An anatomical study of the myelination of human laryngeal nerves

AbstractObjective:To determine the differences in myelination between the human recurrent laryngeal nerve and superior laryngeal nerve.Methods:Fifteen confirmed laryngeal nerve specimens were harvested from five cadavers. Cross-sections were examined under a photomicroscope and morphometric analysis performed.Results:There was a significantly greater number of myelinated fibres than unmyelinated fibres, in both the recurrent laryngeal nerve (p = 0.018) and the superior laryngeal nerve (p = 0.012). There was a significantly greater number of myelinated fibres in the superior laryngeal nerve, compared with the recurrent laryngeal nerve (p = 0.028). However, there was no significant difference in the number of unmyelinated fibres, comparing the two nerves (p = 0.116).Conclusion:These findings support those of previous studies, and provide further evidence against the historical plexus theory of laryngeal nerve morphology. The differences in the degree of myelination, both within and between the human laryngeal nerves, may have clinical consequence regarding recovery of function following nerve injury.

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Pinch, Burn, Cut Parathyroid-sparing Thyroidectomy Saves Recurrent and Superior Laryngeal Nerves (Conventional, PBC and Harmonic Scalpel Techniques Compared)

International Journal of Phonosurgery & Laryngology ◽

10.5005/jp-journals-10023-1104 ◽

2015 ◽

Vol 5 (2) ◽

pp. 48-52

Author(s):

G Raghavendra Prasad ◽

JV Subba Rao ◽

Mohammed Abdul Rahman Hameed

Keyword(s):

Achilles Tendon ◽

Recurrent Laryngeal Nerve ◽

Harmonic Scalpel ◽

Superior Laryngeal Nerve ◽

Laryngeal Nerve ◽

Anatomical Landmarks ◽

Laryngeal Nerves

ABSTRACT Introduction Recurrent laryngeal nerve (RLN) and superior laryngeal nerve (SLN) have been and continue to be the Achilles tendon of thyroidectomy. Many anatomical landmarks described and taught. How to cite this article Prasad RG, Rao JVS, Hameed MAR. Pinch, Burn, Cut Parathyroid-sparing Thyroidectomy Saves Recurrent and Superior Laryngeal Nerves (Conventional, PBC and Harmonic Scalpel Techniques Compared). Int J Phonosurg Laryngol 2015;5(2):48-52.

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Glottic Closure during Swallowing in the Recurrent Laryngeal Nerve-Paralyzed Cat

Otolaryngology ◽

10.1177/019459988910000303 ◽

1989 ◽

Vol 100 (3) ◽

pp. 187-194 ◽

Cited By ~ 10

Author(s):

Takemoto Shin ◽

Toshiro Umezaki ◽

Tadatsugu Maeyama ◽

Ikuro Morikawa

Keyword(s):

Recurrent Laryngeal Nerve ◽

Nerve Stimulation ◽

Pressure Transducer ◽

Peak Pressure ◽

Superior Laryngeal Nerve ◽

Laryngeal Nerve ◽

Glottic Closure ◽

Laryngeal Nerves ◽

Recurrent Laryngeal Nerves ◽

Closing Pressure

Glottic closing pressure and time were quantitatively analyzed during deglutition and in reflex glottic closure elicited by superior laryngeal nerve stimulation by means of a catheter pressure transducer in the cat. Duration and peak pressure of glottic closure during deglutition were 322.6 ± 32.2 msec (mean ± SE) and 57.5 ± 6.0 mmHg, respectively, whereas peak pressure of the reflex glottic closure was 21.7 ± 6.1 mmHg in control animals. When the recurrent laryngeal nerve was denervated unilaterally, decrease in peak glottic closing pressure on swallowing was only about 36%, whereas the peak pressure of reflex glottic closure was markedly diminished to 4.5 ± 4.6%. When bilateral recurrent laryngeal nerves denervated, decrease in peak pressure during deglutition showed no greater significance than It did after unilateral denervation. Inferior constrictors myotomy in addition to bilateral recurrent laryngeal nerve denervation reduced peak pressure to nearly zero. These results indicate that on swallowing, the inferior constrictors cooperate with the intrinsic laryngeal adductors, thus playing a very important role in reinforcing glottic closure, a function that is unlikely during reflex glottic closure.

