Stuttering may be a type of action dystonia

Developmental stuttering, physical concomitants associated with stuttering, and Tourette syndrome: A scoping review

BACKGROUND AND PURPOSE

Developmental stuttering and Tourette syndrome (TS) are common neurodevelopmental disorders. Although disfluencies may co-occur in TS, their type and frequency do not always represent pure stuttering. Conversely, core symptoms of stuttering may be accompanied by physical concomitants (PCs) that can be confused for tics. This scoping review aimed to explore the similarities and differences between stuttering and tics in terms of epidemiology, comorbidities, phenomenology, evolution, physiopathology, and treatment. We also described the nature of PCs in stuttering and disfluencies in TS.

METHODS

A literature search on Medline, Embase and PsycInfo was executed in March 2022. From 426 studies screened, 122 were included in the review (a majority being narrative reviews and case reports).

RESULTS

TS and stuttering have several epidemiological, phenomenological, comorbidity, and management similarities suggesting shared risk factors and physiopathology (involving the basal ganglia and their connections with speech and motor control cortical regions). PCs in stuttering commonly involve the face (eyelids, jaw/mouth/lip movements) and sometimes the head, trunk and limbs. PCs can be present from early stages of stuttering and vary over time and within individuals. The function of PCs is unknown. Some individuals with TS have a distinct disfluency pattern, composed of a majority of typical disfluencies (mostly between-word disfluencies), and a mix of cluttering-like behaviors, complex phonic tics (e.g. speech-blocking tics, echolalia, palilalia), and rarely, atypical disfluencies.

CONCLUSION

Future investigations are warranted to better understand the complex relationships between tics and stuttering and address the management of disfluencies in TS and PCs in stuttering.

Acoustic analysis in stuttering: a machine-learning study

Background

Stuttering is a childhood-onset neurodevelopmental disorder affecting speech fluency. The diagnosis and clinical management of stuttering is currently based on perceptual examination and clinical scales. Standardized techniques for acoustic analysis have prompted promising results for the objective assessment of dysfluency in people with stuttering (PWS).

Objective

We assessed objectively and automatically voice in stuttering, through artificial intelligence (i.e., the support vector machine - SVM classifier). We also investigated the age-related changes affecting voice in stutterers, and verified the relevance of specific speech tasks for the objective and automatic assessment of stuttering.

Methods

Fifty-three PWS (20 children, 33 younger adults) and 71 age-/gender-matched controls (31 children, 40 younger adults) were recruited. Clinical data were assessed through clinical scales. The voluntary and sustained emission of a vowel and two sentences were recorded through smartphones. Audio samples were analyzed using a dedicated machine-learning algorithm, the SVM to compare PWS and controls, both children and younger adults. The receiver operating characteristic (ROC) curves were calculated for a description of the accuracy, for all comparisons. The likelihood ratio (LR), was calculated for each PWS during all speech tasks, for clinical-instrumental correlations, by using an artificial neural network (ANN).

Results

Acoustic analysis based on machine-learning algorithm objectively and automatically discriminated between the overall cohort of PWS and controls with high accuracy (88%). Also, physiologic ageing crucially influenced stuttering as demonstrated by the high accuracy (92%) of machine-learning analysis when classifying children and younger adults PWS. The diagnostic accuracies achieved by machine-learning analysis were comparable for each speech task. The significant clinical-instrumental correlations between LRs and clinical scales supported the biological plausibility of our findings.

Conclusion

Acoustic analysis based on artificial intelligence (SVM) represents a reliable tool for the objective and automatic recognition of stuttering and its relationship with physiologic ageing. The accuracy of the automatic classification is high and independent of the speech task. Machine-learning analysis would help clinicians in the objective diagnosis and clinical management of stuttering. The digital collection of audio samples here achieved through smartphones would promote the future application of the technique in a telemedicine context (home environment).

