Early identification and treatment of communication and swallowing deficits in Parkinson disease

Stemming the Tide: The Proactive Role of Allied Health Therapy in Parkinson's Disease

Motor and nonmotor symptoms occur in early Parkinson's disease (PD), or even in the prodromal stage. Many of these symptoms can be addressed by allied health therapies, including physical therapy, occupational therapy, speech therapy, and psychological therapies. However, referrals to these services early in the disease are low. We provide a review summarizing the efficacy of proactive allied health interventions on motor and nonmotor symptoms and daily function in prodromal and early disease. We also highlight areas for additional research and provide recommendations to improve care for individuals with early PD within each discipline. We recognize the overlapping roles of the allied health disciplines and support integrated or transdisciplinary care beginning soon after diagnosis to help stem the tide in the progression of PD symptoms and disability.

Awareness of Dysphagia-Related Complications and Risks and the Importance of Early Intervention in Patients with Parkinson's Disease: A Qualitative Study

OBJECTIVE

To investigate the awareness of dysphagia-related complications and risks and the importance of early intervention in patients with Parkinson's disease (PD).

METHODS

Using the phenomenological approach of the qualitative study, 18 patients with PD in a Grade A tertiary hospital in Nantong were selected, and semistructured personal in-depth interviews were conducted. The interview content was analyzed using Colaizzi's seven-step method, and the topics and subtopics were further refined.

RESULTS

Awareness of dysphagia-related complications and risks and the importance of early intervention in patients with PD can be summarized into three topics: lack of knowledge about PD and dysphagia, changes in emotional cognition, and low need for early intervention for dysphagia.

CONCLUSIONS

Patients with PD have a low awareness of dysphagia, do not follow any preventative measures, and have difficulty in recognizing the disease symptoms; hence, there is a vital need for early intervention. Medical staff need to create awareness among patients and their families, provide health education through multiple channels, popularize the knowledge of PD complications such as dysphagia, improve patient compliance with respect to medication, regular consultation, and medical treatment, guide the transformation of negative emotions in patients to positive emotions, and help patients with PD to actively prevent dysphagia and other complications and improve their quality of life.

An integrated biometric voice and facial features for early detection of Parkinson's disease

Hypomimia and voice changes are soft signs preceding classical motor disability in patients with Parkinson's disease (PD). We aim to investigate whether an analysis of acoustic and facial expressions with machine-learning algorithms assist early identification of patients with PD. We recruited 371 participants, including a training cohort (112 PD patients during "on" phase, 111 controls) and a validation cohort (74 PD patients during "off" phase, 74 controls). All participants underwent a smartphone-based, simultaneous recording of voice and facial expressions, while reading an article. Nine different machine learning classifiers were applied. We observed that integrated facial and voice features could discriminate early-stage PD patients from controls with an area under the receiver operating characteristic (AUROC) diagnostic value of 0.85. In the validation cohort, the optimal diagnostic value (0.90) maintained. We concluded that integrated biometric features of voice and facial expressions could assist the identification of early-stage PD patients from aged controls.

Effects of Food and Liquid Properties on Swallowing Physiology and Function in Adults

Foods and liquids have properties that are often modified as part of clinical dysphagia management to promote safe and efficient swallowing. However, recent studies have questioned whether this practice is supported by the evidence. To address this, a scoping review was conducted to answer the question: "Can properties of food and liquids modify swallowing physiology and function in adults?" Online search in six databases yielded a set of 4235 non-duplicate articles. Using COVIDENCE software, two independent reviewers screened the articles by title and abstract, and 229 full-text articles were selected for full-text review. One-hundred eleven studies met the inclusion criteria for qualitative synthesis and assessment of risk of bias. Three randomized controlled trials and 108 non-randomized studies were analyzed. Large amounts of variability in instrumental assessment, properties of food and liquids, and swallowing measures were found across studies. Sour, sweet, and salty taste, odor, carbonation, capsaicin, viscosity, hardness, adhesiveness, and cohesiveness were reported to modify the oral and pharyngeal phase of swallowing in both healthy participants and patients with dysphagia. Main swallow measures modified by properties of food and liquids were penetration/aspiration, oral transit time, lingual pressures, submental muscle contraction, oral and pharyngeal residue, hyoid and laryngeal movement, pharyngeal and upper esophageal sphincter pressures, and total swallow duration. The evidence pooled in this review supports the clinical practice of food texture and liquid consistency modification in the management of dysphagia with the caveat that all clinical endeavors must be undertaken with a clear rationale and patient-specific evidence that modifying food or liquid benefits swallow safety and efficiency while maintaining quality of life.

Evaluation of the Psychometric Properties of a Newly Developed Chinese Screening Tool for Speech Disorders in Patients With Parkinson's Disease

The study aimed to analyze the psychometric properties of a newly developed Chinese screening tool, the Chinese Version of the Speech Disorders in Parkinson's Disease Questionnaire (SDPD-C). The SDPD-C contains a 24-item questionnaire with four assessment domains. Overall, 93 patients with idiopathic Parkinson's disease (PD) (age 70.1 ± 8.9 years) and 76 healthy older adults (age 67.2 ± 8.1 years) participated in the psychometric analysis study. The internal consistency of the SDPD-C was .91 (four dimensions: .69-.85), and test-retest reliability was .91 (four dimensions: .85-.88). The SDPD-C was highly correlated with the Voice Handicap Index-10 and Movement Disorder Society-Unified Parkinson's Disease Rating Scale II 2.1 (r = .83 and .78, respectively). The SDPD-C scores also differed significantly between stages 1 and 4 of the Hoehn and Yahr Scale (p < .05). The area under the receiver operating characteristic curve was .955 (95% confidence interval, .927-.983; asymptotic significance p < .001), and the optimal cut-off score of this study was 36, with a sensitivity of .849 and specificity of .947. The results indicate that SDPD-C showed good reliability, validity, accuracy, and discrimination. It can be used as a screening tool for speech disorders in patients with PD.

