by Breanna Waldrup, www.breannawaldrupslp.com
What We Really Need to Be Thinking about When Diagnosing CAS Under Age 3
You’ve probably heard that childhood apraxia of speech (CAS) can not be diagnosed under age three. Or maybe you have heard that’s a myth, that CAS can be diagnosed under age 3. So which one is true and what do we really need to be thinking about when diagnosing CAS in children under age three?
Characteristics of CAS
The diagnostic criteria for CAS have changed multiple times over the years. I’ve been a speech-language pathologist for more than17 years, and I was in graduate school in 2007 when ASHA published the technical report on CAS (ASHA, 2007). This is when the term “childhood apraxia of speech” was deemed to be the preferred term as opposed to verbal dyspraxia, developmental apraxia, and other terms that had been used in the past. In the technical report, ASHA also listed three characteristics of CAS: inconsistent errors on consonants and vowels in repeated productions, difficulty moving from one coarticulatory configuration to another, and atypical prosody.
Fast forward to 2014 at the Seventeenth Biennial Conference on Motor Speech Disorders & Motor Speech Control, Sarasota, Florida, and Dr. Larry Shriberg and Dr. Edythe Strand from the Mayo Clinic started talking about 10 characteristics of CAS, the so-called “Mayo 10 list.” The characteristics of CAS included:
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Vowel errors
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Consonant distortions
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Difficulty with initial articulatory configurations and transitionary movement gestures
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Equal stress; lexical or phrasal stress errors
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Segmentation
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Groping
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Intrusive schwa
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Voicing errors
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Slow speech rate
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Increased difficulty with multisyllabic words
This list didn’t include inconsistency, and that was added in an adaptation by Sue Caspari (Note, 2014). A number of research studies on CAS for the next several years used the Mayo 10 or 10+1 list for diagnosing CAS. Around this time I learned the criteria that a child needs to demonstrate at least 4 characteristics, and each characteristic in at least 3 speech tasks, to be diagnosed with CAS. Researchers were looking for the presence of CAS characteristics across speech tasks to diagnose CAS, although the exact number of characteristics varied from study to study. See Shriberg et al, 2017 for the list of characteristics.
Fast forward again and in 2022 we have the publication of the Profile of Childhood Apraxia of Speech and Dysarthria (ProCAD) by Drs Jenya Iuzzini-Seigel, Kristen Allison and Ruth Stoeckel (Iuzzini-Seigel et al, 2022). In this tool designed to guide clinical thinking, the researchers, who are specialists in CAS and dysarthria, listed features of CAS and dysarthria, as well as shared features, across the speech subsystems. The ProCAD guides clinicians looking for features specific to CAS in both the rate/prosody and articulation subsystems across two-to-three speech tasks to make a diagnosis of CAS.
All of that is well and good, but what does it mean for diagnosing a child with CAS under age three? For one, we have the catch-22 that we are told to assess a child’s speech across multiple speech tasks of varying motoric complexity, and that a child should be demonstrating multiple features across these speech tasks. Many children under age three that are being evaluated for CAS are not talking very much, so having enough speech data to analyze for the characteristics of CAS is very difficult. The other major issue that we must consider is the development of motor speech skills that is happening in the first three years of life.
Motor Speech Skill Development
I don’t know about you, but I recall learning very little about motor speech development in graduate school. I remember learning that jaw movement develops first, so when babies start to babble the sounds they produce are very jaw-driven. As their fine motor skills continue to develop and they develop tongue-jaw disassociation by age three, their production of phonemes becomes more refined. We know that generally the first sounds to develop across languages are those that are produced by the jaw opening and closing, with or without tongue involvement. Sounds like /m, b, n, d/ are commonly first sounds in words across languages.
Namasivayan et al (2020) took a thorough look at motor speech development, which was in line with what I learned in graduate school but also provided a lot more detail. Important motor skills to consider:
Voicing
Babies begin by only producing voiced sounds (vowels and voiced consonants). The greater motor control required to alternate between voiced and voiceless sounds (voicing contrasts) does not start to emerge until about two years of age (Namasivayan et al, 2020). Note that this is when this skill begins emerging, not when it is mastered. Thus, if we are assessing children under three years of age, we should be extremely cautious labeling voicing errors as a feature of CAS, because it may be an emerging skill in the child’s motor speech development.
Vowel Development
Do you know there is a developmental order for vowel development? I think most pediatric speech-language pathologists are familiar with the developmental progression for consonants, but even when I worked exclusively in the birth-to-three population, I do not recall the order of vowel development being common knowledge.
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Low, non-front and non-rounded vowels, such as /ʌ/, /ɑ/, /æ/, develop first, usually by 1 year of age (Namasivayan et al, 2020).
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Lip rounding and retraction emerge but only in jaw high position for vowels such as /i/, /u/, /o/ by two years of age (Namasivayan et al, 2020).
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Jaw height control emerges for vowels such as /ɛ/, /ɔ/ and diphthongs /aʊ/, /ɔɪ/, /aɪ/by three years of age (Namasivayan et al, 2020).