Multimodal explainable AI predicts upcoming speech behavior in adults who stutter

A key goal of cognitive neuroscience is to better understand how dynamic brain activity relates to behavior. Such dynamics, in terms of spatial and temporal patterns of brain activity, are directly measured with neurophysiological methods such as EEG, but can also be indirectly expressed by the body. Autonomic nervous system activity is the best-known example, but, muscles in the eyes and face can also index brain activity. Mostly parallel lines of artificial intelligence research show that EEG and facial muscles both encode information about emotion, pain, attention, and social interactions, among other topics. In this study, we examined adults who stutter (AWS) to understand the relations between dynamic brain and facial muscle activity and predictions about future behavior (fluent or stuttered speech). AWS can provide insight into brain-behavior dynamics because they naturally fluctuate between episodes of fluent and stuttered speech behavior. We focused on the period when speech preparation occurs, and used EEG and facial muscle activity measured from video to predict whether the upcoming speech would be fluent or stuttered. An explainable self-supervised multimodal architecture learned the temporal dynamics of both EEG and facial muscle movements during speech preparation in AWS, and predicted fluent or stuttered speech at 80.8% accuracy (chance=50%). Specific EEG and facial muscle signals distinguished fluent and stuttered trials, and systematically varied from early to late speech preparation time periods. The self-supervised architecture successfully identified multimodal activity that predicted upcoming behavior on a trial-by-trial basis. This approach could be applied to understanding the neural mechanisms driving variable behavior and symptoms in a wide range of neurological and psychiatric disorders. The combination of direct measures of neural activity and simple video data may be applied to developing technologies that estimate brain state from subtle bodily signals.

Enlarged Area of Mesencephalic Iron Deposits in Adults Who Stutter

PURPOSE

Childhood onset speech fluency disorder (stuttering) is possibly related to dopaminergic dysfunction. Mesencephalic hyperechogenicity (ME) detected by transcranial ultrasound (TCS) might be seen as an indirect marker of dopaminergic dysfunction. We here determined whether adults who stutter since childhood (AWS) show ME.

METHODS

We performed TCS in ten AWS and ten matched adults who never stuttered. We also assessed motor performance in finger tapping and in the 25 Foot Walking test.

RESULTS

Compared to controls, AWS showed enlarged ME on either side. Finger tapping was slower in AWS. Walking cadence, i.e., the ratio of number of steps by time, tended to be higher in AWS than in control participants.

DISCUSSION

The results demonstrate a motor deficit in AWS linked to dopaminergic dysfunction and extending beyond speech. Since iron deposits evolve in childhood and shrink thereafter, ME might serve as an easily quantifiable biomarker helping to predict the risk of persistency in children who stutter.

No Evidence for Dystonia-Like Sensory Overflow of Tongue Representations in Adults Who Stutter

Persistent developmental stuttering (PDS) disrupts speech fluency in about 1% of adults. Although many models of speech production assume an intact sensory feedback from the speech organs to the brain, very little is actually known about the integrity of their sensory representation in PDS. Here, we studied somatosensory evoked potentials (SEPs) in adults who stutter (AWS), with the aim of probing the integrity of sensory pathways. In addition, we tested the processing of dual sensory input to address a putative link between stuttering and focal dystonia. In 15 AWS (aged 15-55 years; three females) and 14 matched fluent speaking adults (ANS), we recorded SEPs at C5' and C6' induced by stimulating separately or simultaneously the tongue or the cheek at the corner of the mouth. We determined latencies (N13, P19, and N27) and peak-to-peak amplitudes (N13-P19, P19-N27). We divided amplitudes from simultaneous stimulation by the sum of those from separate stimulation. Amplitude ratios did not differ between groups, indicating normal processing of dual sensory input. This does not support a clinical analogy between focal dystonia and persistent stuttering. SEP latencies as a measure of transmission speed in sensory pathways were significantly shorter in stuttering subjects than in fluent speaking participants, however, this might have been related to a trend for a height difference between groups, and was not confirmed in a replication dataset. In summary, we did not find evidence for dystonia-like sensory overflow of tongue representations in AWS.

Stuttering in Parkinson's disease after deep brain stimulation: A note on dystonia and low-frequency stimulation

Stuttering, a speech fluency disorder, is a rare complication of Deep Brain Stimulation (DBS) in Parkinson's Disease (PD). We report a 61 years-old patient with PD, afflicted by severe On and Off dystonia, treated with Subthalamic Nucleus DBS that developed post-DBS stuttering while on 130 Hz stimulation. Stuttering reduction was noted when frequency was changed to 80 Hz, but the previously observed dystonia improvement was lost. There are no reports in literature on patients developing stuttering with low-frequency stimulation. We question if low-frequency stimulation could have a role for managing PD's post-DBS stuttering, and notice that stuttering improvement was associated with dystonia worsening suggesting that they are distinct phenomena.

