An N-of-1 Randomized Controlled Trial of Interventions for Children With Inconsistent Speech Sound Errors

How to cut the pie is no piece of cake: Toward a process-oriented approach to assessment and diagnosis of speech sound disorders

BACKGROUND

'Speech sound disorder' is an umbrella term that encompasses dysarthria, articulation disorders, childhood apraxia of speech and phonological disorders. However, differential diagnosis between these disorders is a persistent challenge in speech pathology, as many diagnostic procedures use symptom clusters instead of identifying an origin of breakdown in the speech and language system.

AIMS

This article reviews typical and disordered speech through the lens of two well-developed models of production-one focused on phonological encoding and one focused on speech motor planning. We illustrate potential breakdown locations within these models that may relate to childhood apraxia of speech and phonological disorders.

MAIN CONTRIBUTION

This paper presents an overview of an approach to conceptualisation of speech sound disorders that is grounded in current models of speech production and emphasises consideration of underlying processes. The paper also sketches a research agenda for the development of valid, reliable and clinically feasible assessment protocols for children with speech sound disorders.

CONCLUSION

The process-oriented approach outlined here is in the early stages of development but holds promise for developing a more detailed and comprehensive understanding of, and assessment protocols for speech sound disorders that go beyond broad diagnostic labels based on error analysis. Directions for future research are discussed.

WHAT THIS PAPER ADDS

What is already known on the subject Speech sound disorders (SSD) are heterogeneous, and there is agreement that some children have a phonological impairment (phonological disorders, PD) whereas others have an impairment of speech motor planning (childhood apraxia of speech, CAS). There is also recognition that speech production involves multiple processes, and several approaches to the assessment and diagnosis of SSD have been proposed. What this paper adds to existing knowledge This paper provides a more detailed conceptualisation of potential impairments in children with SSD that is grounded in current models of speech production and encourages greater consideration of underlying processes. The paper illustrates this approach and provides guidance for further development. One consequence of this perspective is the notion that broad diagnostic category labels (PD, CAS) may each comprise different subtypes or profiles depending on the processes that are affected. What are the potential or actual clinical implications of this work? Although the approach is in the early stages of development and no comprehensive validated set of tasks and measures is available to assess all processes, clinicians may find the conceptualisation of different underlying processes and the notion of potential subtypes within PD and CAS informative when evaluating SSD. In addition, this perspective discourages either/or thinking (PD or CAS) and instead encourages consideration of the possibility that children may have different combinations of impairments at different processing stages.

Considerations for identifying subtypes of speech sound disorder

BACKGROUND

Speech sound disorders (SSDs) in children are heterogeneous. Differentiating children with SSDs into distinct subtypes is important so that each child receives a treatment approach well suited to the particular difficulties they are experiencing.

AIMS

To study the distinct underlying processes that differentiate phonological processing, phonological planning or motor planning deficits.

METHOD

The literature on the nature of SSDs is reviewed to reveal diagnostic signs at the level of distal causes, proximal factors and surface characteristics.

MAIN CONTRIBUTION

Subtypes of SSDs may be identified by linking the surface characteristics of the children's speech to underlying explanatory proximal factors. The proximal factors may be revealed by measures of speech perception skills, phonological memory and speech-motor control. The evidence suggests that consistent phonological disorder (CPD) can be identified by predictable patterns of speech error associated with speech perception errors. Inconsistent phonological disorder (IPD) is associated with a deficit in the selection and sequencing of phonemes, that is, revealed as within-word inconsistency and poor phonological memory. The motor planning deficit that is specific to childhood apraxia of speech (CAS) is revealed by transcoding errors on the syllable repetition task and an inability to produce [pətəkə] accurately and rapidly.

CONCLUSIONS & IMPLICATIONS

Children with SSDs form a heterogeneous population. Surface characteristics overlap considerably among those with severe disorders, but certain signs are unique to particular subtypes. Careful attention to underlying causal factors will support the accurate diagnosis and selection of personalized treatment options.

