Characteristics of stuttering in Dutch‐speaking individuals

Clinical diagnostic procedures to distinguish stuttering from non‐stuttering individuals partially rely on the observation of characteristics of stuttered words or syllables. The purpose of this study was to examine the sensitivity and specificity of such a procedure, and to describe the observed characteristics of stuttered words. Methods involved the recording of the frequency, duration, and physical tension of stuttered words in conversational speech samples (total 43 100 words) and in an oral reading task (total 43 100 words). In this manner, 351 native Dutch speaking people, aged 8–53, who stutter were compared to a group of non‐stuttering peers (n = 80). Findings suggest that applying a criterion of 3% stuttered words in conversational speech makes it possible to distinguish stuttering from non‐stuttering individuals with high sensitivity (.9345) and perfect specificity (1.0000). Frequency, duration, and physical tension accompanying stuttered words are described for the group of stuttering participants, and these characteristics were compared to the group of non‐stuttering speakers.     

Novel tactile feedback to reduce overt stuttering

Stuttering is generally considered to be a speech disorder that affects ～1% of the global population. Various forms of speech feedback have been shown to reduce overt stuttered speaking, and in particular, second speech signal through speech feedback has drastically reduced utterances of stuttered speech in adults with persistent stuttering. This study reports data for increased overt fluency of speech in an adult stuttering population, whereby the vocalization of the speaker is captured by a microphone or an accelerometer, signal processed, and returned as mechanical tactile speech feedback to the speaker's skin. A repeated measures analysis of variance was used to show that both the microphone and the accelerometer speaking conditions were significantly more fluent than a control (no feedback) condition, with the microphone-driven tactile feedback reducing instances of stuttering by 71% and the accelerometer-driven tactile feedback reducing instances of stuttering by 80%. It is apparent that self-generated tactile feedback can be used to enhance fluency significantly in those who stutter.     

Phonological and language disorders in children who stutter: impact on treatment recommendations

In the profession of speech‐language pathology, it is commonly reported that children who stutter, as a group, are more likely to have phonological and language disorders than their non‐stuttering peers. Some support for this belief comes from survey studies that have questioned speech‐language pathologists about the children on their caseloads who stutter. Recently, one such study reported that 44% of children who stuttered had at least one additional communication disorder (Arndt & Healey, 2001). In the present investigation, speech‐language pathologists (n=127) who were treating children with speech and language disorders were questioned about their views on the treatment of stuttering. The results indicated that children who stutter and have at least one additional disorder are more likely to be recommended for treatment than those whose only disorder is stuttering. This suggests that caseload surveys may overestimate the rate of additional communication disorders in children who stutter. The results provide reason to question the widespread belief that children who stutter have a high rate of concomitant disorders, especially when it is based on caseload surveys. Suggestions are offered for ways to determine more precisely the frequency with which stuttering co‐occurs with other speech and language disorders in children through large‐scale epidemiological research.     

Olanzapine in the treatment of developmental stuttering: a double-blind, placebo-controlled trial.

Stuttering is a speech disorder that affects one-percent of all adults and much has been learned recently of its neurologic correlates. Stuttering has been associated with excessive cerebral activity of the neurotransmitter, dopamine. Pharmacologic research has suggested that older generation dopamine antagonist (i.e. "typical antipsychotic") medications improve stuttering symptoms, but are associated with poorly tolerated adverse effects. The purpose of this study was to compare the efficacy and tolerability of olanzapine, a novel dopamine antagonist (or "atypical antipsychotic"), versus placebo in the treatment of adult developmental stuttering. Twenty-four adults who stutter participated in a twelve-week, randomized, double-blind, placebo-controlled trial conducted at two separate sites. Subjects received either olanzapine (2.5 mg titrated to 5 mg) or matching placebo. Subjects were rated on an objective measure of stuttering severity (SSI-3), a clinician based global impression (CGI), and a subject-rated self-assessment of stuttering (SSS). Subjects were also monitored for potential side-effects. Twenty-three of the twenty-four subjects enrolled in the trial successfully completed the full course of the study. Olanzapine was statistically superior to placebo on the three ratings of stuttering severity, the SSI-3, the CGI and SSS (p < .05). Olanzapine is a promising medication for the treatment of stuttering and further research is warranted.     

