Design of a new somatosensory stimulus delivery device for measuring laryngeal mechanosensory detection thresholds in humans

A neurocomputational view of the effects of Parkinson's disease on speech production

The purpose of this article is to review the scientific literature concerning speech in Parkinson's disease (PD) with reference to the DIVA/GODIVA neurocomputational modeling framework. Within this theoretical view, the basal ganglia (BG) contribute to several different aspects of speech motor learning and execution. First, the BG are posited to play a role in the initiation and scaling of speech movements. Within the DIVA/GODIVA framework, initiation and scaling are carried out by initiation map nodes in the supplementary motor area acting in concert with the BG. Reduced support of the initiation map from the BG in PD would result in reduced movement intensity as well as susceptibility to early termination of movement. A second proposed role concerns the learning of common speech sequences, such as phoneme sequences comprising words; this view receives support from the animal literature as well as studies identifying speech sequence learning deficits in PD. Third, the BG may play a role in the temporary buffering and sequencing of longer speech utterances such as phrases during conversational speech. Although the literature does not support a critical role for the BG in representing sequence order (since incorrectly ordered speech is not characteristic of PD), the BG are posited to contribute to the scaling of individual movements in the sequence, including increasing movement intensity for emphatic stress on key words. Therapeutic interventions for PD have inconsistent effects on speech. In contrast to dopaminergic treatments, which typically either leave speech unchanged or lead to minor improvements, deep brain stimulation (DBS) can degrade speech in some cases and improve it in others. However, cases of degradation may be due to unintended stimulation of efferent motor projections to the speech articulators. Findings of spared speech after bilateral pallidotomy appear to indicate that any role played by the BG in adult speech must be supplementary rather than mandatory, with the sequential order of well-learned sequences apparently represented elsewhere (e.g., in cortico-cortical projections).

Auditory and somatosensory feedback mechanisms of laryngeal and articulatory speech motor control

PURPOSE

Speech production is a complex motor task involving multiple subsystems. The relationships between these subsystems need to be comprehensively investigated to understand the underlying mechanisms of speech production. The goal of this paper is to examine the differential contributions of 1) auditory and somatosensory feedback control mechanisms, and 2) laryngeal and articulatory speech production subsystems on speech motor control at an individual speaker level using altered auditory and somatosensory feedback paradigms.

METHODS

Twenty young adults completed speaking tasks in which sudden and unpredictable auditory and physical perturbations were applied to the laryngeal and articulatory speech production subsystems. Auditory perturbations were applied to laryngeal or articulatory acoustic features of speech. Physical perturbations were applied to the larynx and the jaw. Pearson-product moment correlation coefficients were calculated between 1) auditory and somatosensory reflexive responses to investigate relationships between auditory and somatosensory feedback control mechanisms, and 2) laryngeal and articulatory reflexive responses as well as acuity measures to investigate the relationship between auditory-motor features of laryngeal and articulatory subsystems.

RESULTS

No statistically significant correlations were found concerning the relationships between auditory and somatosensory feedback. No statistically significant correlations were found between auditory-motor features in the laryngeal and articulatory control subsystems.

CONCLUSION

Results suggest that the laryngeal and articulatory speech production subsystems operate with differential auditory and somatosensory feedback control mechanisms. The outcomes suggest that current models of speech motor control should consider decoupling laryngeal and articulatory domains to better model speech motor control processes.

High-Volume Billing and Reimbursement Trends for Endoscopic Swallowing Studies in the Medicare Population

The aim of this study is to delineate the reimbursement trends in fiberoptic endoscopic evaluation of swallowing with sensory testing (FEESST) and without sensory testing (FEES) in relation to that of speech-language pathology's (SLP) portion of modified barium swallow studies (MBS), as well as to document the types of providers billing for these procedures. We performed descriptive analyses of the volume of FEES/FEESST and MBS, and total reimbursements data obtained from 2013-2018 Medicare Part B National Summary files. We also utilized the 2017 Medicare Provider Utilization and Payment Data to analyze the higher volume providers (> 10 procedures annually) of either FEES and/or FEESST. From 2003 to 2018, there has been an average, annual increase of approximately 318 FEES/FEESST performed within the Medicare fee-for-service population (R = 0.9505 [95% CI 0.860-0.983]; p < 0.001) covered under Part B (which is largely outpatient coverage). Similarly, there was an increase in Medicare-specific FEES/FEESST reimbursement from $302,840 in 2003 to $1.2 million in 2018 (R = 0.9721 [95% CI 0.920-0.990; p < 0.001]). Prior to 2010, FEESST was performed more frequently than FEES (maximum annual difference of 1174), though from 2010 onward, relatively more annual FEES was performed. From 2003-2018, the reimbursement per procedure increased by $16.79 and $35.36 for FEESST and FEES, respectively, and by $32.84 for the SLP portion of the MBS. Among high-volume FEES/FEESST billers, 65.4% were otolaryngologists and 32.3% were independently billing SLPs. From 2003 to 2018, there has been a significant rise in the number of performed and reimbursed FEES/FEESST. From 2014 onward, compared to SLP-involved MBS, there has been a relative increase in performance of FEES/FEESST.