Vowel errors are a commonly noted feature of CAS. But considering vowel development extends to three years of age (especially for mid-height vowels and diphthongs), we need to be very cautious labeling vowel errors as features of CAS in children under age three. Children with typical motor speech development are likely producing vowel errors in the first two years of life and possibly up to age three.
Syllable Shapes
Syllable shapes also follow a developmental progression, at least in part due to motor speech development.
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At one year of age, children are expected to produce CV, CVCV, V and possibly VCV syllable shapes (Namasivayan et al, 2020).
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At two years of age, children are expected to have added CVC and CVCVC syllable shapes to their repertoire (Namasivayan et al, 2020).
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By three years of age, we expect CCV to be emerging (Namasivayan et al, 2020).
The use of limited syllable shapes is not a differentiating feature of CAS, but it is frequently seen in children with CAS or young children (1-2 years of age) at risk of being diagnosed with CAS (Overby et al, 2019). However, it is also frequently seen in children with phonological disorders. Regardless, we should definitely be considering the typical developmental progression of syllable shapes if we are assessing for the presence of a speech sound disorder in children under age three.
Difficulty with Multisyllabic Words
Another feature of CAS that we may want to use caution utilizing as evidence of CAS in children under age three is difficulty with multisyllabic words. Again, consider the development of syllable shapes – children under age three are not even expected to be producing many CVCVCV type syllable shapes (or more advanced sequences) yet. Weak syllable deletion is considered a typical developmental pattern until children are almost four years old.
Inconsistency
Inconsistency is a nuanced feature when assessing for CAS in children of all ages. For one, we know that token-to-token tasks are important for assessing inconsistency in children over age 5, with tasks such as Buy Bobby a Puppy (Iuzzini-Seigel et al, 2017). We also know from the work of Iuzzini-Seigel that phonemic inconsistency is the more accurate way to look at inconsistency for three- and four-year-olds. What do we know about children under age three? Basically we know that children under age three can be pretty inconsistent, and this isn’t necessarily indicative of a disorder. Due to the rapid motor speech development (not to mention cognitive and linguistic development) that is happening at this age, we know that children can be inconsistent due to emerging skills, which are by definition not yet consistent.
Summary
In the ASHA technical report (2007) on CAS, the expert committee urged speech-language pathologists to use caution when diagnosing CAS in children under age three. This has been sometimes misinterpreted as meaning that we can not diagnose under age three, which is not true. However, given the vast amount of motor speech skill development that is occurring in children under the age of three, we need to be very cautious about simply applying the criteria/features of CAS that are accepted for older children to children under age three. In particular, using the presence of vowel errors, voicing errors, difficulty with multisyllabic words and inconsistency as data for diagnosis of CAS may not be accurate.
References
American Speech-Language-Hearing Association. (2007). Childhood apraxia of speech [Technical report]. Available from www.asha.org/policy
Iuzzini-Seigel, J., Allison, K., & Stoeckel, R. (2022). A tool for differential diagnosis of childhood apraxia of speech and dysarthria in children: A tutorial. Language, Speech, and Hearing Services in Schools, 53(2), 324–344.
Iuzzini-Seigel, J., Hogan, T., & Green, J. (2017). Speech Inconsistency in Children With Childhood Apraxia of Speech, Language Impairment, and Speech Delay: Depends on the Stimuli. Journal of speech, language, and hearing research : JSLHR. 60. 1-17. 10.1044/2016_JSLHR-S-15-0184.
Namasivayam, A. K., Coleman, D., O’Dwyer, A., & van Lieshout, P. (2020). Speech sound disorders in children: An articulatory phonology perspective. Frontiers in Psychology, 10, 2998. https://doi.org/10.3389/fpsyg.2019.02998
Note. Childhood apraxia of Speech (CAS) Clinical Assessment Worksheet. Adapted by Sue Caspari from “A diagnostic marker to discriminate childhood apraxia of speech from speech delay” by Shriberg, L.D & Strand, E.A., 2014 presented at Seventeenth Biennial Conference on Motor Speech Disorders & Motor Speech Control, Sarasota, FL.
Overby, M., Caspari, S., Schreiber, J. (2019). Volubility Consonant Emergence, and Syllabic Structure in Infants and toddlers Later Diagnosed with Childhood Apraxia of Speech, Speech Sound Disorder and Typical Development: A Retrospective Video Analysis. American Journal of Speech, Language and Hearing Research. Vol 62, p. 1657-1675.
Shriberg, L.D., Strand, E.A., Fourakis, M., Jakielski, K.J., Hall, S.D., Karlsson, H.B., Mabie, H.L., McSweeney, J.L., Tilkens, C.M., & Wilson, D.L. (2017). A diagnostic marker to childhood apraxia of speech from speech delay: I. Development and description of the pause marker. Journal of Speech, Language and Hearing Research, 60 (4), S1096-S1117.
