Inspiratory activation of the vocal cord adductor, part I: human study in patients with restricted abduction of the vocal cords

OBJECTIVES/HYPOTHESIS: In patients with restricted abduction of the vocal cords, it has generally been accepted that glottis narrowing with laryngeal stridor during inspiration is attributed to static and passive obstruction of the glottis. However, active glottis narrowing can also be contributory. We tested the hypothesis that the vocal cord adductor is activated during inspiration in patients with restricted abduction of the vocal cords. STUDY DESIGN: Electromyographic evaluation of vocal cord adductor activity in patients with restricted abduction of the vocal cords. METHODS: Five patients with restricted abduction of the vocal cords who had stridor with mild to severe dyspnea during wakefulness were anesthetized with propofol. We recorded the adductor muscle electromyogram during breathing through a laryngeal mask airway while observing the vocal cord movement endoscopically. In three patients who had undergone tracheostomy, we also recorded adductor firing patterns not only while closing but also while opening the tracheostoma. RESULTS: The adductor was activated during inspiration, and the glottis was narrowed in accordance with inspiratory stridor. This adductor inspiratory activity was abolished by opening the tracheostoma in the tracheostomized patients. CONCLUSION: Not only static or passive glottis narrowing but also active narrowing may contribute to inspiratory flow limitation in patients with restricted abduction of the vocal cords. This active glottis narrowing is probably induced by an airway reflex.     

Variability in nerve patterns of the adductor muscle group supplied by the recurrent laryngeal nerve

INTRODUCTION: Accurate knowledge of the nerve supply of each individual muscle is needed to achieve a successful selective reinnervation of the larynx. The aim of the present work was to study the nerve supply of the adductor laryngeal muscles supplied by the recurrent laryngeal nerve. STUDY DESIGN: Morphologic study of human larynges. METHODS: The muscular nerve supply was studied in a total sample of 75 human larynges obtained from necropsies (47 males and 28 females, age range from 41-95 years) and examined by careful dissection using a surgical microscope. RESULTS: The arytenoid muscle received one branch from each recurrent nerve. In 88% of cases, this branch arose in a common trunk with the upper branch of the posterior cricoarytenoid muscle. In 8% of cases, the nerve for the arytenoid muscle also had a branch going to the lateral cricoarytenoid muscle. The arytenoid muscle also received from one to three pairs of branches from the posterior division of the internal laryngeal nerve; these were interconnected ipsi- and contralaterally and were also connected to the two branches coming from the recurrent laryngeal nerve. The lateral cricoarytenoid muscle received from one to six branches from the recurrent nerve, but in 5.8% of cases, it also received a twig from a connecting branch between the recurrent nerve and the external (5.6%) or the internal laryngeal nerves (0.2%). The thyroarytenoid muscle received from one to four branches from the recurrent nerve, but in 5.6% of cases, it also received a twig from a connecting branch between the recurrent nerve with the external (4.6%) or the internal (1%) laryngeal nerves. CONCLUSION: No abductor or adductor division of the recurrent laryngeal nerve was found in the present study. In 88% of cases, the nerve supply to the arytenoid muscle (adductor) and the posterior cricoarytenoid muscle (abductor) arose from a common trunk, which in 8% of cases, also had a branch to the lateral cricoarytenoid muscle. Furthermore, the high incidence of branches innervating the adductor muscles from connections between the recurrent laryngeal nerve and the internal and external laryngeal nerves led us to reconsider the contribution of these nerves in the supply to this muscle group.     