Inter- and Intra-Rater Reliability of Laryngeal Sensation Testing with the Touch Method During Flexible Endoscopic Evaluations of Swallowing

OBJECTIVES

Sensation is an integral component of laryngeal control for breathing, swallowing, and vocalization. Laryngeal sensation is assessed by elicitation of the laryngeal adductor reflex (LAR), a brainstem-mediated adduction of the true vocal folds. During Flexible Endoscopic Evaluations of Swallowing (FEES), the touch method can be used to elicit the LAR to judge laryngeal sensation. Despite the prevalence of this method in clinical practice and research, prior studies have yet to examine inter- and intra-rater reliability.

METHODS

Four speech-language pathologists rated 125 randomized video clips for the presence, absence, or inability to rate the LAR. Fifty percent of video clips were re-randomized and re-rated 1 week later. Raters then created guidelines and participated in formal consensus training sessions on a separate set of videos. Ratings were repeated post-training.

RESULTS

Overall inter-rater reliability was fair (κ = 0.22) prior to training. Pre-training intra-rater reliability ranged from fair (κ = 0.35) to almost perfect (κ = 0.89). Inter-rater reliability significantly improved after training (κ = 0.42, P < .001), though agreement did not reach prespecified acceptable levels (κ ≥ 0.80). Post-training intra-rater reliability ranged from moderate (κ = 0.49) to almost perfect (κ = 0.85).

CONCLUSION

Adequate inter-rater reliability was not achieved when rating isolated attempts to elicit the LAR. Acceptable within-rater reliability was observed in some raters 1 week after initial ratings, suggesting that ratings may remain consistent within raters over a short period of time. Limitations and considerations for future research using the touch method are discussed.

Relationship Between Laryngeal Sensation, Length of Intubation, and Aspiration in Patients with Acute Respiratory Failure

Dysphagia is common in hospitalized patients post-extubation and associated with poor outcomes. Laryngeal sensation is critical for airway protection and safe swallowing. However, current understanding of the relationship between laryngeal sensation and aspiration in post-extubation populations is limited. Acute respiratory failure patients requiring intensive care unit admission and mechanical ventilation received a Flexible Endoscopic Evaluation of Swallowing (FEES) within 72 h of extubation. Univariate and multivariable analyses were performed to examine the relationship between laryngeal sensation, length of intubation, and aspiration. Secondary outcomes included pharyngolaryngeal secretions, pneumonia, and diet recommendations. One-hundred and three patients met inclusion criteria. Fifty-one patients demonstrated an absent laryngeal adductor reflex (LAR). Altered laryngeal sensation correlated with the presence of secretions (p = 0.004). There was a significant interaction between the LAR, aspiration, and duration of mechanical ventilation. Altered laryngeal sensation was significantly associated with aspiration on FEES only in patients with a shorter length of intubation (p = 0.008). Patients with altered laryngeal sensation were prescribed significantly more restricted liquid (p = 0.03) and solid (p = 0.001) diets. No relationship was found between laryngeal sensation and pneumonia. There is a high prevalence of laryngeal sensory deficits in mechanically ventilated patients post-extubation. Altered laryngeal sensation was associated with secretions, aspiration, and modified diet recommendations especially in those patients with a shorter length of mechanical ventilation. These results demonstrate that laryngeal sensory abnormalities impact the development of post-extubation dysphagia.