Vocal changes in a zebra finch model of Parkinson's disease characterized by alpha-synuclein overexpression in the song-dedicated anterior forebrain pathway

Deterioration in the quality of a person's voice and speech is an early marker of Parkinson's disease (PD). In humans, the neural circuit that supports vocal motor control consists of a cortico-basal ganglia-thalamo-cortico loop. The basal ganglia regions, striatum and globus pallidus, in this loop play a role in modulating the acoustic features of vocal behavior such as loudness, pitch, and articulatory rate. In PD, this area is implicated in pathogenesis. In animal models of PD, the accumulation of toxic aggregates containing the neuronal protein alpha-synuclein (αsyn) in the midbrain and striatum result in limb and vocal motor impairments. It has been challenging to study vocal impairments given the lack of well-defined cortico-basal ganglia circuitry for vocalization in rodent models. Furthermore, whether deterioration of voice quality early in PD is a direct result of αsyn-induced neuropathology is not yet known. Here, we take advantage of the well-characterized vocal circuits of the adult male zebra finch songbird to experimentally target a song-dedicated pathway, the anterior forebrain pathway, using an adeno-associated virus expressing the human wild-type αsyn gene, SNCA. We found that overexpression of αsyn in this pathway coincides with higher levels of insoluble, monomeric αsyn compared to control finches. Impairments in song production were also detected along with shorter and poorer quality syllables, which are the most basic unit of song. These vocal changes are similar to the vocal abnormalities observed in individuals with PD.

Gastrointestinal involvement in Parkinson's disease: pathophysiology, diagnosis, and management

Growing evidence suggests an increasing significance for the extent of gastrointestinal tract (GIT) dysfunction in Parkinson's disease (PD). Most patients suffer from GIT symptoms, including dysphagia, sialorrhea, bloating, nausea, vomiting, gastroparesis, and constipation during the disease course. The underlying pathomechanisms of this α-synucleinopathy play an important role in disease development and progression, i.e., early accumulation of Lewy pathology in the enteric and central nervous systems is implicated in pharyngeal discoordination, esophageal and gastric motility/peristalsis impairment, chronic pain, altered intestinal permeability and autonomic dysfunction of the colon, with subsequent constipation. Severe complications, including malnutrition, dehydration, insufficient drug effects, aspiration pneumonia, intestinal obstruction, and megacolon, frequently result in hospitalization. Sophisticated diagnostic tools are now available that permit more detailed examination of specific GIT impairment patterns. Furthermore, novel treatment approaches have been evaluated, although high-level evidence trials are often missing. Finally, the burgeoning literature devoted to the GIT microbiome reveals its importance for neurologists. We review current knowledge about GIT pathoanatomy, pathophysiology, diagnosis, and treatment in PD and provide recommendations for management in daily practice.

Rat Models of Vocal Deficits in Parkinson's Disease

Parkinson's disease (PD) is a progressive, degenerative disorder that affects 10 million people worldwide. More than 90% of individuals with PD develop hypokinetic dysarthria, a motor speech disorder that impairs vocal communication and quality of life. Despite the prevalence of vocal deficits in this population, very little is known about the pathological mechanisms underlying this aspect of disease. As such, effective treatment options are limited. Rat models have provided unique insights into the disease-specific mechanisms of vocal deficits in PD. This review summarizes recent studies investigating vocal deficits in 6-hydroxydopamine (6-OHDA), alpha-synuclein overexpression, DJ1-/-, and Pink1-/- rat models of PD. Model-specific changes to rat ultrasonic vocalization (USV), and the effects of exercise and pharmacologic interventions on USV production in these models are discussed.

Fidelity of the PINK1 knockout rat to oxidative stress and other characteristics of Parkinson disease

Parkinson disease (PD) is the second most common age-related neurodegenerative disease in the world, and PD significantly impacts the quality of life, especially as in general people are living longer. Because of the numerous and complex features of sporadic PD that progressively develops, it is difficult to build an ideal animal model for PD research. Genetically modified PD rodent animal models are considered as a major tool with which to study the mechanisms and potential therapeutic targets for PD. Up to now, none of the rodent animal models displays all PD characteristics. The Michael J. Fox Foundation for Parkinson's Research (MJFF) funded SAGE Laboratories to generate a PTEN-induced putative kinase-1 (PINK1) knockout (KO) rat model for familial PD using zinc finger nuclease (ZFN) technology. In the current paper, we review all papers from PubMed that report studies with PINK1 KO rats, presenting the research results, and discussing the fidelity of this rat model to PD according to its phenotypes studied by several laboratories. This review will serve as a critical reference for future studies with this rodent model, providing a better understanding of PD etiology, pathology, and potential treatment strategies.

Communication and swallowing changes, everyday impacts and access to speech-language pathology services for people with Parkinson's disease: An Australian survey

PURPOSE

To investigate people with Parkinson's disease (PwPD): 1) self-reported communication and swallowing difficulties due to Parkinson's disease (PD), 2) participation and psychosocial impacts of these difficulties and 3) experience with and access to speech-language pathology (SLP) services.

METHOD

A cross-sectional mix-methods survey was conducted using nonprobability, purposive sampling for recruitment. An inclusion criterion was that participants needed to have self-reported communication and/or swallowing changes due to PD. Descriptive statistics and thematic analysis were utilised.

RESULT

All of the 78 PwPD who participated reported changes to their communication (97%) and/or swallowing (93%). A diverse range of participation restrictions was found in social, recreational, vocational and everyday living activities. Adverse emotional impacts including frustration, loss of self-confidence, depression and isolation were reported due to these changes. Only 59% of our sample had accessed SLP services. The most common reason for PwPD not accessing services was that neither their general practitioner nor neurologist had referred them to SLP. The majority of PwPD wanted to access SLP at some point in the future. Wide variability in the SLP services provided was evident. Most of the PwPD who had received SLP support wanted further ongoing management.

CONCLUSION

This study provided insight into the everyday impacts of communication and swallowing changes experienced by PwPD, and the gap between service supply and demand.