Aerodynamics of the human larynx during vocal fold vibration

OBJECTIVES:: The goal of this study was to comprehensively analyze the influence of aerodynamics on laryngeal function. Three specific aspects were considered: 1) a multidimensional comparison of the interaction of subglottic pressure, sound intensity, and fundamental frequency; 2) examination of instantaneous changes in subglottic pressure during each glottic cycle; and 3) determination of the threshold subglottic pressure for vocal fold vibration and its dependence on other aerodynamic factors. STUDY DESIGN:: Prospective study with six healthy individuals without history of voice disorders. METHODS:: The subjects vocalized the vowel sound /i/ with a variety of different intensities, pitch, and sound intensity. Subglottic air pressure, fundamental frequency, sound intensity, and the electroglottography signal were simultaneously measured. RESULTS:: Linear relationships were seen in all subjects between subglottic air pressure and sound intensity, although there were large variations in the slopes of these relationships. Rapid variations in subglottic pressure during each glottic cycle were detected, corresponding to the opening of the vocal folds with each individual vibration. Threshold pressures for vocal fold vibration were dependent primarily on sound intensity and fundamental frequency and tended to be higher at vibration onset than at offset. CONCLUSION:: The larynx responded in a predictable pattern to general aerodynamic forces, but there was tremendous variability in its specific behavior. Fundamental frequency and sound intensity tended to increase with subglottic air pressure, but that relationship was not seen consistently in all subjects. The relationship between subglottic air pressure and sound intensity was usually linear, unlike the exponential relationship seen in previous studies. Subglottic pressure was noted to undergo rapid change with each glottic cycle in some, but not all, subjects and was most strongly affected by average subglottic pressure. Phonation threshold air pressure was influenced by the sound intensity and, to a smaller extent, by the fundamental frequency of the voiced sound.     

Tracheostomy abolishes paradoxical activation of the vocal cord adductor in multiple system atrophy

OBJECTIVES: Inspiratory activation of the vocal cord adductor, which causes paradoxical vocal cord motion, develops in patients with multiple system atrophy (MSA). To confirm the hypothesis that airway reflexes trigger such paradoxical activation, we investigated the effects of tracheostomy on the adductor activation in a MSA patient. METHODS: We compared the adductor electromyograms before and after breathing was diverted to a tracheostoma under propofol anesthesia. RESULTS: The adductor inspiratory activation disappeared during tracheostoma breathing. CONCLUSION: Airway reflexes as well as MSA-related damage to the respiratory center contribute to the generation of paradoxical adductor activation in MSA patients.     

Association of alirocumab therapy with inflammatory lesions of the vocal folds: A case report

Therapeutic monocolonal antibodies (MAbs) are a new, rapidly growing class of medications that frequently have poorly characterized side‐effect profiles. We present a patient who developed inflammatory lesions of the vocal folds in temporal relation to the initiation of alirocumab. Lesions of the vocal folds represent a previously unreported adverse effect of alirocumab therapy, making it the second MAb documented with such a side effect. The potential laryngeal effects of alirocumab specifically, and of MAbs more broadly, warrant investigation. Laryngoscope , 127:1652–1654, 2017     

神经端侧吻合术治疗声带麻痹的实验研究

目的 :研究神经端侧吻合术治疗声带麻痹的效果及临床应用价值。方法 :6 0只SD大鼠被分为 3组 ,实验组为神经端侧吻合组 ,切断右侧喉返神经 ,将其远断端与右侧膈神经行神经端侧吻合 ,然后切断喉返神经内收支 ,将颈袢的胸骨舌骨肌支与内收支行神经端端吻合 ;对照组为神经端端吻合组 ,切断右侧喉返神经后将其远断端与右侧切断的膈神经近断端行神经端端吻合 ,其他同实验组 ;以上两组均将右侧的喉上神经切断 ,并结扎断端 ,排除环甲肌对声带活动的影响。正常组仅暴露上述神经后不作任何处理。术后 1、3个月利用纤维喉镜及神经肌电图观察声带活动及神经再生情况。结果 :术后 1个月实验组与对照组手术效果差异有显著性意义 (P<0 .0 5 ) ;术后 3个月差异无显著性意义 (P >0 .0 5 )。结论 :神经端侧吻合术手术效果与神经端端吻合术相似 ,并且避免了膈神经的损伤 ,保护了膈肌功能 ,为喉返神经修复术提供了一种新的手术方法。     