Accuracy and reliability of the sensory test performed using the laryngopharyngeal endoscopic esthesiometer and rangefinder in patients with suspected obstructive sleep apnoea hypopnoea: protocol for a prospective double-blinded, randomised, exploratory study

INTRODUCTION

Patients with obstructive sleep apnoea hypopnoea syndrome (OSA) might have varying degrees of laryngopharyngeal mechanical hyposensitivity that might impair the brain's capacity to prevent airway collapse during sleep. However, this knowledge about sensory compromises in OSA comes from studies performed using methods with little evidence of their validity. Hence, the purpose of this study is to assess the reliability and accuracy of the measurement of laryngopharyngeal mechanosensitivity in patients with OSA using a recently developed laryngopharyngeal endoscopic esthesiometer and rangefinder (LPEER).

METHODS AND ANALYSIS

The study will be prospective and double blinded, with a randomised crossover assignment of raters performing the sensory tests. Subjects will be recruited from patients with suspected OSA referred for baseline polysomnography to a university hospital sleep laboratory. Intra-rater and inter-rater reliability will be evaluated using the Bland-Altman's limits of agreement plot, the intraclass correlation coefficient, and the Pearson or Spearman correlation coefficient, depending on the distribution of the variables. Diagnostic accuracy will be evaluated plotting ROC curves using standard baseline polysomnography as a reference. The sensory threshold values ​​for patients with mild, moderate and severe OSA will be determined and compared using ANOVA or the Kruskal-Wallis test, depending on the distribution of the variables. The LPEER could be a new tool for evaluating and monitoring laryngopharyngeal sensory impairment in patients with OSA. If it is shown to be valid, it could help to increase our understanding of the pathophysiological mechanisms of this condition and potentially help in finding new therapeutic interventions for OSA.

ETHICS AND DISSEMINATION

The protocol has been approved by the Institutional Review Board of Fundacion Neumologica Colombiana. The results will be disseminated through conference presentations and peer-reviewed publication.

TRIAL REGISTRATION

This trial was registered at Clinical Trials Accuracy of the sensory test using the lLaryngopharyngeal endoscopic esthesiometer in obstructive sleep apnea. Protocol ID: 201611-22405. ClinicalTrials.gov ID: NCT03109171.

Quantification of rat supraglottic laryngeal sensation threshold

OBJECTIVE

Laryngeal adductor response (LAR) to air puff is used as a reliable method in evaluating sensation thresholds (ST) in human laryngeal sensory disorders. This method has been difficult to perform in small subjects such as rodents. The aims of this study were to 1) evaluate ST to air puff under binocular microlaryngoscopy in rats to evaluate laryngeal sensory disorders, 2) determine sensory thresholds at varying target locations, and 3) determine the ideal depth of anesthesia.

STUDY DESIGN

Animal study.

METHODS

Rats were induced with ketamine/xylazine. The level of anesthesia was monitored by spontaneous glottic closure and corneal reflex testing. Air puffs were delivered to the epiglottis, arytenoid, and piriform sinus at varied pressures with pulse time kept constant. Sensation thresholds were determined by direct visualization of the larynx using a binocular microscope. Topical lidocaine was then applied to the larynx and ST was determined. Trials were repeated in a small subset of animals.

RESULTS

Twenty-six trials were performed in 14 rats. Mean STs were 39 ± 9.7 mm Hg at the epiglottis, 48.8 ± 10.5 at the arytenoid, and not detectable at the pyriform sinus. Repeated trials demonstrated consistent results. Lidocaine effectively ablated the LAR in each trial. The LAR was difficult to induce while corneal reflex was absent and was difficult to distinguish from spontaneous glottic closures while under lighter sedation.

CONCLUSION

Air pulse stimulation in rats is a simple, reliable, and effective way to determine laryngopharyngeal STs in rats and can be used as an efficient and affordable method for experimentation involving laryngeal sensory disorders.

LEVEL OF EVIDENCE

NA. Laryngoscope, 127:E265-E269, 2017.

Expiratory muscle strength training evaluated with simultaneous high-resolution manometry and electromyography

OBJECTIVE

To examine feasibility of a simultaneous high-resolution pharyngeal manometry (HRM) and electromyography (EMG) experimental paradigm to detect swallowing-related patterns of palatal, laryngeal, and pharyngeal muscle activity during expiratory training.

STUDY DESIGN

Technical report.

