Associations between laryngeal and cough dysfunction in motor neuron disease with bulbar involvement

Pathophysiology, Clinical Heterogeneity, and Therapeutic Advances in Amyotrophic Lateral Sclerosis: A Comprehensive Review of Molecular Mechanisms, Diagnostic Challenges, and Multidisciplinary Management Strategies

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder characterized by the progressive degeneration of upper and lower motor neurons, leading to muscle atrophy, paralysis, and respiratory failure. This comprehensive review synthesizes the current knowledge on ALS pathophysiology, clinical heterogeneity, diagnostic frameworks, and evolving therapeutic strategies. Mechanistically, ALS arises from complex interactions between genetic mutations (e.g., in C9orf72, SOD1, TARDBP (TDP-43), and FUS) and dysregulated cellular pathways, including impaired RNA metabolism, protein misfolding, nucleocytoplasmic transport defects, and prion-like propagation of toxic aggregates. Phenotypic heterogeneity, manifesting as bulbar-, spinal-, or respiratory-onset variants, complicates its early diagnosis, which thus necessitates the rigorous application of the revised El Escorial criteria and emerging biomarkers such as neurofilament light chain. Clinically, ALS intersects with frontotemporal dementia (FTD) in up to 50% of the cases, driven by shared TDP-43 pathology and C9orf72 hexanucleotide expansions. Epidemiological studies have revealed a lifetime risk of 1:350, with male predominance (1.5:1) and peak onset between 50 and 70 years. Disease progression varies widely, with a median survival of 2-4 years post-diagnosis, underscoring the urgency for early intervention. Approved therapies, including riluzole (glutamate modulation), edaravone (antioxidant), and tofersen (antisense oligonucleotide), offer modest survival benefits, while dextromethorphan/quinidine alleviates the pseudobulbar affect. Non-pharmacological treatment advances, such as non-invasive ventilation (NIV), prolong survival by 13 months and improve quality of life, particularly in bulb-involved patients. Multidisciplinary care-integrating physical therapy, respiratory support, nutritional management, and cognitive assessments-is critical to addressing motor and non-motor symptoms (e.g., dysphagia, spasticity, sleep disturbances). Emerging therapies show promise in preclinical models. However, challenges persist in translating genetic insights into universally effective treatments. Ethical considerations, including euthanasia and end-of-life decision-making, further highlight the need for patient-centered communication and palliative strategies.

Exploring the relationship between plasma substance P and glottal incompetence in the elderly

We speculated that increased blood-plasma levels of Substance P may serve as an indicator of glottal incompetence, which is usually indicated by reduced maximum phonation time. We performed an initial study to test the plausibility of this hypothesis. Patients with dysphonia caused by glottal incompetence were asked to perform vocal exercises for six months to reduce glottal incompetence and we compared the plasma concentration of Substance P before and after the vocal exercise to detect correlation between maximum phonation time and plasma concentration of Substance P. Based on the results, we further hypothesized that patients exhibiting dysphonia with maximum phonation time less than 14 s, in particular less than 10 sec, caused by glottal incompetence may have increased plasma concentration of Substance P with the results of elevated thresholds of cough reflex associated with subclinical aspiration in airways. Further study is needed on patients with decreased Substance P levels, with low scores on Activities of Daily Living and who are hospitalized with aspiration pneumonia.

Predictors of Peak Expiratory Cough Flow in Individuals with Amyotrophic Lateral Sclerosis

Dystussia is prevalent in individuals with amyotrophic lateral sclerosis (ALS), leading to a diminished physiologic capacity to effectively defend the airway. We aimed to identify predictors of peak expiratory cough flow rate in individuals with ALS. One hundred and thirty-four individuals with a confirmed diagnosis of ALS (El-Escorial criteria revised) completed the ALS Functional Rating Scale-Revised (ALSFRS-R) and underwent pulmonary function and cough spirometry testing. Pearson's correlation coefficients and hierarchical multiple regression modeling were conducted to determine predictors of voluntary cough peak expiratory flow rate (p < 0.05). The full model including age, bulbar disease, cough spirometry metrics, and respiratory parameters had a marginal R² = 0.635, F (7, 126) = 30.241, p < 0.0005, adjusted R² = 0.61. Maximum expiratory pressure, compression phase, and vital capacity did not contribute and were therefore removed (p < 0.05). The most parsimonious predictive model included age, bulbar disease, peak inspiratory flow rate and duration, peak expiratory rise time, and inspiratory pressure generation with a marginal R² = 0.543. Although expiratory pressure generation has historically served as the therapeutic target to improve dystussia in ALS, the current dataset highlighted that the inability to quickly and forcefully inspire during the inspiratory phase of voluntary cough places patients at a mechanical disadvantage to generate subsequent high-velocity expiratory airflow to clear the airway. Thus, therapeutic training programs that include both inspiratory and expiratory strength targets may optimize airway clearance capacity in this challenging patient population.

