Function Of Laryngeal Muscles Research Articles

Terapia vocal com abordagem respiratória em idosos: revisão integrativa da literatura

ABSTRACT Purpose: to characterize voice therapy with a respiratory approach in dysphonic older people. Methods: a search made in PubMed, VHL, Scopus, Web of Science, and EMBASE. Original studies in English, Spanish, and Portuguese, addressing voice therapy in combination with a respiratory approach in the older population, were included. The analysis encompassed sex, age, associated etiology, session frequency and duration, exercise dosage, intervention, and benefits. Results: altogether, 1,425 articles were found, of which only nine were included in the review. In voice therapy for older people, the following strategies stood out: Vocal Function Exercises, Lee Silverman Voice Treatment®, ParkinSong, and tubes immersed in water. These approaches change the laryngeal muscle function and respiratory impulse and support and increase vocal intensity. The main therapeutic findings included improved auditory-perceptual, acoustic, and aerodynamic parameters, maximum phonation time, phonatory effort level, and voice quality. Conclusion: voice therapy with a respiratory approach characteristically used strategies aimed at both the general older population and those with neurological dysphonia. Their results showed improvement in frequency, resonance, intensity control, and breathing/phonation coordination.

Laryngeal Neuromuscular Response to Short- and Long-Term Vocalization Training in Young Male Rats.

Purpose Although vocal training is often purported to restore and rebalance laryngeal muscle function, little is known about the direct effects of vocal training on the laryngeal muscles themselves. Consequently, parameters of vocal exercise dose, such as training duration and intensity, have not been well defined. The goal of this study was to use a behavioral animal model to determine the effects of short- and long-term ultrasonic vocalization (USV) training on USV acoustics, thyroarytenoid (TA) muscle neuromuscular junctions (NMJs), and TA muscle fiber size in adult rats. Method Twenty-four young adult male Long-Evans rats were divided into 3 groups (untrained control, 4-week training, and 8-week training). Baseline and posttraining USVs were recorded and acoustically analyzed for fundamental frequency, frequency bandwidth, amplitude, and duration. Presynaptic and postsynaptic NMJ morphological features and muscle fiber size were measured in the TA. Results USV training had no effect on USV acoustics. Eight weeks of USV training, however, resulted in a lower NMJ motor endplate dispersion ratio, consistent with previous findings. USV training did not affect fiber size within the TA muscle. Conclusions This study demonstrated that 8 weeks of USV training can induce peripheral neural adaptations in the NMJ of the TA muscle in young rats. The observed adaptations suggest that vocal training is consistent with endurance-type exercise, but the adaptations occur on a longer time scale than similar adaptations in the limb muscles.

The effect of routine reversal of neuromuscular blockade on adequacy of recurrent laryngeal nerve stimulation during thyroid surgery.

Testing of the integrity of the recurrent laryngeal nerve during thyroid surgery has become routine practice for many surgeons to aid dissection and minimise the chance of inadvertent nerve injury. We hypothesised that routine reversal of an intermediate-acting, non-depolarising neuromuscular blocking agent would improve conditions for stimulation of the recurrent laryngeal nerve. We conducted a single-centre, randomised, double-blind placebo-controlled trial of patients undergoing thyroid surgery by the same surgeon. After randomisation, the participants received either neostigmine 2.5 mg with glycopyrrolate 0.4 mg or placebo, at 30 minutes after induction of anaesthesia and administration of 0.4 mg/kg of atracurium. The primary outcome was the subjective assessment by the surgeon as to whether the neuromuscular function was adequate for stimulation of the recurrent laryngeal nerve using a neuromuscular integrity monitor (NIM). Time to NIM stimulation was 44.6 minutes in the placebo group and 41.4 minutes in the intervention group (P=0.268). Of the 21 patients who received the neuromuscular blockade reversal, 20 (95.2%) had adequate surgical conditions for NIM stimulation, compared to 9 out of 18 patients (50%) in the placebo group (P=0.002). Three of the ten patients (30%) with inadequate reversal showed no evidence of residual blockade assessed peripherally. The routine reversal of neuromuscular blockade at 30 minutes post induction appears to result in adequate surgical conditions for safe stimulation of the recurrent laryngeal nerve. Return of neuromuscular function at a peripheral site does not guarantee adequate laryngeal muscle function for use of the NIM.