Functional characterization of extrinsic tongue muscles in the Pink1-/- rat model of Parkinson disease

Parkinson disease (PD) is associated with speech and swallowing difficulties likely due to pathology in widespread brain and nervous system regions. In post-mortem studies of PD, pathology has been reported in pharyngeal and laryngeal nerves and muscles. However, it is unknown whether PD is associated with neuromuscular changes in the tongue. Prior work in a rat model of PD (Pink1-/-) showed oromotor and swallowing deficits in the premanifest stage which suggested sensorimotor impairments of these functions. The present study tested the hypothesis that Pink1-/- rats show altered tongue function coinciding with neuromuscular differences within tongue muscles compared to wildtype (WT). Male Pink1-/- and WT rats underwent behavioral tongue function assays at 4 and 6 months of age (n = 7–8 rats per group), which are time points early in the disease. At 6 months, genioglossus (GG) and styloglossus (SG) muscles were analyzed for myosin heavy chain isoforms (MyHC), α-synuclein levels, myofiber size, centrally nucleated myofibers, and neuromuscular junction (NMJ) innervation. Pink1-/- showed greater tongue press force variability, and greater tongue press forces and rates as compared to WT. Additionally, Pink1-/- showed relative increases of MyHC 2a in SG, but typical MyHC profiles in GG. Western blots revealed Pink1-/- had more α-synuclein protein than WT in GG, but not in SG. There were no differences between Pink1-/- and WT in myofiber size, centrally-nucleated myofibers, or NMJ innervation. α-synuclein protein was observed in nerves, NMJ, and vessels in both genotypes. Findings at these early disease stages suggest small changes or no changes in several peripheral biological measures, and intact motor innervation of tongue muscles. Future work should evaluate these measures at later disease stages to determine when robust pathological peripheral change contributes to functional change, and what CNS deficits cause behavioral changes. Understanding how PD affects central and peripheral mechanisms will help determine therapy targets for speech and swallowing disorders.

Self-perceptions of speech, voice, and swallowing in motor phenotypes of Parkinson's disease

Introduction

The ability of people with Parkinson's Disease (PWPD) to perceive and identify impairments related to communication and swallowing is often impaired. This impairment prolongs the time to diagnosis of dysphonia and dysphagia, and can delay implementation of speech or swallowing therapy. We have limited knowledge of how different motor phenotypes of PD impact speech, voice and swallowing, nor how PWPD perceive these impacts. The purpose of this study was to identify how perceptions of speech and voice impairments predict dysphagia in PD, and how those perceptions differ between motor phenotypes.

Methods

38 PWPD completed clinical surveys including V-RQOL, DHI, and a speech, voice, and swallow symptom questionnaire. Participants were categorized as either tremor dominant (TD) or non-tremor dominant (NTD) phenotypes. Multiple regression and MANOVA were utilized to identify predictors of dysphagia perceptions, and for differentiating between motor phenotype based on perceptual severity.

Results

Perceptions of speech and voice impairment predicted perceptions of swallow impairment regardless of phenotype (p < .05, CI = 0.08-0.77). NTD participants reported significantly more communication and swallowing impairments than TD (p < .05) and perceived communication impairment severity was the strongest predictor of group classification (OR = 0.50). The survey battery displayed a robust discriminatory ability between phenotype (AUC = 0.87, CI = 0.76-0.98).

Conclusion

The use of a noninvasive and cost-efficient survey battery may be useful in predicting patient perceived swallow impairment in PWPD. Speech, voice, and swallow impairments based on survey responses were found to differ between motor phenotypes.

Gene expression within the periaqueductal gray is linked to vocal behavior and early-onset parkinsonism in Pink1 knockout rats

Background

Parkinson’s disease (PD) is a degenerative disease with early-stage pathology hypothesized to manifest in brainstem regions. Vocal deficits, including soft, monotone speech, result in significant clinical and quality of life issues and are present in 90% of PD patients; yet the underlying pathology mediating these significant voice deficits is unknown. The Pink1−/− rat is a valid model of early-onset PD that presents with analogous vocal communication deficits. Previous work shows abnormal α-synuclein protein aggregation in the periaqueductal gray (PAG), a brain region critical and necessary to the modulation of mammalian vocal behavior. In this study, we used high-throughput RNA sequencing to examine gene expression within the PAG of both male and female Pink1−/− rats as compared to age-matched wildtype controls. We used a bioinformatic approach to (1) test the hypothesis that loss of Pink1 in the PAG will influence the differential expression of genes that interact with Pink1, (2) highlight other key genes that relate to this type of Mendelian PD, and (3) catalog molecular targets that may be important for the production of rat vocalizations.

Results

Knockout of the Pink1 gene resulted in differentially expressed genes for both male and female rats that also mapped to human PD datasets. Pathway analysis highlighted several significant metabolic pathways. Weighted gene co-expression network analysis (WGCNA) was used to identify gene nodes and their interactions in (A) males, (B) females, and (C) combined-sexes datasets. For each analysis, within the module containing the Pink1 gene, Pink1 itself was the central node with the highest number of interactions with other genes including solute carriers, glutamate metabotropic receptors, and genes associated with protein localization. Strong connections between Pink1 and Krt2 and Hfe were found in both males and female datasets. In females a number of modules were significantly correlated with vocalization traits.

Conclusions

Overall, this work supports the premise that gene expression changes in the PAG may contribute to the vocal deficits observed in this PD rat model. Additionally, this dataset identifies genes that represent new therapeutic targets for PD voice disorders.

Perceptual Characterization of Voice Quality in Nonadvanced Stages of Parkinson's Disease

INTRODUCTION

Parkinson's disease (PD) is a neurodegenerative disorder that impacts motor and nonmotor systems, and consequently influences voice. In later stages of the disease, people with PD develop salient hypokinetic dysarthria. However, it is unclear how extensive the voice impairment is in the nonadvanced stages of PD. Therefore, the aim of the current research was to investigate the auditory-perceptual characteristics of voice in people with Parkinson's disease (PWPD) in nonadvanced stages.

METHODS

29 PWPD and 32 healthy older controls were recruited. For each participant, a recording of the sentence "We were away a year ago" was acquired. These recordings were evaluated by 2 licensed and experienced speech-language pathologists, who provided perceptual ratings of overall dysphonia severity, breathiness, roughness, and perceived age.

RESULTS

MANCOVA analysis showed that, when controlling for age and intensity, there was a significant effect of group (P = 0.001) on perceptual voice quality. PWPD were perceived to be significantly older, more breathy and more severely dysphonic than the older healthy controls. No differences were found for the perceived roughness.