Stroke-associated stuttering.

OBJECTIVE: To present patients with stuttering speech in association with stroke. DESIGN: Case series with follow-up for 5 years, or until the stuttering resolved. SETTING: University and community hospital neurology wards, and ambulatory neurology clinics. PATIENTS: Four patients who developed stuttering speech in association with an acute ischemic stroke. A 68-year-old man acutely developed stuttering with a large left middle cerebral artery distribution stroke. A 59-year-old man who had stuttered as a child began to stutter 2 months after a left temporal lobe infarction, as nonfluent aphasia was improving. Another childhood stutterer, a 59-year-old originally left-handed man developed severe but transient stuttering with a right parietal infarction. A 55-year-old man with a left occipital infarction had a right hemianopia and an acquired stutter, for which he was anosognosic. CONCLUSION: The clinical presentation of stroke-associated stuttering is variable, as are the locations of the implicated infarctions.     

Phonological and language disorders in children who stutter: impact on treatment recommendations

In the profession of speech-language pathology, it is commonly reported that children who stutter, as a group, are more likely to have phonological and language disorders than their non-stuttering peers. Some support for this belief comes from survey studies that have questioned speech-language pathologists about the children on their caseloads who stutter. Recently, one such study reported that 44% of children who stuttered had at least one additional communication disorder (Arndt & Healey, 2001). In the present investigation, speech-language pathologists (n = 127) who were treating children with speech and language disorders were questioned about their views on the treatment of stuttering. The results indicated that children who stutter and have at least one additional disorder are more likely to be recommended for treatment than those whose only disorder is stuttering. This suggests that caseload surveys may overestimate the rate of additional communication disorders in children who stutter. The results provide reason to question the widespread belief that children who stutter have a high rate of concomitant disorders, especially when it is based on caseload surveys. Suggestions are offered for ways to determine more precisely the frequency with which stuttering co-occurs with other speech and language disorders in children through large-scale epidemiological research.     

Prevalence of stuttering.

The prevalence of stuttering in a university population was 2.1%; 3.4% were former stutterers. More men than women stuttered. Right handed female stutterers were less likely to have "lost" their stutter than were right handed males. Stutterers, past stutterers, and questionable stutterers all had a family history of stuttering. The significant prevalence of stuttering, the increased prevalence among males, the lack of a decline of this disorder over the past few decades despite the increased number of speech clinicians and data concerning handedness, emphasise the need to investigate organic causes of stuttering.     

Stuttering as a trait or state – an ALE meta‐analysis of neuroimaging studies

Stuttering is a speech disorder characterised by repetitions, prolongations and blocks that disrupt the forward movement of speech. An earlier meta‐analysis of brain imaging studies of stuttering (Brown et al., 2005) revealed a general trend towards rightward lateralization of brain activations and hyperactivity in the larynx motor cortex bilaterally. The present study sought not only to update that meta‐analysis with recent work but to introduce an important distinction not present in the first study, namely the difference between ‘trait’ and ‘state’ stuttering. The analysis of trait stuttering compares people who stutter (PWS) with people who do not stutter when behaviour is controlled for, i.e., when speech is fluent in both groups. In contrast, the analysis of state stuttering examines PWS during episodes of stuttered speech compared with episodes of fluent speech. Seventeen studies were analysed using activation likelihood estimation. Trait stuttering was characterised by the well‐known rightward shift in lateralization for language and speech areas. State stuttering revealed a more diverse pattern. Abnormal activation of larynx and lip motor cortex was common to the two analyses. State stuttering was associated with overactivation in the right hemisphere larynx and lip motor cortex. Trait stuttering was associated with overactivation of lip motor cortex in the right hemisphere but underactivation of larynx motor cortex in the left hemisphere. These results support a large literature highlighting laryngeal and lip involvement in the symptomatology of stuttering, and disambiguate two possible sources of activation in neuroimaging studies of persistent developmental stuttering.     