Use of Laryngeal Computed Tomography for Noninvasive Assessment of Laryngeal Function in Horses with Recurrent Laryngeal Neuropathy

Reasons for performing studyRecurrent laryngeal neuropathy (RLN) is a common equine distal axonopathy associated with neurogenic atrophy of intrinsic laryngeal muscles (particularly the left) causing laryngeal paresis and poor performance. An objective, reliable method of assessing changes in structure that correlates with laryngeal muscle function in vivo is necessary to determine response to novel treatments, including functional electrical stimulation. This study aimed to determine whether laryngeal muscle and nerve morphology (determined by CT and histopathology) correlated with laryngeal function.Study designProspective cohort study.MethodsResting (grades 1–4) and exercising (grades A–C) laryngeal function was graded in adult Thoroughbred horses. Standing CT of the larynx was performed to compare volume, cross‐sectional area (XSA) and tissue density between left and right cricoarytenoideus dorsalis (CAD) muscles in 22 horses. CAD muscles and recurrent laryngeal nerves were collected in a subgroup of 10 horses and analysed for fibrosis, fat infiltration and nerve fibre density (axons/μm2).ResultsHorses with grade C RLN on exercising endoscopy had significantly (P<0.005) smaller left CAD muscles and reduced nerve fibre density than horses with grades A or B. Horses with grade 4 RLN on resting endoscopy had significantly (P<0.005) smaller left CAD muscles than horses with grades 1 or 2. Left CAD muscles had significantly more collagen than the right in horses with grade C RLN. CT measurements of the CAD muscles were significantly associated with % collagen/fat and nerve fibre density (P<0.05).ConclusionsLaryngeal CT results correlate with laryngeal function at rest and exercise in the horse and provide a noninvasive method of monitoring changes in CAD morphology in response to novel treatments. CAD CT appearance is dependent on % collagen and fat in the muscle and is associated with nerve fibre density.Ethical animal research: Horses destined for euthanasia were recruited for this study with approval of the Institutional Ethical Committee and under UK Home Office Licence. Sources of funding: Med‐El Elektro‐medizinische Geräte GmbH, Innsbruck, Austria. Competing interests: None.

Cough throughout life: Children, adults and the senile

We review cough from premature birth, mature neonatal life, in childhood and adult life, and in old age. There is a regrettable lack of definitive studies, but many clues in the literature. The cough reflex seems weak in premature infants, but develops with maturity. It is pronounced in childhood, but there seem to be no studies comparing its strength then with that in adulthood. In old age the cough may weaken, as indicated by the prevalence of aspiration pneumonia. These changes are presumably related to the development and degeneration of the afferent and central nervous pathways for cough, which may be reflected in the changes in laryngeal muscle function with age. There is much evidence that age influences the development of the respiratory system in general, and of the immune system which would affect the degree, frequency and clinical issues of cough. Other factors that limit our understanding of the changes in cough with age include the reporting of cough by parents in infants and carers in old age and the use of different diagnostic criteria throughout life. Age-related variation in cough sensitivity seems to be well established, but its quantitation and mechanisms require much further research.

Iulius Casserius (1552-1616): the self-made anatomist of Padua's golden age.