Effects of denervation on neuromuscular junctions in the thyroarytenoid muscle

OBJECTIVES/HYPOTHESIS: To evaluate the effects of denervation on muscle fibers and neuromuscular junctions (NMJ) of the rat thyroarytenoid (TA) muscle with a histochemical method to monitor the status of degenerative NMJ. STUDY DESIGN: Quantitative assessment to monitor the status of degenerative muscle fibers and NMJ in the TA muscle. METHODS: Wistar rats were killed at 6, 12, 18, and 24 hours and at 2, 4, and 10 weeks after left recurrent laryngeal nerve (RLN) transection. Hematoxylin-eosin stain was used to evaluate the atrophic changes of the TA muscle. The pre- and postsynaptic structures of the NMJ were detected histochemically. These changes were evaluated by comparing the results between the treated (T) and untreated (U) sides (T/U ratio) in the same section. RESULTS: The atrophic changes in the TA muscle progressed gradually, and at 10 weeks, the T/U ratios of the entire muscle area and of the muscle fiber size decreased to 53.2 +/- 10.7% and 55.5 +/- 6.8%, respectively (P < .01). The number of nerve terminals decreased significantly at 18 hours (P < .01), and they disappeared completely by 24 hours. In contrast, at 10 weeks, 70.5 +/- 12.4% (P < .01) of acetylcholine receptors (AchRs) were preserved. CONCLUSIONS: In the rat TA muscle, denervation influences the presynaptic nerve terminals more than the postsynaptic AchRs and the muscle fibers. The results could be a basis for understanding the mechanism of laryngeal denervation and reinnervation processes in animal models.     

Cysts of the larynx : A clinicopathologic study of nine cases

In this only report from India, nine patients with laryngeal cysts have been diagnosed in the 24 year period from Jan 1971 through Jan 1996 representing 0.01 % of 1,05,279 general biopsies and 1.16% of 774 laryngeal biopsies received. The patients were mainly male with a mean age of 48.87 years. They presented with laryngeal obstructive symptoms. Six of the patients were chronic cigarette smokers. None had history of voice abuse. Laryngoscopic examination showed solitary cysts situated in the supraglottic region in seven cases and in the true vocal cords in two. Using modified DeSanto’s classification of laryngeal cysts putforth by Newman et al (1984), four were ductal, three saccular and one of tonsillar type. However, one of the cysts having features of an epidermoid cyst could not fit into the classification. The major proposed classifications of laryngeal cysts which are in practice have resulted in much confusion for both clinicians and pathologists and these have been studied in depth and their implications discussed here.     

Restoring vocal fold movement after transection and immediate suturing of the recurrent laryngeal nerve with local application of basic fibroblast growth factor: an experimental study in the rat

OBJECTIVE: To evaluate the effects of basic fibro-blast growth factor (bFGF) on the recovery of vocal fold movement and the attenuation of laryngeal muscle atrophy after transection of the recurrent laryngeal nerve (RLN). STUDY DESIGN: Quantitative assessment of vocal fold movement using the video cassette recorder (VCR) image-analysis method and histologic examination of the laryngeal muscle. METHODS: Fifty-eight Wistar rats underwent RLN transection and one of the following three procedures: 1) transection of the RLN alone (transection group, n = 18), 2) suture of the nerve stumps followed by local administration of phosphate-buffered saline (PBS) solution using an osmotic pump (PBS group, n =20), or 3) suture of the nerve stumps followed by local administration of bFGF (FGF group, n = 20). Vocal fold movements were recorded with VCR by way of a rigid endoscope, and the VCR images were analyzed on a computer. Histologic changes in the thyroarytenoid (TA) muscle were evaluated by measuring the cross-sectional area of the muscle and average size of muscle fibers. RESULTS: In the transection group, vocal fold movement did not recover, and atrophy of the TA muscle gradually progressed after sectioning the nerve. In contrast, vocal fold movement as assessed by VCR image-analysis recovered in some cases in the immediate suturing groups, more markedly in the FGF group (34.1 +/- 29.1%) than in the PBS group (5.5 +/- 7.9%) (P <.05). Histologically, atrophy of the laryngeal muscle was significantly attenuated by the local administration of bFGF. CONCLUSION: bFGF facilitates regeneration of the transected RLN and attenuation of intrinsic laryngeal muscle atrophy, thereby restoring laryngeal function.     