WHAT THIS PAPER ADDS

What is already known on the subject SSD in children are heterogenous, with numerous subtypes of primary SSD proposed. Diagnosing the specific subtype of SSD is important in order to assign the most efficacious treatment approach for each child. Identifying the distinct subtype for each child is difficult because the surface characteristics of certain subtypes overlap among categories (e.g., CPD or IPD; CAS). What this paper adds to the existing knowledge The diagnostic challenge might be eased by systematic attention to explanatory factors in relation to the surface characteristics, using specific tests for this purpose. Word identification tasks tap speech perception skills; repetition of short versus long strings of nonsense syllables permits observation of phonological memory and phonological planning skills; and standard maximum performance tests provide considerable information about speech motor control. What are the potential or actual clinical implications of this work? Children with SSDs should receive comprehensive assessments of their phonological processing, phonological planning and motor planning skills frequently, alongside examinations of their error patterns in connected speech. Such assessments will serve to identify the child's primary challenges currently and as they change over developmental time.

Treatment for Childhood Apraxia of Speech: Past, Present, and Future

PURPOSE

The purposes of this review article were to provide an introduction to and "bird's-eye" overview of the current evidence base for treatment of childhood apraxia of speech (CAS), identify some gaps and trends in this rapidly growing literature, and formulate some future research directions, in order to advance the evidence base and clinical practice for children with CAS.

METHOD

Following a brief introduction outlining important concepts, a narrative review of the CAS treatment literature is provided, and trends and future directions are identified based on this review. The review is organized around four fundamental treatment research questions: (a) "Does Treatment X work?", (b) "Does Treatment X work better than Treatment Y?", (c) "For whom does Treatment X work?", and (d) "What does 'work' mean, anyway?"

RESULTS

A wide range of CAS treatments with varying degrees of evidence for efficacy exists. Research is beginning to emerge that compares different treatments and seeks to determine optimal treatment parameters. Few studies to date have explored child-level predictors of treatment response, and the evidence base currently is limited in scope with respect to populations and outcomes studied.

CONCLUSIONS

A growing evidence base supports the efficacy of a number of treatments for CAS. However, many important gaps in the literature were identified that warrant redoubled and sustained research attention. Research is beginning to emerge that addresses treatment optimization, comparison, candidacy, and outcomes. Suggestions for future research are offered, and the concept of a hypothesized pathway was applied to CAS to illustrate how components of an intervention can effect change in a clinical goal and can help guide development and refinement of treatments for children with CAS.

The development of a set of key points to aid clinicians and researchers in designing and conducting n-of-1 trials

INTRODUCTION

n-of-1 trials are undertaken to optimise the evaluation of health technologies in individual patients. They involve a single patient receiving treatments, both interventional and control, consecutively over set periods of time, the order of which is decided at random. Although n-of-1 trials are undertaken in medical research it could be argued they have the utility to be undertaken more frequently. We undertook the National Institute for Health Research (NIHR) commissioned DIAMOND (Development of generalisable methodology for n-of-1 trials delivery for very low volume treatments) project to develop key points to assist clinicians and researchers in designing and conducting n-of-1 trials.

METHODS

The key points were developed by undertaking a stakeholder workshop, followed by a discussion within the study team and then a stakeholder dissemination and feedback event. The stakeholder workshop sought to gain the perspectives of a variety of stakeholders (including clinicians, researchers and patient representatives) on the design and use of n-of-1 trials. A discussion between the study team was held to reflect on the workshop and draft the key points. Lastly, the stakeholders from the workshop were invited to a dissemination and feedback session where the proposed key points were presented and their feedback gained.

RESULTS

A set of 22 key points were developed based on the insights from the workshop and subsequent discussions. They provide guidance on when an n-of-1 trial might be a viable or appropriate study design and discuss key decisions involved in the design of n-of-1 trials, including determining an appropriate number of treatment periods and cycles, the choice of comparator, recommended approaches to randomisation and blinding, the use of washout periods and approaches to analysis.

CONCLUSIONS

The key points developed in the project will support clinical researchers to understand key considerations when designing n-of-1 trials. It is hoped they will support the wider implementation of the study design.

A single case experimental design study using an operationalised version of the Kaufman Speech to Language Protocol for children with childhood apraxia of speech

PURPOSE

A Phase I study was conducted to examine the treatment effectiveness of the Kaufman Speech to Language Protocol using a research-operationalised protocol. It was hypothesised that articulatory accuracy would improve as a result of the treatment and that these improvements would be maintained after treatment was discontinued.

