Importance of Production Frequency in Therapy for Childhood Apraxia of Speech

CAS

Childhood apraxia of speech (CAS) is a rare neurological, sensorimotor speech sound disorder that has limited empirical evidence regarding its treatment. While there are several different treatment methods used to treat this disorder only one, integral stimulation therapy and a child specific modification of this (DTTC) have research evidence regarding effective treatment for CAS (and this evidence is in the form of case studies). Edeal and Gildersleeve-Neumann (2011) were interested in how different treatment intensity effects would affect the treatment outcome using integral training for children with CAS.

At issue here is the notion of "treatment intensity" which can be defined several ways. One way treatment intensity can be defined is the amount of practice that occurs in the treatment session; it is generally thought that more practice (or even more practice sessions) leads to a faster treatment effect. However since there are some instances where large amounts of practice may not be beneficial Edeal and Gildersleeve-Neumann believed that it would be important to define how much intensity is beneficial for treating CAS. The researchers' hypothesis was that greater frequencies of productions of speech targets would lead to increased motor performance and pronunciation in children diagnosed with CAS. In this study the authors were interested in determining whether more practice of speech targets (greater numbers of attempts and cues per session) in CAS participants would lead to increased performance in session, to a generalization effect to words not practiced in the treatment sessions, and if this training effect last post-treatment.

There were two participants in the study. Both were male boys. Both boys are identified in the study by pseudonyms in order to protect confidentiality. Jamie was six years and two months old at the beginning of the study. He was diagnosed with CAS at age 5 and had been adopted from China when he was two years, two months old. Felix was three years and four months old at the beginning of the study and it appears that Felix was diagnosed with CAS at the age of 18 months. Both participants were recruited from a clinic in a university. Intense clinical histories of both subjects are provided in the study.

The study used an alternating AB design. Thus, both of the participants get both of the treatment conditions. There were two treatment intensities administered: In the ModF condition all of the integral stimulation techniques and motor learning principles were implemented to elicit 30 to 40 productions of each target per session. In the HiF treatment condition the exact same treatment protocol was used but the speech targets were produced by the child 100- 150 times each per session. Treatment sessions were 15 min. each for each phase. Baseline probes were administered to each participant before the training sessions and the treatment order was randomized for every session (HiF first or ModF first). All of the treatment sessions consisted of two 15 min. blocks each followed by 5 min. Of probe administration. At the end of the study the participants were given a two-week break and then retested to see if there were long- term effects of the training. The interval stimulation therapy, imitation, cuing techniques, choral speaking and motor learning principles were the same techniques used in each condition (of course different probes and cues were used); however, in the HiF condition the pace was much quicker. Baseline sessions consisted of the participant and clinician working together in a language or reading task for 15 to 20 min. with the probes administered at the end of the period. None of the practice speech targets occurred during baseline sessions.

The clinicians recorded the number of accurate reductions of targets and a number of attempts. A manual counter was also used to track the number of speech productions made by each child for each treatment phase. All sessions were videotaped or audiotaped in order to double check the data. The probes were administered at the end of each treatment session in order to track for generalization of sounds. The independent variable is the condition and the dependent variable is the number of accurate production of targets and probes.

Jamie attended three 40 min. sessions each week for 11 weeks, whereas Felix attended two 50 min. sessions per week for five weeks. Both of the children appeared to benefit from the training in each condition; however, the learning and maintenance of speech production skills for both was greater for targets that were treated with the HiF condition. The researchers hypothesize that because in this condition the subjects had more opportunities to practice and to receive more cues the participants were able to progress at a better rate. There were some differences in treatment outcomes. Jamie made more solid treatment gains that Felix, but there were also fluctuations with both his in -- session progress and generalization to untrained probe words. In fact his is generalization to untrained probes never reached levels of 80% or better. Felix only completed five weeks of treatment and while he did progress there was a lack of motor learning over the course of the treatment. The researchers hypothesized that this may be due to his younger age and/or limited treatment period. However, the overall hypothesis that more intense frequencies would lead to better treatment outcomes was supported despite the variability in Jamie's results and Felix's inability to match Jamie's overall gains.

The authors do discuss a number of limitations to the study. First of course the small number of participants makes it impossible to generalize further than the confines of the studies. The authors also cite the variability in the length of treatment protocols as being a weakness of the study. They do not cite the differences in ages of the participants as a weakness in the methodology; however, that is inferred in the discussion section. There were also some issues with the overall treatment. For example, Jamie separately received an augmentative treatment during the course of the study and Felix did not.