An evaluation of G-protein coupled membrane estrogen receptor-1 level in stuttering

OBJECTIVE

Stuttering is a widespread but little understood disease. There has been a recent increase in neuropathophysiological, genetic, and biochemical studies related to the etiopathogenesis. As developmental stuttering continues in adult males, hormonal factors are thought to have an effect. In this study, an evaluation was made for the first time of serum GPER-1 level in patients with a stutter.

STUDY DESIGN

Prospective case control.

MATERIALS AND METHODS

The study included 30 patients with a stutter, aged < 18 years, and 35 age-matched children as the control group. The Stuttering Severity Instrument-3 form was administered to the patients. Evaluations were made of serum GPER-1, TSH, estradiol, prolactin, and progesterone and testosterone levels.

RESULTS

GPER-1 level was determined as 0.51 (0.42-0.67) ng/mL in the patients and as 0.19 (0.13-0.25) ng/mL in the control group, and the difference was statistically significant (p < 0.001). A statistically significant difference was determined between genders with GPER-1 level of 0.56 (0.44-0.68) ng/mL in the male stuttering patient group and 0.44 (0.35-0.49) ng/mL in the female patient group (p = 0.026). Differential diagnosis with ROC analysis for the serum GPER-1 levels was statistically significant [Area under the ROC curve (AUC): 0.998, confidence interval, CI 0.992-1.000, p < 0.001].

CONCLUSION

The GPER-1 levels of the stuttering patients were found to be higher than those of the control group and GPER-1 levels of male patients were higher than those of females. As GPER-1 has high sensitivity and sensitivity, it could be considered important in the diagnosis and treatment of stuttering.

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.

A muscle spindle abnormity in one laryngeal muscle would be sufficient to cause stuttering

Muscle spindles are increasingly recognized as playing a pivotal role in the cause of dystonia. This development and own laryngeal observations that support the idea of causally "well-intentioned" stuttering motivated us to present the following hypothesis: stuttering events compensate for a sensory problem that arises when the abductor/adductor ratio of afferent impulse rates from the posterior cricoarytenoid and lateral cricoarytenoid muscle spindles is abnormally reduced and processed for the occasional determination of the vocal fold position. This hypothesis implies that functional and structural brain abnormalities might be interpreted as secondary compensatory reactions. Verification of this hypothesis (using technologies such as microneurography, dissection and muscle afferent block) is important because its confirmation could relink dystonia and stuttering research, change the direction of stuttering therapy and destigmatize stuttering radically.

Adult-onset dystonia

Dystonia is defined as involuntary sustained muscle contractions producing twisting or squeezing movements and abnormal postures. The movements can be stereotyped and repetitive and they may vary in speed from rapid to slow; sustained contractions can result in fixed postures. Dystonic disorders are classified into primary and secondary forms. Several types of adult-onset primary dystonia have been identified but all share the characteristic that dystonia (including tremor) is the sole neurologic feature. The forms most commonly seen in neurological practice include cranial dystonia (blepharospasm, oromandibular and lingual dystonia and spasmodic dysphonia), cervical dystonia (also known as spasmodic torticollis) and writer's cramp. These are the disorders that benefit most from botulinum toxin injections. A general characteristic of dystonia is that the movements or postures may occur in relation to specific voluntary actions by the involved muscle groups (such as in writer's cramp). Dystonic contractions may occur in one body segment with movement of another (overflow dystonia). With progression, dystonia often becomes present at rest. Dystonic movements typically worsen with anxiety, heightened emotions, and fatigue, decrease with relaxation, and disappear during sleep. There may be diurnal fluctuations in the dystonia, which manifest as little or no involuntary movement in the morning followed by severe disabling dystonia in the afternoon and evening. Morning improvement (or honeymoon) is seen with several types of dystonia. Patients often discover maneuvers that reduce the dystonia and which involve sensory stimuli such as touching the chin lightly in cervical dystonia. These maneuvers are known as sensory tricks, or gestes antagonistes. This chapter focuses on adult-onset focal dystonias including cranial dystonia, cervical dystonia, and writer's cramp. The chapter begins with a review of the epidemiology of focal dystonias, followed by discussions of each major type of focal dystonia, covering clinical phenomenology, differential genetics, and diagnosis. The chapter concludes with discussions of the pathophysiology, the few pathological cases published of adult-onset focal dystonia and management options, and a a brief look at the future.