Rhythmic speech and stuttering reduction in a syllable-timed language

Speaking rhythmically, also known as syllable-timed speech (STS), has been known for centuries to be a fluency-inducing condition for people who stutter. Cantonese is a tonal syllable-timed language and it has been shown that, of all languages, Cantonese is the most rhythmic (Mok, 2009). However, it is not known if STS reduces stuttering in Cantonese as it does in English. This is the first study to investigate the effects of STS on stuttering in a syllable-timed language. Nineteen native Cantonese-speaking adults who stutter were engaged in conversational tasks in Cantonese under two conditions: one in their usual speaking style and one using STS. The speakers’ percentage syllables stuttered (%SS) and speech rhythmicity were rated. The rhythmicity ratings were used to estimate the extent to which speakers were using STS in the syllable-timed condition. Results revealed a statistically significant reduction in %SS in the STS condition; however, this reduction was not as large as in previous studies in other languages and the amount of stuttering reduction varied across speakers. The rhythmicity ratings showed that some speakers were perceived to be speaking more rhythmically than others and that the perceived rhythmicity correlated positively with reductions in stuttering. The findings were unexpected, as it was anticipated that speakers of a highly rhythmic language such as Cantonese would find STS easy to use and that the consequent reductions in stuttering would be great, even greater perhaps than in a stress-timed language such as English. The theoretical and clinical implications of the findings are discussed.     

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.     

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.     

Brief application of simplified habit reversal to treat stuttering in children

We evaluated a brief therapy protocol involving the simplified regulated breathing method as a treatment for stuttering in children. The simplified treatment included awareness training, competing response training, and social support. Treatment was implemented in a multiple baseline across subjects design for 5 boys between the ages of 5 and 11. Each child received a 1 h treatment session, and 1/2 h booster sessions as needed. Four of the 5 children reduced their stuttering to less than 3% stuttered words (the criterion for successful treatment) after one 1 h treatment session. These results were maintained for 3 of the subjects from 6 to 9 months posttreatment. Social validity measures revealed significant differences between ratings on baseline and posttreatment speech samples. Treatment acceptability and credibility measures indicated that the subjects' guardians found the simplified regulated breathing method a reasonable treatment for stuttering in children.     

Stuttering on function words in bilingual children who stutter: A preliminary study

Evidence suggests young monolingual children who stutter (CWS) are more disfluent on function than content words, particularly when produced in the initial utterance position. The purpose of the present preliminary study was to investigate whether young bilingual CWS present with this same pattern. The narrative and conversational samples of four bilingual Spanish- and English-speaking CWS were analysed. All four bilingual participants produced significantly more stuttering on function words compared to content words, irrespective of their position in the utterance, in their Spanish narrative and conversational speech samples. Three of the four participants also demonstrated more stuttering on function compared to content words in their narrative speech samples in English, but only one participant produced more stuttering on function than content words in her English conversational sample. These preliminary findings are discussed relative to linguistic planning and language proficiency and their potential contribution to stuttered speech.     

Event-Related Potentials Distinguish Fluent and Stuttered Speech

Background. This study aimed to find the best possible approach to neurotherapy for stuttering.

Method. Five right-handed Dysfluent Speakers and five right-handed Fluent Speakers were compared before dysfluent and fluent speech onset with electrical event related potentials. EEG electrodes were at inferior frontal, precentral, and temporoparietal locations on each hemiscalp. Participants processed two words displayed consecutively at center screen, the first or second of which was to be uttered aloud according to the subsequent command digit being 1 or 2.

Results. The Fluent Speakers manifested significant left hemisphere contingent negative variations (CNVs) prior to the words and the contingency stimulus. The Dysfluent Speakers presented overall smaller CNVs that were more marked over the right hemisphere than left. This pattern was observed before both their stuttered and fluent words, with the former differing significantly from the fluent speakers hemispheric CNV pattern.

