Treatment of dysarthria following subthalamic nucleus deep brain stimulation for Parkinson's disease

Behavioral Management of Respiratory/Phonatory Dysfunction for Dysarthria Associated With Neurodegenerative Disease: A Systematic Review

PURPOSE

This systematic review represents an update to previous reviews of the literature addressing behavioral management of respiratory/phonatory dysfunction in individuals with dysarthria due to neurodegenerative disease.

METHOD

Multiple electronic database searches and hand searches of prominent speech-language pathology journals were conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses standards.

RESULTS

The search yielded 1,525 articles, from which 88 met inclusion criteria and were reviewed by two blinded co-investigators. A large range of therapeutic approaches have been added to the evidence base since the last review, including expiratory muscle strength training, singing, and computer- and device-driven programs, as well as a variety of treatment modalities, including teletherapy. Evidence for treatment in several different population groups-including cerebellar ataxia, myotonic dystrophy, autosomal recessive spastic ataxia of Charlevoix-Saguenay, Huntington's disease, multiple system atrophy, and Lewy body dementia-were added to the current review. Synthesis of evidence quality provided strong evidence in support of only one behavioral intervention: Lee Silverman Voice Treatment Program (LSVT LOUD) in people with Parkinson's disease. No other treatment approach or population included in this review demonstrated more than limited evidence, reflecting that these approaches/populations require urgent further examination.

CONCLUSION

Suggestions about where future research efforts could be significantly strengthened and how clinicians can apply research findings to their practice are provided.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.24964473.

Effects of deep brain stimulation of the subthalamic nucleus on patients with Parkinson's disease: a machine-learning voice analysis

Introduction

Deep brain stimulation of the subthalamic nucleus (STN-DBS) can exert relevant effects on the voice of patients with Parkinson's disease (PD). In this study, we used artificial intelligence to objectively analyze the voices of PD patients with STN-DBS.

Materials and methods

In a cross-sectional study, we enrolled 108 controls and 101 patients with PD. The cohort of PD was divided into two groups: the first group included 50 patients with STN-DBS, and the second group included 51 patients receiving the best medical treatment. The voices were clinically evaluated using the Unified Parkinson's Disease Rating Scale part-III subitem for voice (UPDRS-III-v). We recorded and then analyzed voices using specific machine-learning algorithms. The likelihood ratio (LR) was also calculated as an objective measure for clinical-instrumental correlations.

Results

Clinically, voice impairment was greater in STN-DBS patients than in those who received oral treatment. Using machine learning, we objectively and accurately distinguished between the voices of STN-DBS patients and those under oral treatments. We also found significant clinical-instrumental correlations since the greater the LRs, the higher the UPDRS-III-v scores.

Discussion

STN-DBS deteriorates speech in patients with PD, as objectively demonstrated by machine-learning voice analysis.

Repetitive transcranial magnetic stimulation for hypokinetic dysarthria in Parkinson's disease enhances white matter integrity of the auditory-motor loop

BACKGROUND AND PURPOSE

In our previous study, repeated sessions of repetitive transcranial magnetic stimulation (rTMS) over the auditory feedback area were shown to improve hypokinetic dysarthria (HD) in Parkinson's disease (PD) and led to changes in functional connectivity within the left-sided articulatory networks. We analyzed data from this previous study and assessed the effects of rTMS for HD in PD on the diffusion parameters of the left anterior arcuate fasciculus (AAF), which connects the auditory feedback area with motor regions involved in articulation.

METHODS

Patients were assigned to 10 sessions of real or sham 1-Hz stimulation over the right posterior superior temporal gyrus. Stimulation effects were evaluated using magnetic resonance diffusion tensor imaging and by a speech therapist using a validated tool (Phonetics score of the Dysarthric Profile) at baseline, immediately after 2 weeks of stimulation, and at follow-up visits at Weeks 6 and 10 after the baseline.

RESULTS

Altogether, data from 33 patients were analyzed. A linear mixed model revealed significant time-by-group interaction (p = 0.006) for the relative changes of fractional anisotropy of the AAF; the value increases were associated with the temporal evolution of the Phonetics score (R = 0.367, p = 0.028) in the real stimulation group.

CONCLUSIONS

Real rTMS treatment for HD in PD as compared to sham stimulation led to increases of white matter integrity of the auditory-motor loop during the 2-month follow-up period. The changes were related to motor speech improvements.

