Speech dysfluency exacerbated by levodopa in Parkinson's disease

Speech rate and fluency in young-onset Parkinson's disease: A longitudinal case study from early to post brain surgery stage

The aim of this study is to analyse the speech rate, pausing and fluency of a patient with young-onset Parkinson's Disease in different stages of the disease. Speech samples of the patient were recorded in the early stages of the disease until after the brain surgery. The recordings were compared to the speech of healthy control speakers. Speech rate, articulation rate, pausing and the frequency of disfluencies were analysed. Results show that all parameters are influenced by the severity of the disease, but articulation rate is the most affected.

Simple and rapid LC-MS/MS method for determination of Piribedil in human plasma

A sensitive, simple, and fast LC-MS/MS method of analysis was developed and validated for the determination of piribedil in human plasma. Piribedil was extracted by protein precipitation using acetonitrile and separated on C18 Phenomenex Gemini column (150 × 4.6mm, 5 µm) using isocratic elution of 75% of ammonium acetate buffer (10 mM) and 25% acetonitrile at a flow rate of 1 ml.min-1 over 5 min run time. Piribedil and d8-Piribedil, as internal standard, were detected and quantified in positive ion mode via MRM at m/z 299/135 and 307/135 for piribedil and d8–piribedil, respectively. The suggested method for piribedil was validated according to FDA and EMA guidelines. The standard calibration curve was linear over the concentration range of 3.4–5952 pg.ml-1. The intra-day precision was 2.45–9.94% and accuracy 92.78–99.97%. The inter-day precision was 2.14–5.47% and accuracy 95.73–101.99%. The recovery of analyte and IS was 96.94% and 111.18%, respectively. piribedil in plasma was stable at benchtop (short term) for 24 h, in autosampler tray for 48 h, in instrumentation room for 24 h (post-preparative), after 5 freeze-thaw cycles (–70 °C), and 11 days in the freezer (–70 °C). The validated method was successfully applied to a bioequivalence study of piribedil formulations involving 15 healthy Jordanian volunteers.

Drug-induced stuttering: A comprehensive literature review

Drug-induced stuttering (DIS) is a type of neurogenic stuttering (NS). Although DIS has not been reported as frequently as other cases of NS in the literature, it is not a negligible adverse drug reaction (ADR) which can significantly affect the quality of life if not treated. This literature review aims to evaluate the epidemiological and clinical characteristics of DIS and suggests some pathophysiological mechanisms for this ADR. Relevant English-language reports in Google Scholar, PubMed, Web of Science, and Scopus were identified and assessed without time restriction. Finally, a total of 62 reports were included. Twenty-seven drugs caused 86 episodes of stuttering in 82 cases. The most episodes of DIS were related to antipsychotic drugs (57%), mostly including clozapine, followed by central nervous system agents (11.6%) and anticonvulsant drugs (9.3%). The majority of the cases were male and between the ages of 31 and 40 years. Repetitions were the most frequent core manifestations of DIS. In 55.8% of the episodes of DIS, the offending drug was withdrawn to manage stuttering, which resulted in significant improvement or complete relief of stuttering in all cases. Based on the suggested pathophysiological mechanisms for developmental stuttering and neurotransmitters dysfunctions involved in speech dysfluency, it seems that the abnormalities of several neurotransmitters, especially dopamine and glutamate, in different circuits and areas of the brain, including cortico-basal ganglia-thalamocortical loop and white matter fiber tracts, may be engaged in the pathogenesis of DIS.

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.

Deficits in monitoring self-produced speech in Parkinson's disease

OBJECTIVE

Speech deficits are common in Parkinson's disease, and behavioural findings suggest that the deficits may be due to impaired monitoring of self-produced speech. The neural mechanisms of speech deficits are not well understood. We examined a well-documented electrophysiological correlate of speech self-monitoring in patients with Parkinson's disease and control participants.

METHODS

We measured evoked electroencephalographic responses to self-produced and passively heard sounds (/a/ phonemes) in age-matched controls (N = 18), and Parkinson's disease patients who had minor speech impairment, but reported subjectively experiencing no speech deficits (N = 17).

