Developmental apraxia of speech: determiners of differential diagnosis

Developmental apraxia of speech (DAS) is a neurologically based disorder in the programming of sequential articulatory movements. This definition, based purely on motoric limitations, is fraught with controversy concerning aetiology, clinical manifestations, treatment, and even identification of the disorder as a separate clinical entity. An understanding of developmental apraxia depends on consistent utilization of a group of symptoms for diagnosis so that data-based results can be used to generate inferences about the disorder. Results from studies of children who are diagnosed with developmental apraxia, but who may not be apraxic, complicates application to theories attempting to account for observed symptoms. A longitudinal study of children with DAS has been under way at the University of Texas at Austin since 1985. Of 22 children referred as apraxic, a diagnosis has been confirmed in only four. Phonological and language evaluation data for five clients evaluated during this project are presented. One was diagnosed with developmental apraxia of speech. Each of the other four subjects were diagnosed with speech and/or language disorders without the presence of developmental apraxia of speech. Diagnostic results for all five are presented, to illustrate critical features for differential diagnosis of developmental apraxia.