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COMPARISON OF ‘AIRWAY NERVE BLOCK’ VS ‘SPRAY-AS-YOU-GO’ METHOD USED FOR AWAKE FLEXIBLE BRONCHOSCOPIC INTUBATION IN COMBINATION WITH CONSCIOUS SEDATION – A PROSPECTIVE, RANDOMISED, SINGLE BLIND STUDY

10.36106/ijsr/3800263 ◽

2021 ◽

pp. 3-6

Author(s):

Devesh Kumar Gupta ◽

Shinu Kaur ◽

Deepti Gupta

Keyword(s):

Recurrent Laryngeal Nerve ◽

Endotracheal Tube ◽

Nerve Block ◽

Conscious Sedation ◽

Nasotracheal Intubation ◽

Superior Laryngeal Nerve ◽

Laryngeal Nerve ◽

The Mean ◽

Lidocaine Spray ◽

Single Blind

Introduction: Fibreoptic Intubation (FOI) is the gold standard for managing difcult airways. There are various approaches such as: Nebulization with lidocaine; 'Spray as you go'(SAYGO); Airway nerve block - blocking superior laryngeal nerve & recurrent laryngeal nerve & sedation. The present study aims to compare 'airway nerve block' (NB) and 'spray as you go'(SA) method for awake exible bronchoscopic intubation used in combination with conscious sedation. Methods: 60 patients of age group 18 – 65 years with difcult airway undergoing general anaesthesia with nasotracheal intubation, were randomly allocated into two groups. After premedication & nasal preparation, all patients received injection dexmedetomidine at a dose of 1µg/kg in 100ml of 0.9% NS over 10 minutes. In Group SA, 2ml lignocaine 4% was sprayed above and below the cords after visibility of glottic opening via working channel of the bronchoscope and 2 ml lignocaine 4% within trachea before insertion of endotracheal tube. In Group NB, bilateral superior laryngeal nerves & recurrent laryngeal nerve was blocked. Then a exible breoptic bronchoscope preloaded with a exometallic endotracheal tube of appropriate size was then inserted via nasal route. Results: The mean intubation time for Group NB [87.27 ± 7.58 sec] was shorter than that for Group SA [190.33 ± 9.14] (p<0.0001). Conclusion: Awake exible bronchoscopic intubation under sedation with airway nerve block provides better intubating conditions compared to SAYGO

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Superior laryngeal nerve block: an anatomical study comparing two techniques

Journal of Clinical Anesthesia ◽

10.1016/j.jclinane.2014.03.005 ◽

2014 ◽

Vol 26 (7) ◽

pp. 517-522 ◽

Cited By ~ 2

Author(s):

David Jeffrey Canty ◽

Laurence Poon

Keyword(s):

Nerve Block ◽

Superior Laryngeal Nerve ◽

Anatomical Study ◽

Laryngeal Nerve

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Identifying Recurrent Laryngeal Nerve in Thyroid Surgery Using Relationship with Superior Parathyroid Gland and Tubercle of Zuckerkandl

Bengal Journal of Otolaryngology and Head Neck Surgery ◽

10.47210/bjohns.2015.v23i3.55 ◽

2015 ◽

Vol 23 (3) ◽

pp. 99-103

Author(s):

Somesh Mozumder ◽

Shirish Dubey ◽

Aniruddha Dam ◽

Anup Kumar Bhowmick

Keyword(s):

