A one year prospective study of neurogenic stuttering following stroke: incidence and co-occurring disorders.

UNLABELLED: In this prospective study, data on incidence, stuttering characteristics, co-occurring speech disorders, and recovery of neurogenic stuttering in a large sample of stroke participants were assessed. Following stroke onset, 17 of 319 participants (5.3%; 95% CI, 3.2-8.3) met the criteria for neurogenic stuttering. Stuttering persisted in at least 2.5% (95% CI, 1.1-4.7) for more than six months following the stroke. Participants with comorbid aphasia presented with a significantly higher frequency of stuttering compared to the group without aphasia (U=13.00, p((1-tailed))=.02) but no difference was found for participants with co-occurring dysarthria and/or cognitive problems. Participants with neurogenic stuttering did not differ from those without stuttering in terms of stroke risk factors or stroke etiologic subtypes. Although the incidence of stuttering following stroke is lower than that for aphasia or dysarthria, these results show that clinicians should take neurogenic stuttering into account when assessing stroke participants' speech and language. LEARNING OUTCOMES: : Readers will be able to: (1) understand the need for systematic, prospective studies in neurogenic stuttering; (2) know the incidence and prevalence of neurogenic stuttering following stroke; and (3) know how neurogenic stuttering co-occurs with other speech-language disorders following stroke.

Functional neuroimaging of cerebellar activation during single word reading and verb generation in stuttering and nonstuttering adults.

Articulatory discoordinations typically observed in fluent and disfluent speech of stuttering adults suggest an underlying deficiency in the precise timing needed for speech production. Positron emission tomography scans of stuttering adults showed generally higher cerebellar activations pre-treatment compared to nonstuttering control subjects. Intensive fluency treatment resulted in increased cerebellar activation during reading immediately post-treatment and a decrease to near normal levels at the 1 year follow scan. In contrast, verb generation resulted in a gradual but consistent decrease over the three scans. The results suggest that automaticity in motor and cognitive processes during speech production may need to be considered as an important factor in future investigations of stuttering.

The effects of masseter tendon vibration on nonspeech oral movements and vowel gestures.

The role of proprioception in speech and oral motor control was investigated by applying tendon vibration to the masseter during vowel production and nonspeech oral movements. Measures were made of peak jaw-opening amplitude, jaw-opening velocity, and movement time in both vibration and nonvibration conditions. Generally, the tendon vibration caused a consistent and marked reduction in the amplitude and velocity of jaw-opening movements for each subject in both tasks. Movement time remained consistent across the vibration conditions for both tasks. These results indicate that masseter tendon vibration causes significant changes in jaw kinematics during simple speech gestures and nonspeech movements. These findings are consistent with the documented effects of tendon vibration on limb movements. The study demonstrates that tendon vibration is a potent tool for investigating proprioception in speech and oral motor control.

A positron emission tomography study of silent and oral single word reading in stuttering and nonstuttering adults.

Over the last decade positron emission tomography (PET) has been used extensively for the study of language and other cognitive and sensorimotor processes in healthy and diseased individuals. In the present study, [15O]H2O PET scanning was used to investigate the lateralization and functional distribution of cortical and subcortical activity involved in single word reading in stuttering and nonstuttering individuals. Ten right-handed male stuttering adults and matched nonstuttering individuals were instructed to read individually presented single words either silently or out loud. Subtraction of functional brain images obtained during each of the two reading tasks, and during a non-linguistic baseline task, was used to calculate within-group and between-group differences in regional cerebral blood flow by means of statistical parametric mapping. Increased activation in the left anterior cingulate cortex (ACC) was observed during silent reading in the stuttering speakers but not in the nonstuttering group. Because of the hypothesized role of the ACC in selective attention and covert articulatory practice, it is suggested that the observed increased ACC activation in the stuttering individuals reflects the presence of cognitive anticipatory reactions related to stuttering. During the oral reading task, within-group comparisons showed bilateral cortical and subcortical activation in both the stuttering and the nonstuttering speakers. Between-group comparisons showed a proportionally greater left hemisphere activation in the nonstuttering speakers, and a proportionally greater right hemisphere activation in the stuttering individuals. The results of the present study provide qualified support for the hypothesis that stuttering adults show atypical lateralization of language processes.

Kinaesthetic acuity of stutterers and non-stutterers for oral and non-oral movements.

Six adult stutterers and six normal speakers were instructed to make the smallest possible movements of the jaw, lower lip, tongue and right index finger, both with and without continuous visual feedback. In the non-visual (kinaesthetic) condition, the stutterers showed significantly larger minimal displacements (MDs) than did the non-stutterers for oral but not for finger movements. However, movements made in the presence of visual feedback were consistently smaller for all subjects than those made without, and no differences in MD were found between the stutterers and the non-stutterers when visual feedback was provided. The results suggested the presence of a sensorimotor deficit among at least some adult stutterers that is confined to oral movements. Given the importance of somatic sensory feedback during speech production, these observed orosensory deficiencies among stutterers may provide important insights into causal factors which contribute to the breakdowns in stutterers' speech.

Speech-associated attitudes of stuttering and nonstuttering children.

A Dutch version of the Communication Attitude Test (Brutten, 1985) was used to assess the speech-associated attitudes of 70 stuttering and 271 nonstuttering Belgian children of elementary and middle school age. The results showed that the stuttering children evidenced significantly more negative attitudes toward speech than did their nonstuttering peers. This difference was present from age 7, the youngest age group studied, on up. Moreover, a significant group x age interaction revealed that the speech-related attitudes of the stuttering children became more negative with increasing age. In contrast, those of the nonstuttering children became less negative after age 9. These findings suggest that, in the course of fluency therapy for youngsters who stutter, negative attitudes toward speech should be addressed. This is especially true if, as with adults who stutter, negative attitudes are predictive of therapeutic failure.