Language sample analysis of conversation samples from school-age children who stutter: The role of syntactic factors in stuttering.

Introduction: The purpose of the study was to compare school-age children who stutter (CWS) and age-matched children who do not stutter (CWNS) in syntactic abilities and syntactic performance.

Methods: Computerized Language Sample Analysis (LSA) was conducted on the conversation samples obtained from 46 school-age CWS and CWNS between 7 and 16 years (CWS, n = 23). Syntactic abilities were assessed using the Index of Productive Syntax (the IPsyn) and Developmental Sentence Scores (DSS) and mixed effects logistic regression analyses with participants as random effects were conducted to determine if the scores were predictive of group membership. Additionally, the groups were compared in the IPsyn subcategories to assess the use of syntactic structures. Syntactic performance was assessed by: (a) Categorizing the sentences from each conversation sample into high vs. low syntactic complexity categories based on DSS scores and comparing the sentence categories in % stuttered sentences (% SS); and (b) Comparing the groups in the proportion of phrase-level disfluencies (phrase repetitions vs. revisions) that are associated with syntactic planning.

Results: In terms of syntactic abilities, the IPsyn scores interacted with the number of utterances (sample size) used to compute the scores in predicting group membership. In comparison to the CWNS, the CWS obtained higher scores in the IPsyn and the sentence structure subcategory of the IPsyn that were independent of sample size. In terms of syntactic performance: (a) Significantly more sentences were stuttered in the high compared to the low syntactic sentence category; (b) Compared to the CWNS who demonstrated significantly more phrase revisions, the CWS showed comparable and fewer phrase revisions and repetitions. Additionally, post-hoc analysis showed that the CWS used significantly elaborated noun phrases and a similar trend was evident for verb phrase elaborations. A significant association between verb phrase elaborations and%SS was also obtained.

Conclusions: Findings from the IPsyn and the use of elaborate noun phrases, and to some extent verb phrases, suggested that the CWS used more complex syntax even in shorter conversational samples. More stuttered sentences in the high DSS sentence category, the use of fewer phrase revisions, and the association between stuttering and elaborated verb phrases in the CWS are interpreted to suggest the effects of syntactic planning and reformulation demands on fluency during ongoing articulation.