CONCLUSIONS

The results suggest that perceptual features of hypokinetic dysarthria in voice, specifically breathiness, are present in nonadvanced stages of PWPD and may contribute to listener perceptions of speaker age. Moreover, the perceptual voice profiles in PWPD showed great variability, possibly reflecting the heterogeneity of disease impact on individuals. The results of this study may inform how research targets rehabilitation and maintenance of voice and laryngeal function in PWPD at nonadvanced stages.

Communication service provision and access for people with Parkinson's disease in Australia: A national survey of speech-language pathologists

Purpose: To determine the clinical practices of Australian speech-language pathologists in the management of communication disorders in people with Parkinson's disease (PwPD) and their perspectives on service provision.Method: A cross-sectional, mix-methods online survey was conducted. Nonprobability, purposive sampling was utilised to recruit speech-language pathologists who currently work with PwPD. Descriptive statistics and thematic analysis were employed.Result: Ninety-nine clinicians responded. Most offered services for both motor speech and cognitive-communication disorders, but a greater focus on the motor speech disorder was evident. A range of impairment and functional assessments and interventions were reported. Therapy was most commonly delivered one session a week over 4 or 6 weeks. Service, client and evidence barriers in the management of both communication disorders were identified. Most clinicians felt PwPD accessed communication services at stages later than optimal, they recognised a need to improve their services in varying degrees (92.3%), and believed not enough services exist for PwPD in Australia (78%). Cognitive-communication management was the highest requested area for further research evidence.Conclusion: This study captured the current practices of Australian speech-language pathologists in the management of communication disorders in PwPD. Findings may inform future service planning, research on service effectiveness and new management targets.

Multilingual Validation of the First French Version of Munich Dysphagia Test-Parkinson's Disease (MDT-PD) in the Luxembourg Parkinson's Study

Introduction: The Munich Dysphagia Test for Parkinson's disease (MDT-PD) was initially developed and validated in the German population as a highly sensitive and specific self-reported screening questionnaire to detect early oropharyngeal symptoms and aspiration risk in patients with idiopathic Parkinson's disease (iPD). In order to make this tool accessible for prevention in the French speaking populations worldwide, we performed the first French translation and provide a linguistic and psychometric validation in the unique multilingual environment of the Luxembourg Parkinson's Study.

Methods: We performed the translation of the MDT-PD into French according to WHO guidelines and subsequently performed the linguistic validation including native speakers. For psychometric validation, 46 patients with parkinsonism from Luxembourg and the Greater Region without severe cognitive impairment were recruited in the frame of the Luxembourg Parkinson's Study. All patients were fluent in French and German completed the MDT-PD in both languages (three times in total).

Results: Linguistic and psychometric validation of the French MDT-PD was reflected by a high test-retest (10/26 questions with K > 0.6 and 10/26 with 0.4 < K ≤ 0.6) and language reliability (12/26 K > 0.6 and 8/26 0.4 < K ≤ 0.6), with an internal consistency for the French (Cronbach's alpha 0.84) and German version (0.87); strong item collinerarity strengthens the internal consistency. No significant differences between MDT-PD score distribution and clinical parameters assessing, for example, disease progression, motor state, or cognition has been observed.

Conclusion: Based on a multilingual approach in the Luxembourg Parkinson Study, we validated the translation of the first French MDT-PD as a non-invasive tool for early detection of dysphagia in patients with parkinsonism. The unexpectedly high number of positively screened patients at earlier disease stages indicate options for new prevention strategies in large French speaking populations worldwide. Diagnostic validation using clinical and endoscopic swallowing evaluation will be continued soon.

Intervention changes acoustic peak frequency and mesolimbic neurochemistry in the Pink1-/- rat model of Parkinson disease

The neural mechanisms underlying behavioral therapy for vocal acoustic deficits in patients with Parkinson disease is unknown. A primary hypothesis is that voice therapy may modulate mesolimbic brainstem regions, including the ventral tegmental area (VTA). The VTA is implicated in ultrasonic call peak frequency, involved in rewarding behaviors, and impacted by Parkinsonism. We tested the hypothesis that chronic (daily) behavioral vocal exercise of male Pink1-/- rats would alter ultrasonic vocalization acoustics and mesolimbic neurochemistry (catecholamines, GABA, mu-opioid receptor) compared to three different controls: sham-exercised Pink1-/-, unexercised Pink1-/-, and unexercised wildtype (WT) rats. A sub-hypothesis is that sham-exercise rats may exhibit changes to VTA neurochemistry as a result of a type or rewarding intervention. Results demonstrate that average bandwidth (frequency range) of ultrasonic vocalizations did not differ between WT, Pink1-/- no exercise vs. sham and vocal-exercise rats. However, average peak frequency is significantly reduced in vocal-exercised Pink1-/- rats compared to Pink1-/- no exercise, and WT groups. Unexpectedly, there were no significant acoustic differences between the vocal- and sham-exercised groups. There were no differences in catecholamine protein concentrations or tyrosine hydroxylase mRNA expression in the VTA between any of the groups. However, there was significant upregulation of all GABA-related genes in both vocal- and sham-exercised Pink1-/- rats (Gad1, Gad2, Gls, Glul); this finding was confirmed with follow up quantitative Western blotting for GAD. Additionally, there were differential results for mu-opioid receptor quantification in the VTA: vocal-exercised Pink1-/- rats showed increased mRNA expression for mu-opioid receptors whereas Western blotting indicated decreased protein levels in all Pink1-/- rats compared to WT controls suggesting the possible onset of pathology in this model. These data demonstrate modulatory effects of a rewarding behavioral paradigm on ultrasonic vocalization peak frequency. The results suggest that neuromodulators such as GABA and opioid activity, as well as the rewarding aspects of therapy may play a key role in shaping vocal treatments.

