Parkinsonian dysarthria: an aerodynamic and perceptual description of velopharyngeal closure for speech

Research-based Updates in Swallowing and Communication Dysfunction in Parkinson Disease: Implications for Evaluation and Management

PURPOSE

Individuals with Parkinson disease (PD) present with complex and variable symptoms, with recent findings suggesting that the etiology of PD extends beyond the involvement of just the basal ganglia. These symptoms include significant impairments in the speech and swallowing domains, which can greatly affect quality of life and therefore require therapeutic attention. This research-based update reviews the neurophysiological basis for swallowing and speech changes in PD, the effectiveness of various types of treatments, and implications for symptom evaluation and management.

CONCLUSION

The mechanisms responsible for swallowing and speech symptoms in PD remain largely unknown. Dopaminergic medication and deep-brain-stimulation do not provide consistent benefits for these symptoms suggesting a non-dopaminergic network is involved. Importantly, evidence suggests that symptoms of dysphagia and hypokinetic dysarthria may be early indications of PD, so it is critical to investigate the cause of these changes.

Perceptions of Audible Nasal Emission in Speakers with Cleft Palate: A Comparative Study of Listener Judgments

Objective

Audible nasal emission is a common speech distortion observed in persons with cleft palate. This study examined the validity and reliability of perceptual judgments of audible nasal emission using interval scaling and magnitude estimation techniques.

Participants

Speech samples were collected from six adolescents with repaired cleft palate, all of whom demonstrated audible nasal emission. A total of 31 adults performed rating tasks in which they judged the severity of audible nasal emission in speech samples.

Measures

Occurrences of audible nasal emission in speech samples were identified using visual and auditory inspection. Using an acoustic modification technique, samples were digitally modified to amplify perceived occurrences of audible nasal emission to create three stimulus conditions. The original recording of the speech samples served as a control condition. The severity of audible nasal emission in the samples was judged by multiple listeners using interval scaling and magnitude estimation without a modulus. Statistical analysis included analysis of variance, regression, and curve-fitting methods.

Results

Magnitude-estimation ratings demonstrated stronger evidence of validity and reliability than interval scaling. A curvilinear relationship was found between the sets of ratings.

Conclusions

The results of this study suggest that audible nasal emission may be a prothetic or ratio-level perceptual continua. Listeners should consider using magnitude estimation or other ratio-based methods for perceptual judgments of audible nasal emission.

Subthalamic nucleus deep brain stimulation changes velopharyngeal control in Parkinson's disease

PURPOSE

Adequate velopharyngeal control is essential for speech, but may be impaired in Parkinson's disease (PD). Bilateral subthalamic nucleus deep brain stimulation (STN DBS) improves limb function in PD, but the effects on velopharyngeal control remain unknown. We tested whether STN DBS would change aerodynamic measures of velopharyngeal control, and whether these changes were correlated with limb function and stimulation settings.

METHODS

Seventeen PD participants with bilateral STN DBS were tested within a morning session after a minimum of 12h since their most recent dose of anti-PD medication. Testing occurred when STN DBS was on, and again 1h after STN DBS was turned off, and included aerodynamic measures during syllable production, and standard neurological ratings of limb function.

RESULTS

We found that PD participants exhibited changes with STN DBS, primarily consistent with increased intraoral pressure (n=7) and increased velopharyngeal closure (n=5). These changes were modestly correlated with measures of limb function, and were correlated with stimulation frequency.

CONCLUSION

Our findings suggest that STN DBS may change velopharyngeal control during syllable production in PD, with greater benefit associated with low frequency stimulation. However, DBS demonstrates a more subtle influence on speech-related velopharyngeal control than limb motor control. This distinction and its underlying mechanisms are important to consider when assessing the impact of STN DBS on PD.

LEARNING OUTCOMES

As a result of this activity, the participant will be able to (1) describe the effects of deep brain stimulation on limb and speech function; (2) describe the effects of deep brain stimulation on velopharyngeal control; and (3) discuss the possible reasons for differences in limb outcomes compared with speech function with deep brain stimulation of the subthalamic nucleus.

Effects of loud and amplified speech on sentence and word intelligibility in Parkinson disease

PURPOSE

In the two experiments in this study, the author examined the effects of increased vocal effort (loud speech) and amplification on sentence and word intelligibility in speakers with Parkinson disease (PD). Methods Five talkers with PD produced sentences and words at habitual levels of effort and using loud speech techniques. Amplified sets of sentences and words were created by increasing the intensity of habitual stimuli to the level of loud stimuli. Listeners rated the intelligibility of the 3 sets of sentences on a 1-7 scale and transcribed the 3 sets of words.

RESULTS

Both loud speech and amplification significantly improved intelligibility for sentences and words. Loud speech resulted in greater intelligibility improvement than amplification.