METHOD

A single case experimental design was used to evaluate the effectiveness of the Kaufman Speech to Language Protocol. Four children with a confirmed childhood apraxia of speech diagnosis were included in this study. Each child received 12 individual 1 hr treatment sessions that each consisted of an approximation setting phase and a practice phase. Probe data was collected during treatment and at post-treatment time points to measure treatment effectiveness and to measure changes in the untreated words. Untreated (control) sounds were included to test whether recorded improvements in articulatory accuracy could be attributed to the Kaufman Speech to Language Protocol.

RESULT

Two of the four children demonstrated a response to the intervention and maintenance of these changes, while the two remaining children demonstrated some generalisation in the absence of improved target (treatment) words. No specific child factors were clearly associated with positive treatment outcomes.

CONCLUSION

This study replicated the findings of an earlier pilot study and found that the operationalised protocol for the Kaufman Speech to Language Protocol is effective in improving articulatory accuracy for some children with childhood apraxia of speech. Additional replication with a further refined treatment protocol and a larger sample size is needed to support a recommendation of clinical use of the Kaufman Speech to Language Protocol.

Atypical phonological processes in naming errors of children with language impairment

The current study explored the characteristics of phonological errors of preschool children with DLD (Developmental Language Disorder), distinguishing between typical versus atypical phonological processes in segmental, syllabic and word levels. The analysis included 87 responses of words with phonological errors from a naming test, produced by 13 preschool children with DLD, aged 4;4-6;3 years. These responses included 166 phonological processes, which were classified into typical and atypical processes at the levels of: segments, syllables, and prosodic words. The findings revealed that 70% of the phonological processes were atypical. Furthermore, ten children produced more atypical processes, and there were more atypical than typical processes in segmental and word levels. It is suggested that some children with DLD represent phonological processes that are similar to those that children with speech and sound disorders produce. Therefore, clinically, the results emphasise the importance of analysing the typical and atypical characteristics of phonological errors as part of language assessment.

Subtract Before You Add: Toward the Development of a De-Implementation Approach in School-Based Speech Sound Therapy

PURPOSE

It is often difficult for school-based speech-language pathologists (SLPs) to prioritize implementing new practices for children with speech sound disorders (SSDs), given burgeoning caseloads and the myriad of other workload tasks. We propose that de-implementation science is equally as important as implementation science. De-implementation science is the recognition and identification of areas that are of "low-value and wasteful." Critically, the idea of de-implementation suggests that we first remove something from a clinician's workload before requesting that they learn and implement something new.

METHOD

Situated within the Sustainability in Healthcare by Allocating Resources Effectively (SHARE) framework, we review de-implementation science and current speech sound therapy literature to understand the mechanisms behind continuous use of practices that are no longer supported by science or legislation. We use vignettes to highlight real-life examples that clinicians may be facing in school-based settings and to provide hypothetical solutions, resources, and/or next steps to these common challenges.

RESULTS

By focusing on Phase 1 of the SHARE framework, we identified four primary practices that can be de-implemented to make space for new evidence-based techniques and approaches. These four practices were determined based on an in-depth review of SLP-based survey research: (a) overreliance on speech sound norms for eligibility determinations, (b) the omission of phonological processing skills within evaluations, (c) homogeneity of service delivery factors, and (d) the use of only one treatment approach for all children with SSDs.

CONCLUSIONS

De-implementation will take work and may lead to some difficult discussions. Implementing a framework, such as SHARE, can guide SLPs toward a reduction in workloads and improved outcomes for children with SSDs.

Changes in variability during intervention for childhood apraxia of speech: implications for therapy

Typically developing children are variable in their speech production with decreasing variability indicating mastery of speech. Excessive variability which does not change over time may be an indication of unstable motor plans as often seen in children with childhood apraxia of speech (CAS). Dynamic Systems Theory (DST) provides a framework for understanding the role of variability in speech development and disorder. There are few studies that explore the impact of therapy on speech variability. This work explores the impact of therapy on perceptual speech production variability. It is a post-hoc analysis of data collected in two intervention studies of a motor-based treatment approach with children with CAS and explores DST variability effects in speech skill acquisition based on the case data from those studies. There were six participants in total across the two studies. Findings were mixed showing some non-linear changes in variability with larger changes in variability observed in participants who engaged in more extensive therapy. However, the pattern of variability change was not consistent across the participants. These findings suggest that targeting variability in therapy may be an effective way to improve the speech of children with CAS. A model for utilising variability in therapy is presented.