迷走神经劈开术治疗大鼠声带麻痹的实验研究

目的:探讨劈开颈段迷走神经中喉返神经支修复大鼠声带麻痹的手术方法和手术效果。方法:首先运用剥离法及乙酰胆碱酯酶组织化学染色方法确定喉返神经支在颈部迷走神经中的位置,将60只SD大鼠被分为3组,实验组为迷走神经劈开术吻合组,切断右侧喉返神经,将其远断段与劈开的颈段迷走神经的喉返支吻合。对照组为喉返神经端端吻合组,切断右侧喉返神经后立即行神经吻合。正常组不做处理。术后3个月利用纤维喉镜及神经肌电图观察声带活动及神经再生情况。结果:喉返神经束位于颈段迷走神经前内侧,单独成束,直径为总干的1/4。术后3个月2种手术方法效果差异无统计学意义(P>0.05)。结论:对喉返神经在迷走神经中准确定位,为手术操作提供了重要的解剖标志。迷走神经劈开术为喉返神经修复术提供一种新的手术方法。     

Injection of autologous muscle stem cells (myoblasts) for the treatment of vocal fold paralysis: a pilot study

OBJECTIVE: Autologous muscle stem cell (myoblast) therapy may be an ideal treatment for vocal fold paralysis because of its technical ease (administered by injection), its potential to restore muscular defects and dynamic function, and its autologous origin. The goal of this project was to determine whether autologous myoblast injection into the thyroarytenoid (TA) muscle after recurrent laryngeal nerve (RLN) injury could attenuate TA muscle atrophy and enhance spontaneous reinnervation. STUDY DESIGN: This was an animal experiment. METHODS: Unilateral RLN transection and sternocleidomastoid muscle (approximately 1 g) biopsies were performed in 16 male Wistar rats. Biopsies were used to create myoblast cultures for each animal. One month later, 10(6) autologous myoblasts labeled with fluorescent cell membrane marker (PKH26) were injected into the denervated TA of each study animal, with saline injected into controls. Animals were euthanized at 2 weeks and 2 months after myoblast injection. Outcomes included myoblast survival, TA fiber diameter and volume, and reinnervation status (motor endplate to nerve contact staining). RESULTS: All denervated TA study specimens demonstrated viable myoblasts under fluorescent microscopy, with the myoblasts demonstrating fusion with the TA myofibers at 2 months. The myoblast-treated group had greater mean TA fiber diameter than denervated TA controls at 2 months (25.1 vs. 21.1 microm; P = .04) but not at 2 weeks (25.7 microm vs. 23.5 microm; P = .06). Mean TA volumes were greater in the myoblast-treated groups at both time points. Two of the animals in the myoblast-treated group demonstrated adductor motion at 2 months, whereas none of the 2 week study animals or controls recovered adduction. Reinnervation was not significantly different between the myoblast-treated groups and the denervated controls. CONCLUSIONS: Autologous myoblast therapy may be a future treatment for vocal fold paralysis, with current findings demonstrating myoblast survival with attenuation of TA muscle atrophy.     

Neurite regeneration in the cat recurrent laryngeal nerve: an immunohistochemical study

Summary The recurrent laryngeal nerve (RLN) consists of various motor, sensory and autonomic nerve fibers, although it has not been established whether different neuronal types exhibit a similar ability to regenerate. To address this question, freezing was used to injure the cat RLN fibers and the presence or absence of immunoreactivity for neuropeptides or transmitter-synthesizing enzymes was then examined as a marker to classify the fibers. In the control RLN, calcitonin gene-related peptide-immunoreactive (CGRP-IR) fibers were the highest in number and were distributed throughout the nerve fascicles. The number of substance P-immunoreactive (SP-IR) fibers was about 40% that of CGRP-IR fibers, while a portion of CGRP-IR fibers was found to contain SP immunoreactivity. Relatively low numbers of tyrosine hydroxylase-immunoreactive (TH-IR) and neuropeptide Y (NPY-IR) nerve fibers were seen which tended to form clusters. The distribution pattern of NPY-IR fibers was very similar to that of TH-IR fibers. In the regenerating RLN 1 week after the freezing injury, the fastest growing axons were CGRP-IR, while the regenerating rates of SP-IR, TH-IR and NPY-IR fibers were slower than that of CGRP-IR fibers. These results suggest that the ability for neurite regeneration varies among neuron types and that CGRP-IR fibers possess the most rapid ability to regenerate. Correspondence to: I. Nahm     

Anatomic factors affecting the use of ultrasound to predict vocal fold motion: A pilot study