METHODS

Simultaneous HRM, surface submental, and intramuscular EMG were acquired in two healthy participants during five tasks: 10-cc water swallow, maximum expiratory pressure (MEP) testing, and expiratory muscle strength training (EMST) at three pressure levels (sham, 50%, and 75% MEP).

RESULTS

Experimental conditions were feasible. Velopharyngeal closing pressure, palate EMG activity, and pharyngeal EMG activity increased as expiratory load increased. In contrast, thyroarytenoid EMG activity was low during the expiratory task, consistent with glottic opening during exhalation. Submental EMG patterns were more variable during expiratory tasks. Intraluminal air pressures recorded with HRM were correlated with measured expiratory pressures and target valve-opening pressures of the EMST device.

CONCLUSION

Results suggest that a simultaneous HRM/EMG/EMST paradigm may be used to detect previously unquantified swallowing-related muscle activity during EMST, particularly in the palate and pharynx. Our approach and initial findings will be helpful to guide future hypothesis-driven studies and may enable investigators to evaluate other muscle groups active during these tasks. Defining mechanisms of action is a critical next step toward refining therapeutic algorithms using EMST and other targeted treatments for populations with dysphagia and airway disorders.

LEVEL OF EVIDENCE

4. Laryngoscope, 127:797-804, 2017.

Therapeutic intervention in oropharyngeal dysphagia

Oropharyngeal dysphagia is a frequent consequence of several medical aetiologies, and even considered part of the normal ageing process. Early and accurate identification provides the opportunity for early implementation of dysphagia treatments. This Review describes the current state of the evidence related to dysphagia therapies - focusing on treatments most clinically utilized and of current interest to researchers. Despite successes in select studies, the level of evidence to support the efficacy of these treatments remains limited. Heterogeneity exists across studies in both how interventions are administered and how their therapeutic value is assessed, thereby making it difficult to establish external validation. Future work needs to address these caveats. Also, to be most efficacious, dysphagia therapies need to account for influences from pre-morbid patient characteristics as these factors have potential to increase the risk of dysphagia and the resulting complications of aspiration, malnutrition and psychological burden. Dysphagia therapies therefore need to incorporate the medical aetiology that is at its root, the resulting swallow physiology captured from comprehensive clinical and/or instrumental assessments, and the existing needs and supports of patients.

Design, development and validation of a new laryngo-pharyngeal endoscopic esthesiometer and range-finder based on the assessment of air-pulse variability determinants

Background

Laryngo-pharyngeal mechano-sensitivity (LPMS) is involved in dysphagia, sleep apnea, stroke, irritable larynx syndrome and cough hypersensitivity syndrome among other disorders. These conditions are associated with a wide range of airway reflex abnormalities. However, the current device for exploring LPMS is limited because it assesses only the laryngeal adductor reflex during fiber-optic endoscopic evaluations of swallowing and requires a high degree of expertise to obtain reliable results, introducing intrinsic expert variability and subjectivity.

Methods

We designed, developed and validated a new air-pulse laryngo-pharyngeal endoscopic esthesiometer with a built-in laser range-finder (LPEER) based on the evaluation and control of air-pulse variability determinants and on intrinsic observer variability and subjectivity determinants of the distance, angle and site of stimulus impact. The LPEER was designed to be capable of delivering precise and accurate stimuli with a wide range of intensities that can explore most laryngo-pharyngeal reflexes.

Results

We initially explored the potential factors affecting the reliability of LPMS tests and included these factors in a multiple linear regression model. The following factors significantly affected the precision and accuracy of the test (P < 0.001): the tube conducting the air-pulses, the supply pressure of the system, the duration of the air-pulses, and the distance and angle between the end of the tube conducting the air-pulses and the site of impact. To control all of these factors, an LPEER consisting of an air-pulse generator and an endoscopic laser range-finder was designed and manufactured. We assessed the precision and accuracy of the LPEER’s stimulus and range-finder according to the coefficient of variation (CV) and by looking at the differences between the measured properties and the desired values, and we performed a pilot validation on ten human subjects. The air-pulses and range-finder exhibited good precision and accuracy (CV < 0.06), with differences between the desired and measured properties at <3 % and a range-finder measurement error of <1 mm. The tests in patients demonstrated obtainable and reproducible thresholds for the laryngeal adductor, cough and gag reflexes.

Conclusions

The new LPEER was capable of delivering precise and accurate stimuli for exploring laryngo-pharyngeal reflexes.

