Developmental apraxia of speech in children. Quantitive assessment of speech characteristics

Contains fulltext : 18648.pdf (publisher's version ) (Open Access)Developmental apraxia of speech (DAS) in children is a speech disorder, supposed to have a neurological origin, which is commonly considered to result from particular deficits in speech processing (i.e., phonological planning, motor programming). However, the label DAS has often been used as acatch-all' diagnosis owing to imprecise delineation and a confusing overlap of conditions. Motivated by this state of affairs, the main goal of this thesis was to develop appropriate diagnostic assessment procedures in order to identify speech characteristics specific for DAS in school-aged children. More explicitly, the main objectives of this study were: (1) to develop a standardized diagnostic procedure which yields objective, quantitative measures for speech and speech-motoric capacities of relevance for the diagnosis of DAS and (2) to develop procedures of classification, based on quantitative measures, to differentiate DAS from other childhood communication disorders. In the light of the latter objective, quantitative measures, usable to make a differential diagnosis, were re-examined regarding their validity for the assessment of the degree of dyspraxic involvement (i.e., severity of DAS). The studies in this thesis have yielded information about speech characteristics that can serve as valid indices of developmental apraxia of speech in children and procedures to assess these characteristics on an objective and quantitative level. The most important components (measures) that have to form part of a speech-motoric assessment tool: (a) relative frequencies of consonant substitution in words and nonsense words; (b) relative frequencies of place substitutions; (c) patterns of preferences in feature-value substitution; (d) maximum repetition rates (i.e., oral diadochokinesis); (e) maximum fricative duration. Particularly the first two measures (i.e., proportion consonant substitutions and place substitutions) proved their diagnostic value for distinguishing severe expressions of DAS from mild expressions. In clinical practice, the typical speech characteristics of DAS only seldom become manifest in their pure form. A quantitative speech profile determines the extent to which apraxia plays a role in the speech problems of a particular child and thus yields guidelines about the extent to which a treatment approach oriented towards developmental apraxia of speech is indicatedKatholieke Universiteit Nijmegen, 04 maart 1998Promotores : Gabreëls, F.J.M., Schreuder, R. Co-promotor : Maassen, B.A.M.229 p