Attenuated variants of Lesch-Nyhan disease

Lesch–Nyhan disease is a neurogenetic disorder caused by deficiency of the enzyme hypoxanthine–guanine phosphoribosyltransferase. The classic form of the disease is described by a characteristic syndrome that includes overproduction of uric acid, severe generalized dystonia, cognitive disability and self-injurious behaviour. In addition to the classic disease, variant forms of the disease occur wherein some clinical features are absent or unusually mild. The current studies provide the results of a prospective and multi-centre international study focusing on neurological manifestations of the largest cohort of Lesch–Nyhan disease variants evaluated to date, with 46 patients from 3 to 65 years of age coming from 34 families. All had evidence for overproduction of uric acid. Motor abnormalities were evident in 42 (91%), ranging from subtle clumsiness to severely disabling generalized dystonia. Cognitive function was affected in 31 (67%) but it was never severe. Though none exhibited self-injurious behaviours, many exhibited behaviours that were maladaptive. Only three patients had no evidence of neurological dysfunction. Our results were compared with a comprehensive review of 78 prior reports describing a total of 127 Lesch–Nyhan disease variants. Together these results define the spectrum of clinical features associated with hypoxanthine–guanine phosphoribosyltransferase deficiency. At one end of the spectrum are patients with classic Lesch–Nyhan disease and the full clinical phenotype. At the other end of the spectrum are patients with overproduction of uric acid but no apparent neurological or behavioural deficits. Inbetween are patients with varying degrees of motor, cognitive, or behavioural abnormalities. Recognition of this spectrum is valuable for understanding the pathogenesis and diagnosis of all forms of hypoxanthine–guanine phosphoribosyltransferase deficiency.

Relief of acquired stuttering associated with Parkinson's disease by unilateral left subthalamic brain stimulation

PURPOSE

In this article, the authors report a case of acquired stuttering associated with Parkinson's disease (PD) that was responsive to unilateral subthalamic nucleus deep-brain stimulation (STN DBS) in the language-dominant hemisphere.

METHOD

A single-subject, masked, multiple baseline design was used to evaluate the effects of unilateral left STN DBS on stuttering associated with PD. The patient underwent 3 formal speech assessments of spontaneous speech and the reading of passages with DBS off and on. Speech samples were videotaped and placed in random order, and 2 independent speech-language pathologists calculated the percentage of stuttered syllables and classified individual stuttering events.

RESULTS

Stuttering improved significantly in the DBS-on condition. In total, 10% of syllables were affected by stuttering events with DBS off, and less than 1% of syllables were affected by stuttering events with DBS on (n = 2,281 syllables, p < .00001, in a chi(2) test). The effect of unilateral STN DBS on stuttering was relatively independent of whether the patient was on or off dopaminergic medications.

CONCLUSION

This article emphasizes the important role of the subthalamic region in the motor control of speech and language.

Phenomenology of abnormal movements in stuttering

BACKGROUND

Stuttering is often accompanied by involuntary movements, abnormal gestures or changes in facial expression.

OBJECTIVE

To describe the incidence and phenomenology of abnormal movements (AMs) in stuttering patients.

MATERIALS AND METHODS

Eighty-five consecutive patients with stuttering and 119 normal controls videotaped and subsequently reviewed, in which AMs were classified as voluntary or involuntary, and as concurrent or unrelated to speech. Movement phenomenology was correlated with disease severity.

RESULTS

Of 85 stuttering patients studied, 51.7% had AMs and 22 more than one AM. Sixty-six different AMs were identified, of which 83.3% occurred during speech, 72.7% were classified as involuntary, and 27.2% as voluntary. Of 38 involuntary movements concurrent to speech, 25 were originally perceived as voluntary, but had since become involuntary through repeated use during stuttering. All involuntary movements not concurrent to speech fulfilled criteria for tics.