Pink1 -/- Rats Show Early-Onset Swallowing Deficits and Correlative Brainstem Pathology

Parkinson disease (PD) compromises oropharyngeal swallowing, which negatively affects quality of life and contributes to aspiration pneumonia. Dysphagia often begins early in the disease process, and does not improve with standard therapies. As a result, swallowing deficits are undertreated in the PD population. The Pink1 -/- rat is used to model PD, and demonstrates widespread brainstem neuropathology in combination with early-onset sensorimotor dysfunction; however, to date, swallowing behaviors have not been evaluated. To test the hypothesis that Pink1 -/- rats demonstrate early-onset differences in swallowing, we analyzed within-subject oropharyngeal swallowing using videofluoroscopy. Pink1 -/- and wildtype (WT) controls at 4 (Pink1 -/- n = 16, WT = 16) and 8 (Pink1 -/- n = 12, WT = 12) months of age were tested. The average and maximum bolus size was significantly increased in Pink1 -/- rats at both 4 and 8 months. Bolus average velocity was increased at 8 months for all animals; yet, Pink1 -/- animals had significantly increased velocities compared to WT at 8 months. The data show a significant reduction in mastication rate for Pink1 -/- rats at 8 months suggesting the onset of oromotor dysfunction begins at this time point. Relationships among swallowing variables and neuropathological findings, such as increased alpha-synuclein protein in the nucleus ambiguus and reductions in noradrenergic cells in the locus coeruleus in the Pink1 -/- rats, were determined. The presence of early oropharyngeal swallowing deficits and relationships to brainstem pathology in Pink1-/- rat models of PD indicate that this may be a useful model of early swallowing deficits and their mechanisms. These findings suggest clinical implications for early detection and management of dysphagia in PD.

Home-Based Orolingual Exercise Improves the Coordination of Swallowing and Respiration in Early Parkinson Disease: A Quasi-Experimental Before-and-After Exercise Program Study

Introduction: The coordination of swallowing and respiration is important for safety swallowing without aspiration. This coordination was affected in Parkinson disease (PD). A noninvasive assessment tool was used to investigate the effect of an easy-to-perform and device-free home-based orolingual exercise (OLE) program on swallowing and respiration coordination in patients with early-stage PD.

Materials and Methods: This study had a quasi-experimental before-and-after exercise program design. Twenty six patients with early-stage PD who were aged 62.12 ± 8.52 years completed a 12-week home-based OLE program. A noninvasive assessment tool was used to evaluate swallowing and respiration. For each patient, we recorded and analyzed 15 swallows (3 repeats of 5 water boluses: 1, 3, 5, 10, and 20 mL) before and after the home-based OLE program. Oropharyngeal swallowing and its coordination with respiration were the outcome measures. The frequency of piecemeal deglutition, pre- and post-swallowing respiratory phase patterns, and parameters of oropharyngeal swallowing and respiratory signals (swallowing respiratory pause [SRP], onset latency [OL], total excursion time [TET], excursion time [ET], second deflexion, amplitude, and duration of submental sEMG activity, and amplitude of laryngeal excursion) were examined.

Results: The rate of piecemeal deglutition decreased significantly when swallowing 10- and 20-mL water boluses after the program. In the 1-mL water bolus swallowing trial, the rate of protective pre- and post-swallowing respiratory phase patterns was significantly higher after the program. For the parameters of oropharyngeal swallowing and respiratory signals, only the amplitude of laryngeal excursion was significantly lower after the program. Moreover, the volume of the water bolus significantly affected the SRP and duration of submental sEMG when patients swallowed three small water bolus volumes (1, 3, and 5 mL).

Conclusion: The home-based OLE program improved swallowing and its coordination with respiration in patients with early-stage PD, as revealed using a noninvasive method. This OLE program can serve as a home-based program to improve swallowing and respiration coordination in patients with early-stage PD.

Identification of swallowing disorders in early and mid-stage Parkinson's disease using pattern recognition of pharyngeal high-resolution manometry data

BACKGROUND

Parkinson's disease (PD) can cause severe dysphagia, especially later in disease progression. Early identification of swallowing dysfunction may lead to earlier intervention. Pharyngeal high-resolution manometry (HRM) provides complementary information to videofluoroscopy, with advantages of being quantitative and objective. Artificial neural network (ANN) classification can examine non-linear relationships among multiple variables with relatively low bias. We evaluated if ANN techniques could differentiate between patients with PD and healthy controls.

METHODS

Simultaneous videofluoroscopy and pharyngeal HRM were performed on 31 patients with early to mid-stage PD and 31 age- and sex-matched controls during thin-liquid swallows of 2 cc, 10 cc and comfortable sip volume. We performed multilayer-perceptron analyses on only videofluoroscopic data, only HRM data or a combination of the two. We also evaluated variability-based parameters, representing variability in manometric parameters across multiple swallows. We hypothesized that patients with PD and controls would be classified with at least 80% accuracy, and that combined videofluoroscopic and HRM data would classify participants better than either alone.

KEY RESULTS

Classification rates were highest with all parameters considered. Maximum classification rate was 82.3 ± 5.2%, recorded for 2 cc swallows. Inclusion of variability-based parameters improved classification rates. Classification rates using only manometric parameters were similar to those using all parameters, and rates were substantially lower for the comfortable sip volumes.

CONCLUSIONS & INFERENCES

Results from these classifications highlight the differences between swallowing function in patients with early and mid-stage PD and healthy controls. Early identification of swallowing dysfunction is key to developing preventative swallowing treatments for those with PD.

Vocalization development in common marmosets for neurodegenerative translational modeling

Objectives In order to facilitate the study of vocalizations in emerging genetic common marmoset models of neurodegenerative disorders, we aimed to analyze call-type changes across age in a translational research environment. We hypothesized that acoustic parameters of vocalizations would change with age, reflecting growth of the vocal apparatus and a maturation of control needed to make adult-like calls. Methods Nineteen developing common marmosets were longitudinally video- and audio-recorded between the ages of 1-149 days in a naturalistic setting without any vocalization elicitation protocol. Vocalizations were coded for call type (cry, tsik, trill, phee, and trill-phee) and analyzed for duration (sec), minimum and maximum frequency (Hz), and bandwidth (Hz). Mixed model linear regressions were performed to assess the effects of age on call parameters listed above for each call type. Results Cries decreased in duration (P = 0.038), maximum frequency (P = 0.047), and bandwidth (P = 0.023) with age. Tsik calls decreased in duration (P = 0.002) and increased in minimum frequency (P = 0.004) and maximum frequency (P = 0.005) with age. Trill calls increased in duration (P = 0.003), and trillphee bandwidth (P = 0.031) decreased with age. Discussion Our results demonstrate that development of common marmoset vocalizations is call type dependent and that changes in acoustic parameters can be detected without complex vocalization elicitation paradigms or specialized audio recording equipment. Thus, we demonstrate the feasibility of a naturalistic protocol to collect and objectively analyze marmoset vocalizations longitudinally. This approach may be useful for studying vocal communication deficits in genetic models of neurodegenerative disorders.