Deep Brain Stimulation Impact on Voice and Speech Quality in Parkinson's Disease: A Systematic Review

OBJECTIVE

Deep brain stimulation (DBS) has considerable efficacy for the motor dysfunction of idiopathic Parkinson's disease (PD) on patient quality of life. However, the benefit of DBS on voice and speech quality remains controversial. We carried out a systematic review to understand the influence of DBS on parkinsonian dysphonia and dysarthria.

DATA SOURCES

A PubMed/MEDLINE and Cochrane systematic review was carried out following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Population, Intervention, Comparison, Outcome, Timing, and Setting (PICOTS) statements.

REVIEW METHODS

Three investigators screened studies published in the literature from inception to May 2022. The following data were retrieved: age, demographic, sex, disease duration, DBS duration, DBS location, speech, and voice quality measurements.

RESULTS

From the 180 studies identified, 44 publications met the inclusion criteria, accounting for 866 patients. Twenty-nine studies focused on voice/speech quality in subthalamic DBS patients, and 6 included patients with stimulation of pallidal, thalamic, and zona incerta regions. Most studies (4/6) reported a deterioration of the vocal parameters on subjective voice quality evaluation. For speech, the findings were more contrasted. There was an important heterogeneity between studies regarding the voice and speech quality outcomes used to evaluate the impact of DBS on voice/speech quality.

CONCLUSION

The impact of DBS on voice and speech quality significantly varies between studies. The stimulated anatomical region may have a significant role since the stimulation of the pallidal area was mainly associated with voice quality improvement, in contrast with other regions. Future controlled studies comparing all region stimulation are needed to get reliable findings.

LEVEL OF EVIDENCE

Level III: evidence from evidence summaries developed from systematic reviews.

Speech dysfunction, cognition, and Parkinson's disease

Communication difficulties are a ubiquitous symptom of Parkinson's disease and include changes to both motor speech and language systems. Communication challenges are a significant driver of lower quality of life. They are associated with decreased communication participation, social withdrawal, and increased risks for social isolation and stigmatization in persons with Parkinson's disease. Recent theoretical advances and experimental evidence underscore the intersection of cognition and motor processes in speech production and their impact on spoken language. This chapter overviews a growing evidence base demonstrating that cognitive impairments interact with motor changes in Parkinson's disease to negatively affect communication abilities in myriad ways, at all stages of the disease, both in the absence and presence of dementia. The chapter highlights common PD interventions (pharmacological, surgical, and non-pharmacological) and how cognitive influences on speech production outcomes are considered in each.

The impact of Lee Silverman Voice Treatment (LSVT LOUD®) on voice, communication, and participation: Findings from a prospective, longitudinal study

BACKGROUND

Lee Silverman Voice Treatment (LSVT LOUD®), an intensive 4-week program of voice therapy, is regarded as the most well-researched, efficacious treatment for hypokinetic dysarthria in individuals with Parkinson's disease (PD). Although numerous studies have published acoustic and perceptual findings, there is comparatively little information about the impact of LSVT LOUD® on functional communication outcomes.

METHODS

This prospective, longitudinal study investigated the impact of treatment on daily communication in 25 individuals with PD. Three validated communication measures (the Voice Handicap Index, the Communicative Effectiveness Scale, and the Communicative Participation Item Bank) were given before and after treatment and again 4-8 weeks and 3-6 months following treatment. Communication partners were also asked to rate communication effectiveness at all four timepoints.

RESULTS

Significant improvements were found for all three self-reported scales which remained above baseline across all post-treatment timepoints. In addition, self-reported communicative effectiveness was significantly correlated with the assessments of communication partners. Particular benefits were reported for more complex communicative activities such as asking questions, giving detailed information, communicating in noisy situations, and speaking in groups.

CONCLUSIONS

Overall, the findings suggested that LSVT LOUD® promotes an increased sense of personal control over the communication difficulties resulting from PD by decreasing voice handicap and improving communication effectiveness and communicative participation. For individuals with PD, LSVT LOUD® may reduce the risk of social isolation by improving communication and facilitating social participation.

LEARNING OUTCOMES

As a result of this activity, the participant will be able to (1) describe the impact of PD on voice and communication, (2) discuss how these characteristics may be associated with more global measures of functional communication and particularly communicative participation, (3) explain which aspects of functional communication were affected by LSVT LOUD® as assessed by study participants and their communication partners.