RESULTS

During speaking, auditory evoked activity 100 ms after phonation (N1 wave) was less suppressed in Parkinson's disease than controls when compared to the activity evoked by passively heard phonemes. This difference between the groups was driven by increased amplitudes to self-produced phonemes, and reduced amplitudes passively heard phonemes in Parkinson's disease.

CONCLUSIONS

The finding indicates that auditory evoked activity is abnormally modulated during speech in Parkinson's patients who do not subjectively notice speech impairment. This mechanism could play a role in producing speech deficits in as the disease progresses.

SIGNIFICANCE

Our study is the first to show abnormal early auditory electrophysiological correlates of monitoring speech in Parkinson's disease patients.

Freezing of Speech Single Questionnaire as a Screening Tool for Cognitive Dysfunction in Patients With Dementia With Lewy Bodies

Introduction

Freezing phenomenon is a striking feature of Parkinson's disease. However, it has never been studied in people with dementia with Lewy bodies (DLB). We designed a freezing of speech single questionnaire (FOSSQ) and investigated the frequency and association of freezing of speech (FOS) in patients with DLB and other types of dementia.

Methods

This is a retrospective analysis of data from the project of history-based artificial intelligent computerized dementia diagnostic system. We compared the frequencies of FOS among non-demented (ND) participants, patients with Alzheimer's disease (AD), vascular dementia (VaD), and DLB. Further, we explored the association factors of FOS in all the participants.

Results

We enrolled 666 individuals with the following disease distribution: 190, ND; 230, AD; 183, VaD; and 63, DLB. Compared to individuals with ND (2.1%), patients with AD (6.1%), or VaD (18.0%), DLB (54.0%) showed a significantly higher frequency of positive FOS (all p < 0.001). The association factors of FOS were older age, more severe dementia, more severe motor dysfunction, fluctuating cognition, visual hallucinations, parkinsonism, rapid eye movement sleep behavior disorder, attention, mental manipulation, and language.

Conclusion

Our study showed that the informant-based FOSSQ may be a practical screening tool for discriminating DLB from individuals with ND or other forms of dementia. The FOSSQ can be applied in clinical practice as well as on the artificial intelligent platform.

Involvement of the Cortico-Basal Ganglia-Thalamocortical Loop in Developmental Stuttering

Stuttering is a complex neurodevelopmental disorder that has to date eluded a clear explication of its pathophysiological bases. In this review, we utilize the Directions Into Velocities of Articulators (DIVA) neurocomputational modeling framework to mechanistically interpret relevant findings from the behavioral and neurological literatures on stuttering. Within this theoretical framework, we propose that the primary impairment underlying stuttering behavior is malfunction in the cortico-basal ganglia-thalamocortical (hereafter, cortico-BG) loop that is responsible for initiating speech motor programs. This theoretical perspective predicts three possible loci of impaired neural processing within the cortico-BG loop that could lead to stuttering behaviors: impairment within the basal ganglia proper; impairment of axonal projections between cerebral cortex, basal ganglia, and thalamus; and impairment in cortical processing. These theoretical perspectives are presented in detail, followed by a review of empirical data that make reference to these three possibilities. We also highlight any differences that are present in the literature based on examining adults versus children, which give important insights into potential core deficits associated with stuttering versus compensatory changes that occur in the brain as a result of having stuttered for many years in the case of adults who stutter. We conclude with outstanding questions in the field and promising areas for future studies that have the potential to further advance mechanistic understanding of neural deficits underlying persistent developmental stuttering.

Effect of Levodopa on Speech Dysfluency in Parkinson's Disease

Objective

To examine the effect of levodopa medication on speech dysfluency in Parkinson's disease.

Methods

Fifty-one individuals with Parkinson's disease (IWPD) read aloud during off- and on- medication states. Total speech dysfluencies were calculated from transcriptions of recorded speech samples.

Results

Severity of speech dysfluency was not significantly related to the severity of motor symptoms, duration of disease, levodopa equivalent dosage, or age. When the IWPD were divided into two groups based on dysfluency severity, there was a significant group-by-medication state interaction. There was a significant correlation between the medication-related change in speech dysfluency and the off-medication severity of speech dysfluency measure (r = -0.46).