CONCLUSIONS

By comparing loud and amplified scores, about one third to one half of intelligibility improvement with loud speech could be attributed to increases in audibility or signal-to-noise ratio. Thus, factors other than increased intensity must be partly responsible for the loud speech benefit. Changes in articulation appear to play a relatively small role: Initial/h/was the only consonant to consistently show improvement with loud speech. Phonatory changes such as improvements in F(0) and spectral tilt may account for improved speech intelligibility using loud speech techniques.

Speech treatment for Parkinson's disease

Researchers estimate that 89% of people with Parkinson's disease (PD) have speech and voice disorders including disorders of laryngeal, respiratory and articulatory function. Despite the high incidence of speech and voice impairment, studies suggest that only 3-4% of people with PD receive speech treatment. Here, we review the literature on the characteristics and features of speech and voice disorders in people with PD and the types of treatment techniques available (medical, surgical and behavioral), with a focus on behavioral therapies. We provide a summary of the current status of the field of speech treatment in PD and recommendations for implementation of the current efficacy of treatment interventions. Directions for future research, including a speculative viewpoint on how the field will evolve in 5 years time, are discussed.

Análise vocal (auditiva e acústica) nas disartrias

TEMA: as disfonias neurológicas são comuns nas disartrias e desempenham um importante papel no diagnóstico diferencial. A análise acústica da voz é importante para o entendimento dos distúrbios motores presentes nas disartrias. OBJETIVO: descrever auditiva e acusticamente a voz nos diferentes tipos de disartria. MÉTODO: 42 pacientes disártricos, 21 do sexo masculino e 21 do sexo feminino foram submetidos à análise perceptual-auditiva e acústica. Todos os pacientes foram submetidos à gravação da voz, tendo sido avaliados, na análise auditiva, tipo de voz, ressonância (equilibrada, hipernasal ou laringo-faríngea), loudness (adequado, diminuído ou aumentado), pitch (adequado, grave, agudo) ataque vocal (isocrônico, brusco ou soproso), e estabilidade (estável ou instável). Para a análise acústica foram utilizados os programas GRAM 5.1.7 para a análise da qualidade vocal e comportamento dos harmônicos na espectrografia e o Programa Vox Metria, para a obtenção das medidas objetivas. RESULTADOS: na análise auditiva os dados indicam que a voz rouca e soprosa foi a qualidade vocal mais presente, ressonância laringo-faríngea e instabilidade na emissão. Na acústica: traçado espectrográfico instável, ausência dos harmônicos superiores e presença de ruído entre os harmônicos e tempos máximos de fonação diminuídos. As medidas de Jitter, Shimmer e Glottal to Noise Excitation Ratio foram alteradas em todas disartrias. CONCLUSÃO: a análise acústica, complementar à perceptual-auditiva, auxilia no diagnóstico clínico das disartrias.

Direct magnitude estimation and interval scaling of hypernasality

Hypernasality is most commonly assessed using equal-appearing interval (EAI) scaling. Recently, the validity of EAI scaling for the evaluation of hypernasality has been questioned. The issue of validity rests on the psychophysical nature of the dimension to be rated. The purpose of this study was to compare EAI scaling with direct magnitude estimation (DME), in order to determine whether EAI scaling is a valid procedure for the evaluation of hypernasality. Connected speech samples from 20 individuals with repaired cleft palate and hypernasality were used. Twenty listeners undertook the listening tasks, which included EAI scaling, DME with modulus (DME-M), and DME without modulus (DME-WM). The results showed a curvilinear relationship between EAI and DME-M and between EAI and DME-WM, suggesting that EAI may not be a valid method for the evaluation of hypernasality; DME is recommended.

Nasal airflow patterns during the velopharyngeal closing phase in speech in children with and without cleft palate

OBJECTIVES

(1) To study the nasal airflow patterns during the velopharyngeal closing phase in speech produced by children with and without cleft palate. (2) To compare the nasal airflow patterns in bilabial, dental, and velar articulation in these children.

DESIGN

Prospective, cross-sectional study of a consecutive series of children with cleft palate referred for routine speech evaluation and controls.

SETTING

Sahlgrenska University Hospital, Göteborg, Sweden.

PARTICIPANTS

Seventeen children with cleft lip and palate or cleft palate only and 22 controls aged 7 and 10 years.

METHOD

Nasal airflow was transduced with a pneumotachograph attached to a nose mask and registered together with the acoustic speech signal. Sentences containing nasal-to-stop combinations in bilabial, dental, and velar articulatory positions were used.

MAIN OUTCOMES MEASURES

The duration from peak to 5% nasal airflow, the maximum flow declination rate, and the nasal airflow at selected points in time during the transition from nasal-to-stop consonants.

RESULTS

In the cleft palate group, duration from peak to 5% nasal airflow was clearly longer than among the controls (p <.0001). The declination of airflow was slower (p <.006) and the rate of nasal airflow at the release of the stop consonant was higher (p <.004) in the cleft palate group. Differences between bilabial versus dental and velar articulation were found in the control group.

