This study will investigate the feasibility of applying the Rapid Syllable Transition Treatment (ReST) protocol in children with Childhood Apraxia of Speech, considering the scarcity of evidence in the context of Brazilian Portuguese and the need to implement evidence-based interventions in clinical practice. The objective is to evaluate the feasibility of the protocol and estimate preliminary effects on articulatory accuracy, prosody, and speech motor planning. This is a randomized clinical trial with a quantitative and qualitative approach. Participants will be children between five and twelve years old, diagnosed with Childhood Apraxia of Speech. The intervention will be carried out over six weeks, with two weekly sessions, using pseudowords structured according to the ReST protocol. After an initial assessment, participants will be randomized to an intervention group or a control group on a waiting list. Pre- and post-intervention assessments and a one-month follow-up will be conducted. Data analysis will be exploratory, focusing on evaluating the feasibility of the procedures and estimating parameters for future studies. Primary outcomes will include feasibility indicators such as recruitment rate, adherence, therapeutic fidelity, acceptability, and retention. Secondary outcomes will include preliminary measures of speech performance and effect size estimation. The results are expected to provide preliminary effect estimates and inform the design of a definitive randomized clinical trial.

This research corresponds to the comparison between the group submitted to the intervention with the ReST method and the control group, maintaining the methodological rigor of the experimental design. The interventions will be conducted by different master's students, each responsible for one of the therapeutic approaches, while the doctoral student will be responsible for randomization, evaluations, and methodological supervision. The study design will follow the SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials) recommendations, and the results will be reported in accordance with the CONSORT (Consolidated Standards of Reporting Trials) guidelines, in their most recent versions, including a checklist and participant flowchart. In addition, as this is a pilot randomized clinical trial, the study will also follow recommendations for pilot and feasibility studies, focusing not only on preliminary effects of the intervention, but also on assessing the feasibility of the procedures and generating parameters for a future confirmatory trial.

All participants and their guardians will receive information about the research and, after agreeing to participate, will sign the Informed Consent Form (ICF), the Assent Form, with the study having been previously submitted to and approved by the Research Ethics Committee. Considering recommendations for pilot studies and the rarity and clinical heterogeneity of the population, the inclusion of approximately 12 to 20 participants is expected. These will be Brazilian, monolingual individuals, aged between five and twelve years, all diagnosed with Childhood Apraxia of Speech (CAS). The sample size will be defined based on methodological justification specific to randomized pilot studies, and not on power calculations for confirmatory efficacy testing.

The inclusion criteria adopted will be: signed informed consent form by the guardians; patients who are native speakers of Brazilian Portuguese; absence of associated comorbidities, verified from a detailed clinical history and information provided by the parents; superior receptive language performance compared to expressive performance, confirmed by clinical observation and simple comprehension tasks; hearing thresholds within normal limits; preserved visual acuity; and age between five and eight years.

Children with significant cognitive impairments or severe comprehension difficulties that prevent participation in the proposed activities will be excluded.

In addition to the eligibility criteria, the diagnosis of AFI will be established by clinical consensus among experienced evaluators, based on multiple diagnostic sources and the presence of the clinical markers described for the disorder, including inconsistency in productions, prolonged and/or interrupted coarticulatory transitions, and prosodic alterations. Complementary instruments will be used to increase diagnostic accuracy and reduce clinical heterogeneity in the sample.

After screening, confirmation of eligibility criteria, and completion of the initial assessment, participants will be randomized, using a computerized procedure conducted by an independent researcher, into one of three clinical trial groups: intervention with ReST, or a control group on a waiting list, ensuring random allocation and reduction of biases. For the purposes of this research, data from participants allocated to the ReST group and the control group will be analyzed.

Participants allocated to the control group on the waiting list will not receive intervention during the experimental period and will subsequently be referred for therapeutic intervention at the end of data collection.

Data collection for this study will be organized into three main stages. The first will include anamnesis and speech-language pathology assessment, performed using the Orofacial Praxis Skills Assessment (The Orofacial Praxis Test) and the ABFW assessment. Following this, a diagnostic speech motor assessment will be conducted, involving the Speech Inconsistency Test The Multisyllabic Word Repetition Test and the Lexical Phrase Test. The third stage consists of therapeutic intervention with the ReST method, post-intervention evaluation, with the possibility of follow-up to analyze the maintenance of therapeutic gains .

For the intervention, four vowels and four consonants will be selected, which serve as the basis for the construction of a list of 20 pseudowords. These pseudowords, disyllabic or trisyllabic, should be elaborated according to the level of difficulty of each child, following the protocol of Oliveira and Oliveira (2023), which provides for variation in the position of the lexical accent. It is noteworthy that the choice of pseudowords will follow linguistic criteria (control of structure and accentual pattern), as recommended by the ReST protocol, favoring interpretation and replicability. Therapeutic dose parameters will be monitored, including the number of attempts per session, the expected number of correct productions, criteria for stimulus progression, and the frequency and type of feedback offered. The fidelity of the intervention will be monitored using a structured checklist and procedures inspired by the TIDieR checklist, ensuring standardization, replicability, and consistency in the application of the protocol. The principal investigator will receive prior training and ongoing supervision to maintain therapeutic fidelity.

The intervention will be conducted in person, with a frequency of two sessions per week over six weeks, totaling 12 sessions, according to protocols previously described in the literature for the ReST method, considered adequate to promote measurable changes in initial studies. Each session will be structured in two stages: a pre-practice phase, characterized by greater support from the therapist, including modeling and explicit instructions, and a structured practice phase, consisting of intensive repetition of stimuli, with progressive reduction of feedback, favoring motor learning and participant autonomy, with an estimated 100 to 150 productions per session, in order to guarantee adequate intensity of motor practice. The intervention will be conducted by the researcher responsible for this study.

Due to the nature of the interventions, therapists and participants cannot be blinded to the treatment received. However, the initial and post-intervention assessments will be conducted by the doctoral candidate, who will not act as a therapist for the participants. When operationally feasible, the analysis of part of the samples will be performed with blinding regarding the allocation group.

In addition, independent judges blinded to the allocation of participants may analyze speech samples for certain perceptual measures, with inter-rater reliability estimated to reinforce the robustness of the analyses and reduce measurement biases.

The intervention sessions will be structured in two phases: a pre-practice phase, in which the therapist offers greater support with immediate feedback and modeling, and a practice phase, in which the pseudowords will be repeated in blocks, with non-immediate and random outcome feedback, interspersed with two-minute rest intervals .

As outcomes, preliminary measures related to articulatory precision, prosodic accuracy, generalization to untrained items, and maintenance of gains in follow-up will be analyzed.

The fidelity of the intervention will be ensured through the standardized application of the ReST protocol, controlling the number of trials per session, organization of practice, type and frequency of feedback, as well as criteria for stimulus progression. Sessions may be recorded for monitoring and later analysis, ensuring consistency in the application of the method.

Inclusion Criteria:

• Signed informed consent form provided by the child's legal guardians
• Native speakers of Brazilian Portuguese
• Absence of associated comorbidities, verified through detailed clinical history and parent-reported information
• Receptive language abilities superior to expressive language abilities, confirmed through clinical observation and simple comprehension tasks
• Hearing thresholds within normal limits
• Preserved visual acuity
• Age between five and eight years

Exclusion Criteria:

• Significant cognitive impairments;
• Severe comprehension difficulties that prevent participation in the proposed activities.

Apenas a pessoa que avaliar os resultados pós-tratamento terá conhecimento da alocação dos grupos.