Apraxia of Speech, Childhood

Childhood apraxia of speech (CAS) is a complex neurodevelopmental speech disorder with an unknown etiology and lack of clarity regarding its pathophysiology. CAS has also been discussed as a motor speech disorder because of an associated inability to plan movements that produce speech. Previously, CAS was labeled as either developmental apraxia of speech (DAS) or developmental verbal apraxia (DVA). However, DAS and DVA are no longer recommended as diagnostic terminology as the term developmental infers that the child may outgrow the disorder, according to the American Speech-Language-Hearing Association (ASHA). CAS persists through late childhood with children reported to average 9 years of speech and other types of therapy. As children mature and maintain characteristics of CAS, their speech is still considered childhood apraxia to distinguish it from the speech of adult-acquired apraxia, which is often associated with strokes or other brain lesions.

In the absence of visible structural deformities of the face and articulators, precision and consistency of movements underlying speech are thought to be impaired. CAS typically emerges early in life, is found in specific neurological disabilities, and occurs in complex neurobehavioral disorders with either known or unknown causes. To determine early motor speech abilities, parental interviews or questionnaires may be used to ask whether infants and toddlers had difficulty feeding, swallowing, sucking, or chewing. B. L. Davis and S. L. Velleman and M. Fish describe the common characteristics used as diagnostic cues to determine the presence of CAS to include whether the child played with babbling, produced canonical babbling, had limited productions of vowels and consonants, and had better receptive language than expressive language.

Lack of skill in producing intelligible speech is recognized as a primary impairment in children with CAS, although such children understand speech and language and seem to know what they want to say. This suggests that the neural circuitry from the brain may not have an uninterrupted pathway to speech musculature. One primary hallmark of CAS is variability of speech sound production, where each child has different combinations of speech sound errors. Another hallmark is the inconsistency of speech sound production, which involves the same sound being [Page 17]spoken differently each time the child produces that sound. There are characteristics of CAS that overlap with multiple phonological or articulation disorders. Speech disabilities such as initial (time → ime) or final consonant deletion (boat → bo), cluster reductions (school → kool), syllable omission (apple → ap), substitution (th → t), and distortion (s → sh) may be observed in children with CAS and in those with other types of phonological disabilities. Inaccuracy in producing consonants and vowels, the appearance of groping for target speech sounds, difficulty imitating speech sounds and words, more errors on longer utterances, and oral motor difficulties also characterize CAS. While a number of other traits have been reported for CAS, a single child rarely experiences all of the reported characteristics. Prosodic difficulties involving the rate and timing of speech often distinguish CAS from other types of childhood disorders of language and of sound production. CAS observed in the absence of any known medical or neurological condition is called idiopathic CAS.

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