Distance to white matter tracts is associated with deep brain stimulation motor outcome in Parkinson's disease

OBJECTIVE

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) alleviates motor symptoms in patients with Parkinson's disease (PD). However, the underlying mechanism of tremor suppression is not well understood. Stimulation of white matter tracts, such as the dentatorubrothalamic tract (DRT), might be involved. Also, side effects, including dysarthria, might result from (unwanted) stimulation of white matter tracts in proximity to the STN. The aim of this study was to establish an association between stimulation effect on tremor and dysarthria and stimulation location relative to relevant white matter tracts.

METHODS

In 35 PD patients in whom a bilateral STN DBS system was implanted, the authors established clinical outcome measures per electrode contact. The distance from each stimulation location to the center of the DRT, corticopontocerebellar tract, pyramidal tract (PT), and medial lemniscus was determined using diffusion-weighted MRI data. Clinical outcome measures were subsequently related to the distances to the white matter tracts.

RESULTS

Patients with activated contacts closer to the DRT showed increased tremor improvement. Proximity of activated contacts to the PT was associated with dysarthria.

CONCLUSIONS

Proximity to specific white matter tracts is associated with tremor outcome and side effects in DBS. This knowledge can help to optimize both electrode placement and postsurgical electrode contact selection. Presurgical white matter tract visualization may improve targeting and DBS outcome. These findings are of interest not only for treatment in PD, but potentially also for other (movement) disorders.

Technology-enabled management of communication and swallowing disorders in Parkinson's disease: a systematic scoping review

BACKGROUND

Communication and swallowing disorders are highly prevalent in people with Parkinson's disease (PD). Maintenance of functional communication and swallowing over time is challenging for the person with PD and their families and may lead to social isolation and reduced quality of life if not addressed. Speech and language therapists (SLTs) face the conundrum of providing sustainable and flexible services to meet the changing needs of people with PD. Motor, cognitive and psychological issues associated with PD, medication regimens and dependency on others often impede attendance at a centre-based service. The access difficulties experienced by people with PD require a disruptive service approach to meet their needs. Technology-enabled management using information and telecommunications technologies to provide services at a distance has the potential to improve access, and enhance the quality of SLT services to people with PD.

AIMS

To report the status and scope of the evidence for the use of technology in the management of the communication and swallowing disorders associated with PD.

METHODS & PROCEDURES

Studies were retrieved from four major databases (PubMed, CINAHL, EMBASE and Medline via Web of Science). Data relating to the types of studies, level of evidence, context, nature of the management undertaken, participant perspectives and the types of technologies involved were extracted for the review.

MAIN CONTRIBUTION

A total of 17 studies were included in the review, 15 of which related to the management of communication and swallowing disorders in PD with two studies devoted to participant perspectives. The majority of the studies reported on the treatment of the speech disorder in PD using Lee Silverman Voice Treatment (LSVT LOUD^® ). Synchronous and asynchronous technologies were used in the studies with a predominance of the former. There was a paucity of research in the management of cognitive-communication and swallowing disorders.

CONCLUSIONS & IMPLICATIONS

Research evidence supporting technology-enabled management of the communication and swallowing disorders in PD is limited and predominantly low in quality. The treatment of the speech disorder online is the most developed aspect of the technology-enabled management pathway. Future research needs to address technology-enabled management of cognitive-communication and swallowing disorders and the use of a more diverse range of technologies and management approaches to optimize SLT service delivery to people with PD.

Challenges in PD Patient Management After DBS: A Pragmatic Review

BACKGROUND

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) or internal globus pallidus (GPi) represents an effective and universally applied therapy for Parkinson's disease (PD) motor complications. However, certain procedure-related problems and unrealistic patient expectations may detract specialists from indicating DBS more widely despite significant clinical effects.

METHODS

This review provides a pragmatic educational summary of the most conflicting postoperative management issues in patients undergoing DBS for PD.

RESULTS

DBS in PD has been associated with certain complications and post-procedural management issues, which can complicate surgical outcome interpretation. Many PD patients consider DBS outcomes negative due to unfulfilled expectations, even when significant motor symptom improvement is achieved. Speech, gait, postural stability, and cognition may worsen after DBS and body weight may increase. Although DBS may induce impulse control disorders in some cases, in others, it may actually improve them when dopamine agonist dosage is reduced after surgery. However, apathy may also arise, especially when dopaminergic medication tapering is rapid. Gradual loss of response with time suggests disease progression, rather than the wearing off of DBS effects. Furthermore, implantable pulse generator expiration is considered a movement disorder emergency, as it may worsen parkinsonian symptoms or cause life-threatening akinetic crises due to malignant DBS withdrawal syndrome.

