The Distribution and Severity of Tremor in Speech Structures of Persons with Vocal Tremor.

BACKGROUND: Vocal tremor may be associated with cyclic oscillations in the pulmonary, laryngeal, velopharyngeal, or oral regions. OBJECTIVES: This study aimed to correlate the overall severity of vocal tremor with the distribution and severity of tremor in structures involved. METHODS: Endoscopic and clinical examinations were completed on 20 adults with vocal tremor and two age-matched controls during sustained phonation. Two judges rated the severity of vocal tremor and the severity of tremor affecting each of 13 structures. RESULTS: Participants with mild vocal tremor typically presented with tremor in three laryngeal structures, moderate vocal tremor in five structures (laryngeal and another region), and severe vocal tremor in eight structures affecting all regions. The severity of tremor was lowest (mean = 1.2 out of 3) in persons with mild vocal tremor and greater in persons with moderate (mean = 1.5) and severe vocal tremor (mean = 1.4). Laryngeal structures were most frequently (95%) and severely (1.7 out of 3) affected, followed by velopharynx (40% occurrence, 1.3 severity), pulmonary (40% occurrence, 1.1 severity), and oral (40% occurrence, 1.0 severity) regions. Regression analyses indicated tremor severity of the supraglottic structures, and vertical laryngeal movement contributed most to vocal tremor severity during sustained phonation (r = 0.77, F = 16.17, P < 0.0001). A strong positive correlation (r = 0.72) was found between the Tremor Index and the severity of the vocal tremor during sustained phonation. CONCLUSION: It is useful to obtain a wide endoscopic view of the larynx to visualize tremor, which is rarely isolated to the true vocal folds alone.

The effects of articulation on the perceived loudness of the projected voice.

UNLABELLED: Arthur Lessac developed a voice training approach that concentrated on three energies: structural action, tonal action, and consonant action. In Lessac-Madsen Resonant Voice Therapy (LMRVT), speech-language pathologists help patients achieve a resonant voice through structural posturing and awareness of tonal changes. However, LMRVT many not necessarily include the third component of Lessac's approach: consonant action.This study examines the effect that increased effort on consonant production has on the speaking voice-particularly regarding vocal loudness and projection. METHODS: Audio samples were collected from eight actor participants who read a monologue using three distinct styles: normal articulation, poor articulation (elicited using a bite block), and overarticulation (elicited using a Lessac-based training intervention). Twenty graduate students of speech-language pathology listened to speech samples from the different conditions and made comparative judgments regarding articulation, loudness, and projection. RESULTS: Group results showed a strong correlation between the articulatory condition and the level of perceived loudness and projection. That is, as precision of articulation increased, the ratings of perceived loudness and projection increased, as well. CONCLUSIONS: These findings indicate that articulation treatment may have a positive influence on the perception of vocal loudness and projection. This has implications for future directions in expanding voice therapy modalities.

Cricothyroid muscle and thyroarytenoid muscle dominance in vocal register control: preliminary results.

HYPOTHESIS: Headmix and head registers use cricothyroid (CT) muscle dominant voicing, whereas chest and chestmix registers use thyroarytenoid (TA) muscle dominant voicing. STUDY DESIGN: Cross-sectional study. METHODS: CT and TA electromyographic data obtained from five untrained singers and two trained singers were analyzed to determine CT and TA muscle dominance as a function of register. Simultaneous recordings of TA and CT muscle activity and audio were obtained during production of pitch glides and a variety of midrange and upper pitches in chest, chestmix, headmix, and head registers. RESULTS: TA dominant phonation was only observed for chest productions and headmix/head register productions below 300 Hz. All phonation above 300 Hz, regardless of register, showed CT:TA muscle activity ratios that were CT dominant or close to 1, indicating nearly equal CT and TA muscle activity. This was true for all subjects on all vocal tasks. For the subjects sampled in this study, pitch level appeared to have a greater effect on TA and CT muscle dominance than vocal register. CONCLUSION: Preliminary findings regarding CT and TA dominance and register control do not support the assumption that all chest and chestmix production has greater TA muscle activity than CT muscle activity or that all headmix and head production require greater CT muscle activity than TA muscle activity. The data indicate that pitch level may play a greater role in determining TA and CT dominance than register.