Speech Intervention for Children With Cleft Palate Using Principles of Motor Learning

PURPOSE

This is a pilot study to apply an articulatory kinematic speech intervention that uses the principles of motor learning (PML) to improve speech and resonance outcomes for children with cleft palate. It is hypothesized that (a) treatment that applies select PML during practice will improve production of treated phonemes, representing both active and inconsistent passive errors, at word level in children with cleft palate; (b) effects of practice on phonemes with active or inconsistent passive errors will generalize to untreated exemplars of treated phonemes; and (c) learning will be retained for at least 1-month posttreatment.

METHOD

A multiple-baseline design across participants combined with a crossover single-case experimental model was used. Participants attended two 8-week blocks of twice-weekly face-to-face speech therapy (40-50 min/treatment) to treat active and inconsistent passive cleft speech errors using articulatory kinematic speech intervention that applied PML. The participants were four children with cleft-type speech errors. The primary dependent variable measured was percentage of words correct across treatment items, generalization items, and control items. Perceptual accuracy of target words was scored. Effect sizes were calculated to quantify the magnitude of treatment effect.

RESULTS

For three children with active and inconsistent passive cleft speech errors and one child with active cleft speech errors and developmental phonological speech errors, this approach resulted in improvements to their treated items and generalization to their untreated items. Inconsistent passive cleft speech errors were particularly responsive to the treatment in the three children who presented with these errors.

CONCLUSION

This Phase I study has shown that articulatory kinematic speech intervention that applies the PML is effective in improving the speech outcomes for children with cleft palate and that there is validity in pursuing further research into this approach.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21644831.

Speech Perception Variability in Childhood Apraxia of Speech: Implications for Assessment and Intervention

PURPOSE

Beyond hallmark production deficits characterizing childhood apraxia of speech (CAS), largely attributed to disruption(s) in speech motor planning, children with CAS often present with co-occurring speech perception and language difficulties. Thus, careful consideration of the potential for speech perception difficulties to have cascading downstream effects on intervention responsiveness and real-life functioning for some children with CAS is highly important. The purpose of this tutorial was to consider the impact of speech perception abilities in children with CAS, which carries implications for caring for the needs of the whole child.

METHOD

This tutorial summarizes the current literature on speech perception and how it relates to speech production, language, and reading abilities for children with CAS. We include case illustrations that are adapted from real clinical scenarios illustrating how speech perception difficulties may impact some children with CAS and provide recommendations for incorporating speech perception into assessment and intervention practices.

RESULTS

Although speech perception difficulties do not seem to be a core deficit of CAS, they are strongly linked to language difficulties, which are highly prevalent among children with CAS. Speech perception and language difficulties are also associated with reading difficulties and risk for lower academic achievement.

CONCLUSIONS

Children with CAS who have co-occurring language difficulties likely also demonstrate speech perception deficits, which puts them at heightened risk for reading difficulties and struggles with academic achievement. Comprehensive assessment of children with CAS should address speech perception and production, language, and reading abilities, which carries important implications for multifaceted approaches to intervention.

A temporal-based therapy for children with inconsistent phonological disorder: A case-series

Deficits in temporal auditory processing, and in particular higher gap detection thresholds have been reported in children with inconsistent phonological disorder (IPD). Here we hypothesized that providing these children with extra time for phoneme identification may in turn enhance their phonological planning abilities for production, and accordingly improve not only consistency but also accuracy of their speech. We designed and tested a new temporal-based therapy, inspired by Core Vocabulary Therapy and called it T-CVT, where we digitally lengthened formant transitions between phonemes of words used for therapy. This allowed to target both temporal auditory processing and word phonological planning. Four preschool Persian native children with IPD received T-CVT for eight weeks. We measured changes in speech consistency (% inconsistency) and accuracy (percentage of consonants correct PCC) to assess the effects of the intervention. Therapy significantly improved both consistency and accuracy of word production in the four children: % inconsistency decreased from 59% on average before therapy to 2% post-T-CVT, and PCC increased from 61% to 92% on average. Consistency and accuracy were furthermore maintained or even still improved at three-month follow-up (2% inconsistency and 99% PCC). Results in a nonword repetition task showed the generalization of these effects to non-treated material: % inconsistency for nonwords decreased from 67% to 10% post-therapy, and PCC increased from 63% to 90%. These preliminary findings support the efficacy of the T-CVT intervention for children with IPD who show temporal auditory processing deficits as reflected by higher gap detection thresholds.