CONCLUSION

Studies of the temporal and dynamic characteristics of the nasal airflow variations during speech appear potentially useful for the assessment of velopharyngeal function.

Changes in vocal intensity in Parkinson's disease following pallidotomy surgery

The present study was designed to examine changes in vocal intensity following unilateral posteroventral pallidotomy (PVP) in a large sample of speakers with Parkinson's disease (PD) that exhibited a range of hypokinetic dysarthria. Twenty-five persons with PD were recorded using a variety of speech tasks, once prior to and once following PVP. The pre-PVP vocal SPL was subtracted from the post-PVP vocal SPL to derive a relative change in vocal SPL. Mildly dysarthric participants had significantly greater relative increases in vocal SPL following PVP than either moderately or severely dysarthric participants who had reduced vocal SPL following PVP. If future results follow those observed in the present data, mildly dysarthric Parkinson's patients may benefit most from unilateral PVP perhaps due to less overall destruction of the basal ganglia sensorimotor control circuits involved in oral facial functions, thus increasing the chances to observe improvements postsurgery.

Effects of speech therapy and pharmacologic and surgical treatments on voice and speech in Parkinson's disease: a review of the literature

The purpose of this review was to examine the different treatment approaches for persons with Parkinson's Disease (PD) and to examine the effects of these treatments on speech. Treatment methods reviewed include speech therapy, pharmacological, and surgical. Research from the 1950s through the 1970s had not demonstrated significant improvements following speech therapy. Recent research has shown that speech therapy (when persons with PD are optimally medicated) has proven to be the most efficacious therapeutic method for improving voice and speech function. Pharmacological methods of treatment in isolation do not appear to significantly improve voice and speech function in PD across research studies. Surgical treatment methods including pallidotomy and deep brain stimulation may be significant treatment options which improve voice and speech function in some persons with PD. Possible explanations for the differential responses to treatment are discussed. Future studies should investigate the effects of combined treatment approaches. Perhaps the combination of pharmacological, surgical and speech treatment will prove superior to treatments combining pharmacological and surgical or pharmacological and speech therapy in improving the communication abilities of persons with PD.

Variability in the perceptual and physiological features of dysarthria following severe closed head injury: an examination of five cases

The perceptual and physiological features of the dysarthric speech of five severely closed-head-injured (CHI) subjects were examined in a case-by-case analysis. The five male CHI subjects included in the study were selected to reflect the range of severity and types of dysarthria evident in the CHI population. The perceptual profiles of each subject consisted of the findings of a perceptual speech analysis, the Frenchay Dysarthria Assessment (FDA) and the Assessment of the Intelligibility of Dysarthric Speakers (ASSIDS). The subjects' physiological profiles included the results of instrumental assessments of the respiratory, laryngeal, velopharyngeal and articulatory subsystems of the speech-production mechanism. The case studies highlighted the variability among the individual subjects with respect to the location, physiological nature, and severity of impairment in their speech-production mechanisms. In addition, the interdependence of the various speech subsystems in determining speech outcome, the presence of differential subsystem impairment in dysarthria following CHI, and the varied therapeutic requirements of the individual subjects were identified. Clinically, the case studies highlighted the importance of developing individual treatment programmes based on comprehensive perceptual and physiological evaluations of the speech mechanism in each CHI subject with dysarthric speech.

Laryngeal dysfunction in dysarthric speakers following severe closed-head injury

The laryngeal function of 19 severely closed head-injured subjects with a perceptible dysarthria was assessed using electrolaryngography and a computerized airflow/air pressure analysis system (Aerophone II). Variables measured included parameters of the Lx waveform (Fo, duty cycle and closing time) as well as aerodynamic parameters such as subglottal pressure, glottal resistance, average phonatory sound pressure level, phonatory flow rate and ad/abduction rate. Values were compared to those recorded from a non-neurologically impaired control group matched for age and sex, and correlated with the findings of a perceptual speech analysis. The findings are discussed in relation to the effects of a severe closed-head injury on laryngeal function. The clinical implications of the findings for the assessment and treatment of vocal dysfunction in head-injured subjects are also discussed.

Perceptual speech characteristics of dysarthric speakers following severe closed head injury

The perceptual speech characteristics of a group of 20 severely closed head-injured (CHI) subjects were compared with those of a normal non-neurologically impaired control group matched for age and sex. The CHI subjects were found to be significantly less intelligible than the controls, and exhibited deficits in the prosodic, resonatory, articulatory, respiratory and phonatory aspects of speech production. The most frequently occurring deviant speech dimensions related to disturbances of prosody, resonance, articulation and respiration, with those deviant speech dimensions pertaining to phonation being less apparent in the speech of the CHI subjects. The findings are discussed in relation to the heterogeneity of the CHI population and the effects of CHI on neuromuscular function. The study highlights the need for accurate, instrumental physiological evaluation of the motor subsystems involved in speech production.