Extreme Sawtooth-Sign in Motor Neuron Disease (MND) suggests Laryngeal Resistance to Forced Expiratory Airflow

OBJECTIVE

The impact of laryngeal dysfunction on airflow has not been well characterized in motor neuron disease (MND). This study aimed to detect and characterize extreme airflow oscillations informally observed during volitional cough and forced vital capacity (FVC) tasks in individuals with MND who demonstrated neurolaryngeal impairments including reduced speed and extent of vocal fold abduction compared to healthy controls during volitional cough expulsion. The extreme airflow oscillations in the MND group, when viewed as a flow-volume loop, appeared similar to the "sawtooth-sign." If the airflow oscillations are periodic in a range similar to phonation, they may reflect reduced laryngeal patency.

METHODS

Volitional cough and FVC airflow data (3 trials each) from 12 participants with MND with bulbar/laryngeal involvement (3 F; ages 45-76) and 12 healthy controls (6 F; ages 41-68) were analyzed for periodicity. Percent and absolute durations of periodicity of the flow oscillations were calculated by an algorithm applied to the airflow signals. In addition, the frequency, magnitude, and kurtosis of the periodic airflow oscillations were described and compared between groups.

RESULTS

In both volitional cough and FVC trials, the percent of airflow periodicity during forced expiration was significantly higher (z = 3.54) in individuals with MND, adjusted for age and sex. Periodic airflow accounted for on average 28% of the total time in participants with MND and was within a frequency range similar to phonation. Magnitude of the airflow oscillations was also larger for participants with MND (z = 3.46), and kurtosis of airflow was smaller (z = -4.70) during forced expiration, indicating persistent airflow oscillations throughout exhalation.

CONCLUSIONS

The significantly larger-magnitude, lower-kurtosis, and more prominent presence of sawtooth-like airflow periodicity within a frequency range similar to phonation observed in individuals with MND with neurolaryngeal impairments suggests glottic airflow resistance during forced expiration.

Reflexive Airway Sensorimotor Responses in Individuals with Amyotrophic Lateral Sclerosis

BACKGROUND

Progressive motor denervation in amyotrophic lateral sclerosis (ALS) leads to reduced expiratory cough flow and diminished airway clearance physiologic capacity. Although ALS is thought to primarily impact motor systems, preliminary data from our laboratory suggest degradation of afferent pathways that regulate reflexive cough responses to radiographically confirmed aspiration. We, therefore, aimed to delineate both sensory and motor responses to a tussigenic airway irritant in individuals with ALS compared to healthy controls.

METHODS

Thirty-two individuals with ALS and 34 healthy age and gender-matched controls completed reflex cough testing. Capsaicin stimuli (0, 50, 100, 150, 200 μM) were presented in a randomized three-block design and motor (cough spirometry metrics) and sensory (patient-rated urge to cough, UtC) ratings collected. ALS patients underwent videofluoroscopy with penetration-aspiration ratings completed. Descriptives, Mann-Whitney U, and mixed models ANOVAs were performed.

RESULTS

Sensory: Individuals with ALS demonstrated greater UtC sensitivity slopes (i.e., increased stimulus sensitivity) vs. healthy controls (p = 0.036). Within the ALS group, however, silent aspirators (PAS = 8) demonstrated blunted UtC sensitivity slopes compared to ALS patients who did not (PAS ≤ 7, p = 0.0001). Motor: Compared to healthy controls, ALS individuals demonstrated reduced peak expiratory flow rates (p = 0.004), longer peak expiratory rise time (p = 0.017), and lower cough volume acceleration (p = 0.000).

CONCLUSIONS

ALS individuals demonstrated increased sensitivity to an upper airway irritant; however, they demonstrated slower and weaker expiratory cough motor output compared to healthy controls. In ALS silent aspirators, blunted sensorimotor responses were observed, suggesting that sensory degradation may occur at the final or most severe stage of bulbar disease progression.