Conclusions

The results of this study indicate that levodopa medication can have a significant effect on speech dysfluency. The beneficial levodopa effect appears to be related to the severity of the off-medication speech dysfluency. Results did not provide strong support for the excess dopamine theory of stuttering in IWPD. A dualistic model of the effects of dopamine on speech fluency in PD is proposed.

A case of multiple system atrophy-parkinsonian type with stuttering- and palilalia-like dysfluencies and putaminal atrophy

Both developmental and acquired stuttering are related to the function of the basal ganglia-thalamocortical loop, which includes the putamen. Here, we present a case of stuttering- and palilalia-like dysfluencies that manifested as an early symptom of multiple system atrophy-parkinsonian type (MSA-P) and bilateral atrophy of the putamen. The patient was a 72-year-old man with no history of developmental stuttering who presented with a stutter for consultation with our otorhinolaryngology department. The patient was diagnosed with MSA-P based on parkinsonism, autonomic dysfunction, and bilateral putaminal atrophy revealed by T2-weighted magnetic resonance imaging. Treatment with levodopa improved both the motor functional deficits related to MSA-P and stuttering-like dysfluencies while reading; however, the palilalia-like dysfluencies were much less responsive to levodopa therapy. The patient died of aspiration pneumonia two years after his first consultation at our hospital. In conclusion, adult-onset stuttering- and palilalia-like dysfluencies warrant careful examination of the basal ganglia-thalamocortical loop, and especially the putamen, using neuroimaging techniques. Acquired stuttering may be related to deficits in dopaminergic function.

Frequency of speech disruptions in Parkinson's Disease and developmental stuttering: A comparison among speech tasks

OBJECTIVE

To analyze the frequency of speech disruptions across different speech tasks, comparing the performance of individuals with Parkinson's Disease (PD) and DS.

METHOD

Participants were 20 people with PD, 20 people with DS and 40 fluent individuals. Speech samples were recorded during monologue speech, choral and solo oral reading. Transcriptions of 200 fluent syllables were performed to identify stuttering-like disfluencies (SLDs) and other disfluencies (ODs).

RESULTS

People with PD presented significantly less speech disruptions when compared to people with DS, but significantly more speech disruptions than the control group. Stuttering-like disfluencies ocurred more frequently during monologue speech and solo oral reading for both PD and DS, whereas the control group did not present difference between these tasks.

CONCLUSION

The stuttering pattern presented by people with PD is different from what is usually described as being neurogenic stuttering.

Speech fluency profile on different tasks for individuals with Parkinson's disease

Purpose

To characterize the speech fluency profile of patients with Parkinson's disease.

Methods

Study participants were 40 individuals of both genders aged 40 to 80 years divided into 2 groups: Research Group - RG (20 individuals with diagnosis of Parkinson's disease) and Control Group - CG (20 individuals with no communication or neurological disorders). For all of the participants, three speech samples involving different tasks were collected: monologue, individual reading, and automatic speech.

Results

The RG presented a significant larger number of speech disruptions, both stuttering-like and typical dysfluencies, and higher percentage of speech discontinuity in the monologue and individual reading tasks compared with the CG. Both groups presented reduced number of speech disruptions (stuttering-like and typical dysfluencies) in the automatic speech task; the groups presented similar performance in this task. Regarding speech rate, individuals in the RG presented lower number of words and syllables per minute compared with those in the CG in all speech tasks.

Conclusion

Participants of the RG presented altered parameters of speech fluency compared with those of the CG; however, this change in fluency cannot be considered a stuttering disorder.

