Abstract
In Word of Mouth issue 36.3, I reviewed an article by Rvachew and Matthews (2024) on subtypes of speech sound disorders. Appropriately diagnosing SSDs can lead to more effective treatment methods. Rvachew and Matthews described the characteristics and implications for intervention for three types of SSDs: consistent phonological disorder (CPD), inconsistent phonological disorder (IPD), and childhood apraxia of speech (CAS). A number of intervention programs have been proposed for treating childhood apraxia of speech. Namasivayam and colleagues (2024) evaluated the effectiveness of the Kaufman Speech to Language Protocol (K-SLP, Kaufman, 2013). They note that a number of interventions have been developed that target a range of underlying speech processes in CAS and encompass augmentative and alternative communication, cognitive-linguistic methods, speech-motor approaches, or a combination of methods, for example,
Primarily motor-based: Rapid Syllable Transition (ReST; Murray et al., 2015), Motor Speech Treatment Protocol (Namasivayam et al., 2015), Prompts for Restructuing Oral Muscular Phonetic Targets (PROMPT, Dale & Hayden, 2013), Dynamic Dyspraxia Programme (DTTC; Strand et al., 2006), Nuffield Dyspraxia Programme (Murray et al., 2015), Ultrasound Biofeedback (McCabe et al., 2023).
Cognitive-linguistic principles: Integrated Phonological Awareness Program (McNeill et al., 2010), Core vocabulary (Crosbie et al., 2005)
Combined approach: Kaufman Speech to Language Protocol (K-SLP; Kaufman, 2013)
Although none of these CAS methodologies have conclusive evidence for effectiveness, they all have some evidence. CAS researchers are seeking to identify best dosage parameters, operationalize procedures, and implement interventions through phases of clinical research.
Treatment efficacy for CAS is affected by the child’s age, cognitive abilities, and language skills. ReST and ultrasound interventions are more applicable for children over 4 years of age because they require children to have receptive language/cognitive skills to comprehend feedback. Furthermore, children must have some ability to sit through drill activities and produce at least four consonants and four vowels. Younger children and those with limited spoken language or comorbid cognitive/behavioral issues respond better to play-based, semi-structured interventions that target vocabulary and grammar expansion in addition to targeting speech motor skills.
The K-SLP approach to CAS applies verbal shaping and motor learning principles. In the K-SLP’s verbal shaping process (referred to as progressive approximation [Gomez et al., 2018; Kaufman, 2013]), simple word structures are targeted first and reinforced, followed by teaching progressively more complex articulatory patterns that eventually match adult forms. The process of verbal shaping or progressive approximation gradually increases speech motor and cognitive–linguistic demands (simple to more complex) to improve speech and language output. The initial simplification and successive word approximations gradually build complex syllable shapes (e.g., V, CV, VC, CVC, CVCV, CCV, and CCVCVC). The approach facilitates incremental progress in speech motor control, while simultaneously enabling the acquisition of functional vocabulary. When children with CAS learn new words, their speech motor control can be destabilized, resulting in more variable motor production. The K-SLP’s progressive approximation addresses the destabilizing effects of emerging new vocabulary on motor control.
The K-SLP program is popular with speech-language pathologists (SLPs) (Gomez et al., 2022), but specific outcome data are limited. According to Preferred Practice Patterns for the Profession of Speech-Language Pathology (ASHA, 2004), SLPs should employ the World Health Organization’s International Classification of Functioning (ICF) in assessment and intervention. The ICF framework has a broad perspective on outcomes—outcomes at the ICF impairment level regarding functioning of the body (e.g., speech accuracy) and outcomes at the ICF activity/participation level regarding use of skills and behaviors in social/life situations. Effects of CAS intervention have more frequently been assessed at the impairment level (as assessed by articulation standard scores, percent consonants correct, and speech intelligibility), but seldom at the functional communication level. Namasivayam et al. (2024) also remark that CAS interventions have focused on direct 1-on-1 teaching. They suggest that interventions conducted with dyads or groups offer additional benefits because they provide opportunities for transferring and applying language and communication skills in real-life situations. Group settings support conversational turn-taking, practice of various sentence structures and prosodies, and development of social-emotional and self-regulation skills. Children receiving motor speech therapy in group settings have been observed to have positive outcomes both in accuracy of speech movements and listener judgment of speech accuracy (Square et al., 2014).
The Study
The study by Namasivayam et al. (2024) summarized in this article was designed to examine the effects of the K-SLP approach on children with CAS and comorbidities using the following research questions:
Is K-SLP treatment delivered in dyadic format effective for improving word level accuracy (whole word match, WWM), articulatory level accuracy (percent consonants correct, PCC), speech intelligibility (Children’s Speech Intelligibility Measure, CSIM), and functional communication skills (Focus on the Outcomes of Communication Under Six [FOCUS] Thomas-Stonell et al., 2013)?
Are the treatment effects maintained 3–4 months post-intervention?
Participants
Six children participated in the study (one did not complete the study). All children presented moderate to severe SSD based on PCC (<64% correct) and a Goldman-Fristoe Text of Articulation–Third Edition (GFTA-3; Goldman & Fristoe, 2015) score <7th percentile, delays in receptive and expressive language on standardized language testing, and at least 7 out of 12 features on a CAS checklist. Children were excluded from the study if they showed any signs of global motor involvement (e.g., such as cerebral palsy), autism spectrum disorders, oral structural deficits (e.g., cleft lip/palate), feeding impairments, or significant drooling and/or dysarthric speech.