Diagnosis and Treatment of Childhood Apraxia of Speech Among Children With Autism: Narrative Review and Clinical Recommendations

PURPOSE

Treatment for children with autism spectrum disorder (ASD) and low verbal ability is a largely neglected area of study. Existing research focuses on language abilities; however, a subset of children with ASD also has speech sound disorders (SSDs). The purpose of this tutorial is to provide clinicians with evidence-based recommendations to guide speech assessment and treatment among children with ASD, low verbal ability, and suspected childhood apraxia of speech (CAS).

METHOD

Multifaceted search procedures were used to identify studies that have assessed or treated speech sound production among children with ASD. A narrative review and synthesis of the literature is followed by practical clinical recommendations based on best available evidence.

CONCLUSIONS

It is critically important to consider all possible hindrances to the development of functional communication ability for children with ASD. Speech sound production has been identified as a key predictor of expressive language outcomes, yet there are very few studies that address assessment and treatment of SSDs among children with ASD. Less is known about the presentation of CAS among children with ASD and low verbal ability. More research is needed to determine whether existing speech assessment and treatment methods are appropriate for children with ASD, if modifications are needed, or if new methods should be designed.

Using the Experience Sampling Method to Examine the Details of Dosage in School-Based Speech Sound Therapy

PURPOSE

The purpose of this project was to collect practice-based evidence regarding dosage in speech sound therapy sessions in school-based settings. Dosage is the number of trials within a therapy session for any one particular child. School-based speech-language pathologists (SLPs) face a variety of obstacles to service delivery, often making the implementation of evidence-based practices difficult. To that end, we were interested in exploring how therapy parameters, such as group size and session frequency were associated with dosage.

METHOD

Using the experience sampling method, we queried school-based SLPs (n = 90) across the United States. SLPs participated via a phone application, which randomly alerted them to participate 3 times per day for 5 days. SLPs also completed a demographic questionnaire that included information regarding caseload size and job satisfaction.

RESULTS

We report results from 670 therapy sessions. Results revealed that the therapy parameter of group size was negatively related to dosage. The SLP parameter of caseload size was positively related to dosage, but this was a small association. The child parameter of comorbidity was negatively related to dosage.

CONCLUSIONS

Our results support that as group size increases, children receive smaller doses of speech sound practice. Similarly, children who have a reported comorbidity received smaller doses compared to children who have an isolated speech sound disorder. We discuss implications for school-based practitioners and researchers.

Application of the Challenge Point Framework During Treatment of Speech Sound Disorders

Purpose The purpose of this article is to provide trial-by-trial practice performance data in relation to learning (outcome probe data) as collected from 18 treatment sessions provided to children with severe speech sound disorders. The data illustrate the practice-learning paradox: Specific, perfect practice performance is not required for speech production learning. Method We detailed how nine student speech-language pathologists (SSLPs) implemented and modified the motor learning practice conditions to reach a proposed challenge point during speech practice. Eleven participants diagnosed with a severe speech sound disorder received high-intensity speech therapy 3 times per week for 6 weeks. SSLPs implemented treatment procedures with the goal of achieving at least 100 practice trials while manipulating practice parameters to maintain practice at the challenge point. Specifically, child performance was monitored for accuracy in five-trial increments, and practice parameters were changed to increase functional task difficulty when the child's performance was high (four or five correct responses) or to decrease functional task difficulty when the child's performance was low (fewer than four correct responses). The practice stimulus, type and amount of feedback, structure of practice, or level of support might be changed to ensure practice at the challenge point. Results On average, the children achieved 102 practice trials per session at a level of 58% correct responses. Fast achievement of connected speech with the lowest amount of support was associated with high scores on generalization probes. Even with high levels of error during practice, the children improved percent consonants correct with maintenance of learning 3 months posttreatment. Conclusion The results of this study show that it may not be necessary to overpractice or maintain a high degree of performance accuracy during treatment sessions to achieve transfer and retention of speech production learning.