Laryngeal Reflexes: Physiology, Technique, and Clinical Use

This review examines the current level of knowledge and techniques available for the study of laryngeal reflexes. Overall, the larynx is under constant control of several systems (including respiration, swallowing and cough) as well as sensory motor reflex responses involving glossopharyngeal, pharyngeal, laryngeal, and tracheobronchial sensory receptors. Techniques for the clinical assessment of these reflexes are emerging and need to be examined for sensitivity and specificity in identifying laryngeal sensory disorders. Quantitative assessment methods for the diagnosis of sensory reductions and sensory hypersensitivity may account for laryngeal disorders, such as chronic cough, paradoxical vocal fold disorder, and muscular tension dysphonia. The development of accurate assessment techniques could improve our understanding of the mechanisms involved in these disorders.

Improving the Utility of Laryngeal Adductor Reflex Testing

Objectives

Evaluation of the laryngeal adductor reflex (LAR) entails delivering air through an endoscope positioned 1 to 2 mm from the arytenoid mucosa to elicit bilateral vocal fold (VF) closure. This short working distance limits visualization to only the ipsilateral arytenoid and results in quantification of a single LAR metric: threshold pressure that evokes the LAR. Our goal was to evolve the LAR procedure to optimize its utility in clinical practice and translational research.

Study Design

Prospective translational experiment.

Setting

Academic institution.

Subjects

Young healthy human adults (n = 13) and 3 groups of mice: healthy, primary aging mice (n = 5), a transgenic mouse model of amyotrophic lateral sclerosis (ALS; n = 4), and young healthy controls (n = 10).

Methods

The VFs were visualized bilaterally during supramaximal air stimulation through an endoscope. Responses were analyzed to quantify 4 novel metrics: VF adduction phase duration, complete glottic closure duration, VF abduction phase duration, and total LAR duration.

Results

The 4 LAR metrics are remarkably similar between healthy young humans and mice. Compared to control mice, aging mice have shorter glottic closure durations, whereas ALS-affected mice have shorter VF abduction phase durations.

Conclusions

We have established a new LAR protocol that permits quantification of novel LAR metrics that are translatable between mice and humans. Using this protocol, we showed that VF adduction is impaired in primary aging mice, whereas VF abduction is impaired in ALS-affected mice. These preliminary findings highlight the enhanced diagnostic potential of LAR testing.

Impact of Vagal Nerve Stimulation on Objective Vocal Quality, a Pilot Study

OBJECTIVE

The purpose of this study was to determine the impact of vagal nerve stimulation (VNS) on the vocal quality using the dysphonia severity index (DSI). It was hypothesized that the objective vocal quality and other vocal characteristics are disordered in comparison with an age- and gender-matched control group. In addition, the acoustic vocal parameters were compared during three conditions: at rest, during normal stimulation, and raised stimulation. A significant relation between the amount of stimulation and the presence of disturbed acoustic parameters was hypothesized.

METHODS

Subjective (auditory-perceptual evaluation and voice handicap index) and objective (aerodynamic, vocal range, acoustic measurements and determination of the DSI) measurements were used to determine the vocal quality in 13 subjects with VNS in three different conditions (at rest and during normal and raised stimulation) and the age- and gender-matched control group.

RESULTS

The subjects with VNS had a disordered perceptual vocal quality mainly characterized by the presence of a moderate roughness and slight breathiness, and the objective vocal quality by means of the DSI value is -2.4. During stimulation and especially during raised stimulation, the fundamental frequency is significantly increased. However, the subjects experienced no psychosocial handicapping effect of the vocal quality on the quality of life.

CONCLUSIONS

Subjects with VNS have typical vocal characteristics. Ear, nose, and throat specialists and voice therapist must be aware of the presence of this vocal pattern at rest and during normal and raised stimulation. Especially, professional voice users and elite vocal performers must be informed before implantation.

A comparison of 2 methods of endoscopic laryngeal sensory testing: a preliminary study

OBJECTIVE

This study examined the association between laryngeal sensory deficits and penetration or aspiration. Two methods of testing laryngeal sensation were carried out to determine which was more highly correlated with Penetration-Aspiration Scale (PAS) scores.

METHODS

Healthy participants and patients with dysphagia received an endoscopic swallowing evaluation including 2 sequential laryngeal sensory tests-air pulse followed by touch method. Normal/impaired responses were correlated with PAS scores.

