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At least 19 recordsLinked to original sources
PubMedDate not supplied

[Central projections of the rat recurrent laryngeal nerve].

Laryngeal nerves contain the fibres that control the laryngeal function. The studies carried out on the rat with the purpose of having a better knowledge of the functional components and the real origin of the fibres conveyed by the recurrent laryngeal nerve (RLN) are few and in disagreement. No one of such papers were developed using biotinylated dextrane amines (BDA), a powerful tool for tracing neural pathways. The aim of our study was to identify in the rat using BDA, the nuclei of real origin of the fibres of the RLN, knowing in this way the functional components of this nerve. The study has been developed in 31 adult male Sprague-Dawley rats, applying the BDA into the lesioned RLN. The results obtained in all the animals show that the rat's RLN does not contain afferent fibres, whereas the efferent fibres were originated within the ipsilateral nucleus ambiguus (NA). So, in the rat, the RLN seems to contain exclusively efferent fibres, probably been the superior laryngeal nerve who conveyed the afferent fibres.

Animals↗
PubMed1990

[Systematization and histomorphometry of human laryngeal nerves].

Laryngeal nerves were dissected from 100 fresh subjects in order to compare right and left superior and inferior laryngeal nerves. The origin and the distribution of the vascularization was studied. The structure of these nerves was precised through an histomorphometric approach (distribution number of myelinated fibers per mm2, diameter of myelinated fibers). A cartographic study of the laryngeal nerves confirmed the structure of this innervation. The main conclusion of this study is the importance of the plexis structure of the laryngeal innervation and the variations of the nerve fibers diameter as a function of the length of the fiber.

Computers↗
PubMedDate not supplied

[Central projections of the rat superior laryngeal nerve].

Laryngeal nerves contain the fibres that control the laryngeal function. On the rat, the studies on the functional components and the real origin of the fibres conveyed by the superior laryngeal nerve (SLN) are few. No one of such works were developed using biotinylated dextrane amines (BDA), a powerful tool for tracing neural pathways. The aim of our study was to identify by using BDA, in the rat, the nuclei of real origin of the fibres of the SLN, knowing in this way the functional components of this nerve. The study has been developed in 11 adult male Sprague-Dawley rats, applying the BDA into the damaged SLN. The results obtained in all the animals shown that the rat SLN carries efferent fibres originated within the ipsilateral nucleus ambiguous (NA) and dorsal nucleus of the vagus (DNV), and that afferent fibres reach the tractus solitari and the nucleus tractus solitari. So, in the rat, the SLN seems to convey efferent fibres from the NA and DNV and, probably, all the laryngeal afferent fibres.

Animals↗
PubMed1996

Intraoperative identification of laryngeal nerves with laryngeal electromyography.

The laryngeal nerves are at risk during thyroid surgery, and several techniques have been described for their intraoperative identification to minimize potential damage. Nerve protection is based on the electromyographic recording from the muscles innervated by the laryngeal nerves, and that electrical activity is picked up by various techniques. We evaluated an electrode attachment to the endotracheal tube that provides a stable method for continuous recording of the laryngeal electromyogram. In addition, we tested various modalities of electrical stimulation in the region where the nerves are located, identified the most reliable evoked electromyographic activity, and characterized the wave form and latency. The results, obtained in 28 patients scheduled for thyroid and parathyroid surgery, indicate that the technique of recording from electrodes attached to the endotracheal tube is safe and reliable. Insulated bipolar forceps or a monopolar electrode was used to deliver low-voltage pulses (1 to 3 V) at 1 to 2 pulses/s generated by either battery-operated or optically isolated stimulators. The most unequivocal recordings were obtained with the monitoring equipment set to the nerve-conduction velocity modality, with the sweep set at 2 msec/cm. The technique clearly differentiated the evoked electromyographic responses obtained from the superior or recurrent laryngeal nerve and was easily performed with no perioperative complications.

Adult↗
PubMed2005

Detailed investigation of the relationship between the inferior laryngeal nerve including laryngeal branches and ligament of Berry.

