Differentiating between adductor and abductor spasmodic dysphonia using airflow interruption

Effects of Sustained Semi-Occluded Vocal Tract Exercises in Non-Disordered Populations

INTRODUCTION

Semi-occluded vocal tract (SOVT) exercises, including straw phonation therapy, are effective for treating vocal disorders and increasing ease of phonation by decreasing phonation threshold pressure (PTP) and increasing subglottic pressure. While the short-term effects of SOVT straw phonation therapy have been demonstrated, the sustained and lingering effects remain largely unexplored. This study aims to assess the effects of sustained daily SOVT exercises (SOVTEs) across three different straw lengths by evaluating aerodynamic parameters, including PTP, mean flow rate (MFR), subglottic pressure (PS), laryngeal resistance (RL), and phonation power (PW) to help guide optimized straw phonation usage and configurations.

METHODS

Twenty-two normophonic participants completed a 4-week daily protocol of SOVT straw phonation exercise with a randomly assigned straw length (7.50, 15.00, or 30.00 cm). Aerodynamic measurements were recorded via mechanical interruption and electroglottography (EGG) at week zero (baseline), week two (mid-therapy), week four (post therapy), and week five (post therapy).

RESULTS

A significant main effect of time was observed for PTP, with post hoc tests showing significant and gradual decreases in PTP from week zero to week four, with PTP returning to baseline at week five. All three straw lengths generated the same statistical results. No significant main effects of time and straw length were observed for MFR, PS, RL, or PW, indicating that these parameters did not change in non-disordered participants following 4-week SOVTEs.

CONCLUSION

Sustained SOVT straw phonation therapy in a non-disordered population significantly reduces PTP, demonstrating improvements in ease of phonation over time. Lingering effects of daily SOVTEs lasted greater than one and less than seven days in terms of PTP. No significant differences were observed between straw lengths, suggesting that straw lengths tested do not impact sustained phonatory outcomes in a non-disordered population.

Efficacy of a Tesla Valve Straw in a Semi-Occluded Vocal Tract Exercise in a Normal-Voiced Population

OBJECTIVE

Voice disorders affect a significant portion of the US population, affecting communication and professional performance. Semi-occluded vocal tract (SOVT) straw phonation exercises are widely used in voice therapy to enhance phonation efficacy. The Tesla valve, a structure Nikola Tesla designed, could be applied to SOVT straw phonation therapy and increase its effectiveness by increasing resistance without requiring a longer straw length. This study aimed to evaluate the effectiveness of the Tesla valve straw compared to a standard straw and assess the impact of straw length on phonation efficiency.

METHODS

Twenty-nine normal-voiced participants were randomly assigned to complete SOVT tasks using standard and Tesla valve straws of lengths 25.50 and 31.50 cm. Participants' aerodynamic and acoustic measurements, including phonation threshold pressure (PTP), mean flow rate (MFR), and fundamental frequency (F0), were recorded before and after completing the SOVT task involving sustained phonation into a mechanical interrupter. Repeated measures ANOVA analyses were used to analyze the effects of straw type, length, and time on the measured parameters.

RESULTS

Significant reductions in PTP were observed across all conditions regardless of straw type or length, supporting the use of SOVT straw phonation exercises to reduce PTP. However, no significant differences were observed between the standard and Tesla valve straw types or between the short and long straw lengths. MFR and F0 did not display significant changes before and after the SOVT exercises, as statistical analyses showed no significant interactions between straw type, length, and time.

CONCLUSION

The results suggest that while long and short Tesla valve straws generated a greater average PTP decrease than standard straws, the differences were not statistically significant. Additionally, the length of the straws tested did not significantly affect the therapeutic effects of the exercises in the confines of this study. These results support the presence of straw is the most important consideration in straw phonation therapy. Further Tesla valve straw designs should be tested to understand the efficacy of the Tesla valve straw at a wider range of lengths and configurations.

Tremor Makes a Difference: A Comparative Study of the Demographics and Treatment Outcomes in Patients With Adductor Spasmodic Dysphonia With or Without Vocal Tremor

OBJECTIVES

This study aims to evaluate the demographic differences between those with adductor spasmodic dysphonia with vocal tremor (AdSD(+)VT) and those without vocal tremor (AdSD(-)VT) and to analyze their response to treatment with botulinum neurotoxin (BoNT-A).

STUDY DESIGN

Retrospective cohort study.

METHODS

A database review of all spasmodic dysphonia patients treated with BoNT from 1989 to 2018 at the Mayo Clinic in Arizona was performed. Only patients who had received ≥4 injections of BoNT-A for AdSD were included. Patients were divided into two cohorts: those with coexistent vocal tremor (AdSD(+)VT) and those without vocal tremor (AdSD(-)VT).

