A Randomized Control Trial of Motor-based Intervention for CAS

Childhood apraxia of speech (CAS) is a complex, multivariate speech motor disorder characterized by difficulty planning and programming movements of the speech articulators (ASHA, 2007; Ayres, 1985; Campbell et al., 2007; Davis et al., 1998; Forrest, 2003; Shriberg et al., 1997). Despite the profound impact that CAS can have on a child's ability to communicate, little data are available to direct treatment in this challenging population. Historically, children with CAS have been treated with articulation and phonologically based approaches with limited effectiveness in improving speech, as shown by very slow treatment progress and poor generalization of skills to new contexts. With the emerging data regarding speech motor deficits in CAS, there is a critical need to test treatments that directly refine speech movements using methods that quantify speech motor control. This research is a Randomized Control Trial designed to examine the outcomes of a non-traditional, motor-based approach, Dynamic Temporal and Tactile Cuing (DTTC), to improve speech production in children with CAS. The overall objectives of this research are (i) to test the efficacy of DTTC in young children with CAS (N=72) by examining the impact of DTTC on treated words, generalization to untreated words and post-treatment maintenance, and (ii) to examine how individual patterns of speech motor variability impact response to DTTC.

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.