braz J Otorhinolaryngol. 2011;77(2):249-258. doi: https://doi.org/10.1590/s1808-86942011000200016.Estrela F, Záquia Leão H, Pereira Jotz G. Anatomic relation between the external branch of the superior laryngeal nerve and the thyroid gland. Braz J Otorhinolaryngol. 2011;77(2):249-258. doi: https://doi.org/10.1590/s1808-86942011000200016.Uludağ M, Yetkin G, Oran EŞ, et al. Extralaryngeal division of the recurrent laryngeal nerve: A common and asymmetric anatomical variant. Turk J Surg. 2017;33(3):164-168. Published 2017 Sep 1. doi: https://doi.org/10.5152/UCD.2016.3321.Uludağ M, Yetkin G, Oran EŞ, et al. Extralaryngeal division of the recurrent laryngeal nerve: A common and asymmetric anatomical variant. Turk J Surg. 2017;33(3):164-168. Published 2017 Sep 1. doi: https://doi.org/10.5152/UCD.2016.3321.Wojtczak B, Kaliszewski K, Sutkowski K, et al. A functional assessment of anatomical variants of the recurrent laryngeal nerve during thyroidectomies using neuromonitoring. Endocrine. 2018;59(1):82-89. doi: https://doi.org/10.1007/s12020-017-1466-3.Wojtczak B, Kaliszewski K, Sutkowski K, et al. A functional assessment of anatomical variants of the recurrent laryngeal nerve during thyroidectomies using neuromonitoring. Endocrine. 2018;59(1):82-89. doi: https://doi.org/10.1007/s12020-017-1466-3.Henry BM, Vikse J, Graves MJ, et al. Extralaryngeal branching of the recurrent laryngeal nerve: a meta-analysis of 28,387 nerves. Langenbecks Arch Surg. 2016;401(7):913-923. doi: https://doi.org/10.1007/s00423-016-1455-7.Henry BM, Vikse J, Graves MJ, et al. Extralaryngeal branching of the recurrent laryngeal nerve: a meta-analysis of 28,387 nerves. Langenbecks Arch Surg. 2016;401(7):913-923. doi: https://doi.org/10.1007/s00423-016-1455-7.Gurleyik E. Extralaryngeal terminal division of the inferior laryngeal nerve: anatomical classification by a surgical point of view. J Thyroid Res. 2013;2013:731250. doi: https://doi.org/10.1155/2013/731250.Gurleyik E. Extralaryngeal terminal division of the inferior laryngeal nerve: anatomical classification by a surgical point of view. J Thyroid Res. 2013;2013:731250. doi: https://doi.org/10.1155/2013/731250.Noussios G, Chatzis I, Konstantinidis S, et al. The Anatomical Relationship of Inferior Thyroid Artery and Recurrent Laryngeal Nerve: A Review of the Literature and Its Clinical Importance. J Clin Med Res. 2020;12(10):640-646. doi: https://doi.org/10.14740/jocmr4296.Noussios G, Chatzis I, Konstantinidis S, et al. The Anatomical Relationship of Inferior Thyroid Artery and Recurrent Laryngeal Nerve: A Review of the Literature and Its Clinical Importance. J Clin Med Res. 2020;12(10):640-646. doi: https://doi.org/10.14740/jocmr4296.Sormaz IC, Tunca F, Şenyürek YG. Bilateral patterns and motor function of the extralaryngeal branching of the recurrent laryngeal nerve. Surg Radiol Anat. 2018;40(9):1077-1083. doi: https://doi.org/10.1007/s00276-018-1989-1.Sormaz IC, Tunca F, Şenyürek YG. Bilateral patterns and motor function of the extralaryngeal branching of the recurrent laryngeal nerve. Surg Radiol Anat. 2018;40(9):1077-1083. doi: https://doi.org/10.1007/s00276-018-1989-1.Barczyński M, Stopa M, Konturek A, et al. The Overwhelming Majority but not All Motor Fibers of the Bifid Recurrent Laryngeal Nerve are Located in the Anterior Extralaryngeal Branch. World J Surg. 2016;40(3):629-635. doi: https://doi.org/10.1007/s00268-015-3257-4.Barczyński M, Stopa M, Konturek A, et al. The Overwhelming Majority but not All Motor Fibers of the Bifid Recurrent Laryngeal Nerve are Located in the Anterior Extralaryngeal Branch. World J Surg. 2016;40(3):629-635. doi: https://doi.org/10.1007/s00268-015-3257-4.Sancho JJ, Pascual-Damieta M, Pereira JA, et al. Risk factors for transient vocal cord palsy after thyroidectomy. Br J Surg. 2008;95(8):961-967. doi: https://doi.org/10.1002/bjs.6173.Sancho JJ, Pascual-Damieta M, Pereira JA, et al. Risk factors for transient vocal cord palsy after thyroidectomy. Br J Surg. 2008;95(8):961-967. doi: https://doi.org/10.1002/bjs.6173.