A Randomized Control Trial of Motor-based Intervention for CAS

Seventy-two children with CAS, between the ages of 2.5 and 7.11 years of age will be treated with DTTC. This work will employ a delayed treatment control group design across multiple behaviors. Participants will be seen in two groups: an Immediate Treatment group and a Delayed Treatment group. Probe data will be collected during the Pre-Treatment (5 data points), Treatment (12 data points) and Maintenance (minimum 5 data points) phases. The study duration is 28 weeks in total duration for all participants. The study will address the following specific aims:

Aim 1: Quantify the effects of DTTC on improved speech production (perceptual ratings) in treated words that are maintained post-treatment and generalized to untreated words in children with CAS. The working hypothesis is that DTTC will increase accuracy of treated words (primary outcome measure) and this effect will be maintained post-treatment and generalized to untreated words. We also predict that DTTC will increase speech intelligibility pre to post-treatment (secondary outcome measure).

Aim 2: Quantify the effects of DTTC on refined speech motor control (kinematic/acoustic measures) in treated words that are maintained post-treatment and generalized to untreated words in children with CAS. The working hypothesis is that DTTC will be associated with decreases in speech motor variability and duration of treated words (secondary outcome measures) that are maintained pre- to post-treatment and generalized to untreated words.

Aim 3: Characterize the effects of speech motor variability (within-subject) at baseline as a predictor of DTTC efficacy in children with CAS. The working hypothesis is that children with CAS who demonstrate higher levels of speech motor variability at baseline will display greater improvements in speech production accuracy following DTTC than children with lower levels of variability at baseline.

Treatment will be provided four times/week for 45-minute sessions. Principles of motor learning will be incorporated into sessions by controlling the type of practice (blocked vs. randomized), type of feedback (knowledge of results vs. knowledge of performance) and amount of feedback provided.

Inclusion criteria

• Diagnosis of childhood apraxia of speech (CAS). Diagnostic classification for CAS will be determined according to the presence of the three core features identified in the ASHA position statement on CAS: 1) inconsistent consonant and vowel errors over productions of repeated trials; 2) difficulties forming accurate movement between sounds and syllables; and 3) prosodic errors (ASHA, 2007). These three characteristics must be present in more than one speaking context (i.e. single words, connected speech, sequencing tasks). In addition to the three core features, children with CAS must demonstrate at least four of the following characteristics: vowel errors, timing errors, phoneme distortions, articulatory groping, impaired volitional oral movement, reduced phonetic inventory and poorer expressive than receptive language skills, which is consistent with the Strand 10-point checklist (Shriberg et al., 2012). We will identify the presence of these factors from the Dynamic Evaluation of Motor Speech Skills (DEMSS, Strand et al., 2013), Verbal Motor Production Assessment for Children (VMPAC, Hayden & Square, 1999), Goldman Fristoe Test of Articulation (GFTA-3, Goldman & Fristoe, 2016), and a connected speech sample. We have used these stringent criteria for diagnosing CAS in our past research (Please see the Diagnostic Framework and Criteria for CAS in Grigos and Case (2017)). The diagnosis will be made independently by two speech language pathologists (one being the PI) with expertise in assessing and treating children with CAS.
• Age between 2.5 and 7.11 years of age.
• Normal structure of the oral-peripheral mechanism.
• Participants must pass a hearing screening conducted at 20 dB SPL at 500, 1000, 2000 and 4000 Hz.
• No prior DTTC treatment.

Exclusion criteria

• Positive history of neurological disorder (e.g. cerebral palsy), developmental disorder (e.g. autism spectrum disorder) or genetic disorder (e.g. Down syndrome).
• Characteristics of dysarthria, even if the child meets criteria for CAS.
• Fluency disorder, even if the child meets criteria for CAS.
• Conductive or sensorineural hearing loss, even if the child meets criteria for CAS.
• History of DTTC treatment.