BACKGROUND: Studies about the anatomic relationship between the inferior laryngeal nerve (ILN) and the ligament of Berry are insufficient, despite controversy in the literature. In addition, the relationship between the laryngeal branches of the ILN and the ligament of Berry has not been investigated. STUDY DESIGN: Sixty specimens (120 sides) were examined for this study, including 41 male and 19 female cadavers between the ages of 40 and 89 years at death. RESULTS: The nerve trunk or its anterior and posterior laryngeal branches run posterolateral to the ligament in 51 and 39 sides, respectively. The nerve trunk or both its laryngeal branches passed posteromedial to the ligament in 12 and 7 sides, respectively. In seven sides, the anterior branch of the ILN was located posterolateral and the posterior branch was posteromedial to the ligament. In three sides, the anterior (motor) branch of the ILN penetrated the ligament of Berry. In one right side, a nonrecurrent laryngeal nerve arose from the vagal nerve at the level of ligament of Berry. The nerve divided into the anterior and posterior laryngeal branches just above posterior surface of the ligament; both branches extended parallel to it. CONCLUSIONS: We have shown that the nerve was located not only posterolateral to the ligament but also posteromedial to it. Additionally, unlike other authors, we have shown that the anterior (motor) branch of the recurrent laryngeal nerve penetrated the ligament of Berry in 2.5% of 60 specimens.

Adult↗
PubMed2006

Diagnosis of unilateral recurrent laryngeal nerve paralysis: laryngeal electromyography, subjective rating scales, acoustic and aerodynamic measures.

OBJECTIVE/HYPOTHESIS: To determine whether specific laryngeal electromyography (LEMG) patterns in patients with unilateral vocal fold paralysis/paresis (UVFP) are related to etiology of injury, time from onset of injury, patient perception of symptom severity, acoustic measures, and laryngeal aerodynamic measures. STUDY DESIGN: This is a retrospective review of 75 patients. METHODS: Each patient received LEMG, acoustic and aerodynamic testing, and a subjective rating scale assessment (the Glottal Closure Index). Statistical analysis by groups were performed using both chi and single-factor analysis of variance testing. RESULTS: An iatrogenic etiology was associated with poor tone on LEMG (P = .05). Those individuals evaluated after 3 months after onset demonstrated more nascent units, a sign of reinnervation, compared with individuals evaluated before 3 months (P < .02). Individuals with fewer normal motor units on LEMG had significantly higher mean translaryngeal air flows (P = .044). Individuals with poor recruitment had significantly shorter maximum phonation times (P = .034) and higher mean flows (P = .044). Individuals with better laryngeal tone as noted on LEMG had significantly lower mean flows (P = .06). CONCLUSIONS: Specific LEMG patterns are related to the etiology of the UVFP and time course since recurrent laryngeal nerve injury. LEMG appears to reflect vocal fold muscle tone as seen on laryngeal function studies. In combination, these studies provide a cohesive assessment of laryngeal function in patients with UVFP.

Adult↗
PubMed2000

Anastomosis between the external branch of the superior laryngeal nerve and the recurrent laryngeal nerve.

An incidental finding in the anatomy lab showed up a plexus of the external branch of the right superior laryngeal nerve (SLN), including an anastomosis with the recurrent laryngeal nerve (RLN). The external branch of the SLN divided in two extensions: The ventral extension reached the mesopharynx laterally and by supplying the latter, ended at the cricothyroid muscle. The dorsal extension formed a plexus a finger's breadth beneath the inferior margin of the pharynx, on the lateral aspect of the esophagus. The anastomosis ran from the lower part of the plexus to the RLN along the esophagus, laterally.

Cadaver↗
PubMed2001

Effect of recurrent laryngeal nerve paralysis on superior laryngeal nerve afferents during evoked vocalization.

We tested the hypothesis that vocal fold paresis leads to a substantial reduction in activity from the internal branch of the superior laryngeal nerve (iSLN) during respiration and evoked vocalization. The iSLN afferent activity was measured before and after recurrent laryngeal nerve paresis by cold block in decerebrate cats during spontaneous respiration and electrically evoked vocalization. Response rate patterns of 33 iSLN single units from 11 cats were categorized into 5 groups based on responses to vocalization. Only 24% of single units during spontaneous respiration and 18% during evoked phonation displayed activity pattern changes as a result of paresis. Those fibers affected were heterogeneous in discharge pattern, but none of the units that followed voice frequency lost this characteristic when the motor nerve was cooled. The relative insensitivity of iSLN activity to motor paralysis suggests that the receptors studied are coupled to tissue such that passive interaction rather than active muscular contraction is the major stimulus.