RESULTS

The final analysis included 398 patients, with 210 AdSD(+)VT patients (53%) and 188 AdSD(-)VT patients (47%). The length of follow-up and median number of treatments were similar between cohorts. AdSD(+)VT patients were more likely to be female (P < 0.001), and older at onset (P < 0.001) and first injection (P < 0.001). The mean maximal benefit was significantly lower for the AdSD(+)VT cohort (P < 0.01), however the mean length of benefit was similar (P = 0.70).

CONCLUSIONS

Demographic differences exist between AdSD(+)VT and AdSD(-)VT patients. AdSD(+)VT patients benefit from BoNT-A treatment; however, our analysis suggests that the degree of their maximal benefit is less than in those without VT.

Comparison of Outcome Measures (Subjective, Objective, and Patient-Based) in Laryngeal Dystonia Treatment With Botulinum Toxin A Injection

BACKGROUND

Outcome assessment in laryngeal dystonia is hindered by lack of consensus on a core set of outcome measures to quantify treatment effect and disease severity on quality of life. Potential outcome measure domains include objective voice, clinician reported, and patient reported outcome measures (PROMs) for determining treatment success and longitudinal disease tracking. We aim to determine correlations between a selections of outcome measure tools following Botulinum toxin injection.

METHODS

A selection of instruments were administered to assess adductor laryngeal dystonia patient outcomes before and after Botulinum toxin injection. Voice samples recorded using a cellular telephone application were used for objective acoustic measures (CPPS, acoustic voice quality index) and speech language pathologist perceptual analysis (CAPE-V). Additionally, patients completed a PROMs battery consisting of the Voice Handicap Index-10, Communicative Participation Item Bank-10, OMNI-Vocal Effort Scale, 3 visual analog scale (VAS) questions. Changes in these outcome measures pre-post treatment were compared between each other and with a global rating of change questionnaire (GRCQ) using Spearman's rank correlation coefficients.

RESULTS

Twenty six patients (20 female, mean age 57.7 years) participated. Using an anchor based GRCQ, patients reported Botox efficacy was the only outcome measure found to have significant correlation (r = 0.54, P = 0.022); all other outcome measures did not meet statistically significant correlation. Amongst the selected outcome tools, several moderate-strong correlations were identified, largely for outcome measures within the same domain. Most notable were correlations between the patient reported OMNI-VES and VAS questions (r > 0.68, P < 0.05), clinician CAPE-V strain and overall severity (r = 0.900, P < 0.001), and acoustic voice quality index with sustained vowel CPPs (r = -0.797, P = 0.002).

CONCLUSION

Correlation between outcome measures instruments used for patients with adductor laryngeal dystonia requires further attention. Weak correlations with an anchor based GRCQ were found for this study's selected outcome instruments. A select number of correlations were found between outcome instruments within each of the individual outcome measure domains (patient perception, clinical perception, objective acoustics), but there was largely a lack of correlation found for instruments between these three separate domains.

Use of Botulinum Toxin in Spasmodic Dysphonia: A Review of Recent Studies

Spasmodic dysphonia (SD), also known as laryngeal dystonia, is a neurological voice disorder that causes involuntary spasms of the vocal cord muscles. This impacts speech to varying degrees and results in strained and strangled voice quality, as in adductor spasmodic dysphonia, or weak, quiet, and breathy, as in abductor spasmodic dysphonia. While there is currently no cure for SD, voice therapy and chemodenervation with botulinum toxin (btx) injections remain the mainstay of management. Surgery may be performed in some cases; however, btx injections are widely used to treat both adductor and abductor forms of SD. While btx injections may show vocal improvement in both types of SD, results can depend on several factors such as the general health of the patient, onset and severity of the condition, dosage, interval between injections, and expertise of the practitioner. While many studies have documented the efficacy of btx for improving vocal symptoms in individuals with SD, this review aims to discuss some of those studies from the last 10 years.

Pre- and Postoperative High-Speed Videolaryngoscopy Findings in Adductor Spasmodic Dysphonia Following Transoral CO2 LASER-Guided Thyroarytenoid Myoneurectomy

INTRODUCTION

Vocal cord vibration after transoral CO₂ LASER-guided thyroarytenoid (TA) myoneurectomy in adductor spasmodic dysphonia (AdSD) patients is unclear to date. The precise vibratory patterns in AdSD patients are difficult to evaluate with routine videolaryngostroboscopy. High-speed videolaryngoscopy (HSV) is an ideal choice to evaluate such patients. This study was performed to compare pre- and postoperative, after 6 months, vocal fold vibratory onset delay (VFVOD) and closed phase glottal cycle (CPGC) in AdSD patients following transoral CO₂ LASER-guided TA myoneurectomy using the HSV.