The Effect of Practice on Variability in Childhood Apraxia of Speech: A Multidimensional Analysis

Purpose Variability has been interpreted in differing ways according to context (e.g., development, speech impairment, and learning). A challenge arises when interpreting variability in the context of learning for children with speech impairment characterized by high movement variability, as in childhood apraxia of speech (CAS). The objective of this study is to investigate changes in variability in CAS with practice in comparison to patterns seen in children with non-CAS speech sound disorders (SSD) and typical development. Method Speech production variability was examined in 24 children (5-6 years of age) with CAS, non-CAS SSD, and typical development in production of nonwords of varied motoric complexity. Multidimensional analyses were performed using measures of token-to-token speech consistency (percent word consistency), acoustic variability (acoustic spatiotemporal index), and movement variability (lip aperture spatiotemporal index). Changes in variability were examined in each group of children by comparing the first half to the last half of nonword tokens in the same data collection session. The impact of token complexity on practice effects was also explored across groups of children. Results All children displayed increased speech consistency within this practice period (p = .01). Only children with CAS displayed increased movement variability following practice (p = .01). Differences in acoustic and kinematic variability were observed across complexity levels in all groups, though these did not interact with practice effects. Discussion These findings suggest that increased movement variability in children with CAS might be facilitating perceptual consistency. It is believed that this finding reflects an inefficient strategy adapted by children with CAS in the absence of motor-based cueing and feedback to guide speech performance with practice.

Concurrent Validity Between Two Sound Sequencing Tasks Used to Identify Childhood Apraxia of Speech in School-Age Children

Purpose To assess the concurrent validity of two tasks used to inform diagnosis of childhood apraxia of speech (CAS), this study evaluated the agreement between the Syllable Repetition Task (SRT) and the Maximum Repetition Rate of Trisyllables (MRR-Tri). Method A retrospective analysis was conducted with 80 children 7-16 years of age who were referred for treatment studies. All children had a speech sound disorder, and all completed both the SRT and the MRR-Tri. On each task, children were classified as meeting or not meeting the tool's threshold for CAS based on the sound sequencing errors demonstrated. Results The two tasks were in agreement for 47 participants (59% of the sample); both tasks classified 13 children as meeting the threshold for CAS and 34 children as not meeting the threshold for CAS. However, the two tasks disagreed on CAS classification for 33 children (41% of the sample). Overall, the MRR-Tri identified more children as having sound sequencing errors indicative of CAS (n = 39) than did the SRT (n = 20). Conclusions These two tasks of sound sequencing differ in the children they identify with CAS, possibly due to aspects of the underlying task requirements (e.g., time pressure). The SRT and the MRR-Tri should not be used in isolation to identify CAS but may be useful as part of a balanced CAS assessment battery that includes additional tasks that inform the nature of the impairment and that aid treatment planning. Supplemental Material https://doi.org/10.23641/asha.14110280.

Re-Evaluating Evidence for Best Practice in Paediatric Speech-Language Pathology

BACKGROUND

Systematic reviews of treatment trials for children with speech and language difficulties often exemplify the limited clinical usefulness of the evidence base, reflecting recent literature in evidence-based medicine. Other studies report that clinicians often fail to seek information about best practice, across the health professions. Consequently, clinical researchers, including those in speech-language pathology, have sought alternative methodologies for determining best practice.

SUMMARY

Some approaches focus on "pragmatic trials," usually as part of existing health services. Others place case management of individuals at the centre of intervention presenting studies of one or more cases, including N-of-1 randomized controlled trials and cross-over group designs. Clinical case studies can provide important theoretical data contributing to our understanding of the development of typical and atypical communication. Precision medicine (also known as personalized medicine) is an emerging approach to building the clinical evidence base that acknowledges the importance of individual genetic and environmental differences between people. With increasing knowledge of aetiological heterogeneity, even within children presenting with the same diagnosis (e.g., childhood apraxia of speech), data reinforce the edict that children are not all born equal. Key Message: This review argues that to understand response to treatment, it is critical to examine child-related factors as well as the variables of the intervention itself.