Purpose

Ultrasonography is a well-established modality for visualization of head and neck anatomy. Using ultrasound to detect vocal fold mobility has been described before, but no study has evaluated factors affecting the exam reliability. The aim of the study is to determine anatomic factors influencing the reliability of ultrasound to detect vocal fold motion.Methods and materialsPatients underwent ultrasound evaluation and flexible laryngoscopy to assess vocal fold motion from August 2015 to March 2016. Length, accuracy, and clarity of ultrasound examination were assessed, compared to flexible laryngoscopy. For patients with prior neck CT scan imaging, laryngeal anatomy was independently assessed by a blinded neuroradiologist.

Preventive effects of bortezomib on denervation-induced atrophy of the intrinsic laryngeal muscles: an experimental study in the rat

Conclusion: Bortezomib was effective in attenuating atrophy of the posterior cricoarytenoid (PCA) muscle, but not the thyroarytenoid (TA) muscle. This was probably due to differences in the fiber composition of the two muscles. The PCA muscle is composed of a combination of fast- and slow-twitch fibers, and therefore is more resistant to atrophy than the TA muscle, which is composed solely of fast-twitch fibers. Objectives: To investigate the preventive effects of bortezomib on denervation-induced atrophy of the TA and PCA muscles in the rat. Methods: Following transection of the left recurrent laryngeal nerve, bortezomib (100 μg/kg) was administered subcutaneously on post-denervation days 1 and 4, followed by a 10-day rest period every 14 days; each 2-week period constituted a single treatment cycle. In controls, saline was administered instead. Animals were killed for histological examination at 4 (n = 6), 8 (n = 7), and 12 (n = 7) weeks post-denervation. Muscle atrophy was assessed using three indices: wet muscle weight, muscle fiber cross-sectional area, and the number of muscle fibers/mm². The effects of bortezomib were evaluated by comparing the left (L) and right (R) muscles, with sequential changes in the L/R ratio assessed. Results: In saline-administered animals, atrophy of the left-sided TA and PCA muscles progressed rapidly during the first 4 weeks post-denervation, following which progression slowed. Atrophy was greater in the TA compared with the PCA muscle, although this difference was not statistically significant. In bortezomib-administered animals, atrophy of the PCA muscle was attenuated significantly at post-denervation weeks 8 and 12; no such reduction in atrophy was observed for the TA muscle.     

Lidocaine block of the recurrent laryngeal nerve in adductor spasmodic dysphonia: a multidimensional assessment

OBJECTIVES/HYPOTHESIS: Lidocaine block of the recurrent laryngeal nerve (RLN) has been reported as a procedure for surgical selection of patients with adductor spasmodic dysphonia (ADSD). However, its effects on phonation have not been rigorously assessed in a prospective fashion using strict entry criteria and multiple measures of phonatory function. This investigation assessed the phonatory effects of RLN lidocaine block in ADSD to explore its potential as a diagnostic tool. STUDY DESIGN: Single group, pre/postexperimental trial. METHODS: Twenty-one consecutive patients with suspected ADSD underwent unilateral RLN block, causing temporary ipsilateral vocal fold paralysis. Voices were recorded before and during the block. Patients completed self-ratings of overall level of dysphonia severity, vocal effort, and laryngeal tightness. Blinded listeners completed auditory-perceptual ratings, and the frequency of phonatory breaks was acoustically analyzed. RESULTS: During the block, patients reported significant reductions on overall severity (P = .045), vocal effort (P < .001), and laryngeal tightness (P = .002). Listeners rated the voices during the block as significantly more breathy (P < .001), less strained (P < .001), and less severe (P = .059). Acoustic analysis confirmed significantly fewer phonatory breaks during the block (P < .001). Patient-based ratings of improvement were more consistent than listener ratings, and reduction in overall severity correlated with perceived breathiness. CONCLUSIONS: Although individuals varied in their outcomes, group results suggest that response to RLN lidocaine block warrants further study as a possible diagnostic tool in ADSD.     

支撑喉镜下CO2激光杓状软骨部分切除术治疗双侧声带麻痹的疗效分析

探讨支撑喉镜下CO₂激光杓状软骨部分切除治疗双侧声带麻痹的疗效。