Characterization of early-onset motor deficits in the Pink1-/- mouse model of Parkinson disease

In Parkinson disease (PD), a complex neurodegenerative disorder that affects nearly 10 million people worldwide, motor skills are significantly impaired. However, onset and progression of motor deficits and the neural correlates of these deficits are poorly understood. We used a genetic mouse model of PD (Pink1-/-), with phenotypic similarities to human PD, to investigate the manifestation of early-onset sensorimotor deficits. We hypothesized this mouse model would show early vocalization and gross motor dysfunction that would be progressive in nature. Pink1-/- mice, compared to wild type (WT) controls, were evaluated at 2, 3, 4, 5, and 6 months of age. To quantify deficit progression, ultrasonic vocalizations and spontaneous locomotor activity (cylinder test and pole test) were analyzed. Although somewhat variable, in general, Pink1-/- mice produced significantly more simple calls with reduced intensity as well as a larger percentage of cycle calls compared to WT counterparts. However, there were no significant differences in duration, bandwidth, or peak frequency for any of the ultrasonic call types between genotypes. Pink1-/- mice showed a significant impairment in limb motor skills with fewer hindlimb steps, forelimb steps, and rears and lands in the cylinder test compared to WT. Additionally, Pink1-/- mice took significantly longer to turn and traverse during the pole test. Immunohistochemical staining showed no significant difference in the number of tyrosine hydroxylase (TH) positive cells in the substantia nigra or density of TH staining in the striatum between genotypes. These data suggest the Pink1-/- mouse model may be instrumental in defining early motor biomarkers of PD in the absence of nigrostriatal dopamine loss.

Characterization of oromotor and limb motor dysfunction in the DJ1 -/- model of Parkinson disease

Parkinson disease (PD) is devastating to sensorimotor function that includes cranial/oromotor and limb motor deficits. However, the onset, progression, and neural correlates of PD-related dysfunctions are poorly understood. To address this gap, we used a genetic rat model of PD, DJ1 -/-, and hypothesized that motor deficits would manifest early in the disease process, be progressive in nature, and be related to pathologies in brainstem structures associated with sensorimotor function. The present study compares homozygous DJ1 -/- male rats to age-matched wild type controls. Progressive cranial sensorimotor function (ultrasonic vocalizations and tongue motor performance) and limb motor function (tapered balance beam) was analyzed at 2, 4, 6, and 8 months of age. Additionally, tyrosine hydroxylase cell counts were performed in the locus coeruleus and correlated to behavioral measures. We found that compared to wild type controls, DJ1 -/- show deficits in ultrasonic vocalizations as well as oromotor (tongue) deficits that were progressive. Overtime, DJ1 -/- rats cross a tapered balance beam with significantly decreased speed of traversal. Additionally, in the DJ1 -/-, tyrosine hydroxylase positive cells in the locus coeruleus are significantly reduced and are negatively correlated to oromotor behaviors. Characterizing the DJ1 -/- model of PD provides important foundational work necessary to define behavioral and early-onset biomarkers that parallels early-stage PD pathology in humans.

Therapeutic singing as an early intervention for swallowing in persons with Parkinson's disease

OBJECTIVE

For persons with Parkinson's disease (PD), secondary motor symptoms such as swallow impairment impact the quality of life and are major contributors to mortality. There is a present need for therapeutic interventions aimed at improving swallow function during the early stages of PD. The purpose of this pilot study was to examine the effects of a group therapeutic singing intervention on swallowing in persons with PD with no significant dysphagia symptoms.

DESIGN

Cohort study.

SETTING

University in the United States.

PARTICIPANTS

Twenty-four participants with PD.

INTERVENTION

Eight weeks of group therapeutic singing.

MAIN OUTCOME MEASURES

Electromyography (EMG) was used to assess muscle activity associated with swallow pre and post the group singing intervention. Swallow quality of life (SWAL-QOL) and the Unified Parkinson's Disease Rating Scale (UPDRS) were also obtained pre- and post-intervention.

RESULTS

Participants reported minimal difficulty with swallowing, yet results revealed a significant increase in EMG outcome measures, as well as significant improvement in UPDRS total and UPDRS motor scores. No significant differences were revealed for SWAL-QOL.

CONCLUSION

Increases in EMG timing measures may suggest that group singing results in the prolongation of laryngeal elevation, protecting the airway from foreign material for longer periods of time during swallow. Combined with the improvement in UPDRS clinical measures, therapeutic singing may be an engaging early intervention strategy to address oropharyngeal dysphagia while also benefiting additional clinical symptoms of PD.

Multimodal Swallowing Evaluation with High-Resolution Manometry Reveals Subtle Swallowing Changes in Early and Mid-Stage Parkinson Disease

BACKGROUND

Parkinson disease (PD) has detrimental effects on swallowing function. Treatment options are largely behavioral; thus, patients would benefit from an earlier start to therapy. Early swallowing changes in PD are not well-known, so patients do not typically receive swallowing treatment until later in the progression of PD.

OBJECTIVE

We used predictive modeling to determine what quantitative swallowing variables best differentiate individuals with early to mid-stage PD from healthy controls.

METHODS

Participants included twenty-six individuals with early to mid-stage PD and 26 healthy, age- and sex-matched controls. Swallowing was evaluated by simultaneous high-resolution manometry and videofluoroscopy as well as the Sydney Swallow Questionnaire (SSQ). Binomial logistic regression was performed on 4 sets of data: 1) high-resolution manometry only; 2) videofluoroscopy only; 3) SSQ only; and 4) all data combined.