Phonatory characteristics of the excised human larynx in comparison to other species.

OBJECTIVE: The purpose of this study was to determine the conditions needed to elicit phonation from excised human larynges and the resultant range of phonations produced; compare that with similar information previously obtained from canine, pig, sheep, and cow; and relate those findings to previously reported information about viscoelastic properties of the vocal fold tissue (ie, stress-strain curves and Young's modulus). METHODS: Six human larynges of the geriatric group (age range, 70-89) were mounted on the bench without supraglottic structures, and phonation was achieved with the flow of heated and humidified air through the tracheal tube. Using various sutures to mimic the function of the laryngeal muscles, the larynges were put through a series of sustained oscillations with adduction as a control parameter. RESULTS: The human larynges oscillated with an average frequency that was close to the canine larynges, but the oscillation behavior and wide frequency range were similar to those of pig larynges. The similarity of the wide vibration frequency ranges of human and pig larynges may be because of the nonlinear behavior of their elasticity, which is related to the high collagen content of the vocal folds. On the contrary, other species with limited frequency ranges showed almost linear stress-strain curves because of the higher elastin and lower collagen contents. CONCLUSIONS: The physiological differences in the linearity and ranges of oscillation of excised larynges reported in this study and previous studies are reflective of the tissue composition and mechanics.

Laryngeal muscle activity and vocal fold adduction during chest, chestmix, headmix, and head registers in females.

HYPOTHESIS: Commercial singers produce chestmix register by maintaining or increasing adduction of the vocal processes (VPs) and by engaging the thyroarytenoid (TA) muscle to a greater degree than they would to produce head register. STUDY DESIGN: Prospective cohort study. METHODS: Simultaneous recordings of TA and cricothyroid (CT) muscle activity, videonasendoscopy, and audio were obtained from seven female singers during production of a variety of midrange pitches in chest, chestmix, headmix, and head registers. Fast Fourier transforms were performed to measure the energy in the fundamental frequency and in mid and upper frequency harmonics to determine if the productions that were judged as perceptually distinct registers also showed distinctive acoustic characteristics. Then, measures of TA and CT muscle activity and vocal fold adduction ratings were obtained to determine how these varied as a function of pitch and register. RESULTS: Spectral tilt increased as subjects shifted from chest to chestmix to headmix and finally into head register. For same pitch phonation, subjects increased TA muscle activity and vocal fold adduction as they shifted register from head to headmix to chestmix to chest, particularly during production of higher frequencies. CT activity appeared to be more related to pitch rather than register control. CONCLUSION: Nonclassically trained singers were able to produce pitches at the high end of the midrange in chestmix register by increasing TA muscle activity and adduction of the VPs.

Phonatory effects of supraglottic structures in excised canine larynges.

The aim of this study is to determine how phonation is affected by the presence and by alteration in the position of the supraglottic structures. The study used three excised canine larynges. A series of pressure-flow experiments were completed first on the excised larynx with false folds and epiglottis intact, then with the epiglottis removed, and finally with the false folds removed. Aerodynamic and acoustic effects were quantified with the analysis of the pressure, flow, and audio signals. The results of the study indicated that (1) elevation of the epiglottis to upright position from a horizontal position decreased subglottal pressure, increased flow (decreased laryngeal resistance), and slightly decreased fundamental frequency; (2) vibration of the false vocal folds induced some irregularity into the acoustic output of the larynx; (3) the presence of the epiglottis and the false vocal folds enhanced the second partial of the acoustic signal; and (4) the absence of the epiglottis and false folds increased low-frequency noise (between 0 and 300 Hz). Alteration in the position of the supraglottic structures affects laryngeal aerodynamics and acoustics, possibly due to biomechanical linkage with true vocal folds. When the supraglottic structures are present they act as resonators, enhancing the second partial and when they are absent (as in persons with supraglottic laryngectomy), low-frequency noise is increased perhaps due to the loss of boundary conditions or due to the presence of loose tissue.