RESULTS

Fourteen participants completed the endoscopic swallowing evaluation and both sensory tests. The air pulse method identified sensory impairment with greater frequency than the touch method (P<.0001). However, the impairment identified by the air pulse method was not associated with abnormal PAS scores (P=.46). The sensory deficits identified by the touch method were associated with abnormal PAS scores (P=.05).

CONCLUSION

Sensory impairment detected by the air pulse method does not appear to be associated with risk of penetration/aspiration. Significant laryngeal sensory loss revealed by the touch method is associated with compromised airway protection.

Multiple factors are involved in the dysarthria associated with Parkinson's disease: a review with implications for clinical practice and research

PURPOSE

Motor speech abnormalities are highly common and debilitating in individuals with idiopathic Parkinson's disease (IPD). These abnormalities, collectively termed hypokinetic dysarthria (HKD), have been traditionally attributed to hypokinesia and bradykinesia secondary to muscle rigidity and dopamine deficits. However, the role of rigidity and dopamine in the development of HKD is far from clear. The purpose of the present study was to offer an alternative view of the factors underlying HKD.

METHOD

The authors conducted an extensive, but not exhaustive, review of the literature to examine the evidence for the traditional view versus the alternative view.

RESULTS

The review suggests that HKD is a highly complex and variable phenomenon including multiple factors, such as scaling and maintaining movement amplitude and effort; preplanning and initiation of movements; internal cueing; sensory and temporal processing; automaticity; emotive vocalization; and attention to action (vocal vigilance). Although not part of the dysarthria, nonmotor factors, such as depression, aging, and cognitive-linguistic abnormalities, are likely to contribute to the overall speech symptomatology associated with IPD.

CONCLUSION

These findings have important implications for clinical practice and research.

Airway somatosensory deficits and dysphagia in Parkinson's disease

BACKGROUND

Individuals with Parkinson's disease (PD) often experience substantial impairment of swallow control, and are typically unaware of the presence or severity of their impairments suggesting that these individuals may also experience airway sensory deficits. However, the degree to which impaired swallow function in PD may relate to airway sensory deficits has yet to be formally tested.

OBJECTIVE

The purpose of this study was to examine whether airway sensory function is associated with swallow impairment in PD.

METHODS

Eighteen PD participants and 18 healthy controls participated in this study and underwent endoscopic assessment of airway somatosensory function, endoscopic assessment of swallow function, and clinical ratings of swallow and disease severity.

RESULTS

PD participants exhibited abnormal airway somatosensory function and greater swallow impairment compared with healthy controls. Swallow and sensory deficits in PD were correlated with disease severity. Moreover, PD participants reported similar self-rated swallow function as healthy controls, and swallow deficits were correlated with sensory function suggesting an association between impaired sensory function and poor self-awareness of swallow deficits in PD.

CONCLUSIONS

These results suggest that control of swallow is influenced by airway somatosensory function, that swallow-related deficits in PD are related to abnormal somatosensation, and that swallow and airway sensory function may degrade as a function of disease severity. Therefore, the basal ganglia and related neural networks may play an important role to integrate airway sensory input for swallow-related motor control. Furthermore, the airway deficits observed in PD suggest a disintegration of swallow-related sensory and motor control.

Voice-related modulation of mechanosensory detection thresholds in the human larynx

Rapidly adapting mechanoreceptors within the laryngeal mucosa provide the central nervous system with perceptual and proprioceptive afference for a variety of essential yet diverse human functions including voice sound production and airway protection. It is unknown why mechanosensory information that yields a defensive response when an individual breathes may go largely unnoticed when the individual voices. Therefore, a central question is whether there is voice-related modulation of laryngeal mechanosensory detection. Such modulation would be consistent with current models of afferent laryngeal control, and may be important to maintain fluent voice in the presence of potentially distracting sensory input. Therefore, we employed endoscopic assessment of laryngeal mechanosensory detection thresholds in ten healthy adults during tidal breathing and a voice task. We tested the hypothesis that laryngeal mechanosensory detection thresholds would be higher during the voice task. We found that thresholds were significantly higher for all participants during the voice task and that these changes were significantly more modest in women. Our findings suggest that the laryngeal sensorium may modulate mechanosensory afference to attenuate the potentially distracting influence of sensory input during voice. The finding that women maintain a greater sensitivity during the voice task than men (lower thresholds) may have important implications for the higher prevalence of sensorimotor voice disturbances in women. Our results are consistent with the presence of mechanosensory modulation in other motor systems and with observed sensory differences between women and men. Such modulation has important implications for understanding the underlying neural mechanisms of laryngeal control and how these mechanisms may operate in individuals with laryngeal disturbances.