CONCLUSION

Major unsolved issues occurring after DBS therapy preclude complete patient satisfaction. Multidisciplinary management at experienced centers, as well as careful and comprehensive delivery of information to patients, should contribute to make DBS outcome expectations more realistic and allow post procedural complications to be better accepted.

Early detection of speech and voice disorders in Parkinson's disease patients treated with subthalamic nucleus deep brain stimulation: a 1-year follow-up study

We previously reported that Parkinson's disease (PD) patients treated with subthalamic nucleus deep brain stimulation (STN-DBS) had distinct phenotypes of speech and voice disorders: hypokinetic dysarthria, stuttering, breathy voice, strained voice, and spastic dysarthria. However, changes over time remain unclear. In the present study, 32 consecutive PD patients were assessed before and up to 1 year after surgery (PD-DBS). Eleven medically treated PD patients were also assessed (PD-Med). Speech, voice, motor, and cognitive functions were evaluated. At baseline, the incidence of hypokinetic dysarthria (63% of PD-DBS vs. 82% of PD-Med), stuttering (50% vs. 45%), breathy voice (66% vs. 73%), and strained voice (3% vs. 9%) was similar between groups. At 1 year, a slight but significant deterioration in speech intelligibility (p < 0.001) and grade of dysphonia (p = 0.001) were observed only in PD-DBS group compared with baseline. During the follow-up, stuttering (9% vs. 18%) and breathy voice (13% vs. 9%) emerged in PD-DBS and PD-Med, but strained voice (28%) and spastic dysarthria (44%) emerged only in PD-DBS. After the stimulation was stopped, strained voice and spastic dysarthria improved in most patients, while stuttering and breathy voice improved in a minority of patients. These findings indicate that the most common DBS-induced speech and voice disorders are strained voice and spastic dysarthria and that STN-DBS potentially aggravates stuttering and breathy voice. An improved understanding of these types of disorders may help detect speech and voice deteriorations during the early phase and lead to appropriate treatments.

Feasibility of Diffusion Tractography for the Reconstruction of Intra-Thalamic and Cerebello-Thalamic Targets for Functional Neurosurgery: A Multi-Vendor Pilot Study in Four Subjects

Functional stereotactic neurosurgery by means of deep brain stimulation or ablation provides an effective treatment for movement disorders, but the outcome of surgical interventions depends on the accuracy by which the target structures are reached. The purpose of this pilot study was to evaluate the feasibility of diffusion tensor imaging (DTI) based probabilistic tractography of deep brain structures that are commonly used for pre- and perioperative targeting for functional neurosurgery. Three targets were reconstructed based on their significance as intervention sites or as a no-go area to avoid adverse side effects: the connections propagating from the thalamus to (1) primary and supplementary motor areas, (2) to somatosensory areas and the cerebello-thalamic tract (CTT). We evaluated the overlap of the reconstructed connectivity based targets with corresponding atlas based data, and tested the inter-subject and inter-scanner variability by acquiring repeated DTI from four volunteers, and on three MRI scanners with similar sequence parameters. Compared to a 3D histological atlas of the human thalamus, moderate overlaps of 35-50% were measured between connectivity- and atlas based volumes, while the minimal distance between the centerpoints of atlas and connectivity targets was 2.5 mm. The variability caused by the MRI scanner was similar to the inter-subject variability, except for connections with the postcentral gyrus where it was higher. While CTT resolved the anatomically correct trajectory of the tract individually, high volumetric variability was found across subjects and between scanners. DTI can be applied in the clinical, preoperative setting to reconstruct the CTT and to localize subdivisions within the lateral thalamus. In our pilot study, such subdivisions moderately matched the borders of the ventrolateral-posteroventral (VL_pv) nucleus and the ventral-posterolateral (VPL) nucleus. Limitations of the currently used standard DTI protocols were exacerbated by large scanner-to-scanner variability of the connectivity-based targets.

Speech intelligibility in Parkinson's disease patients with zona incerta deep brain stimulation

OBJECTIVES

To investigate the effects of l-dopa (Levodopa) and cZi-DBS (deep brain stimulation in caudal zona incerta) on spontaneous speech intelligibility in patients with PD (Parkinson's disease).