Giulio Cesare Casseri (1552– 1616), whose name was Latinized into Iulius Casserius, was born in Piacenza; therefore, the nickname Piacentino (Placentinus) was often used. According to Sterzi (1910), who based his claim on a statement contained in Casserius’s will, his date of birth was around 1552. It should be noted, however, that although most modern authors accept this date (Roberts and Tomlinson, 1992; Premuda, 1993), some (Singer, 1957) still report 1561 as his birth date on the basis of the inscription (Fig. 1) appearing on the portrait published in Casserius’s work De Vocis Auditusque organis that ascribes to the author the age of 39 years. According to most of his early biographers (Tomasini, 1630; Ghilini, 1647; Papadopoli, 1726), Casserius’s family was very poor and the young Iulius, perhaps as the servant of some student (Sterzi, 1910), moved to Padua, the city that shared with Bologna the reputation of being the seat of Italy’s most illustrious university. He soon assumed the job of servant in the house of the famed Gerolamo Fabrici d’Acquapendente (Fabricius, 1533– 1619) (Fig. 2), Public Lecturer of Anatomy and Surgery (Tomasini, 1630; Ghilini, 1647). As Tomasini (1630) reports, “from a servant he became first Fabricius’s auditor, then instructor and brilliant disciple.” We do not know when Casserius matriculated in the School of Medicine of the Universita Artista. As mentioned several times in his works, Casserius, in addition to Fabricius, had the well-known physician Gerolamo Mercuriale (Mercurialis) as a teacher and mentor, who held the chair of Clinical Medicine of Padua in the years 1569–1587. The precise date he obtained his degree in medicine and philosophy is unknown, because the official records are missing from 1580 to 1587; a likely date is ca.1580 (Sterzi, 1910; De Ferrari, 1978; Premuda, 1993). After the award of his degree, Casserius, in addition to giving private lectures on anatomy to the students of the Universita Artista and working as Fabricius’s preparator, started a practice as physician and surgeon in Padua that was very successful (Tomasini, 1630). In 1584, Casserius’s reputation was already so great that he took Fabricius’s place as member of the board of examiners for the finals in surgery. These examinations, held in private houses in the presence of the Rector of the University, conferred the license to practice surgery. The profession of surgery was considered in those days as a minor branch of Medicine and the surgeon had to take an oath that he would not involve himself in the treatment of serious diseases, but would call a licensed physician whenever the patient was in real danger.

Effects of vecuronium and rocuronium in antagonistic laryngeal muscles and the anterior tibial muscle in the cat.

Adequate vocal cord paralysis and full recovery of laryngeal muscle function are important when muscle relaxants are used perioperatively. This study was designed to compare the effects of vecuronium and rocuronium at the vocal cord abductor and adductor muscles and the anterior tibial muscle in cats. Twelve adult cats were studied under pentobarbitone-N2O/O2-anesthesia. After supramaximal electrical stimulation of the peroneal nerve and the recurrent laryngeal nerve (0.1 Hz and intermittent train-of-four) evoked electromyographic responses were obtained from the anterior tibial muscle, the posterior cricoarytenoid muscle (vocal cord abductor) and two vocal cord adductor muscles, the lateral cricoarytenoid and the vocal muscle. Six cats received bolus doses of increasing size of vecuronium (ED90 22.5 microg x kg(-1)) and six cats rocuronium (ED90 90 microg x kg(-1)). Equipotent doses of vecuronium and rocuronium caused a similar degree of paralysis in all muscles (vecuronium ED90: 70% blockade at the posterior cricoarytenoid, 83% at the lateral cricoarytenoid, 84% at the vocal muscle and 90% at the anterior tibial muscle; rocuronium ED90: 71% at the posterior cricoarytenoid, 67% at the lateral cricoarytenoid, 78% at the vocal muscle and 90% at the anterior tibial muscle; vecuronium 2 x ED90: 93% blockade at the posterior cricoarytenoid, 95% at the lateral cricoarytenoid, 97% at the vocal muscle and 99% at the anterior tibial muscle; rocuronium 2 x ED90: 89% blockade at the posterior and lateral cricoarytenoid, 93% at the vocal muscle and 100% at the anterior tibial muscle). Onset time was significantly shorter at the posterior cricoarytenoid muscle (290 s) compared to the lateral cricoarytenoid muscle (400 s) after vecuronium ED90 and to the vocal muscle (150 s versus 210 s) after rocuronium ED90. Compared to the anterior tibial muscle (interval 25-75%: 6.5 min after vecuronium 2 x ED90 and 3.3 min after rocuronium 2 x ED90 and to the posterior cricoarytenoid muscle (interval 25-75%: 7 min after vecuronium 2 x ED90 and 4.3 min after rocuronium 2 x ED90), recovery of laryngeal adductor muscle function was markedly delayed with both neuromuscular blocking drugs (interval 25-75% at the lateral cricoarytenoid and vocal muscle: 14 min and 15.8 min after vecuronium 2 x ED90 and 10.3 min and 11.6 min after rocuronium 2 x ED90 respectively). In cats, the time course of neuromuscular blockade after vecuronium and rocuronium differs in antagonistic laryngeal muscles. The protective laryngeal function of glottis closure recovers later than vocal cord abduction after both vecuronium and rocuronium.