Neurochemical Systems of the Retina Involved in the Control of Movement

Recent studies have revealed that the retina may exert control over deep brain function and may be importantly involved in the etiology, progression, and treatment of disorders such as Parkinson's disease (PD). While such a concept is uncharted territory and even less is known about the mechanism by which this might be achieved, this study was undertaken to determine how retinal dopamine (DA), serotonin (5-HT), and melatonin (MEL) neurotransmitter systems might be involved in the control of movement in their own right. To explore these further, intravitreal (IVIT) injections of DA, 5-HT, and MEL were made 0.5 or 3 h prior to testing horizontal and vertical movement in the open field as well as assessment on three motor tests used routinely to evaluate movement as a preclinical model of PD. The doses of DA (2 µl of 25 and 75 µg/µl), 5-HT (2 µl of 5 and 15 µg/µl), and MEL (2 µl of 5 µg/µl) were chosen because of previous work demonstrating an anatomically precise effect of these transmitters after they were injected directly into the brain. The postinjection times of testing were also chosen on the basis of previous intracerebral and IVIT work intimating the importance of the circadian cycle in determining the efficacy of such effects. 0.5 h after IVIT injection of DA at the 25 and 75 µg/µl doses, significant inhibition of motor function was observed. While IVIT injection of 10 or 30 µg of 5-HT also inhibited motor performance, this was significantly less than that seen with DA. In fact, IVIT injection increases motor performance compared to vehicle injection on some parameters. The IVIT injection of 10 µg of MEL facilitated motor function on many parameters compared to DA, 5-HT, and vehicle injection. When rats were tested 3 h after IVIT injection, the inhibition of vertical movement was also observed compared to controls. The present results illustrate that specific retinal neurotransmitter systems participate in the normal control of bodily motor function. The possible involvement of these systems in movement disorders such as PD is the subject of ongoing research.

How language flows when movements don't: An automated analysis of spontaneous discourse in Parkinson's disease

To assess the impact of Parkinson's disease (PD) on spontaneous discourse, we conducted computerized analyses of brief monologues produced by 51 patients and 50 controls. We explored differences in semantic fields (via latent semantic analysis), grammatical choices (using part-of-speech tagging), and word-level repetitions (with graph embedding tools). Although overall output was quantitatively similar between groups, patients relied less heavily on action-related concepts and used more subordinate structures. Also, a classification tool operating on grammatical patterns identified monologues as pertaining to patients or controls with 75% accuracy. Finally, while the incidence of dysfluent word repetitions was similar between groups, it allowed inferring the patients' level of motor impairment with 77% accuracy. Our results highlight the relevance of studying naturalistic discourse features to tap the integrity of neural (and, particularly, motor) networks, beyond the possibilities of standard token-level instruments.

Assessment of Nonverbal and Verbal Apraxia in Patients with Parkinson's Disease

Objective. To assess the presence of nonverbal and verbal apraxia in patients with Parkinson's disease (PD) and analyze the correlation between these conditions and patient age, education, duration of disease, and PD stage, as well as evaluate the correlation between the two types of apraxia and the frequency and types of verbal apraxic errors made by patients in the sample. Method. This was an observational prevalence study. The sample comprised 45 patients with PD seen at the Movement Disorders Clinic of the Clinical Hospital of Porto Alegre, Brazil. Patients were evaluated using the Speech Apraxia Assessment Protocol and PD stages were classified according to the Hoehn and Yahr scale. Results. The rate of nonverbal apraxia and verbal apraxia in the present sample was 24.4%. Verbal apraxia was significantly correlated with education (p ≤ 0.05). The most frequent types of verbal apraxic errors were omissions (70.8%). The analysis of manner and place of articulation showed that most errors occurred during the production of trill (57.7%) and dentoalveolar (92%) phonemes, consecutively. Conclusion. Patients with PD presented nonverbal and verbal apraxia and made several verbal apraxic errors. Verbal apraxia was correlated with education levels.

A review of brain circuitries involved in stuttering

Stuttering has been the subject of much research, nevertheless its etiology remains incompletely understood. This article presents a critical review of the literature on stuttering, with particular reference to the role of the basal ganglia (BG). Neuroimaging and lesion studies of developmental and acquired stuttering, as well as pharmacological and genetic studies are discussed. Evidence of structural and functional changes in the BG in those who stutter indicates that this motor speech disorder is due, at least in part, to abnormal BG cues for the initiation and termination of articulatory movements. Studies discussed provide evidence of a dysfunctional hyperdopaminergic state of the thalamocortical pathways underlying speech motor control in stuttering. Evidence that stuttering can improve, worsen or recur following deep brain stimulation for other indications is presented in order to emphasize the role of BG in stuttering. Further research is needed to fully elucidate the pathophysiology of this speech disorder, which is associated with significant social isolation.