MATERIALS AND METHODS

Spontaneous utterances were extracted from anechoic recordings from 11 patients with PD preoperatively (off and on l-dopa medication) and 6 and 12 months post bilateral cZi-DBS operation (off and on stimulation, with simultaneous l-dopa medication). Background noise with an amplitude corresponding to a clinical setting was added to the recordings. Intelligibility was assessed through a transcription task performed by 41 listeners in a randomized and blinded procedure.

RESULTS

A group-level worsening in spontaneous speech intelligibility was observed on cZi stimulation compared to off 6 months postoperatively (8 adverse, 1 positive, 2 no change). Twelve months postoperatively, adverse effects of cZi-DBS were not frequently observed (2 positive, 3 adverse, 6 no change). l-dopa administered preoperatively as part of the evaluation for DBS operation provided the overall best treatment outcome (1 adverse, 4 positive, 6 no change).

CONCLUSIONS

cZi-DBS was shown to have smaller negative effects when evaluated from spontaneous speech compared to speech effects reported previously. The previously reported reduction in word-level intelligibility 12 months postoperatively was not transferred to spontaneous speech for most patients. Reduced intelligibility due to cZi stimulation was much more prominent 6 months postoperatively than at 12 months.

Distinct phenotypes of speech and voice disorders in Parkinson's disease after subthalamic nucleus deep brain stimulation

OBJECTIVES

To elucidate the phenotypes and pathophysiology of speech and voice disorders in Parkinson's disease (PD) with subthalamic nucleus deep brain stimulation (STN-DBS).

METHODS

We conducted a cross-sectional study on 76 PD patients treated with bilateral STN-DBS (PD-DBS) and 33 medically treated PD patients (PD-Med). Speech and voice functions, electrode positions, motor function and cognitive function were comprehensively assessed. Moreover, speech and voice functions were compared between the on-stimulation and off-stimulation conditions in 42 PD-DBS patients.

RESULTS

Speech and voice disorders in PD-DBS patients were significantly worse than those in PD-Med patients. Factor analysis and subsequent cluster analysis classified PD-DBS patients into five clusters: relatively good speech and voice function type, 25%; stuttering type, 24%; breathy voice type, 16%; strained voice type, 18%; and spastic dysarthria type, 17%. STN-DBS ameliorated voice tremor or low volume; however, it deteriorated the overall speech intelligibility in most patients. Breathy voice did not show significant changes and stuttering exhibited slight improvement after stopping stimulation. In contrast, patients with strained voice type or spastic dysarthria type showed a greater improvement after stopping stimulation. Spastic dysarthria type patients showed speech disorders similar to spastic dysarthria, which is associated with bilateral upper motor neuron involvement. Strained voice type and spastic dysarthria type appeared to be related to current diffusion to the corticobulbar fibres.

CONCLUSIONS

Stuttering and breathy voice can be aggravated by STN-DBS, but are mainly due to aging or PD itself. Strained voice and spastic dysarthria are considered corticobulbar side effects.

Behavioral treatments for speech in Parkinson's disease: meta-analyses and review of the literature

SUMMARY 

Parkinson's disease (PD) results from neurodegenerative processes leading to alteration of motor functions. Most motor symptoms respond well to pharmacological and neurosurgical treatments, except some axial symptoms such as speech impairment, so-called dysarthria. However, speech therapy is rarely proposed to PD patients. This review aims at evaluating previous research on the effects of speech behavioral therapies in patients with PD. We also performed two meta-analyses focusing on speech loudness and voice pitch. We showed that intensive therapies in PD are the most effective for hypophonia and can lead to some improvement of voice pitch. Although speech therapy is effective in handling PD dysarthria, behavioral speech rehabilitation in PD still needs further validation.

Effects of the Lee Silverman Voice Treatment (LSVT® LOUD) on hypomimia in Parkinson's disease

Given associations between facial movement and voice, the potential of the Lee Silverman Voice Treatment (LSVT) to alleviate decreased facial expressivity, termed hypomimia, in Parkinson's disease (PD) was examined. Fifty-six participants--16 PD participants who underwent LSVT, 12 PD participants who underwent articulation treatment (ARTIC), 17 untreated PD participants, and 11 controls without PD--produced monologues about happy emotional experiences at pre- and post-treatment timepoints ("T1" and "T2," respectively), 1 month apart. The groups of LSVT, ARTIC, and untreated PD participants were matched on demographic and health status variables. The frequency and variability of facial expressions (Frequency and Variability) observable on 1-min monologue videorecordings were measured using the Facial Action Coding System (FACS). At T1, the Frequency and Variability of participants with PD were significantly lower than those of controls. Frequency and Variability increases of LSVT participants from T1 to T2 were significantly greater than those of ARTIC or untreated participants. Whereas the Frequency and Variability of ARTIC participants at T2 were significantly lower than those of controls, LSVT participants did not significantly differ from controls on these variables at T2. The implications of these findings, which suggest that LSVT reduces parkinsonian hypomimia, for PD-related psychosocial problems are considered.