Turbulent glottal flow during phonation

Human phonation is the flow-induced oscillation of the vocal folds, producing pulsatile jet through the glottis, which may become turbulent. This turbulent jet was investigated in an excised canine larynx model with simultaneous recordings of air particle velocity, subglottal pressure, airflow rate, and EGG signal for various conditions of phonation. Canine larynges were mounted on a plastic air tube and sustained oscillations were established and maintained by mechanically manipulating the cartilages to mimic the function of laryngeal muscles. The major control parameters were the airflow rate and the glottal adduction. The velocity was measured with a constant-temperature hot-wire anemometer system. To separate the turbulence from the periodic component of the velocity signal, the technique of phase shift averaging was employed. Results suggest that subglottal inlet flow to the larynx is pulsatile but mostly laminar, while the exiting jet is nonuniform and turbulent. The Reynolds number based on the mean glottal velocity and glottal hydraulic diameter varied between 1600 and 7000, the Strouhal number varied between 0.002 and 0.032, and the Womersley number ranged from 2.6 to 15.9. These results help define the conditions required for computational models of laryngeal flow. [This work was supported by NIDCD Grant No. DC03566-01.]

Motor innervation of the cricopharyngeus muscle by the recurrent laryngeal nerve.

Patients with recurrent laryngeal nerve (RLN) paresis demonstrate impaired function of laryngeal muscles and swallowing. The cricopharyngeus muscle (CPM) is a major component of the upper esophageal sphincter. It was hypothesized that the RLN innervates this muscle. A nerve branch leading from the RLN to the CPM was found in adult sheep by anatomic dissection. Electrical stimulation of the RLN elicited a muscle action potential recorded by electrodes placed in the ipsilateral CPM. Swallowing was investigated by mechanical stimulation of oropharynx pre- and postsectioning of the RLN. Severing of the RLN resulted in a loss of the early phases of swallow-related CPM electromyographic activity; however, late-phase CPM electromyographic activity persisted. The RLN provides motor innervation of the CPM, which also has innervation from the pharyngeal plexus.

Laryngeal deglutition movement in Parkinson's disease.

Laryngeal muscle function is defective in Parkinson's disease (PD) patients; the intrinsic group (vocal cords) is defective during phonation and the extrinsic group (laryngeal strap muscles) is slow during deglutition. There are no studies of vocal cord motility during deglutition in PD. We investigated laryngeal motility during deglutition in 71 patients with PD in a videofluoroscopic swallowing study. Patients were subdivided into two groups by the Hoehn and Yahr disability scale, stages II and III (n = 38) and stages IV and V (n = 33). At least one abnormality of laryngeal movement was present in 68 of 71 patients (95.8%); most patients had multiple abnormalities. There was statistically significant slowing of vertical laryngeal excursion; true vocal cord closure; or delayed, incomplete, or absent opening of the true vocal cords. Patients with more advanced disease manifested more deficits of laryngeal movement. Laryngeal dysmotility in PD may be related to defective descending basal ganglionic control of medullary deglutory and phonatory motor functions.

An Experimental Study of Pulsatile Flow in Canine Larynges

Pulsatile flow in an excised canine larynx was investigated with simultaneous recordings of air velocity, subglottal pressure, volume flow rate, and the signal from an electro-glottograph (EGG) for various conditions of phonation. Canine larynges were mounted on a pseudotrachea and sustained oscillations were established and maintained with sutures attached to cartilages to mimic the function of laryngeal muscles. The pitch and amplitude of the oscillations were controlled by varying the airflow, and by adjusting glottal adduction and vocal-fold elongation. Measurements with hot-wire probes suggest that subglottal inlet flow to the larynx is pulsatile but mostly laminar, while the exiting jet is non-uniform and turbulent. In the typical ranges of flow rate, subglottal pressure, and oscillation frequencies, the Reynolds number based on the mean glottal velocity and glottal hydraulic diameter varied between 1600 to 7000, the Strouhal number based on the same parameters varied between 0.002 and 0.032, and the Womersley number ranged from 2.6 to 15.9. These results help define the conditions required for computational models of laryngeal flow.