Бондаренко В.О. Возвратный гортанный нерв в хирургии щитовидной и паращитовидной желез. Атлас. — М.; 2006. [Bondarenko VO. Vozvratnyy gortannyy nerv v khirurgii shchitovidnoy i parashchitovidnoy zhelez. Atlas. Moscow; 2006. (In Russ.)].Bondarenko VO. Vozvratnyy gortannyy nerv v khirurgii shchitovidnoy i parashchitovidnoy zhelez. Atlas. Moscow; 2006. (In Russ.).Ветшев П.С., Янкин П.Л., Животов В.А., и др. Результаты применения интраоперационного нейромониторинга возвратных гортанных нервов в хирургии щитовидной железы // Вестник Национального медико-хирургического центра им. Н.И. Пирогова. — 2018. — Т. 13. — №4. — С. 41-48.Vetshev PS, Yankin PL, Zhivotov VA, at al. Results of intraoperative neuro-monitoring of recurrent laryngeal nerves in thyroid surgery. Bulletin Of the national medical and surgical center named after N. I. Pirоgov. 2018;13(4):41-48 (In Russ.). doi: https://doi.org/10.2588BPNC. 2018.90.41.007.Uludag M, Aygun N, Isgor A. Motor function of the recurrent laryngeal nerve: Sometimes motor fibers are also located in the posterior branch. Surgery. 2016;160(1):153-160. doi: https://doi.org/10.1016/j.surg.2016.02.003.Uludag M, Aygun N, Isgor A. Motor function of the recurrent laryngeal nerve: Sometimes motor fibers are also located in the posterior branch. Surgery. 2016;160(1):153-160. doi: https://doi.org/10.1016/j.surg.2016.02.003.Campos BA, Henriques PR. Relationship between the recurrent laryngeal nerve and the inferior thyroid artery: a study in corpses. Rev Hosp Clin Fac Med Sao Paulo. 2000;55(6):195-200. doi: https://doi.org/10.1590/s0041-87812000000600001Campos BA, Henriques PR. Relationship between the recurrent laryngeal nerve and the inferior thyroid artery: a study in corpses. Rev Hosp Clin Fac Med Sao Paulo. 2000;55(6):195-200. doi: https://doi.org/10.1590/s0041-87812000000600001Малюга В.Ю., Куприн А.А. Клинико-анатомические особенности кровоснабжения околощитовидных желез: серия наблюдений на аутопсийном материале // Эндокринная хирургия. — 2018. — Т. 12. — №1. — С. 40-54.Malyuga VY, Kuprin AA. Clinical and anatomical features of blood supply of parathyroid glands: autopsy case series. Endocrine Surgery. 2018;12(1):40-54. (In Russ.). doi: https://doi.org/10.14341/serg9637.Randolph GW. Surg Thyroid Parathyroid Glands. 2nd ed. Philadelphia: Elsevier Saunders; 2012.Randolph GW. Surg Thyroid Parathyroid Glands. 2nd ed. Philadelphia: Elsevier Saunders; 2012.Arrangoiz R, Cordera F, Caba D, et al. Parathyroid embryology, anatomy, and pathophysiology of primary hyperparathyroidism. Int J Otorhinolaryngol Head Neck Surg. 2017;06(04):39-58. doi: https://doi.org/10.4236/ijohns.2017.6400.Arrangoiz R, Cordera F, Caba D, et al. Parathyroid embryology, anatomy, and pathophysiology of primary hyperparathyroidism. Int J Otorhinolaryngol Head Neck Surg. 2017;06(04):39-58. doi: https://doi.org/10.4236/ijohns.2017.6400.Delattre JF, Flament JB, Palot JP, et al. Variations in the parathyroid glands. Number, situation and arterial vascularization. Anatomical study and surgical application. J Chir (Paris). 1982;119(11):633-641.Delattre JF, Flament JB, Palot JP, et al. Variations in the parathyroid glands. Number, situation and arterial vascularization. Anatomical study and surgical application. J Chir (Paris). 1982;119(11):633-641.Barczynski M, Randolph GW, Cernea CR, et al. External branch of the superior laryngeal nerve monitoring during thyroid and parathyroid surgery: International Neural Monitoring Study Group standards guideline statement. Laryngoscope. 2013;123(4):S1-14. doi: https://doi.org/10.1002/lary.24301.Barczynski M, Randolph GW, Cernea CR, et al. External branch of the superior laryngeal nerve monitoring during thyroid and parathyroid surgery: International Neural Monitoring Study Group standards guideline statement. Laryngoscope. 2013;123(4):S1-14. doi: https://doi.org/10.1002/lary.24301.

The authors declare that there are no conflicts of interest present.