Fluency in Parkinson’s disease: disease duration, cognitive status and age

The objective of this study was to determine the frequency of occurrence and to characterize the typology of dysfluencies in individuals with Parkinson’s disease (PD), including the variables age, gender, schooling, disease duration, score on the Hoehn and Yahr scale and cognitive status (score on Mini-Mental State Examination). A cross-sectional study of a sample comprising 60 adults matched for gender, age and schooling was conducted. Group I comprised 30 adults with idiopathic PD, and Group II comprised 30 healthy adults. For assessment of fluency of speech, subjects were asked to utter a narrative based on a sequence of drawings and a transcription of 200 fluent syllables was performed to identify speech dysfluencies. PD patients exhibited a higher overall number of dysfluencies in speech with a large number of atypical dysfluencies. Additionally, results showed an influence of the variables cognitive status, disease duration and age on occurrence of dysfluencies.

Computational modeling of stuttering caused by impairments in a basal ganglia thalamo-cortical circuit involved in syllable selection and initiation

Atypical white-matter integrity and elevated dopamine levels have been reported for individuals who stutter. We investigated how such abnormalities may lead to speech dysfluencies due to their effects on a syllable-sequencing circuit that consists of basal ganglia (BG), thalamus, and left ventral premotor cortex (vPMC). "Neurally impaired" versions of the neurocomputational speech production model GODIVA were utilized to test two hypotheses: (1) that white-matter abnormalities disturb the circuit via corticostriatal projections carrying copies of executed motor commands and (2) that dopaminergic abnormalities disturb the circuit via the striatum. Simulation results support both hypotheses: in both scenarios, the neural abnormalities delay readout of the next syllable's motor program, leading to dysfluency. The results also account for brain imaging findings during dysfluent speech. It is concluded that each of the two abnormality types can cause stuttering moments, probably by affecting the same BG-thalamus-vPMC circuit.

The effects of practice on the concurrent performance of a speech and postural task in persons with Parkinson disease and healthy controls

Purpose. Persons with Parkinson disease (PD) demonstrate deficits in motor learning as well as bidirectional interference (the performance of one task concurrently interferes with the performance of another task) during dual-task performance. Few studies have examined the practice dosages necessary for behavioral change in rehabilitation relevant tasks. Therefore, to compare the effects of age and PD on motor learning during dual-task performance, this pilot study examined persons with PD as well as neurologically healthy participants during concurrent performance of postural and speaking tasks. Methods. Seven persons with PD and 7 healthy age-matched and 10 healthy young control subjects were tested in a motion capture facility. Task performances were performed concurrently and recorded during 3 time periods (acquisition (beginning and ending), 48-hour retention, and 1-week retention). Postural control and speech articulatory acoustic variables were measured. Results. Healthy young participants consistently performed better than other groups on all measured postural and speech variables. Healthy young participants showed decreased variability at retention, while persons with PD and healthy age-matched controls were unable to consistently improve their performance as a result of practice. No changes were noted in the speech variables. Conclusion. The lack of consistent changes in motor performance in any of the tasks, except in the healthy young group, suggests a decreased efficiency of motor learning in the age-matched and PD groups and argues for increased practice dosages during balance training.

Regulation of bat echolocation pulse acoustics by striatal dopamine

The ability to control the bandwidth, amplitude and duration of echolocation pulses is a crucial aspect of echolocation performance but few details are known about the neural mechanisms underlying the control of these voice parameters in any mammal. The basal ganglia (BG) are a suite of forebrain nuclei centrally involved in sensory-motor control and are characterized by their dependence on dopamine. We hypothesized that pharmacological manipulation of brain dopamine levels could reveal how BG circuits might influence the acoustic structure of bat echolocation pulses. A single intraperitoneal injection of a low dose (5 mg kg(-1)) of the neurotoxin 1-methyl-4-phenylpyridine (MPTP), which selectively targets dopamine-producing cells of the substantia nigra, produced a rapid degradation in pulse acoustic structure and eliminated the bat's ability to make compensatory changes in pulse amplitude in response to background noise, i.e. the Lombard response. However, high-performance liquid chromatography (HPLC) measurements of striatal dopamine concentrations revealed that the main effect of MPTP was a fourfold increase rather than the predicted decrease in striatal dopamine levels. After first using autoradiographic methods to confirm the presence and location of D(1)- and D(2)-type dopamine receptors in the bat striatum, systemic injections of receptor subtype-specific agonists showed that MPTP's effects on pulse acoustics were mimicked by a D(2)-type dopamine receptor agonist (Quinpirole) but not by a D(1)-type dopamine receptor agonist (SKF82958). The results suggest that BG circuits have the capacity to influence echolocation pulse acoustics, particularly via D(2)-type dopamine receptor-mediated pathways, and may therefore represent an important mechanism for vocal control in bats.