Aerodynamic and acoustic effects of abrupt frequency changes in excised larynges.

PURPOSE: To determine the aerodynamic and acoustic effects due to a sudden change from chest to falsetto register or vice versa. It was hypothesized that the continuous change in subglottal pressure and flow rate alone (pressure-flow sweep [PFS]) can trigger a mode change in the canine larynx. METHOD: Ten canine larynges were each mounted over a tapered tube that supplied pressurized, heated, and humidified air. Glottographic signals were recorded during each PFS experiment, during which airflow was increased in a gradual manner for a period of 20-30 s. RESULTS: Abrupt changes in fundamental frequency (F(0)) and mode of vibration occurred during the PFS in the passive larynx without any change in adduction or elongation. The lower frequency mode of oscillation of the vocal folds, perceptually identified as the chest register, had relatively large amplitude oscillation, significant vocal fold contact, a rich spectral content, and a relatively loud audio signal. The higher frequency mode of oscillation, perceptually identified as falsetto, had little or no vocal fold contact and a dominant first partial. Relatively abrupt F(0) changes also occurred for gradual adduction changes, with the chest register corresponding to greater adduction, falsetto to less adduction.

Quantitative contributions of the muscles of the tongue, floor-of-mouth, jaw, and velum to tongue-to-palate pressure generation.

PURPOSE: The purpose of this investigation was to evaluate the relationship between tongue-to-palate pressure and the electromyography (EMG) measured from the mylohyoid, anterior belly of the digastric, geniohyoid, medial pterygoid, velum, genioglossus, and intrinsic tongue muscles. Methods Seven healthy adults performed tongue-to-palate pressure tasks at known percentages of their maximum pressure while intramuscular EMG was recorded from the muscles stated above. Multiple regression analysis was performed. RESULTS: Predictors of pressure included the posterior fibers of the genioglossus, mylohyoid, anterior belly of digastric, medial pterygoid, and intrinsic tongue. CONCLUSIONS: Increasing tongue-to-palate pressure coincides with increased muscle activity. Activation of the floor-of-mouth, tongue, and jaw closing muscles increased tongue-to-palate pressure. These findings support the use of a tongue-press exercise to strengthen floor-of-mouth muscles, tongue, and jaw-closing muscles.

Laryngeal muscle activity in giggle: a damped oscillation model.

The acoustic properties of giggle, a mild form of laughter, were studied. The purpose was to determine if there is some uniqueness to the frequency and number of vocalization bursts in giggle. The underlying hypothesis was that a neuromechanical oscillator serves as an activator for rhythmic vocalizations, as in vibrato, with a pair of agonist-antagonist adductor muscles alternating in a 180 degrees phase relationship. Electromyographic activity of the posterior cricoarytenoid muscle was always measured, in conjunction with either lateral cricoarytenoid or thyroarytenoid muscle activity. Results indicate that muscle activations do alternate and that these activations do not diminish during successive bursts, even though the amplitude and duty ratio of the bursts decreases. It is reasoned that reduced lung pressure and lung volume limit the number of bursts and their duty ratio, while speed of intrinsic laryngeal muscle contraction dictates the burst frequency.

Small-molecule cyclic alpha V beta 3 antagonists inhibit sickle red cell adhesion to vascular endothelium and vasoocclusion.