CONCLUSION

AMs occurring during stuttering were not always involuntary; movements not concurrent with speech clearly fulfilled clinical criteria for tics and were similar in incidence to normal controls. Inverse correlation was found between conscious control of movement during speech and stuttering severity. Many involuntary movements occurring during speech were clearly referred by patients as initially voluntary early on in the development of their speech disorder (starters or unblockers), underlining the importance of repetitive use of complex motor sequences as a source for putative involuntary movement genesis.

Multimodal neurosurgical strategies for the management of dystonias

Dystonia have many subtypes, and is classified as focal, segmental and generalized. As for focal dystonia, spasmodic torticollis (cervical dystonia) and writer's cramp are most common. Cervical dystonia is mainly treated effectively with selective peripheral denervation, and task specific focal dystonia of the hand (writer's cramp) is effectively alleviated by stereotactic ventro-oral thalamotomy. Generalized dystonia is dramatically improved with deep brain stimulation of the globus pallidus interna. Because the majority of dystonia is medically refractory and surgical treatment results in marked improvement, the authors strongly believe that dystonia should be regarded as a definite neurosurgical indication. Based on personal experience of nearly 200 cases of dystonia surgery, the authors describe a multimodal approach to various types of dystonias. Also we discuss possible relation between dystonias and psychiatric conditions, and future new indication of dystonia surgery.

Copper in Developmental Stuttering

It has previously been reported that men with developmental stuttering showed reduced concentration of copper in the blood, and a negative correlation between the copper level and the severity of stuttering. Disorders of copper metabolism may result in dysfunction of the basal ganglia system and dystonia, a motor disorder sharing some traits of stuttering. It has been shown that copper ions affect the dopamine and the GABA systems. With this background we investigated the plasma level of copper, the copper binding protein ceruloplasmin, and the estimated level of free copper in stuttering adults. Sixteen men with developmental stuttering were compared with 16 men without speech problems. The samples were assayed in one batch in a pseudorandom and counterbalanced order. No significant differences were found between stuttering men and the control group in any of the biological variables, and no negative correlation between copper and the general severity of stuttering was shown. On the contrary, an explorative analysis resulted in a positive correlation between high plasma copper and superfluous muscular activity during stuttering (r=0.51, p=0.04). This result indicates that there is no relation between developmental stuttering and low plasma copper in the main population of stuttering adults.

Stuttering and the basal ganglia circuits: a critical review of possible relations

The possible relation between stuttering and the basal ganglia is discussed. Important clues to the pathophysiology of stuttering are given by conditions known to alleviate dysfluency, like the rhythm effect, chorus speech, and singing. Information regarding pharmacologic trials, lesion studies, brain imaging, genetics, and developmental changes of the nervous system is reviewed. The symptoms of stuttering are compared with basal ganglia motor disorders like Parkinson's disease and dystonia. It is proposed that the basal ganglia-thalamocortical motor circuits through the putamen are likely to play a key role in stuttering. The core dysfunction in stuttering is suggested to be impaired ability of the basal ganglia to produce timing cues for the initiation of the next motor segment in speech. Similarities between stuttering and dystonia are indicated, and possible relations to the dopamine system are discussed, as well as the interaction between the cerebral cortex and the basal ganglia. Behavioral and pharmacologic information suggests the existence of subtypes of stuttering.

LEARNING OUTCOMES

As a result of this activity, the reader will (1) become familiar with the research regarding the basal ganglia system relating to speech motor control; (2) become familiar with the research on stuttering with indications of basal ganglia involvement; and (3) be able to discuss basal ganglia mechanisms with relevance for theory of stuttering.

Normal intracortical excitability in developmental stuttering

Persistent developmental stuttering (PDS) shares clinical features with task-specific dystonias. In these dystonias, intracortical inhibition is abnormally weak. We therefore sought to determine intracortical inhibition and intracortical facilitation in PDS. In 18 subjects with PDS since childhood (mean age, 39.4 [SD 13.0] years) and 18 speech-fluent controls (43.6 [14.3] years), we investigated resting and active motor thresholds as well as intracortical inhibition and facilitation of the optimal representation of the abductor digiti minimi of the dominant hand using transcranial magnetic stimulation. In PDS, the resting and active motor thresholds were increased, whereas intracortical inhibition and facilitation were normal. Normal intracortical excitability makes a pathophysiological analogy between focal dystonia and PDS less likely. The enhanced motor threshold suggests reduced motor cortical neuronal membrane excitability in PDS.