Prospective Study ◽

Recurrent Laryngeal Nerve ◽

Parathyroid Gland ◽

Thyroid Surgery ◽

Intimate Relationship ◽

Laryngeal Nerve ◽

Laryngeal Nerves ◽

Recurrent Laryngeal Nerves ◽

A Prospective Study ◽

Relationship Of

Introduction: Recurrent laryngeal nerves (RLN) are particularly prone to injury during thyroid surgeries due to its intimate relationship and proximity with the gland. Zuckerkandl’s tubercle (ZT) helps in preserving RLN intra operative. Material and Methods: A prospective study for identifying RLN in thyroid surgery using relationship with superior parathyroid gland and tubercle of Zuckerkandl was conducted on 50 thyroidectomy patients between August 2013 and February 2014. Results: In all cases ZT was identified. Temporary paralysis of RLN was seen in 3 (6%) cases and permanent paralysis in 2 (4%) of cases. Discussion: The site of greatest risk during thyroidectomy to the RLN is in the last 2-3 cm extralaryngeal course of the nerve. Relationship of recurrent laryngeal nerve with superior parathyroid gland and tubercle of Zukerkandl (ZT) is known. Conclusion: Use of ZT and superior parathyroids as a landmark allows safe dissection of RLN.

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Chronic Cough as a Sign of Laryngeal Sensory Neuropathy: Diagnosis and Treatment

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348940511400401 ◽

2005 ◽

Vol 114 (4) ◽

pp. 253-257 ◽

Cited By ~ 113

Author(s):

Bryant Lee ◽

Peak Woo

Keyword(s):

Recurrent Laryngeal Nerve ◽

Chronic Cough ◽

Symptomatic Relief ◽

Superior Laryngeal Nerve ◽

Sensory Neuropathy ◽

Sudden Onset ◽

Laryngeal Nerve ◽

Motor Neuropathy ◽

Throat Clearing ◽

Postnasal Drip

Chronic cough is often attributed to reflux, postnasal drip, or asthma. We present 28 patients who had chronic cough or throat-clearing as a manifestation of sensory neuropathy involving the superior or recurrent laryngeal nerve. They had been identified as having sudden-onset cough, laryngospasm, or throat-clearing after viral illness, surgery, or an unknown trigger. Cough and laryngospasm were the most common complaints. Seventy-one percent of the patients had concomitant superior laryngeal nerve or recurrent laryngeal nerve motor neuropathy documented by laryngeal electromyography or videostroboscopy. After a negative workup for reflux, asthma, or postnasal drip, these patients were treated with gabapentin at 100 to 900 mg/d. Symptomatic relief was achieved in 68% of the patients. Sensory neuropathy of the recurrent laryngeal nerve or superior laryngeal nerve should be considered in the workup for chronic cough or larynx irritability. Symptomatic management of patients with cough and laryngospasm due to a suspected sensory neuropathy may include the use of antiseizure medications such as gabapentin.

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Thyroidectomy: Technique, Tips, and Troubleshooting

DeckerMed Surgery ◽

10.2310/surg.2408 ◽

2018 ◽

Author(s):

Lindsay EY Kuo ◽

Matthew A. Nehs

Keyword(s):

Recurrent Laryngeal Nerve ◽

Superior Laryngeal Nerve ◽

Recurrent Laryngeal Nerve Injury ◽

Laryngeal Nerve ◽

Remote Access ◽

Postoperative Hypocalcemia ◽

Minimally Invasive Thyroidectomy ◽

Perioperative Morbidity ◽

Postoperative Hematoma ◽

Thyroid Lobectomy

Historically, thyroidectomy was associated with a high mortality rate, now understood to likely be secondary to postoperative hypocalcemia. In the modern age, perioperative morbidity and mortality rates are extremely low, although some complications, such as recurrent laryngeal nerve injury, can have significant consequences. Understanding the safe approach to total thyroidectomy and thyroid lobectomy is key to minimizing operative morbidity. In particular, the capsular dissection technique facilitates identification and preservation of the recurrent laryngeal nerve and parathyroid glands. The postoperative care of the patient, including diagnosis and management of the more common complications such as hematoma or hypocalcemia, is crucial to optimize patient outcomes. Although novel thyroidectomy techniques have been developed to avoid or minimize the traditional neck incision, these approaches have not become widely used. This review contains 9 figures, 1 table, and 29 references. Key Words: capsular dissection, external branch of the superior laryngeal nerve, intraoperative nerve monitoring, minimally invasive thyroidectomy, postoperative hematoma, postoperative hoarseness, postoperative hypocalcemia, recurrent laryngeal nerve, remote access thyroidectomy