The effectiveness of traditional methods and altered auditory feedback in improving speech rate and intelligibility in speakers with Parkinson's disease

Communication problems are a frequent symptom for people with Parkinson's disease (PD) which can have a significant impact on their quality-of-life. Deciding on the right management approach can be problematic though, as, with the exception of LSVT, very few studies have been published demonstrating the effectiveness of treatment techniques. The aim of this study was to compare traditional rate reduction methods with altered auditory feedback (AAF) with respect to their effectiveness to reduce speech rate and improve intelligibility in speakers with PD. Ten participants underwent both types of treatments in once weekly sessions for 6 weeks. Outcomes measures were speech rate for passage reading as well as intelligibility on both a passage reading and a monologue task. The results showed that, as a group, there was no significant change in either speech rate or intelligibility resulting from either treatment type. However, individual speakers showed improvements in speech performance as a result of each therapy technique. In most cases, these benefits persisted for at least 6 months post-treatment. Possible reasons for the variable response to treatment, as well as issues to consider when planning to use AAF devices in treatment are discussed.

Sequential changes in motor speech across a levodopa cycle in advanced Parkinson's disease

Previous research has indicated that in Parkinson's disease (PD) some motor speech characteristics are changed by levodopa administration, while others are not. In advanced PD, the time course of these changes and the correlations with motor performance have not been sufficiently investigated. The purpose was to investigate the sequential changes of respiratory, articulatory, and phonatory speech characteristics across a levodopa drug cycle, using spirometry, acoustic, and motor speech analysis. Seven patients with advanced PD were included. All patients were evaluated sequentually at 15 minute intervals before and following levodopa intake. Data were analysed using repeated measures ANOVA and non-parametric analysis. Significant changes were found in motor function, vital capacity, and standard deviation of the diadochokinetic period. A trend was present for shimmer and frequency of the first formant. Significant inter-individual differences in the sequential changes were demonstrated for nearly all evaluated parameters. The conclusion is that, in advanced PD, the evaluation of speech characteristics at one moment after levodopa administration is not representative of an entire drug cycle and that an individualized evaluation of an entire drug cycle is warranted before initiation of a speech-language pathology program.

Kinematic analysis of lingual function in dysarthric speakers with Parkinson's disease: An electromagnetic articulograph study

Dysarthria in people with Parkinson's disease (PD) has been widely studied. However, a limited number of studies have investigated lingual function during speech production in this population. This study aimed to investigate lingual kinematics during speech production using electromagnetic articulography (AG-200 EMA). The PD group consisted of eight dysarthric speakers with PD and was matched with a group of eight controls. The tongue tip and tongue back movements of all participants during sentence production were recorded by EMA. Results showed that, perceptually, the participants with PD were mildly dysarthric. Kinematic results documented comparable (for alveolar sentence production) and increased (for velar sentence production) range of lingual movement in the PD group when compared to the control group. Lingual movement velocity, acceleration, and deceleration were also increased in the PD group, predominantly for the release phase of consonant production during sentence utterances. The PD group had longer duration in the production of alveolar consonant and comparable duration in the production of velar consonant. The results of the present study suggest the presence of impaired lingual control in individuals with PD. Increased range of articulatory movement, primarily in the release phase of consonant production, may account for articulatory imprecision in this population.

