Longitudinal case study of syntactic, lexical and articulation rate development at stuttering onset in a young japanese child.

PURPOSE: This study investigated the relationship between syntactic, lexical and articulation rate development and the onset of stuttering in a young Japanese child from the pre-onset stage. We also examined the linguistic factors influencing stuttering-like disfluency (SLD) immediately after stuttering onset. METHODS: The case was a female child aged 1 year 11 months at the beginning of the study. Twenty free-play sessions were video-recorded over approximately two years and four months to analyze SLD, physical concomitants, predicate-argument structures, mean length of utterances (MLU), lexical diversity (VocD), and articulation rate. The influence of sentence-level factor (utterance length), and word-level factors (bunsetsu length, and syllable weight) on SLD was also assessed immediately after onset. RESULTS: SLD frequency was near zero until the sixth session, and prior to the emergence of predicate-argument structures, SLDs were rarely observed. Stuttering onset occurred two days before the seventh session, at which point SLD frequency increased rapidly alongside the appearance of physical concomitants. During this period, predicate-argument structures and VocD values increased sharply, though MLU and articulation rate did not. Additionally, no significant influences of utterance length, bunsetsu length, and syllable weight were observed immediately after onset. CONCLUSIONS: Our findings suggest that, at least for the present case, rapid syntactic and lexical development can be associated with stuttering onset. Furthermore, the results imply that selected sentence- and word-level factors might not influence the occurrence of stuttering immediately after onset in this case.