Pulsatile airflow during phonation: an excised larynx model.

Pulsatile airflow in the excised larynx was investigated with simultaneous recordings of air velocity, subglottal pressure, volume flow, and the electroglottograph signal for various conditions of the larynx. Canine larynges were mounted on a bench with sutures attached to cartilages to mimic the function of laryngeal muscles. Sustained oscillations were established and maintained with the flow of heated and humidified air through the trachea. The instantaneous air velocity above the glottis, which is the summation of a periodic velocity and the turbulent component, was measured with a constant temperature hot-wire probe at various locations. The phase-averaged velocity was used to construct the patterns of jet flow at selected time frames of the oscillation cycle. Results suggest that supraglottal air velocity is highly spatially and temporally dependent. Cycles of local air velocity with double peaks were not uncommon and a case is provided. For one phase-averaged phonatory cycle, a 9 x 13 velocity measurement grid demonstrated strongly nonuniform velocity surfaces for eight phases of the cycle, with greater velocities located anteriorly.

A study of pulsatile airflow in the excised larynx model

The pulsatile airflow in the excised larynx was investigated with the simultaneous measurements of glottal pressure, volume flow, EGG, and particle velocity at various dynamic conditions of the larynx. Canine larynges were mounted in a bench with some sutures attached to cartilages to mimic the function of laryngeal muscles. The sustained oscillations were obtained and maintained with the flow of heated and humidified air through the trachea. The pitch and amplitude of oscillations were controlled with amount of airflow and the mechanical adjustment of glottal adduction and vocal‐fold elongation. The particle velocity was measured above the glottis with a constant temperature hot‐wire probe at various locations and oscillating conditions. The measured subglottal pressure with a pressure transducer had a periodic variation and its mean value was higher than the manometer’s reading of the same location. The measured particle velocity showed some turbulence superimposed on a periodic flow. The mean particle velocity showed some variations in the glottal exit area both along the vocal folds and across the glottis. [Work supported by NIDCD Grant No. DC00831‐02.]

A Method to Measure Elicited Contraction of Laryngeal Adductor Muscles during Anesthesia

The recurrent laryngeal nerve was stimulated with surface electrodes to produce vocal cord adduction, and the response was measured as pressure changes in the inflatable cuff of a tracheal tube positioned between the vocal cords. To test the linearity of the system, a model of the larynx consisting of a syringe barrel was constructed, and weights were applied to two bands of tissue simulating the vocal cords. Tests on Mallinckrodt size-7.5 tubes showed that the pressure increase produced by a given force was independent of baseline pressure in the range 10-30 mmHg. In addition, the pressure inside the inflatable cuff was linear with increasing weight (or force) for a baseline pressure of 10 mmHg. Thirty ASA physical status 1 or 2 adults were anesthetized with propofol and fentanyl. Tracheal intubation was performed in the absence of muscle relaxants, and the inflatable cuff of the tracheal tube was positioned between the vocal cords. Pressure inside the cuff was measured with an air-filled transducer. Stimulation was produced at different sites along the course of the recurrent laryngeal nerve. A surface electrode placed over the notch of the thyroid cartilage produced consistent adduction of the cords, measured as an increase of 8.9 +/- 5.1 mmHg (mean +/- standard deviation [SD]) in the cuff pressure. Neuromuscular blocking drugs produced train-of-four fade, and large doses abolished the response completely, ruling out direct muscle stimulation. It is concluded that this assembly can provide useful information on intrinsic laryngeal muscle function.