Animals↗
PubMedDate not supplied

Networks of peptide-containing nerve fibres in laryngeal nerve paraganglia. An immunohistochemical study.

Sections of rat superior and recurrent laryngeal nerves (SLN and RLN) with enclosed paraganglia and ganglionic cells were incubated with antisera against five different neuropeptides. Vasoactive intestinal polypeptide-like immunoreactivity (VIP-LI) and neuropeptide Y (NPY)-LI was detected in a large number of varicose nerve fibres in the paraganglia. A few varicosities of the paraganglia showed substance P (SP)-LI or calcitonin gene-related peptide (CGRP)-LI, whereas there were no signs of enkephalin (ENK)-LI in these varicosities. The paraganglionic cells never exhibited immunoreactivity for any of the peptides tested, whereas some of the associated ganglionic cells showed NPY-LI, VIP-LI or ENK-LI. The study shows that the paraganglia of the SLN and RLN receive a significant peptidergic innervation and suggests that the peptide-containing nerve fibres in these structures originate from cells other than the paraganglionic cells. The findings imply that in further studies defining the function of laryngeal nerve paraganglia in larynx physiology, the role of neuropeptides should be examined.

Animals↗
PubMed1996

Fiber types of the lingual branch of the trigeminal nerve, chorda tympani, lingual-tonsillar and pharyngeal branches of the glossopharyngeal nerve, and superior laryngeal nerve and their relation to the cardiovascular responses in rats.

The effect of repetitive electrical stimulation at 50 Hz for 20 s of the lingual branch of the trigeminal nerve (LN), chorda tympani (CT), lingual-tonsillar (LT-IXth) and pharyngeal (PH-IXth) branches of the glossopharyngeal nerve, and superior laryngeal nerve (SLN) on the changes in arterial blood pressure (BP) and heart rate (HR) were investigated in anesthetized and paralyzed rats. The compound action potentials in these nerves were simultaneously recorded to know the relationships between the fiber types and the cardiovascular responses. In all nerves except the CT, repetitive electrical stimulation of the nerve elicited a tachycardia and an increase in BP. These cardiovascular responses were mainly related to the component-2 in the compound action potentials in respective nerves. The conduction velocities of the component-2 in the five nerves examined in the present experiment were between 9.5 and 17.0 m/s (mean, n = 4-7). Other components which have faster (component-1) or slower conduction velocities (component-3 and -4) than the component-2 were not likely to elicit the cardiovascular responses. These results suggest that nociceptive and taste fibers of A-delta fibers innervating the oral cavity and pharyngolaryngeal region largely contribute to the cardiovascular responses.

Animals↗
PubMed1987

[Effect of a modified struma resection technic on the rate of lesions of the recurrent laryngeal nerve].

Recurrent laryngeal nerve injury still remains the major problem in thyroid gland surgery and is influenced both by morphology and function of the goitre and essentially by the resection technique. Between 1982 and 1985 a total of 825 patients was operated on for the first time due to a benign goitre. In period A (Jan. 1982 to Dec. 1983) we always-- preceding the resection of the goitre--performed the ligature of the A.thyreoidea inferior (n = 412) whereas in period B (Jan. 1984 to Dec. 1985) we dispensed with it (n = 413). In neither of the two periods the preparation of the N.laryngeus recurrens--save few exceptional cases--was performed. The immediate postoperative recurrent laryngeal nerve palsy rate decreased from 4.9% in period A to 2.2% in period B, the persistent palsy rate (laryngeal control half a year postoperatively) from 2.18% to 0.48%. Due to the change to smaller, more hyperfunctional goitres in endemic areas we believe it possible to perform the resection of benign goitres without the preliminary ligature of the A.thyreoidea inferior and the preparation of the recurrent laryngeal nerve. On one hand this can lead to the facilitation of the surgical task, on the other hand to the decrease of the injury risk on the recurrent laryngeal nerve.

Adult↗
PubMed2001

Bilateral investigation of the anatomical relationships of the external branch of the superior laryngeal nerve and superior thyroid artery, and also the recurrent laryngeal nerve and inferior thyroid artery.

