Childhood Apraxia of Speech (CAS) is a type of pediatric speech disorder characterized by imprecision and inconsistency of motor speech movements in the absence of any neuromuscular problem. Children with CAS are at increased risk for early and persistent problems in speech, expressive language and literacy. The American Speech-Language-Hearing Association (ASHA, 2007) has proposed that the core impairment in CAS is in the planning and/or programming spatiotemporal parameters of movement sequences that results in errors in speech sound production and prosody 2. It is believed that CAS is neurologic in origin, however the specific neuroanatomic sites and circuits affected remain for the most part unknown. The objective of the proposed exploratory study is to use functional Magnetic Resonance Imaging (fMRI) to identify and characterize a unique neural signature for CAS. The central hypothesis of this study is that the functional neural network supporting motor planning and/or programming for basic speech production is altered in CAS and differs from that in individuals with typical speech and language (SL) development and from those with a developmental speech sound disorder without CAS (SSD). The hypothesis will be tested by pursuing two Specific Aims: 1) To adapt fMRI techniques that have been successfully applied in our pilot study to identify the functional neural network supporting speech production in adolescents and adults for use in children 7-10 years in age with typical SL. 2) To apply the fMRI methodology outlined in Specific Aim 1 to children diagnosed with CAS and to compare it with that observed for children with typical SL development and SSD without CAS. The proposed study is the first of its kind applied to assess the neural network supporting speech production in children in general, and to the investigation of SSD and CAS in particular. The proposed study is expected to provide methodology and pilot data to support and inform the design of future large scale studies. The proposed and future studies are expected to yield the following outcomes: First, the findings will improve the understanding of neurological underpinnings of the deficit in the planning and/or programming of spatiotemporal parameters of movement for speech sound production in children with CAS. Second, this approach will allow for the development of a definition of CAS based upon neurologic characteristics rather than a behavioral phenotype and to distinguish it from developmental SSD without CAS. Third, knowing how the functional neuronal substrate supporting speech production in young children with CAS differs from those with typical SL and SSD will allow for more appropriate assessment and differential diagnosis of CAS and for the development and introduction of more targeted and individualized interventional therapies.
The results of the proposed exploratory study are expected to yield methodology and pilot data for a larger study, the outcomes of which have the potential to make a significant impact by leading to the identification of a neural signature for CAS. This in turn would enable differential diagnosis and advance the development and introduction of more focused intervention strategies for CAS based on neurological processing differences, thereby improving the academic and social outcomes for these children.
| Redle, Erin; Vannest, Jennifer; Maloney, Thomas et al. (2015) Functional MRI evidence for fine motor praxis dysfunction in children with persistent speech disorders. Brain Res 1597:47-56 |