Methods
A single-subject experimental design (SSED) with multiple baselines across behaviors was replicated across 6 children with CAS. The K-SLP program, which is an operationalized and manualized intervention program (Gomez et al., 2018, 2022; Kaufman, 2013), was administered to three dyads of children by trained SLPs. Three goals were identified for each child based on their performance on the Kaufman Speech Praxis Test (KSPT; Kaufman, 1995). The goals included targets with specific sounds, syllables, and word shapes that were most frequently scored incorrect during pretreatment assessment. Approximately eight to nine words were chosen per child as target words in treatment across those three goals. In addition, two sets of untreated “test” words for assessing generalization were included. The test words were matched for specific sounds, syllables, and word shapes similar to the targeted trained words.
All participants attended a 2.5-hour day camp, 4 days a week for 3 weeks. K-SLP intervention was delivered with the following dose parameters: dose form (structured play in a quiet setting; boot camp), dose (approximately 90 attempts at targets per day per goal), dose frequency (four sessions per week; Monday to Thursday), session duration (2.5 hours/day), total intervention duration (3 weeks), total sessions (12), and Cumulative Intervention Intensity (CII; CII = 90 × 4 × 3 = 1,080). Each day the children had two 30-min sessions in the dyad format with targeted practice on their speech goals (i.e., own individualized “trained” words). Some of the children in a dyad had overlapping goals; however, none had all identical goals.
Outcome Measures
Using the ICF framework, outcome measures were assessed at the body structures/functions level and the activities/participation—three measurements at body structures/functions level and one at the activities/participation level:
Body Structures and Functions Level
Speech Production Complexity
Whole word match (WWM) measure: the percentage of words that matched the adult target in terms of word/syllable structures (Bernhardt et al., 2020; Major & Bernhardt, 1998). For example, for adult target “swing” /swɪŋ/ (word/syllable structure: CCVC), if the child’s response is /siŋ/ (word/syllable structure: CVC), then score = 0. For adult target “mop” /mɑp/ (word/ syllable structure: CVC), if the child’s response is /mɑp/ (word/syllable structure: CVC), then score = 1.
Speech articulation measure: percent of consonants correct (PCC) (Shriberg et al., 1997), derived from the 60-item picture-naming task in the GFTA-3 (Goldman & Fristoe, 2015). PCC scores were calculated by dividing the number of consonant errors by the total number of consonants (152) and multiplying by 100 to obtain a percentage.
Speech intelligibility: assessed using the Children’s Speech Intelligibility Measure (CSIM; Wilcox & Morris, 1999). With the CSIM, children imitated lists of 50 words pretreatment, immediately posttreatment, and 3–4 months after treatment completion. Naïve listeners selected the target word produced by the child from a set of 12 phonetically similar words.
Activities and Participation Level
Functional Communication Outcomes
The Focus on the Outcomes of Communication Under Six (FOCUS; Thomas-Stonell et al., 2013) was used to assess changes in activities and participation levels based on the WHO-ICF framework (WHO, 2007). FOCUS is a standardized 50-item measure that evaluates children’s communication abilities in daily life, rated on a 7-point scale by caregivers or clinicians.
Sample FOCUS questions for Activity:
“My child uses new words.”
“My child can string words together.”
“My child uses words to ask for things.”
“My child talks a lot.”
Sample FOCUS questions for Participation:
“My child is included in play activities by other children.”
“My child gets along with other children.”
“My child is included in games by other children.”
“My child can communicate effectively with other children.”
Results
Overall, the participant success rate in the study was about 80%. With regard to the WWW complexity measure, four of five participants demonstrated significant improvements to words targeted in treatment and three out of five generalized these to untreated words.
Four out of five participants demonstrated clinically significant changes in PCC scores, word-level speech intelligibility, and functional outcomes at 3 months follow-up.
Consistency of outcomes. There was not consistency of outcomes across all participants. Only Participant 2 exhibited improvement across all variables (whole word measure, percent consonant correct, speech intelligibility, functional communication outcomes). Participant 4 progressed in all areas except PCC; Participant 5 improved in every area except WWW; Participant 6 improved in all areas except functional communication outcomes.
There was an 80% success rate in maintenance and a 60% rate in generalization. This was higher than in other studies that reported similar dosages. The differences have been related to factors such as clinician experience, dyad vs. individual treatment, and camp structure that facilitated socialization.
Conclusions
This study measured children’s response to the K-SLP treatment for CAS at both the impairment and functional communication levels as advocated by the ICF. Clinically significant outcomes occurred in four of the five participating children immediately following treatment and were maintained 3–4 months after the intervention. In clinical practice, determination of effectiveness of SSD intervention is usually limited to a standardized measure of articulation such as the Goldman-Fristoe Test of Articulation or The Clinical Assessment of Articulation and Phonology, Second Edition (CAAP-2; Secord & Donohue, 2013), which assess changes at the impairment level. There was variability among the participants in which aspects of articulation changed the most in response to the intervention. Clinicians should consider multiple ways of assessing children’s speech production at both impairment and participation levels. The study provides preliminary support for the effectiveness of the K-SLP program when delivered in dyads to children with CAS with comorbidities.