小児発話失行症に対する運動ベース介入の無作為化比較試験：DTTC-Connect

Participants in the Immediate Treatment Group will receive Dynamic Temporal and Tactile Cueing-Connect (DTTC-Connect) Treatment two times per week (45-minute sessions each) for 8 weeks. Total duration will be 90 minutes/week over 16 sessions. Treatment will begin following the diagnostic evaluation.

DTTC-Connect is a motor-based intervention designed to improve speech accuracy in children with CAS by targeting movement transitions within phrases. Treatment begins with selecting a target phrase identified through dynamic assessment as being within the child's optimal challenge point. Using this initial target, four additional phrases are constructed that systematically build in structural, phonetic, and grammatical complexity to support gradual progression in motor skill. Treatment begins with two-word phrases and follows the first three levels of the DTTC temporal hierarchy: Simultaneous Production → Direct Imitation → Delayed Imitation. The final step is Elicited Production where children produce the target at random intervals in the absence of a prior model. Aligned with standard DTTC, children initially receive maximal support during Simultaneous Production. As accuracy improves, support is faded and the child progresses to less supported levels of production.

The Delayed Treatment Group serves as a control during the period in which participants are waiting to begin treatment. A delayed treatment onset is employed to control for maturation effects. Participants in the Delayed Treatment Group will receive Dynamic Temporal and Tactile Cueing-Connect (DTTC-Connect) Treatment two times per week (45-minute sessions each) for 8 weeks. Total duration will be 90 minutes/week over 16 sessions. Treatment will begin after an 8-week delay following the diagnostic evaluation.

DTTC-Connect is a motor-based intervention designed to improve speech accuracy in children with CAS by targeting movement transitions within phrases. Treatment begins with selecting a target phrase identified through dynamic assessment as being within the child's optimal challenge point. Using this initial target, four additional phrases are constructed that systematically build in structural, phonetic, and grammatical complexity to support gradual progression in motor skill. Treatment begins with two-word phrases and follows the first three levels of the DTTC temporal hierarchy: Simultaneous Production → Direct Imitation → Delayed Imitation. The final step is Elicited Production where children produce the target at random intervals in the absence of a prior model. Aligned with standard DTTC, children initially receive maximal support during Simultaneous Production. As accuracy improves, support is faded and the child progresses to less supported levels of production.

The primary outcome measure will be untreated phrase accuracy, quantified using the adapted Multilevel word Accuracy Composite Score (MACS) ratings for phrase-level stimuli. This composite score reflects the accuracy of four key areas: (I) segments (consonant & vowel accuracy within-word and across-word boundaries); (II) phrase structure (maintenance of structures across the phrase); (III) movement transitions (smoothness and fluency across sounds, syllable, or words); and (IV) prosody (lexical & phrasal stress). Each component receives a binary rating (0/1). Ratings will consider co-articulatory effects that naturally occur between words within connected speech.

Speech intelligibility will be assessed to evaluate how well a listener understands a child's connected speech. To elicit naturalistic yet structured speech, children will be audio-recorded while narrating a short story depicting a picture card series using the School-Aged Language Assessment Measures (SLAM). Ten representative utterances per child per time point will be selected, randomized, and presented to five naïve adult listeners for transcription. A mean intelligibility score will be derived from the percentage of words correctly transcribed. This method captures connected speech in a developmentally appropriate and controlled format while supporting consistency and ecological validity.

Acoustic variability will be quantified using the coefficient of variation from phrase duration. Kinematic variability will be measured using jaw and lip aperture Spatiotemporal Index (STI) values. To ensure reliable estimates, each session must yield a minimum of four analyzable productions per target, with a maximum of eight to balance representation across children with differing levels of speech accuracy.

The treating SLP will administer the Focus on the Outcomes of Communication Under Six (FOCUS-34) and the Intelligibility in Context Scale (ICS) to caregivers, who can complete these measures in person while their child receives treatment. If the caregiver is not present, the forms will be sent electronically, and the clinician will schedule a brief Zoom meeting to provide instructions. Completed forms can then be returned electronically.

To examine children's feelings towards speech, the Communication Attitude Test (CAT) will be administered to children age six years and older and the KiddyCAT Communication Attitude Test for Preschool and Kindergarten Children Who Stutter (KiddyCAT) will be administered to children under 6 years of age.