RESULTS

A model from a combined data set had the highest accuracy in differentiating individuals with PD from controls. The model included maximum pressure in the velopharynx (soft palate), pressure variability in the velopharynx, and the SSQ item concerning difficulty with swallowing saliva. No significant models could be generated using the videofluoroscopy data.

CONCLUSIONS

Individuals with PD show quantitative changes in pressure generation and are able to self-assess aspects of swallowing function in the early and mid-stages of PD, even in the absence of swallowing changes seen on videofluoroscopy. A multimodal approach for the assessment of swallowing may be more accurate for determining subtle swallowing changes that occur in the early stages of PD.

Atp13a2 expression in the periaqueductal gray is decreased in the Pink1 -/- rat model of Parkinson disease

Vocal communication deficits are common in Parkinson disease (PD). Widespread alpha-synuclein pathology is a common link between familial and sporadic PD, and recent genetic rat models based on familial genetic links increase the opportunity to explore vocalization deficits and their associated neuropathologies. Specifically, the Pink1 knockout (-/-) rat presents with early, progressive motor deficits, including significant vocal deficits, at 8 months of age. Moreover, this rat model exhibits alpha-synuclein pathology compared to age-matched non-affected wildtype (WT) controls. Aggregations are specifically dense within the periaqueductal gray (PAG), a brainstem region involved in the coordination of emotional and volitional control of vocalizations. Here, we investigated changes in gene expression within the PAG at 8 months of age in Pink1 -/- rats compared to WT. Our data demonstrate that Pink1 -/- rat mRNA expression levels of alpha-synuclein are comparable to WT. However, Pink1 -/- rats show significantly decreased levels of Atp13a2, a transmembrane lysosomal P5-type ATPase suggesting a potential mechanism for the observed abnormal aggregation. We found no difference in the expression of glucocerebrosidase (Gba) or the CASP8 and FADD-like apoptosis regulator (Cflar). Further, we show that mRNA expression levels of dopaminergic markers including Th, D1 and D2 receptor as well as GABA signaling markers including Gaba-A and glutamate decarboxylase 2 (Gad2) do not differ between genotypes. However, we found that glutamate decarboxylase 1 (Gad1) is significantly reduced in this PD model suggesting possible disruption of neurotransmission within the PAG. These results are the first to suggest the hypothesis that alpha-synuclein aggregation in this model is not a result of increased transcription, but rather a deficit in the breakdown and clearance, and that the observed vocal deficits may be related to impaired neural transmission. Altogether, these findings are consistent with the hypothesis that differences in neural substrate sensitivity contribute to the early pathogenesis of vocalizations and motivation to communicate in the Pink1 -/- rat model of PD. Our results suggest novel therapeutic pathways, including the lysosomal degradation pathway, which can be used in to further study the pathogenesis and treatment of vocal dysfunction PD.

Vocal training, levodopa, and environment effects on ultrasonic vocalizations in a rat neurotoxin model of Parkinson disease

Levodopa does not improve dysarthria in patients with Parkinson Disease (PD), although vocal exercise therapy, such as "LSVT/LOUD(®)", does improve vocal communication. Most patients receive vocal exercise therapy while concurrently being treated with levodopa, although the interaction between levodopa and vocal exercise therapy on communication in PD is relatively unknown. Further, carryover of vocal exercise therapy to novel situations is critical for successful outcomes, but the influence of novel situations on rehabilitated vocal communication is not well understood. To address the influence of exercise, medications, and environment on vocal communication with precise experimental control, we employed the widely used 6-OHDA rat neurotoxin model of PD (infusion to the medial forebrain bundle), and assessed ultrasonic vocalizations after: vocal exercise, vocal exercise with levodopa, levodopa alone, and control conditions. We tested USVs in the familiar training environment of the home cage and a novel cage. We hypothesized that parkinsonian rats that undergo vocal exercise would demonstrate significant improvement of ultrasonic vocalization (USV) acoustic parameters as compared to the control exercise and levodopa-only treatment groups. We further hypothesized that vocal exercise in combination with levodopa administration, similar to what is common in humans, would lead to improvement in USV outcomes, particularly when tested in a familiar versus a novel environment. We found that the combination of exercise and levodopa lead to some improvement in USV acoustic parameters and these effects were stronger in a familiar vs. a novel environment. Our results suggest that although treatment can improve aspects of communication, environment can influence the benefits of these effects.

Biofeedback eletromiográfico no tratamento das disfunções orofaciais neurogênicas: revisão sistemática de literatura

RESUMO Objetivo Investigar se o uso do biofeedback eletromiográfico na terapia voltada às funções orofaciais (expressão facial, mastigação, deglutição, fonação e fala) produz efeitos benéficos para os indivíduos com doenças neurológicas. Estratégia de pesquisa Foi realizada busca nas bases de dados MEDLINE, LILACS e SciELO, por meio dos descritores “electromyographic biofeedback”, “swallowing”, “speech” “chewing”, “phonation”, e “facial expression”. A busca nas bases de dados e a seleção dos artigos foram realizadas independentemente, por duas pesquisadoras e, nos casos de não concordância, houve discussão fundamentada nos critérios de inclusão e exclusão para que chegassem a um consenso. Critérios de seleção Foram incluídos estudos experimentais em seres humanos, em inglês e português, que descreveram e discutiram a utilização do biofeedback eletromiográfico no tratamento das alterações das funções orofaciais provenientes de doenças neurológicas. Resultados Foram encontrados 175 artigos, sendo que somente 10 se adequaram aos critérios de inclusão. A maioria dos trabalhos relacionou-se a estudo de caso, seguido por estudos de série de casos, caso controle e ensaio clínico randomizado. A maior parte dos artigos abordou a aplicação da terapia com biofeedback eletromiográfico na função da deglutição, seguida da função da fala e apenas um artigo utilizou esta modalidade de tratamento na terapia para melhora da expressão facial. Não foram encontrados estudos que abordassem o tratamento fonoaudiológico utilizando o biofeedback eletromiográfico em pacientes com doenças neurológicas, nas funções de fonação e mastigação. Conclusão O uso do biofeedback eletromiográfico na terapia voltada às funções orofaciais pode produzir efeitos benéficos para os indivíduos com doenças neurológicas, nas funções de deglutição, fala e expressão facial.