[A case of Parkinson's disease treated effectively with a pacing board for repetitive speech phenomena after deep brain stimulation]

We report a 61-year-old Parkinson's disease patient presenting with severe repetitive speech phenomena after deep brain stimulation. On admission, he showed impaired loudness, rough hoarseness, monoloudness and monopitch. It had been difficult for him to converse because of voice repetitive speech phenomena since 57 years of age. Medical control, regulation of contact location and voltage amplitude did not improve these symptoms. Lee Silverman Voice Treatment(®) improved loudness and voice quality, but did not improve repetitive speech phenomena. After speech treatment with a pacing board, his repetitive speech phenomena improved more than before. Treatment with a pacing board may be effective for repetitive speech phenomena in Parkinson's disease after deep brain stimulation.

Closing the loop of deep brain stimulation

High-frequency deep brain stimulation is used to treat a wide range of brain disorders, like Parkinson's disease. The stimulated networks usually share common electrophysiological signatures, including hyperactivity and/or dysrhythmia. From a clinical perspective, HFS is expected to alleviate clinical signs without generating adverse effects. Here, we consider whether the classical open-loop HFS fulfills these criteria and outline current experimental or theoretical research on the different types of closed-loop DBS that could provide better clinical outcomes. In the first part of the review, the two routes followed by HFS-evoked axonal spikes are explored. In one direction, orthodromic spikes functionally de-afferent the stimulated nucleus from its downstream target networks. In the opposite direction, antidromic spikes prevent this nucleus from being influenced by its afferent networks. As a result, the pathological synchronized activity no longer propagates from the cortical networks to the stimulated nucleus. The overall result can be described as a reversible functional de-afferentation of the stimulated nucleus from its upstream and downstream nuclei. In the second part of the review, the latest advances in closed-loop DBS are considered. Some of the proposed approaches are based on mathematical models, which emphasize different aspects of the parkinsonian basal ganglia: excessive synchronization, abnormal firing-rate rhythms, and a deficient thalamo-cortical relay. The stimulation strategies are classified depending on the control-theory techniques on which they are based: adaptive and on-demand stimulation schemes, delayed and multi-site approaches, stimulations based on proportional and/or derivative control actions, optimal control strategies. Some of these strategies have been validated experimentally, but there is still a large reservoir of theoretical work that may point to ways of improving practical treatment.

Effect of training frequency on maximum expiratory pressure

PURPOSE

To determine the effects of expiratory muscle strength training (EMST) frequency on maximum expiratory pressure (MEP).

METHOD

We assigned 12 healthy participants to 2 groups of training frequency (3 days per week and 5 days per week). They completed a 4-week training program on an EMST trainer (Aspire Products, LLC). MEP was the primary outcome measure used to determine the effect of training frequency.

RESULTS

Participants who trained 3 days per week produced equivalent amounts of improvement in MEP compared with participants who trained 5 days per week. An overall improvement in MEP over the 4-week training period indicated a 33% increase when the data was collapsed across the 2 training groups.

CONCLUSION

The effects occurring with respiratory muscle strength training in healthy young adults are likely to be different from those occurring in patient populations. Therefore, the results of the present study suggest exploring the variable of training frequency in patient populations. Such knowledge will be informative for designing clinical protocols that are effective and may result in improved treatment compliance for those suffering from expiratory muscle weakness.

Speech, voice and language in Parkinson’s disease: changes and interventions

SUMMARY This article covers recent developments in the understanding of communication changes in idiopathic Parkinson’s disease and selected issues in intervention. By contrast to earlier narrow considerations of voice and speech, the effects on communication of cognitive–linguistic and prosody perception and production are also highlighted. Decline can occur from the earliest stages, even when listeners perceive no frank changes. Communication may be relatively trouble-free in one-to-one quiet clinical situations but declines in multi-talker, dual/competing task situations. Assessment should reflect this to gain more accurate insights into daily living performance. Currently, therapies focusing on attention-to-effort in voice production and on monitoring the sense of effort and loudness production appear to be most successful. Medical and surgical treatments have little effect on intelligibility and communication and may even exacerbate the situation.