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Effects of Recurrent Laryngeal Nerve Transection and Vagotomy on Respiratory Contraction of the Cricothyroid Muscle

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348948909800512 ◽

1989 ◽

Vol 98 (5) ◽

pp. 373-378 ◽

Cited By ~ 6

Author(s):

Gayle E. Woodson

Keyword(s):

Recurrent Laryngeal Nerve ◽

Superior Laryngeal Nerve ◽

Upper Airway ◽

Vocal Folds ◽

Laryngeal Nerve ◽

Electromyographic Activity ◽

Airway Occlusion ◽

Cricothyroid Muscle ◽

Bilateral Vagotomy ◽

Posterior Cricoarytenoid

The cricothyroid muscle (CT) appears to be an accessory muscle of respiration. Phasic inspiratory contraction is stimulated by increasing respiratory demand. Reflex activation of the CT may be responsible for the paramedian position of the vocal folds, and hence airway obstruction, in patients with bilateral recurrent laryngeal nerve (RLN) paralysis. Previous research has demonstrated the influence of superior laryngeal nerve (SLN) afferents on CT activity. The present study addresses the effects of vagal and RLN afferents. Electromyographic activity of the CT and right posterior cricoarytenoid muscle was monitored in anesthetized cats during tracheotomy breathing and in response to tracheal or upper airway occlusion in the intact animal. This was repeated following left RLN transection, bilateral vagotomy, and bilateral SLN transection. Vagotomy abolished CT response to tracheal occlusion and markedly reduced the response to upper airway occlusion. Vocal fold position following RLN transection appeared to correlate with CT activity; however, observed changes were minor.

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RA07.05: DIAGNOSTIC VALUE OF INTRAOPERATIVE ULTRASONOGRAPHY IN ASSESSING THORACIC RECURRENT LARYNGEAL NERVE LYMPH NODES IN PATIENTS WITH ESOPHAGEAL CANCER

Diseases of the Esophagus ◽

10.1093/dote/doy089.ra07.05 ◽

2018 ◽

Vol 31 (Supplement_1) ◽

pp. 35-35

Author(s):

Hong Yang

Keyword(s):

Esophageal Cancer ◽

Recurrent Laryngeal Nerve ◽

Predictive Value ◽

Conflicts Of Interest ◽

Nodal Metastasis ◽

Laryngeal Nerve ◽

Intraoperative Ultrasonography ◽

Nodal Metastases ◽

Thoracic Esophageal Cancer ◽

Significant Difference

Abstract Background To evaluate the ability of intraoperative ultrasonography (IU) to detect recurrent laryngeal nerve (RLN) nodal metastases in esophageal cancer patients. Methods Sixty patients with esophageal cancer underwent IU, computed tomography (CT), and endoscopic ultrasonography (EUS) to assess for RLN nodal metastasis. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were compared. Results The sensitivities of IU, CT, and EUS in diagnosing right RLN nodal metastases were 71.4%, 14.3%, and 30.0%, respectively, and a significant difference among these three examinations was observed (c2 = 10.077, P = .006). The specificities of IU, CT, and EUS for diagnosing right RLN nodal metastasis were 67.4%, 97.8%, and 95.0%, respectively, and a significant difference was observed (c2 = 21.725, P < .001). No significant differences in either PPV or NPV were observed when diagnosing right RLN nodal metastases. For diagnosis of left RLN lymph nodal metastases, the sensitivities of IU, CT, and EUS were 91.7%, 16.7%, and 40.0% respectively. There was a significant difference among these diagnostic sensitivities (c2 = 14.067, P = .001). The specificities of IU, CT, and EUS for diagnosis of left RLN nodal metastases were 79.2%, 100%, and 82.5%, respectively and a significant difference was observed (c2 = 10.819, P = .004). No significant differences were observed in PPV or NPV for these examinations when diagnosing left RLN nodal metastases. Conclusion Intraoperative ultrasonography showed superior sensitivity compared with preoperative CT or EUS in detecting RLN lymph node metastasis in patients with thoracic esophageal cancer. Disclosure All authors have declared no conflicts of interest.

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