Videofluorographic assessment of deglutitive behaviors in a rat model of aging and Parkinson disease

Dysphagia is commonly associated with aging and Parkinson disease and can have a significant impact on a person's quality of life. In some cases, dysphagia may be life-threatening. Animal models may be used to study underlying mechanisms of dysphagia, but paradigms that allow adequate imaging of the swallow in combination with measurement of physiological variables have not been forthcoming. To begin development of methods that allow this, we used videofluorography to record the deglutition behaviors of 22 Fisher 344/Brown Norway rats in young adult (9 months old), old (32 months old), and parkinsonian (unilateral lesion to the medial forebrain bundle) groups. We hypothesized that the old and parkinsonian rats would manifest deficits in deglutition behaviors analogous to those found in human clinical populations. Our results supported our hypothesis in that the old group demonstrated reductions in bolus transport speeds and mastication rate while the parkinsonian rats showed impairments in oral processing. Interpretation of these results should consider the particular animal model, lesion type, and videofluorographic protocol used in this work. Future studies will link swallow imaging data of this kind with physiological and anatomical data in a manner not possible with human participants.

Aerodynamic assessment of phonatory onset in Parkinson's disease: evidence of decreased scaling of laryngeal and respiratory control

BACKGROUND

Phonatory onset is important for speech and voice and may be substantially impaired in people with Parkinson's Disease (PD). However, the physiologic contributions of laryngeal and respiratory control to phonatory onset in PD are not well understood. Acoustic measurement of phonatory onset in neurological disease has been limited due to the confounding effects of dysarthria and the limited yield of physiologic detail.

OBJECTIVE

The purpose of this study was to test whether air flow measures would be useful to characterize respiratory and laryngeal contributions to phonatory onset, whether acoustic and air flow measures of phonatory onset were aberrant in PD, and whether deficits were significantly associated with voice severity.

METHODS

Twenty-one PD participants were tested and compared with 25 healthy controls. Testing included acoustic and air flow measures of phonatory onset during syllable production ([pa]) and measures of voice severity.

RESULTS

Air flow assessment was possible for all participants; acoustic assessment was only possible for 86% of PD participants. Air flow and acoustic measures revealed shorter phonatory onset times for PD participants than controls. Air flow measures also revealed that PD participants expelled less lung air volume per syllable. Aberrant timing of phonatory onset and reduced lung air volume were associated with increased voice severity.

CONCLUSIONS

These findings suggest that air flow measures may be useful to assess the laryngeal and respiratory contributions to phonatory onset. These results also suggest that both respiratory and laryngeal control deficits may contribute to phonatory errors in PD, and that phonatory onset deficits are associated with voice severity.

Laryngeal somatosensory deficits in Parkinson's disease: implications for speech respiratory and phonatory control

Parkinson's disease (PD) is often associated with substantial impairment of speech respiratory and phonatory control. However, the degree to which these impairments are related to abnormal laryngeal sensory function is unknown. This study examined whether individuals with PD exhibited abnormal and more asymmetric laryngeal somatosensory function compared with healthy controls, and whether these deficits were associated with disease and voice severity. Nineteen PD participants were tested and compared with 18 healthy controls. Testing included endoscopic assessment of laryngeal somatosensory function, with aerodynamic and acoustic assessment of respiratory and phonatory control, and clinical ratings of voice and disease severity. PD participants exhibited significantly abnormal and asymmetric laryngeal somatosensory function compared with healthy controls. Sensory deficits were significantly associated with timing of phonatory onset, voice intensity, respiratory driving pressure, laryngeal resistance, lung volume expended per syllable, disease severity, and voice severity. These results suggest that respiratory and phonatory control are influenced by laryngeal somatosensory function, that speech-related deficits in PD are related to abnormal laryngeal somatosensory function, and that this function may degrade as a function of disease severity. Thus, PD may represent a model of airway sensorimotor disintegration, highlighting the important role of the basal ganglia and related neural networks in the integration of laryngeal sensory input for speech-related motor control.