Deep brain stimulation of the subthalamic nucleus reversibly deteriorates stuttering in advanced Parkinson’s disease

The etiology of developmental stuttering is still unknown. In some patients, stuttering re-emerges or is aggravated with the onset of Parkinson's disease (PD). We here report on a patient with PD treated by deep brain stimulation of the subthalamic nucleus and severe deterioration of stuttering under effective stimulation. Positron emission tomography (PET) of regional cerebral blood flow (rCBF) in stimulation on- and off-conditions showed overactivation of cerebral and cerebellar motor systems during speech activation and was in line with recent PET studies investigating brain activation during stuttering. The abnormal rCBF pattern increased in the stimulation on-condition and was associated with a marked worsening of stuttering. Clinical and imaging findings in this patient support the hypothesis that the basal ganglia circuitry plays an important role in the pathophysiology of stuttering.

The effects of levodopa on word intelligibility in Parkinson's disease

Dysarthria is a common manifestation in patients with idiopathic Parkinson's disease. This study investigated the effects of levodopa on intelligibility in patients with Parkinson's disease. Ten participants were tested during on- and off-states using the Yorkston and Beukelman intelligibility test (1980). Intelligibility as scored by a panel of speech therapists was significantly improved in the on-condition. No correlation was found, however, between intelligibility and overall severity of the disease or severity of the motor problems. EDUCATIONAL OUTCOMES: As a result of this activity the participant will be able to discuss the effects of levodopa on intelligibility in patients with Parkinson's disease.

Parkinsonian speech disfluencies: effects of L-dopa-related fluctuations

The excess dopamine theory of stuttering (Wu et al., 1997) contends that stuttering may be related to excess levels of the neurotransmitter dopamine in the brain. As Parkinson's disease (PD) patients commonly exhibit changes in dopamine levels accompanied by changes in motor performance, the present study examined disfluency in PD patients to gain information on the role of dopamine in speech disfluencies. Nine PD patients with no history of developmental stuttering were recorded once before and twice after taking their morning medication (on separate days). They read a passage and produced a monologue. Within-word and overall speech disfluencies were calculated at each recording. Through motor testing, it was inferred that participants had relatively low dopamine levels before taking medication, and relatively high dopamine levels after taking medication. There were no group changes in disfluency levels when the low-dopamine and high-dopamine states were compared. There were, however, significant differences in percent disfluencies between the PD participants and age-matched controls. The results of this study do not strongly support the excess dopamine theory of stuttering. Rather, the disfluency changes exhibited by individual participants support a hypothesis that speech disfluencies may be related to increases or decreases in dopamine levels in the brain.

EDUCATIONAL OBJECTIVES

The reader will learn about: (1). the characteristics of disfluent speech exhibited by speakers with Parkinson's disease. (2). The effect of L-dopa based medications on disfluencies of Parkinsonian speakers. (3). The complex role brain dopamine levels may play in disfluent speaking behavior.

Visuoperceptual and visuomotor deficits in developmental stutterers: an exploratory study

Although the cause of stuttering is unknown, there is strong evidence for it being a neuromotor disorder characterised by an abnormality of higher control encompassing not only speech but other motor systems. The aim of this exploratory study was to look for the presence of non-speech/language deficits--in particular, visuomotor and visuoperceptual deficits--in persons who stutter. Twelve moderate to severe developmental stutterers were compared with a group of fluent speakers, matched for age and sex, on a range of computerized sensory-motor tasks. These tasks covered various aspects of visuomotor function--ballistic movement, dynamic steadiness, and several types of tracking--and visuoperceptual function--acuity, static perception, and dynamic perception. A novel technique was used to remove the visuospatial component from tracking performance. Stutterers had slower reaction times, less accurate random tracking, and impaired dynamic visual perception. Severity of stuttering correlated with reaction time and dynamic perception. Removal of the visuoperceptual component from tracking performance indicated that the impaired tracking in the stutterers was predominantly due to reduced dynamic perception. This is the first study to provide preliminary evidence for the presence of non-linguistic visuoperceptual and upper-limb visuomotor tracking deficits in people with moderate to severe stuttering. These findings support a neurogenic aetiology for stuttering and are compatible with evidence of an overactive dopamine system in stutterers.