MATERIALS AND METHODS

Retrospective study, conducted from January, 2016 to January, 2019, of the AdSD patients who underwent transoral CO₂ LASER-guided TA myoneurectomy using the HSV. Patient data were acquired from the hospital database to evaluate VFVOD and CPGC from HSV recordings of the patients. VFVOD was calculated as sum of prephonatory delay (PPD) and steady-state delay (SSD). The PPD and SSD were evaluated and compared separately for each patient. The MedCal Version 19.2.6 was used for data analysis. Paired sample t test was performed to compute the significance of the difference between the mean of the dataset. A P value less than 0.05 was considered significant.

RESULTS

A total of nine patients were included in the study, out of which three were females and six were males. The average age was 45.5 ± 6.9 years. The mean of postoperative PPD (166.8 ± 22.1), SSD (76.5 ± 8.6), and CPGC (62.6 ± 4.8) were significantly less than mean of preoperative PPD (222.6 ± 22.1), SSD (97.7 ± 9.5), and CPGC (71.6 ± 5 %), with P values of 0.0007, 0.0001, and 0.0001, respectively.

CONCLUSIONS

There was a significant decrease in VFVOD and CPGC posttransoral CO₂ LASER-guided TA myoneurectomy in AdSD patients after 6 months follow-up. This study also establishes efficiency of the HSV to measure the vocal cord vibration in the patients with AdSD. The primary limitations of the study were the small sample size and its retrospective nature. Future prospective studies with increased sample size can further substantiate the findings of the work performed here.

Validation of the OMNI vocal effort scale in the treatment of adductor spasmodic dysphonia

OBJECTIVES

To establish the validity of the OMNI Vocal Effort Scale (OMNI-VES) for resistance exercise, a single-question pictorial scale, in voice-related perceived exertion. Additionally, the study aimed to assess the role of the OMNI-VES as an outcome measurement in the treatment of adductor spasmodic dysphonia (ADSD).

METHODS

A prospective validation study was conducted on 226 participants. The case group was comprised of 178 patients receiving botulinum toxin (BTX) injections for ADSD and 48 controls without a voice disorder. Prior to a planned injection, the participants were asked to complete the OMNI-VES and the Voice-Related Quality-of-Life (V-RQOL) questionnaires, and the clinician completed the Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V). A subgroup of 17 patients were administered a repeat assessment 1 month after injection.

RESULTS

There was a weak correlation between the OMNI-VES and the V-RQOL score (Tau-b = -0.252, P < 0.001), and no significant correlation with the CAPE-V. Participants with ADSD had significantly higher OMNI-VES scores compared with normal controls, 5.07 ± 2.18 and 1.47 ± 2.28, respectively (P value < 0.0001). The average OMNI-VES score significantly improved 1 month following a BTX injection, from 6 ± 2.4 to 3.4 ± 2.8 (P value = 0.0003). Eighty-eight percent of the patients demonstrated a decrease in the OMNI-VES score following injection, whereas only 47% demonstrated an improvement in the V-RQOL score.

CONCLUSION

The OMNI-VES is a validated tool for rating perceived voice-related exertion in people with ADSD and can be used for evaluating response to BTX injection treatment.

LEVEL OF EVIDENCE

2b Laryngoscope, 129:448-453, 2019.

The Measurement of Airflow Using Singing Helmet That Allows Free Movement of the Jaw

OBJECTIVES

Airflow measurement is a useful method of evaluating laryngeal physiology. We introduce a noninvasive device that measures airflow without restricting jaw movement or requiring phonation into a mouthpiece, thus facilitating measurement during singing and connected speech.

STUDY DESIGN

Validation and human subject trials were conducted. Airflow measurements were obtained from 16 male and 16 female subjects during singing, speech, and constant vowel production tasks.

METHODS

A similar helmet was designed by Stevens and Mead in 1968. The new device validity was evaluated by comparing the measured volume of air to a known volume of administered air using a calibration syringe. Subjects were asked to voice sustained vowels at low, medium, and high vocal intensity, read two sentences at a conversational volume, and perform different singing exercises while airflow was recorded.

RESULTS

The device accurately and reliably measured airflow with mean airflow values falling within previously published ranges. There was an experimentally determined response time of 0.173 ± 0.014 seconds. Subjects were able to comfortably perform speech and singing exercises. Male subjects had higher airflow for all sustained vowels (P < 0.05). Airflow was higher for abduction rather than adduction sentences (P < 0.05).