Abnormal adhesion of sickle red blood cells (SS RBCs) to vascular endothelium may play an important role in vasoocclusion in sickle cell disease. Accruing evidence shows that endothelial alpha V beta 3-integrin has an important role in SS RBC adhesion because of its ability to bind several adhesive proteins implicated in this interaction. In the present studies, we tested therapeutic efficacy of small-molecule cyclic pentapeptides for their ability to block alpha V beta 3-mediated SS RBC adhesion by using two well-established assay systems, i.e., cultured human umbilical vein endothelial cells (HUVEC) and artificially perfused mesocecum vasculature of the rat under flow conditions. We tested the efficacy of two RGD-containing cyclic pentapeptides, i.e., cRGDFV (EMD 66203) and cRGDF-ACHA (alpha-amino cyclohexyl carboxylic acid) (EMD 270179), based on their known ability to bind alpha V beta 3. An inactive peptide, EMD 135981 (cR beta-ADFV) was used as control. Cyclization and the introduction of D-Phe (F) results in a marked increase in the ability of cyclic peptides to selectively bind alpha V beta 3 receptors. In the mesocecum vasculature, both EMD 66203 and EMD 270179 ameliorated platelet-activating factor-induced enhanced SS RBC adhesion, postcapillary blockage, and significantly improved hemodynamic behavior. Infusion of a fluorescent derivative of EMD 66203 resulted in colocalization of the antagonist with vascular endothelium. Also, pretreatment of HUVEC with either alpha V beta 3 antagonist resulted in a significant decrease in SS RBC adhesion. Because of their metabolic stability, the use of these cyclic alpha V beta 3 antagonists may constitute a novel therapeutic strategy to block SS RBC adhesion and associated vasoocclusion under flow conditions.

Adherent leukocytes capture sickle erythrocytes in an in vitro flow model of vaso-occlusion.

Recent in vivo studies suggest that adherent leukocytes bind RBCs and contribute to the microvascular pathology that characterizes sickle cell disease (SCD). A parallel-plate flow assay was used: to investigate the capture of RBCs by adherent neutrophils, monocytes, and T-lymphocytes; to examine whether RBC capture is elevated in patients with SCD; and to determine whether hydroxyurea (HU) therapy affects these interactions. Four measures of cell-cell adhesion were used: adhesion of leukocytes to TNF-alpha-treated human umbilical vein endothelial cells (HUVECs), percent of adherent leukocytes that captured RBCs, number of RBCs captured per interacting leukocyte, and duration of RBC capture. Leukocyte subpopulations from sickle patients were more adherent to activated ECs and captured more RBCs per interacting leukocyte than the corresponding subpopulations from healthy controls. While HU did not affect leukocyte adhesion to activated ECs, it reduced the proportion of adherent leukocytes that captured RBCs, as well as the number of RBCs captured per neutrophil. T-lymphocytes demonstrated elevated adhesion in all measures, and may be the leukocyte subpopulation whose behavior is most altered in SCD. Our findings suggest that neutrophils, monocytes, and T-lymphocytes could all be involved in adhesive interactions with autologous RBCs in patients with SCD.

Patterns of laryngeal electromyography and the activity of the respiratory system during spontaneous laughter.

Laryngeal muscle electromyography (EMG) and measures of the behavior of the respiratory system have been made during spontaneous laughter in two groups of subjects. The smaller group also had a direct measure of tracheal pressure during this behavior. Laryngeal adductors such as the thyroarytenoid (TA) and lateral cricoarytenoid (LCA) exhibited brief high-amplitude bursts of activity, at a rate of approximately 5 Hz, which were usually associated on a 1 : 1 basis with the sound bursts (ha ha ha) of laughter. The laryngeal abductor, posterior cricoarytenoid (PCA), also showed bursts of activity that were out of phase with TA and LCA. The cricothyroid (CT) was only weakly, if at all, modulated during the bursting activity of the other laryngeal muscles. Tracheal pressure usually exhibited positive pressure pulses during laughter that were often, but not always, temporally correlated to the bursts of laryngeal adductor EMG activity. Such pressure modulations appeared to precisely determine when-and if-phonation was produced during the laugh. During laughter, laryngeal EMG is highly stereotyped both within and between subjects. In most instances, this activity appears to be supported by coordinated pulses of tracheal pressure. The periaqueductal gray (PAG) has been shown in animal studies to produce emotionally indicative vocalizations, in which the laryngeal and respiratory system are coordinated. Therefore, it is suggested that the PAG is involved with the production of laughter.

