Speech Disfluencies in Adults with Neurogenic Stuttering Associated with Stroke and Traumatic Brain Injury

Article excerpt

This study is part of a larger project aimed at exploring the speech, language, cognitive, psychosocial, and medical characteristics of adult neurogenic stuttering. In the present article, speech disfluency patterns in adults with neurogenic stuttering in two diagnostic groups, traumatic brain injury and stroke, were compared. The results revealed that people with neurogenic stuttering do not present as a homogeneous group but that they may present with different speech disfluency characteristics, as well as etiology-dependent self-perceptions. It is anticipated that the observations in the present article ultimately will lead to a greater understanding of the neural mechanisms underlying speech fluency and will result in more effective diagnostic and interventional approaches.

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Neurogenic stuttering is a condition in which previously fluent individuals gradually or suddenly become clinically disfluent after experiencing a head injury (Ardila, Rosselli, Surloff, & Buttermore, 1999), stroke (Grant, Biousse, Cook, & Newman, 1999), or other form of brain damage (Lebrun, Retif, & Kaiser, 1983). Typically, this disorder occurs in adults, but individual case studies of suspected acquired stuttering in young children also have been reported (Nass, Schreter, & Heier, 1994).

It has been reported frequently that the disfluency patterns seen in neurogenic acquired stuttering tend to differ from those typical of developmental stuttering. For instance, while developmental stuttering is characterized by disfluencies that occur primarily on initial sounds or syllables, some have argued that disfluencies in neurogenic stuttering may occur at initial, as well as medial and final positions in the word or syllable (Canter 1971; Lebrun, Leleux, Rousseau, & Devreux, 1983).

Furthermore, neurogenic stuttering has been associated with more diffuse distribution of disfluencies across words of various grammatical classes compared to developmental stuttering as well as a low incidence of secondary behaviors (Canter, 1971; Helm-Estabrooks, 1993; Helm-Estabrooks & Hotz, 1998; Ringo & Dietrich, 1995). In a recent publication, Manning (2001, p. 171) listed six speech features that are useful in differentiating neurogenic from developmental stuttering:

1. Disfluencies occur on functor and content words equally;

2. No anxiety about disfluencies;

3. Stuttered moments are not restricted to initial syllables;

4. Secondary behaviors occur rarely;

5. No adaptation effect; and

6. Disfluencies occur on all speech tasks.

This view of two distinct speech fluency disorders has been challenged by some, who have argued that it may be difficult to differentiate between the two types of stuttering based on verbal output alone (Van Borsel & Taillieu, 2000). In addition, it is apparent that any characterization of neurogenic stuttering based on behavioral characteristics needs to take into consideration the etiology of the neurogenic disorder (Helm-Estabrooks, 1993). Although accurate incidence of neurogenic stuttering is lacking, a number of survey studies (Market, Montague, Buffalo, & Drummond, 1990; Stewart & Rowley, 1996), as well as a review of published case studies and other reports in the literature, suggest that neurogenic stuttering is most frequently observed following the occurrence of stroke or head injury. Therefore, in this article we will focus primarily on neurogenic stuttering following these two neurological conditions.

Neurogenic stuttering following a stroke may occur in isolation (Helm-Estabrooks, Yeo, Geschwind, Freedman, & Weinstein, 1986) or be accompanied by aphasia and/or apraxia of speech (Knopman et al., 1983; Lebrun, Leleux, & Retif, 1987; Mazzucchi, Moretti, Carpeggiani, & Parma, 1981). The clinical manifestation of disfluencies may result from a single lesion (e. …