CONCLUSIONS

No other portable device has been shown to measure airflow during singing and speech while allowing for free movement of the jaw. This device provides a more natural environment to measure airflow that could be used to help evaluate laryngeal function and aid in singing training.

Measurement of phonation threshold power in normal and disordered voice production

OBJECTIVES

Phonation threshold pressure (PTP) and phonation threshold flow (PTF) are useful aerodynamic parameters, but each is sensitive to different disorders. A single comprehensive aerodynamic parameter sensitive to a variety of disorders might be beneficial in quantitative voice assessment. We performed the first study of phonation threshold power (PTW) in human subjects.

METHODS

PTP and PTF were measured in 100 normal subjects, 19 subjects with vocal fold immobility, and 94 subjects with a benign mass lesion. PTW was calculated from these two parameters. In 41 subjects with a polyp, measurements were obtained before and after excision. Receiver operating characteristic (ROC) analysis was used to determine the ability of the three parameters to distinguish between controls and disordered groups.

RESULTS

The PTW (p < 0.001), PTP (p < 0.001), and PTF (p < 0.001) were different among the three groups. All parameters decreased after polyp excision. PTW had the highest area under the ROC curve for all analyses.

CONCLUSIONS

PTW is sensitive to the presence of mass lesions and vocal fold mobility disorders. Additionally, changes in PTW can be observed after excision of mass lesions. PTW could be a useful parameter to describe the aerodynamic inputs to voice production.

Evaluation of auditory and visual feedback for airflow interruption

INTRODUCTION

Clinical application of mechanical interruption methods for measuring aerodynamic parameters has been hindered by relatively high intrasubject variability. To improve the intrasubject reliability, we evaluated the effect of auditory and visual feedback on subject performance when measuring aerodynamic parameters with the airflow interrupter.

METHODS

Eleven subjects performed four sets of 10 trials with the airflow interrupter: no feedback (control); auditory feedback (tone matching subject's F0 played over headphones); visual feedback (real-time feedback of sound pressure level, frequency, and airflow); and combined auditory and visual feedback. Task order was varied across subjects. The effect of each feedback method on mean and coefficient of variation (CV) of subglottal pressure (Ps), mean flow rate (MFR), and laryngeal airway resistance (RL; Ps/MFR) compared with that of the control trials was determined using paired t tests. Feedback methods were compared against each other using one-way repeated measures analysis of variance.

RESULTS

Each feedback method significantly decreased CV of RL compared with that of the control trials (auditory feedback: P=0.005; visual feedback: P=0.008; and combined feedback: P<0.001). Auditory feedback (P=0.011) and combined feedback (P=0.026) also decreased CV of MFR. Mean MFR was significantly higher during trials with visual feedback compared with that of the auditory feedback.

CONCLUSIONS

Each feedback method improved the intrasubject consistency when measuring RL. Feedback appeared to have a greater effect on MFR than Ps. Although there is no clear optimal feedback method, each is preferable to not providing any feedback during trials. Evaluating new methods of visual feedback to further improve MFR and thus RL measurement would be valuable.

Comparison of labial and mechanical interruption for measurement of aerodynamic parameters

OBJECTIVES/HYPOTHESIS

To directly compare the mechanical and labial interruption techniques of measuring subglottal pressure (P(s)), mean flow rate (MFR), and laryngeal resistance (R(L)).

METHODS

Thirty-four subjects performed 10 trials with both mechanical and labial interruption. P(s) and MFR were recorded, whereas R(L) was calculated by dividing P(s) by MFR. Coefficients of variation were calculated to compare intrasubject precision. A subset of 10 subjects performed the tasks twice with 30 minutes between sessions. Bland-Altman plots were used to determine intrasubject repeatability for each of the methods.

RESULTS

Mechanical interruption produced coefficients of variation for P(s), MFR, and R(L) of 0.0995, 0.127, and 0.129, respectively. Labial interruption produced coefficients of variation of 0.102, 0.147, and 0.169, respectively. P values were 0.824 for P(s), 0.159 for MFR, and 0.043 for R(L). The Bland-Altman plots revealed comparable repeatability between the two methods. The 95% confidence intervals of the Bland-Altman plots for mechanical interruption were (-0.050, 0.072), (-0.543, 1.832), and (-2.498, 10.528) for MFR, P(s), and R(L). Confidence intervals for labial interruption were (-0.018, 0.031), (0.057, 2.442), and (-3.267, 10.595) for MFR, P(s,) and R(L).

CONCLUSIONS

Mechanical interruption produced higher precision when measuring R(L) because of more reliable airflow measurements. Mechanical and labial interruption showed comparable repeatability. Further research into using mechanical interruption clinically is warranted.