Tics and developmental stuttering

BACKGROUND

Developmental stuttering affects 1% of the population but its cause remains unclear. Recent PET studies of metabolism in the central nervous system suggest that it may be related to dysfunction in the basal ganglia or its connections with regions of the cortex associated with speech and motor control.

OBJECTIVE

To determine the presence and characteristics of involuntary movements (IMs) in people who stutter and to investigate the hypothesis that these movements may be of a very similar nature to the IMs seen in patients with movement disorders due to basal ganglia dysfunction.

METHODS

Sixteen adults with developmental stuttering and 16 controls matched for sex and age were audio-videotaped while freely speaking 300 words in conversation and reading aloud 300 words. The audio data was inspected for dysfluencies and the video data was scrutinised for the presence and characteristics of IMs.

RESULTS

Subjects who stuttered produced more IMs than controls during free speech (354 vs 187, p<0.05) and reading (297 vs 47, p<0.001). Most of the IMs in both groups were tics, with a greater number of both simple and complex motor tics (CMTs) in subjects who stuttered. CMTs were more frequent than simple motor tics in those who stuttered, but not in controls. The combination of repetitive eye blink followed by prolonged eye closure was found exclusively in the stuttering group, as were simple tics consisting of eyebrow raise or jaw movement. Dystonia in the form of blepharospasm was identified in a small number of subjects who stuttered. Choreic movements were not associated with stuttering.

CONCLUSIONS

Developmental stuttering is associated with the presence of IMs that are predominantly simple and CMTs. This association suggests that tics and stuttering may share a common pathophysiology and supports the view that, in common with tics, stuttering may reflect dysfunction in the basal ganglia or its immediate connections.

Stuttering: a dynamic motor control disorder

The purpose of this review is to determine what neural mechanisms may be dysfunctional in stuttering. Three sources of evidence are reviewed. First, studies of dynamic inter-relationships among brain regions during normal speech and in persons who stutter (PWS) suggest that the timing of neural activity in different regions may be abnormal in PWS. Second, the brain lesions associated with acquired stuttering are reviewed. These indicate that in a high percentage of cases, the primary speech and language regions are not affected but lesions involve other structures, such as the basal ganglia, which may modulate the primary speech and language regions. Third, to characterize the motor control disorder in stuttering, similarities and differences from focal dystonias such as spasmodic dysphonia (SD) and Tourette's syndrome (TS) are reviewed. This review indicates that the central control abnormalities in stuttering are not due to disturbance in one particular brain region but rather a system dysfunction that interferes with rapid and dynamic speech processing for production.

EDUCATIONAL OBJECTIVES

The reader will be able to describe: (1) the similarities and differences between stuttering and other speech motor control disorders, (2) which brain lesions are most likely to produce acquired stuttering in adults, and (3) what type of brain abnormality most likely underlies stuttering.

Dysfluency and involuntary movements: a new look at developmental stuttering

Studies using modern imaging techniques suggest that, in developmental stuttering, there is dysfunction within the cortical and subcortical areas of the motor control system wider than that pertaining to speech motor control alone. If this is the case, one might expect motor deficits extending beyond and unrelated to the production of speech in people who stutter. This study explored this proposal by investigating the presence and characteristics of involuntary movements accompanying stuttering. Sixteen adults with developmental stuttering and 16 controls matched for age and sex were audio-videotaped during 5 minutes of conversational speech and reading a passage of 350 words. Audio-data were examined for dysfluencies. Movements of the face, head and upper body considered involuntary and not part of normal facial expression or gesture and not part of the mechanics of speech were identified and described from muted video-data. Subjects who stuttered had a higher proportion of classic (within-word) dysfluencies accompanied by involuntary movements (IMs) than controls during speech (24.4% vs. 4.5%, p = .054) and reading (28.6% vs. 4.9%, p = .033). There was no difference in proportion of classic dysfluencies accompanied by IMs between speech and reading for either group. IMs were also seen in both groups during fluent speech, with a similar incidence during free speech (3.9% vs. 3.0%, NS) but a greater incidence in the subjects who stuttered during reading (2.4% vs. 0.8%, p = .03). In contrast, there was no difference between the two groups for IMs accompanying normal (between-word) dysfluencies. This suggests that classic and normal dysfluency and their accompanying IMs have different etiologies. The notion that stuttering and IMs are due to altered function in a motor control system wider than that of speech motor control alone is supported by a higher incidence of IMs in people who stutter during both classic dysfluencies and fluent speech.