Optimising medication for Parkinson's disease patients with dysphagia

In addition to movement disorders, Parkinson's disease (PD) is associated with several nonmotor symptoms, including dysphagia (swallowing difficulties). Dysphagia can make the consumption of solid medicines difficult, which potentially contributes to the poor adherence that is common among people with PD. However, patients may be reluctant to admit that they experience dysphagia. Community nurses should actively enquire into swallowing difficulties among all patients, not only those with PD, and should work with pharmacists and other members of the multidisciplinary team to help optimise medication management to help improve adherence.

Evidence for early and progressive ultrasonic vocalization and oromotor deficits in a PINK1 gene knockout rat model of Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disease that leads to a wide range of motor and nonmotor deficits. Specifically, voice and swallow deficits manifest early, are devastating to quality of life, and are difficult to treat with standard medical therapies. The pathological hallmarks of PD include accumulation of the presynaptic protein α-synuclein (αSyn) as well as degeneration of substantia nigra dopaminergic neurons. However, there is no clear understanding of how or when this pathology contributes to voice and swallow dysfunction in PD. The present study evaluates the effect of loss of function of the phosphatase and tensin homolog-induced putative kinase 1 gene in rats (PINK1(-/-) ), a model of autosomal recessive PD in humans, on vocalization, oromotor and limb function, and neurodegenerative pathologies. Behavioral measures include ultrasonic vocalizations, tongue force, biting, and gross motor performance that are assayed at 2, 4, 6, and 8 months of age. Aggregated αSyn and tyrosine hydroxylase immunoreactivity (TH-ir) were measured at 8 months. We show that, compared with wild-type controls, PINK1(-/-) rats develop (1) early and progressive vocalization and oromotor deficits, (2) reduced TH-ir in the locus coeruleus that correlates with vocal loudness and tongue force, and (3) αSyn neuropathology in brain regions important for cranial sensorimotor control. This novel approach of characterizing a PINK1(-/-) genetic model of PD provides the foundational work required to define behavioral biomarkers for the development of disease-modifying therapeutics for PD patients.

Evidence for early and progressive ultrasonic vocalization and oromotor deficits in a PINK1 gene knockout rat model of Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disease that leads to a wide range of motor and nonmotor deficits. Specifically, voice and swallow deficits manifest early, are devastating to quality of life, and are difficult to treat with standard medical therapies. The pathological hallmarks of PD include accumulation of the presynaptic protein α-synuclein (αSyn) as well as degeneration of substantia nigra dopaminergic neurons. However, there is no clear understanding of how or when this pathology contributes to voice and swallow dysfunction in PD. The present study evaluates the effect of loss of function of the phosphatase and tensin homolog-induced putative kinase 1 gene in rats (PINK1(-/-) ), a model of autosomal recessive PD in humans, on vocalization, oromotor and limb function, and neurodegenerative pathologies. Behavioral measures include ultrasonic vocalizations, tongue force, biting, and gross motor performance that are assayed at 2, 4, 6, and 8 months of age. Aggregated αSyn and tyrosine hydroxylase immunoreactivity (TH-ir) were measured at 8 months. We show that, compared with wild-type controls, PINK1(-/-) rats develop (1) early and progressive vocalization and oromotor deficits, (2) reduced TH-ir in the locus coeruleus that correlates with vocal loudness and tongue force, and (3) αSyn neuropathology in brain regions important for cranial sensorimotor control. This novel approach of characterizing a PINK1(-/-) genetic model of PD provides the foundational work required to define behavioral biomarkers for the development of disease-modifying therapeutics for PD patients.

Changes in Rat 50-kHz Ultrasonic Vocalizations During Dopamine Denervation and Aging: Relevance to Neurodegeneration

Vocal communication is negatively affected by neurodegenerative diseases, such as Parkinson disease, and by aging. The neurological and sensorimotor mechanisms underlying voice deficits in Parkinson disease and aging are not well-understood. Rat ultrasonic vocalizations provide a unique behavioral model for studying communication deficits and the mechanisms underlying these deficits in these conditions. The purpose of this review was to examine the existing literature for methods using rat ultrasonic vocalization with regard to the primary disease pathology of Parkinson disease, dopamine denervation, and aging. Although only a small amount of papers were found for each of these topics, results suggest that both shared and unique acoustic deficits in ultrasonic vocalizations exist across conditions and that these acoustic deficits are due to changes in either dopamine signaling or denervation and in aging models changes to the nucleus ambiguus, at the level of the neuromuscular junction, and the composition of the vocal folds in the larynx. We conclude that ultrasonic vocalizations are a useful tool for studying biologic mechanisms underlying vocal communication deficits in neurodegenerative diseases and aging.

Exercise Effects on Early Vocal Ultrasonic Communication Dysfunction in a PINK1 Knockout Model of Parkinson's Disease

BACKGROUND

Parkinson's disease (PD) is a complex neurodegenerative disease with vocal communication deficits that manifest early, progress, and are largely resistant to medical interventions; however, they do respond to exercise-based speech and voice therapies.

OBJECTIVE AND METHODS

To study how exercise-based vocal treatment can affect the progression of communication deficits related to PD, we studied ultrasonic vocalizations (USVs) in rats with homozygous knockout (-/-) of PINK1, a gene mutation known to cause PD, under the manipulation of a behavioral vocal exercise paradigm that allows us to precisely control dose and timing of exercise in the prodromal (prior to diagnosis) stages.

RESULTS

We show that intensive vocal-training rescues frequency range and intensity deficits as well as leads to an increase in call complexity and duration of calls compared to sham-training; however, over time this training regime loses significant effect as the disease progresses. We also show effects of frequent handling and conspecific (male-female) interaction in the sham-training group as they demonstrated significantly higher call rate, intensity, frequency range, and call complexity compared to rats without any form of training and consequently less handling/interaction. Further, we confirm that this model exhibits progressive gross motor deficits that indicate neurodegeneration.

DISCUSSION

This study suggests that the evolving nature of vocal communication deficits requires an adjustment of therapy targets and more intensive training over the course of this progressive disease and demonstrates the importance of frequent social experiences.