Urgent need for well-designed studies of childhood apraxia of speech

Children who have childhood apraxia of speech (CAS) find it very difficult to make sounds in the right order, which makes it hard for others to understand them. Communication can thus break down between speaker and listener.  

At present, there is a lack of agreement in the clinical and research community about how to diagnose CAS (ASHA 2007). The number of treatment investigations reported in the literature has been severely limited, perhaps at least in part due to this lack of consensus on the underlying nature or diagnosis of CAS. This review investigates the effectiveness of treatment delivered by Speech Language Pathologists targeting CAS in children and adolescents.

The review demonstrates that there are currently too few well-controlled studies in this field to enable conclusions to be drawn about the efficacy of treatment for the entire CAS population, and calls for SLPs working in this area to design better studies.

Authors' conclusions: 

The review demonstrates a critical lack of well controlled treatment studies addressing treatment efficacy for CAS, making it impossible for conclusions to be drawn about which interventions are most effective for treating CAS in children or adolescents.

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Background: 

The diagnostic criteria for Childhood Apraxia of Speech (CAS), and the underlying cause(s) for this disorder, remain heavily debated. Some agreement exists that children with CAS may have impairments in one or more of the following domains: non-speech oral motor function, motor speech function, speech sounds and structures (i.e., syllable and word shapes), prosody, language, phonemic awareness / metalinguistic skills, and literacy .Recently consensus has been reached that only three features across these domains have diagnostic validity: (1) inconsistent error production on both consonants and vowels across repeated productions of syllables or words, (2) lengthened and impaired coarticulatory transitions between sounds and syllables, and (3) inappropriate prosody  (ASHA 2007). Perhaps due to the ongoing deliberation over aetiology and diagnosis, little evidence on intervention for CAS is published.

Objectives: 

To assess the efficacy of intervention delivered by Speech and Language Pathologists(s)/Speech and Language Therapists targeting CAS in children and adolescents.

Search strategy: 

The following databases were searched: CENTRAL (Issue 4, 2006), MEDLINE (1966 to 01/2007), CINAHL (1982 to 12/2006), EMBASE (1980 to 01/2007), ERIC (1965 to 01/2007), Linguistics Abstracts Online (1985 to 01/2007),  PsycINFO (1872 to 01/2007). Reference lists of articles thus identified were examined. 

Selection criteria: 

The review considered randomised controlled trials (RCTs) and quasi-randomised studies of children aged 3 to 16 years with CAS, grouped by treatment types (e.g., perceptual and instrumentally-based biofeedback treatment techniques).

Data collection and analysis: 

Two authors independently assessed titles and abstracts identified from the searches and obtained full text versions of all potentially relevant articles. Articles were assessed for design and risk of bias. In addition to outcome data, a range of variables about participant group and outcomes were documented.

Main results: 

Of 825 titles and abstracts searched, only 31 abstracts appeared to meet inclusion criteria. The remaining 794 papers were excluded predominantly on the basis of not including participants with CAS (e.g., focused on other developmental speech disorders or adult acquired apraxia of speech), or for not being intervention studies (i.e. being diagnostic or descriptive). All 31 full text articles obtained were excluded following evaluation as they did not meet inclusion criteria on design. . Thus no studies are included in this review.

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