Reliability of voluntary cough assessments using respiratory flow waveform

[Purpose] Voluntary cough can be assessed by recording flow waves. The purpose of this study was to examine the reliability of the measurements of respiratory flow waveforms, using equipment that recorded flow waves during cough. [Participants and Methods] Twenty healthy participants were recruited for this study. They underwent spirometry on them and, subsequently, their flow waves during single and consecutive voluntary cough tasks in the sitting position were recorded. The intra-class correlation coefficient was used to assess the intra-rater and inter-rater reliabilities for the voluntary cough data. [Results] The intra-class correlation coefficients were 0.6 to 0.8 for 'intra-rater reliability' and higher than 0.9 for 'inter-rater reliability', for single and consecutive cough tasks. The first assessment of cough peak flow was significantly higher than the second, during consecutive cough tasks. Similarly, the first assessment of cough volume acceleration was significantly higher than the second. [Conclusion] Our results demonstrated high intra-rater and inter-rater reliabilities for single and consecutive cough tasks. Following additional procedures and valuations, including the storage of data and standard range decisions, this method of cough assessment will be applied to patients with reduced cough function.

Numerical Analysis of Airway Mucus Clearance Effectiveness Using Assisted Coughing Techniques

Cough is a protective respiratory reflex used to clear respiratory airway mucus. For patients with cough weakness, such as chronic obstructive pulmonary disease, neuromuscular weakness disease and other respiratory diseases, assisted coughing techniques are essential to help them clear mucus. In this study, the Eulerian wall film model was applied to simulate the coughing clearance process through a computational fluid dynamics methodology. Airway generation 0 to generation 2 based on realistic geometry is considered in this study. To quantify cough effectiveness, cough efficiency was calculated. Moreover, simulations of four different coughing techniques applied for chronic obstructive pulmonary disease and neuromuscular weakness disease were conducted. The influences of mucus film thickness and mucus viscosity on cough efficiency were analyzed. From the simulation results, we found that with increasing mucus film thickness and decreasing mucus viscosity, cough efficiency improved accordingly. Assisted coughing technologies have little influence on the mucus clearance of chronic obstructive pulmonary disease models. Finally, it was observed that the cough efficiency of the mechanical insufflation-exsufflation technique (MIE) is more than 40 times the value of an unassisted coughing technique, which indicates that the MIE technology has a great effect on airway mucus clearance for neuromuscular weakness disease models.

Adductory Vocal Fold Kinematic Trajectories During Conventional Versus High-Speed Videoendoscopy

Objective Prephonatory vocal fold angle trajectories may supply useful information about the laryngeal system but were examined in previous studies using sigmoidal curves fit to data collected at 30 frames per second (fps). Here, high-speed videoendoscopy (HSV) was used to investigate the impacts of video frame rate and sigmoidal fitting strategy on vocal fold adductory patterns for voicing onsets. Method Twenty-five participants with healthy voices performed /ifi/ sequences under flexible nasendoscopy at 1,000 fps. Glottic angles were extracted during adduction for voicing onset; resulting vocal fold trajectories (i.e., changes in glottic angle over time) were down-sampled to simulate different frame rate conditions (30-1,000 fps). Vocal fold adduction data were fit with asymmetric sigmoids using 5 fitting strategies with varying parameter restrictions. Adduction trajectories and maximum adduction velocities were compared between the fits and the actual HSV data. Adduction trajectory errors between HSV data and fits were evaluated using root-mean-square error and maximum angular velocity error. Results Simulated data were generally well fit by sigmoid models; however, when compared to the actual 1,000-fps data, sigmoid fits were found to overestimate maximum angle velocities. Errors decreased as frame rate increased, reaching a plateau by 120 fps. Conclusion In healthy adults, vocal fold kinematic behavior during adduction is generally sigmoidal, although such fits can produce substantial errors when data are acquired at frame rates lower than 120 fps.

Characteristics of impaired voluntary cough function in individuals with amyotrophic lateral sclerosis

OBJECTIVE

Although cough impairment (dystussia) is common in individuals with amyotrophic lateral sclerosis (ALS) and contributes to a reduced physiologic capacity to defend the airway, characteristics of dystussia have not yet been delineated. Therefore, we aimed to compare voluntary cough spirometry airflow patterns between individuals with ALS and healthy age and gender-matched controls.