Resonant voice: spectral and nasendoscopic analysis.

Although resonant voice therapy is a widely used therapeutic approach, little is known about what characterizes resonant voice and how it is physiologically produced. The purpose of this study was to test the hypothesis that resonant voice is produced by narrowing the laryngeal vestibule and is characterized by first formant tuning and more ample harmonics. Videonasendoscopic recordings of the laryngeal vestibule were made during nonresonant and resonant productions of /i/ in six subjects. Spectrums of the two voice types were also obtained. Spectral analysis showed that first formant tuning was exhibited during resonant voice productions and that the degree of harmonic enhancement in the range of 2.0 to 3.5 kHz was related to voice quality: nonresonant voice had the least amount of energy in this range, whereas a resonant-relaxed voice had more energy, and a resonant-bright voice had the greatest amount of energy. Visual-perceptual judgments of the videoendoscopic data indicated that laryngeal vestibule constriction was not consistently associated with resonant voice production.

Synchrony of laryngeal muscle activity in persons with vocal tremor.

OBJECTIVE: To determine if the tremor activity in laryngeal muscles is synchronous, which would indicate a single central source of tremor. DESIGN: Six persons with vocal tremor participated in this study. Laryngeal muscle activity was recorded from 2 intrinsic and 2 extrinsic laryngeal muscles during production of a sustained \i\ sound. Correlations were computed between electromyographic activity in pairs of laryngeal muscles to measure the degree to which electromyographic activity in one muscle was synchronous with electromyographic activity in another laryngeal muscle. In addition, correlations were computed between each of the 4 laryngeal muscles and the voice signal to determine which muscle had activity that was most highly related to amplitude modulations in the voice. Multiple samples from each subject were analyzed to obtain measures of the consistency and strength of the correlations. RESULTS: In most subjects, the bursts of electromyographic activity in one muscle were not consistently related to tremor activity in other affected muscles. Half the subjects exhibited moderate to strong correlations between thyroarytenoid muscle activity and the amplitude of the voice signal. Although the thyroarytenoid and cricothyroid muscles were always active during sustained phonation, half of the subjects did not activate either the thyrohyoid or the sternothyroid muscle during this task. CONCLUSIONS: The results of this study did not support the hypothesis that essential voice tremor is generated by a single central oscillator. Differences in the presence and timing of modulations in laryngeal muscle activity, as described in this study, may reflect clinically in the variable regularity and severity of vocal tremor.

Head and neck muscle spasm after radiotherapy: management with botulinum toxin A injection.

OBJECTIVE: To introduce the concept of neck muscle pain and spasm after radiotherapy and its treatment with botulinum toxin A. DESIGN: Case series. SETTING: Ambulatory patients at a tertiary care medical center. PATIENTS: Individuals who had undergone primary or adjuvant radiotherapy for treatment of carcinoma of the head and neck were asked about painful spasms of the neck musculature. A volunteer sample was used. If they desired treatment with botulinum toxin A, they were included in the study. INTERVENTION: Patients received botulinum toxin A injections to the affected sternocleidomastoid muscle(s) in 1 or 2 locations. OUTCOME MEASURE: Subjective pain relief. RESULTS: Four of 6 patients with painful tightness of the neck who received botulinum toxin A injections to the sternocleidomastoid muscle achieved pain relief. CONCLUSIONS: A subset of patients with irradiation-induced cervical muscle spasm benefit from treatment with botulinum toxin A injections. Further study is needed to more clearly define the entity and treatment.