The relationships of both the external branch of superior laryngeal nerve with the superior thyroidal artery and the recurrent laryngeal nerve with the inferior thyroidal artery were examined on the fixed cadavers of 4 adult women and 26 adult men. A total of 32 external branches of superior laryngeal nerve, 16 on each side, were dissected. When left and right sides were assessed altogether, 71.9% were medial to the artery while 28.1% were in between the branches. No nerve was found to be lateral to the artery. Thus the type in which the nerve is exposed to surgical trauma was found to be present in 28.1% of the cases. Only 12 of the cadavers could be assessed for symmetry and three fourths were found to have bilaterally symmetric relationship. A total of 52 Recurrent Laryngeal Nerves, 27 on the left and 25 on the right side were dissected. When bilateral symmetry was assessed in 21 cadavers, one third of the Recurrent Laryngeal Nerves were found to be bilaterally symmetrical. Inferior Thyroidal Artery was missing in 4 sides; bilaterally in one cadaver and unilaterally in 2 cadavers. Thus, artery-nerve relationship was assessed on 48 sides, 25 on the left and 23 on the right. On the right, 39.2% were in between the branches while 30.4% were anterior to the artery and 30.4% were posterior. On the left, 52% were in between the branches whereas 44% were posterior and 4% was anterior to the artery. Thus the position of the nerve in between the branches had the highest incidence while the anterior position had the lowest, the differences being statistically insignificant.

Arteries↗
PubMed1996

Convergent carotid sinus nerve and superior laryngeal nerve afferent inputs to neurons in the NTS.

A population of 43 neurons in the nucleus of the solitary tract (NTS) was identified in pentobarbital sodium anesthetized, paralyzed, and artificially ventilated cats that received convergent inputs from carotid sinus nerve (CSN) and superior laryngeal nerve (SLN) afferents. In 21 neurons, electrical stimulation of the CSN and SLN each evoked an excitatory postsynaptic potential (EPSP; mean onset latency +/- SE of CSN-evoked input = 7.2 +/- 0.8 ms, range 2.1-14.1 ms; of SLN-evoked input = 10.3 +/- 2.1 ms, range 2.8-46.8 ms). In 22 neurons, electrical stimulation of either the CSN or SLN evoked an EPSP/ inhibitory postsynaptic potential (IPSP) sequence (CSN-evoked input = 6.7 +/- 0.6 ms, range 2.1-12.2 ms; SLN-evoked input = 8.4 +/- 0.8 ms, range 3.0-19.4 ms). Spatial interactions (facilitation, summation, occlusion) and time-dependent inhibitory interactions were observed between the convergent inputs. Natural stimulation of specific receptors indicated that 14 cells received a convergent excitatory input from carotid sinus baroreceptors and laryngeal mechanoreceptors, 10 received a convergent excitatory input from carotid body chemoreceptors and laryngeal mechanoreceptors, and 5 received a convergent excitatory input from baroreceptors, chemoreceptors, and laryngeal mechanoreceptors. The interactions and various patterns of convergence suggest a significant integration of convergent inputs from disparate afferent sources by these neurons.

Afferent Pathways↗
PubMed2003

Surgical anatomy of the recurrent laryngeal nerve: implications for laryngeal reinnervation.

Functional laryngeal reinnervation depends upon the precise reinnervation of the laryngeal abductor and adductor muscle groups. While simple end-to-end anastomosis of the recurrent laryngeal nerve (RLN) main trunk results in synkinesis, functional reinnervation can be achieved by selective anastomosis of the abductor and adductor RLN divisions. Few previous studies have examined the intralaryngeal anatomy of the RLN to ascertain the characteristics that may lend themselves to laryngeal reinnervation. Ten human larynges without known laryngeal disorders were obtained from human cadavers for RLN microdissection. The bilateral intralaryngeal RLN branching patterns were determined, and the diameters and lengths of the abductor and adductor divisions were measured. The mean diameters of the abductor and adductor divisions were 0.8 and 0.7 mm, while their mean lengths were 5.7 and 6.1 mm, respectively. The abductor division usually consisted of one branch to the posterior cricoarytenoid muscle; however, in cases in which multiple branches were seen, at least one dominant branch could usually be identified. We conclude that the abductor and adductor divisions of the human RLN can be readily identified by an extralaryngeal approach. Several key landmarks aid in the identification of the branches to individual muscles. These data also indicate the feasibility of selective laryngeal reinnervation in patients who might be candidates for laryngeal transplantation after total laryngectomy.

Aged↗