METHODS

Thirty-two individuals with a diagnosis of probable-definite ALS (El-Escorial Criterion) and 29 healthy age and gender-matched controls underwent voluntary cough spirometry testing. Two blinded raters derived six objective voluntary cough airflow measures including: peak inspiratory phase duration, peak inspiratory flow rate, compression phase duration, peak expiratory rise time, peak expiratory flow rate, and cough volume acceleration. Independent samples t-tests with Cohen's d effect sizes were performed between Healthy versus ALS groups for cough metrics (alpha =0.05).

RESULTS

ALS individuals demonstrated prolonged inspiratory phase and expiratory phase rise time durations, reduced inspiratory and expiratory flow rates, and lower cough volume acceleration during voluntary cough production compared with healthy controls (p < 0.05). No differences in compression phase duration were observed (p > 0.05).

CONCLUSIONS

This study compared characteristics of voluntary cough airflow patterns of individuals with ALS to healthy-matched controls. Findings identified impairments in both inspiratory and expiratory voluntary cough airflow, resulting in slower, weaker, and thus less effectiveness voluntary cough production in ALS individuals. These data afford insight into the impaired physiology underlying inadequate airway clearance and secretion management in individuals with ALS.

Screening and evaluation tools of dysphagia in adults with neuromuscular diseases: a systematic review

Background:

The purpose of this systematic review was to summarize the different dysphagia screening and evaluation tools, and to identify their measurement properties in adults with neuromuscular diseases (NMDs).

Methods:

A systematic review was performed based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The search strategy was conducted across three databases (PubMed, CINAHL and ScienceDirect). Measurement properties of each tools and the Quality Index, developed by Downs and Black, were considered for the different investigated studies.

Results:

The search strategy produced 2221 articles. After removal of duplicates and full-text analysis, 19 studies were included. Most of the publications focused on amyotrophic lateral sclerosis (ALS; n = 10) and Duchenne muscular dystrophy (DMD; n = 4). A total of 12 tools, listed as instrumental and noninstrumental examinations, were retrieved. A total of five of them used videofluoroscopic swallow study (VFSS). Measurement properties of the tools are not completely described in detail in many studies. The neuromuscular disease swallowing status scale, a noninstrumental tool, is the only one that assessed all measurement properties in ALS patients. The median score reported for the Quality Index was 16.

Conclusions:

This systematic review identified 12 different tools for the screening and evaluation of dysphagia in adults with NMD. Majority of the studies presented VFSS as a valid and reliable examination to assess dysphagia in ALS and DMD. Other tools were mainly evaluated in ALS patients, but further studies are needed to complete their measurement properties. In other NMDs, no firm conclusion can be made because of insufficient data and heterogeneity of NMDs.

A Mobile Cough Strength Evaluation Device Using Cough Sounds

Although cough peak flow (CPF) is an important measurement for evaluating the risk of cough dysfunction, some patients cannot use conventional measurement instruments, such as spirometers, because of the configurational burden of the instruments. Therefore, we previously developed a cough strength estimation method using cough sounds based on a simple acoustic and aerodynamic model. However, the previous model did not consider age or have a user interface for practical application. This study clarifies the cough strength prediction accuracy using an improved model in young and elderly participants. Additionally, a user interface for mobile devices was developed to record cough sounds and estimate cough strength using the proposed method. We then performed experiments on 33 young participants (21.3 ± 0.4 years) and 25 elderly participants (80.4 ± 6.1 years) to test the effect of age on the CPF estimation accuracy. The percentage error between the measured and estimated CPFs was approximately 6.19%. In addition, among the elderly participants, the current model improved the estimation accuracy of the previous model by a percentage error of approximately 6.5% (p < 0.001). Furthermore, Bland-Altman analysis demonstrated no systematic error between the measured and estimated CPFs. These results suggest that the developed device can be applied for daily CPF measurements in clinical practice.