Re-emergence of childhood stuttering in Parkinson's disease: a hypothesis

OBJECTIVE

To characterize speech patterns in patients with Parkinson's disease (PD) who have a history of childhood stuttering.

BACKGROUND

Childhood stuttering usually resolves, but it re-emerges in some patients after stroke or other brain disorders. This phenomenon of recurrent stuttering has not been characterized in childhood stutterers who later develop PD.

METHODS/PATIENTS

Twelve patients with a history of childhood stuttering that remitted and subsequently recurred were included in the study. A structured interview was administered to seven patients, and six were able to answer questions about childhood stuttering. The Johnson Severity Scale (JSS) (range 0-7) and a Situation Avoidance Scale (SAS) were used to rate stuttering severity (range 0-15) and avoidance (range 0-15).

RESULTS

The mean age at onset of childhood stuttering was 6.2 years (range 5-10); the mean latency from the onset of childhood stuttering to adult stuttering was 46.1 years; and the stuttering recurred on average 5.9 years (range 0-21) after the onset of PD. The stuttering characteristics in childhood and adulthood included repetitions of sounds and syllables at the beginnings of words, blocks and interjections, physical tension, and a worsening of symptoms with stress. The patients rated themselves as having mild-to-moderate childhood stuttering by the JSS (mean 3.0, range 2-4) and mild-to-moderate stuttering and avoidance by the SAS (mean stuttering score 5.3, range 3-7; mean avoidance score 4.2, range 3-6). There was no apparent association between the severity of childhood stuttering and the severity of PD, but those patients who had higher Unified Parkinson's Disease Rating Scale scores tended to have more and worse symptoms of stuttering.

CONCLUSION

Our patients provide evidence for the hypothesis that childhood stuttering may re-emerge in adulthood with the onset of PD.

Features resembling Tourette's syndrome in developmental stutterers

Developmental stuttering (DS) may be related to the extrapyramidal motor system and shares many clinical similarities with Tourette's syndrome (TS), which is widely believed to be associated with extrapyramidal dysfunction. Twenty-two stutterers were examined for neuropsychiatric features commonly seen in TS, including tics, obsessive-compulsive behaviors (OCB), and attention deficit disorders. Eleven stutterers displayed motor tics, and symptoms of OCB were observed at rates similar to those seen in persons with TS. Few stutterers demonstrated significant attentional deficits. Findings are consistent with models suggesting extrapyramidal involvement in DS and raise the possibility that DS and TS are pathogenetically related.

Speech impairment in Parkinson's disease is improved by transcranial application of electromagnetic fields

A 52 year old fully medicated physician with juvenile onset Parkinsonism experienced 4 years ago severe "on-off" fluctuations in motor disability and debilitating speech impairment with severe stuttering which occurred predominantly during "on-off" periods. His speech impairment improved 20%-30% when sertraline (75 mg/day), a serotonin reuptake inhibitor, was added to his dopaminergic medications which included levodopa, amantadine, selegiline and pergolide mesylate. A more dramatic and consistent improvement in his speech occurred over the past 4 years during which time the patient received, on a fairly regular basis, weekly transcranial treatments with AC pulsed electromagnetic fields (EMFs) of picotesla flux density. Recurrence of speech impairment was observed on several occasions when regular treatments with EMFs were temporarily discontinued. These findings demonstrate that AC pulsed applications of picotesla flux density EMFs may offer a nonpharmacologic approach to the management of speech disturbances in Parkinsonism. Furthermore, this case implicates cerebral serotonergic deficiency in the pathogenesis of Parkinsonian speech impairment which affects more than 50% of patients. It is believed that pulsed applications of EMFs improved this patient's speech impairment through the facilitation of serotonergic transmission which may have occurred in part through a synergistic interaction with sertraline.