Conclusion. These results indicate that dysfluent speech is related to abnormal hemispheric asymmetry. Neurofeedback therapy for persons who stutter could aim at normalizing contingent negativity asymmetry seconds prior to speech.     

Stuttering as a manifestation of right-hemispheric subcortical stroke

A right-handed man developed stuttering, without aphasia, as a result of a circumscribed subcortical infarction in the right hemisphere. He never stuttered before and has no family history of stuttering. Damage to callosal pathways coordinating the activity of both hemispheres during speech is proposed as a possible explanation for the stuttering.     

Simulating the neural correlates of stuttering

For functional neuroimaging studies of stuttering, two challenges are (1) the elicitation of naturally stuttered versus fluent speech and (2) the separation of activation associated with abnormal motor execution from activation that reflects the cognitive substrates of stuttering. This paper reports on a proof-of-concept study, in which a single-subject approach was applied to address these two issues. A stuttering speaker used his insight into his own stuttering behavior to create a list of stutter-prone words versus a list of “fluent” words. He was then matched to a non-stuttering speaker, who imitated the specific articulatory and orofacial motor pattern of the stuttering speaker. Both study participants performed a functional MRI experiment of single word reading, each being presented with the same lexical items. Results suggest that the generally observed right-hemisphere lateralization appears to reflect a true neural correlate of stuttering. Some of the classically reported activation associated with stuttering appears to be driven more by nonspecific motor patterns than by cognitive substrates of stuttering, while anterior cingulate activation may reflect awareness of (upcoming) dysfluencies. This study shows that it is feasible to match stuttering speakers’ utterances more closely to simulated stutters for the investigation of neural correlates of real stuttering. Significant main effects and contrast effects were obtained for the differences between fluent and stuttered speech, and right-hemisphere lateralization associated with real stuttered speech was shown in a single subject.     

Speech timing in children after the Lidcombe Program of early stuttering intervention

It is known that operant treatments can control stuttering in children. However, at present it is unknown why such treatments are effective. Changes in the usual way of speaking are frequently observed after behavioural treatments for adults who stutter, and it is possible that operant treatments for children also invoke such changes. To explore this idea, selected acoustic measures of speech timing were made in eight preschool children before and after receiving the Lidcombe Program, which is an operant treatment for stuttering. No systematic changes were detected after treatment. Considering this finding and a previous report, there is no evidence to suggest that the reductions in stuttering that occur with this treatment are related to systematic changes in speech timing or curtailment of language function.     

An operant intervention for early stuttering. The development of the Lidcombe program

Stuttering is a common speech disorder that causes significant distress and may cause social maladjustment and hinder occupational potential. Treatments for chronic stuttering in adults can control stuttering by teaching the speaker to use a new speech pattern. However, these treatments are resource intensive and relapse prone, and they produce speech that sounds unnatural to the listener and feels unnatural to the speaker. This article describes the development and evaluation of an operant treatment for early stuttering. Parents are trained to present verbal contingencies for stuttered and stutter-free speech during everyday speaking situations with their children. The authors overview outcome data from several studies that suggest that this program produces relapse-free control of stuttered speech in preschool children in the medium and long term in a cost-effective manner.     

Speech timing in children after the Lidcombe Program of early stuttering intervention

It is known that operant treatments can control stuttering in children. However, at present it is unknown why such treatments are effective. Changes in the usual way of speaking are frequently observed after behavioural treatments for adults who stutter, and it is possible that operant treatments for children also invoke such changes. To explore this idea, selected acoustic measures of speech timing were made in eight preschool children before and after receiving the Lidcombe Program, which is an operant treatment for stuttering. No systematic changes were detected after treatment. Considering this finding and a previous report, there is no evidence to suggest that the reductions in stuttering that occur with this treatment are related to systematic changes in speech timing or curtailment of language function.