Trends in Research Literature Describing Dysphagia in Motor Neuron Diseases (MND): A Scoping Review

Dysphagia in motor neuron diseases (MNDs) is highly complex, affecting all stages of swallowing and leading to impaired swallowing safety and efficiency. In order to explore the degree to which research is capturing the symptom of dysphagia in MND, we conducted a scoping review of the existing literature. The primary aims of this review were to identify common themes within the literature on dysphagia in MND, explore patterns and trends in research focus, and identify if any imbalances exist between the research themes related to dysphagia description and management. A comprehensive search strategy yielded 1690 unique articles for review. Following relevance screening, a total of 157 articles were included in the synthesis. Relevant data and keywords were extracted from each article and grouped into themes. Frequency estimates were calculated for each theme to identify trends across research literature. Swallowing impairment in MNDs is described in a variety of ways across current research. The most commonly reported theme was Aspiration/Penetration, mentioned in 73.2% of all included articles; a significant imbalance was identified between reports of swallowing safety and efficiency (p = 0.008). The most frequently reported theme related to dysphagia management was Enteral Nutrition, and very few studies have reported on the efficacy of Rehabilitation/Compensatory recommendations. It is suggested that researchers and clinicians remain mindful of imbalances and gaps in research, and aim to characterize dysphagia in MNDs in a comprehensive manner. Further research investigating discrete, measureable changes in swallowing pathophysiology would be beneficial to delineate the key factors contributing to impaired swallowing safety and efficiency.

Changes in Peak Airflow Measurement During Maximal Cough After Vocal Fold Augmentation in Patients With Glottic Insufficiency

Importance

Compromised cough effectiveness is correlated with dysphagia and aspiration. Glottic insufficiency likely yields decreased cough strength and effectiveness. Although vocal fold augmentation favorably affects voice and likely improves cough strength, few data exist to support this hypothesis.

Objective

To assess whether vocal fold augmentation improves peak airflow measurements during maximal-effort cough following augmentation.

Design, Setting, and Participants

This case series study was conducted in a tertiary, academic laryngology clinic. Participants included 14 consecutive individuals with glottic insufficiency due to vocal fold paralysis, which was diagnosed via videostrobolaryngoscopy as a component of routine clinical examination. All participants who chose to proceed with augmentation were considered for the study whether office-based or operative augmentation was planned. Postaugmentation data were collected only at the first follow-up visit, which was targeted for 14 days after augmentation but varied on the basis of participant availability. Data were collected from June 5, 2014, to October 1, 2015. Data analysis took place between October 2, 2015, and March 3, 2017.

Main Outcomes and Measures

Peak airflow during maximal volitional cough was quantified before and after vocal fold augmentation. Participants performed maximal coughs, and peak expiratory flow during the maximal cough was captured according to American Thoracic Society guidelines.

Results

Among the 14 participants (7 men and 7 women), the mean (SD) age was 62 (18) years. Three types of injectable material were used for vocal fold augmentation: carboxymethylcellulose in 5 patients, hyaluronic acid in 5, and calcium hydroxylapatite in 4. Following augmentation, cough strength increased in 11 participants and decreased cough strength was observed in 3. Peak airflow measurements during maximal cough varied from a decrease of 40 L/min to an increase of 150 L/min following augmentation. When preaugmentation and postaugmentation peak airflow measurements were compared, the median improvement was 50 L/min (95% CI, 10-75 L/min; P = .01). Immediate peak airflow measurements during cough collected within 30 minutes of augmentation varied when compared with measurements collected at follow-up (103-380 vs 160-390 L/min).

Conclusions and Relevance

Peak airflow during maximal cough may improve with vocal fold augmentation. Additional assessment and measurements are needed to further delineate which patients will benefit most regarding their cough from vocal fold augmentation.

Glottis effects on the cough clearance process simulated with a CFD dynamic mesh and Eulerian wall film model

In this study, we have reproduced the cough clearance process with an Eulerian wall film model. The simulated domain is based on realistic geometry from the literature, which has been improved by adding the glottis and epiglottis. The vocal fold movement has been included due to the dynamic mesh method, considering different abduction and adduction angles and velocities. The proposed methodology captures the deformation of the flexible tissue, considers non-Newtonian properties for the mucus, and enables us to reproduce a single cough or a cough epoch. The cough efficiency (CE) has been used to quantify the overall performance of the cough, considering many different boundary conditions, for the analysis of the glottis effect. It was observed that a viscous shear force is the main mechanism in the cough clearance process, while the glottis closure time and the epiglottis position do not have a significant effect on the CE. The cough assistance devices improve the CE, and the enhancement rate grows logarithmically with the operating pressure. The cough can achieve an effective mucus clearance process, even with a fixed glottis. Nevertheless, the glottis closure substantially improves the CE results.