Evaluation of Laryngeal Muscle Function by Quantitative Analysis of the EMG Interference Pattern

A computerized method for quantitative analysis of the EMG interference pattern was tested in the cricothyroid and thyroarytenoid muscles with the purpose of evaluating its usefulness for clinical purposes. In a normal male subject the mean amplitude and the number of turns/s were extracted from the EMG signal of sustained chest register phonations, with systematic variation of vocal pitch and intensity. In the cricothyroid, as well as the thyroarytenoid muscle, there was a considerable increase in mean amplitude and turns/s with both increased pitch and increased intensity. Pitch variation was the most effective way to induce changes in turns and amplitude levels in both muscles. In contrast to results from studies of larger muscles, the increase in both amplitude and turns was proportional to muscle force also at the highest loads.

A pressure curve monitor for intratracheal jet ventilation

Most of the complications during intratracheal jet ventilation for laryngomicroscopy are due to the unnoticed wearing off of laryngeal muscle relaxation. Recovering laryngeal muscle function will, by slightly narrowing the size of the glottis, influence the slope of the quickly rising part of the pressure curve, when influences on maximum airway pressure are still not detectable. An electronic device incorporating the window comparator technique monitors the pressure curve and sets off an alarm before changes in maximum airway pressure or recovery of muscle strength in the forearm are detectable. The pressure curve monitor could be useful also with intratracheal jet ventilation for treating adult respiratory deficiency and with conventional ventilators during anaesthesia to detect the wearing off of muscle relaxation.

Physiological aspects of the glottal sound generator

This paper describes the function of laryngeal muscles in regulating the glottal sound generator. The glottal sound generator, i.e., the vocal fold, has a layered structure. From the anatomical point of view, one can differentiate five layers, all having different mechanical properties [M. Hirano et al., J. Acoust. Soc. Am. 58, S13 (1975)]. From the physiological point of view, the layers may be divided into two major categories: the outer layer, i.e., the mucous membrane, which receives only passive regulation of the mechanical property, and the inner layer, i.e., the vocalis muscle, which has both active and passive regulations for the mechanical property. The ratio of the stiffness of each layer during normal phonation is estimated based on the measurement of the degree of elongation of each layer of an excised fresh human vocal fold. Then, the effect of laryngeal adjustment on the change in stiffness of the entire vocal fold is investigated by simulating the contraction of each of the cricothyroid and the vocalis muscles in dogs' larynx. The results are examined in reference to behavior of each layer during normal vibration of vocal fold observed with ultra‐high‐speed photography.

Measurement of specific laryngeal muscle function by ultrasound.

Ultrasonic dimension gauges were implanted in the crico-arytenoideus dorsalis muscle in a mature horse. Resting and contracted muscle length and average contraction rate were measured serially in the conscious state over a period of 25 days. Results suggest that specific laryngeal muscle function in the horse may be defined with this approach. Since man and horse are both known to suffer from laryngeal hemiplegia, this experimental preparation may help provide information of benefit to both species.

The function of laryngeal muscles in regulating fundamental frequency and intensity of phonation.

The activity of three intrinsic laryngeal muscles in the regulation of fundamental frequency and intensity of phonation was studied electromyographically in six subjects. The regulatory mechanism of fundamental frequency and intensity differed for different registers and fundamental frequencies. In general, the contribution of the laryngeal muscles in changing these parameters was greater in chest register than in falsetto and particularly less in high falsetto. There was no essential difference in the muscular activity patterns between singing in chest register and normal speech as far as control of these two aspects of voice is concerned.

Function of Laryngeal Muscles in Regulating Fundamental Frequency and Intensity of Phonation

Electromyographic recordings of the activity of selected intrinsic laryngeal muscles of a professional singer and several untrained subjects were made during both singing and speech. The mechanism regulating fundamental frequency and intensity differed for different registers and fundamental frequencies. For low-pitched phonation in chest register, laryngeal muscles contributed pronouncedly to changes in fundamental frequency and intensity; whereas for high-pitched phonation in falsetto register, their contribution was less. Therefore, one can presume that for high falsetto the air-flow rate was the dominant factor regulating fundamental frequency and intensity. There was no essential difference of the muscular activity patterns between speech and singing in chest register as far as regulation of fundamental frequency and intensity of voice is concerned. [This research was partially supported by the National Institutes of Health, U. S. Department of Health, Education, and Welfare, and the Office of Naval Research.]