Non-speech behaviours in neurogenic stuttering

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Neurogenic stuttering is characterised by the occurrence of speech disfluencies following neurological brain damage. While people with a developmental onset of stuttering typically present with non-speech behaviours associated with their stuttering (e.g. eye blinking, facial grimacing), it has been argued that such behaviours are absent in people with a neurological onset of stuttering (Helm-Estabrooks, 1999). However, a number of case-studies suggested otherwise (e.g., Tani and Sakai (2010), Vanhoutte et al. (2014)). This study aimed to investigate, for the first time, the non-speech behaviours in a larger group of people with neurogenic stuttering. This study consisted of 22 participants with a diagnosis of neurogenic stuttering and a control group of 17 healthy older adults. Their speech was analysed by annotating all stuttering-like disfluencies (SLD), other disfluencies (OD) and non-speech behaviours (NSB). For each non-speech behaviour, duration and severity was also coded. The results showed that the frequency of occurrence of non-speech behaviours was higher within the neurogenic stuttering group (M = .12, SD = .13) compared to the control group (M = .02, SD =.19). The duration and severity of the NSBs were also different between the groups. SLDs were a significant predictor of proportion of NSBs (β = .4, t = 3.39, p .01) and duration of NSBs (β =.43, t = 2.9, p .01), as well as of a score combining all three NSB measurements (β = .5, t = 4.05, p .001). In a model without outliers, the severity of NSBs was also significantly predicted by SLD proportion (β = .67, t = 5.46, p .001). Within the neurogenic stuttering group, SLDs were the most important predictor of the combined NSB score (βSLD = .41, tSLD = 3.2, pSLD .01) and the proportion of NSBs (β = .34, t = 2.32, p =.03). The results show that non-speech behaviours do occur more frequently and are more severe in people with neurogenic stuttering compared to a control group of healthy speakers. This is in contrast with previous publications stating that non-speech behaviours do not present in neurogenic stuttering. Time post-onset and emotions and attitudes associate with speech were not significant predictors of the proportion of NSBs, contradicting the theory that NSBs develop as a reaction to stuttering.
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