Measurement of the Maximum Frequency of Electroglottographic Fluctuations in the Expiration Phase of Volitional Cough as a Functional Test for Cough Efficiency

The hypotheses of the present study were that the maximum frequency of fluctuation of electroglottographic (EGG) signals in the expiration phase of volitional cough (VC) reflects the cough efficiency and that this EGG parameter is affected by impaired laryngeal closure, expiratory effort strength, and gender. For 20 normal healthy adults and 20 patients diagnosed with unilateral vocal fold paralysis (UVFP), each participant was fitted with EGG electrodes on the neck, had a transnasal laryngo-fiberscope inserted, and was asked to perform weak/strong VC tasks while EGG signals and a high-speed digital image of the larynx were recorded. The maximum frequency was calculated in the EGG fluctuation region coinciding with vigorous vocal fold vibration in the laryngeal HSDIs. In addition, each participant underwent spirometry for measurement of three aerodynamic parameters, including peak expiratory air flow (PEAF), during weak/strong VC tasks. Significant differences were found for both maximum EGG frequency and PEAF between the healthy and UVFP groups and between the weak and strong VC tasks. Among the three cough aerodynamic parameters, PEAF showed the highest positive correlation with the maximum EGG frequency. The correlation coefficients between the maximum EGG frequency and PEAF recorded simultaneously were 0.574 for the whole group, and 0.782/0.717/0.823/0.688 for the male/female/male-healthy/male-UVFP subgroups, respectively. Consequently, the maximum EGG frequency measured in the expiration phase of VC was shown to reflect the velocity of expiratory airflow to some extent and was suggested to be affected by vocal fold physical properties, glottal closure condition, and the expiratory function.

Disordered voluntary cough as freezing phenomenon in parkinsonism

[Purpose] In patients with parkinsonism, the precise mechanism of impaired voluntary cough remains poorly understood. This study used the flow–volume curve to clarify whether disordered voluntary cough reflects the freezing phenomenon. [Subjects and Methods] Case 1 was a 58-year-old female who had been suffering from progressive supranuclear palsy-pure akinesia with gait freezing. Case 2 was a 59-year-old female who had advanced juvenile parkinsonism. The subjects were asked to take a deep inspiration to the total lung capacity and then cough more than five times through the face mask into the spirometer without intervening inspirations between the coughing efforts. [Results] Hesitation in cough initiation (case 2), decreased peak cough flow (case 1), and rounding of the first spike (cases 1 and 2) were observed. In addition, movements of the spike wave at a lower lung volume became progressively smaller and faster (cases 1 and 2). [Conclusion] These clinical manifestations in our patients are similar to those observed in the freezing phenomenon. However, to date, the concept of cough freezing has been underrecognized in clinical practice. From the present study, it could be hypothesized that the freezing phenomenon can occur in voluntary cough as well as in gait, speech, and writing.

Independent exercise for glottal incompetence to improve vocal problems and prevent aspiration pneumonia in the elderly: a randomized controlled trial

Objectives:

To evaluate the effect of a self-controlled vocal exercise in elderly people with glottal closure insufficiency.

Design:

Parallel-arm, individual randomized controlled trial.

Methods:

Patients who visited one of 10 medical centers under the National Hospital Organization group in Japan for the first time, aged 60 years or older, complaining of aspiration or hoarseness, and endoscopically confirmed to have glottal closure insufficiency owing to vocal cord atrophy, were enrolled in this study. They were randomly assigned to an intervention or a control group. The patients of the intervention group were given guidance and a DVD about a self-controlled vocal exercise. The maximum phonation time which is a measure of glottal closure was evaluated, and the number of patients who developed pneumonia during the six months was compared between the two groups.

Results:

Of the 543 patients enrolled in this trial, 259 were allocated into the intervention group and 284 into the control; 60 of the intervention group and 75 of the control were not able to continue the trial. A total of 199 patients (age 73.9 ±7.25 years) in the intervention group and 209 (73.3 ±6.68 years) in the control completed the six-month trial. Intervention of the self-controlled vocal exercise extended the maximum phonation time significantly (p < 0.001). There were two hospitalizations for pneumonia in the intervention group and 18 in the control group, representing a significant difference (p < 0.001).

Conclusion:

The self-controlled vocal exercise allowed patients to achieve vocal cord adduction and improve glottal closure insufficiency, which reduced the rate of hospitalization for pneumonia significantly.

ClinicalTrial.govIdentifier-UMIN000015567