Currently, there are no validated diagnostic features that differentiate CAS from other childhood speech sound disorders. However, three segmental and suprasegmental features consistent with a deficit in the planning and programming of movements for speech have gained some consensus among those investigating CAS:
- Inconsistent errors on consonants and vowels in repeated productions of syllables or words.
- Lengthened and disrupted coarticulatory transitions between sounds and syllables.
- Inappropriate prosody, especially in the realization of lexical or phrasal stress.
"Importantly, these features are not proposed to be the necessary and sufficient signs of CAS" (ASHA, 2007b, Definitions of CAS section, para. 1). The frequency of these and other signs may change depending on task complexity, age of the child, and severity of symptoms (Lewis et al., 2004).
Other characteristics that have been reported in children diagnosed with CAS and that represent difficulty with the planning and programming movement gestures for speech include
- articulatory groping—articulatory searching prior to phonating;
- consonant distortions;
- difficulty with smooth, accurate movement transitions from one sound to the next;
- increasing difficulty with longer or more complex syllable and word shapes;
- schwa additions/insertions—insertion of schwa between consonants or at the end of words;
- slower than typical rate of speech
- syllable segregation—pauses between sounds, syllables, or words that affect smooth transitions;
- voicing errors—voiceless sounds produced as their voiced cognates; and
- vowel errors—vowel distortions or substitutions.
See Iuzzini-Seigel (2017) and Strand (2017) for summaries of CAS characteristics that help discriminate CAS from other speech sound disorders and that represent expert consensus.
The presence of error patterns in the child’s speech does not necessarily indicate a phonological problem rather than a motoric problem. Many patterns can have either linguistic or motoric bases. For example, a child may consistently reduce consonant clusters either because of lack of understanding of the phonological rule or because of a motoric inability to sequence consonants.
The behavioral features reportedly associated with CAS place a child at increased risk for problems in expressive language and weakness in the phonological foundations for literacy (Lewis et al., 2004; McNeill, Gillon, & Dodd; 2009b).
As in children with other speech disorders, co-occurring language and literacy problems can be present, including
- delayed language development;
- expressive language problems, such as word order confusion and grammatical errors;
- problems learning to read, spell, and write; and
- problems with social language/pragmatics.
Co-occurring nonspeech sensory and motor problems can also be present (Crary & Anderson, 1991; Davis et al., 1998; Dewey, Roy, Square-Storer, & Hayden, 1988; McCabe, Rosenthal, & McLeod, 1998; Shriberg et al., 1997). These include
- gross and fine motor delays;
- motor clumsiness;
- oral apraxia;
- limb apraxia;
- feeding difficulties; and
- abnormal orosensory perception (hyper- or hyposensitivity in the oral area).