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What are some challenges facing SLP’s in making a diagnosis of CAS?

Published | By
Ruth Stoeckel, MA, CCC-SLP, Mayo Clinic

There is much yet to be learned about CAS as a disorder and how best to arrive at a differential diagnosis. This is especially true for children who are younger than 2 ½-3 years of age, because these children are still in a stage of rapid growth and change. Attempting to determine if a child is at risk for language delay rather than being a “late talker” (Olswang, Rodriguez, & Timler, 1998) or has a speech problem other than or in addition to CAS can be a complicated decision-making process. But the payoff of making the correct diagnosis is in knowing that a child will receive appropriate intervention.

One of the first challenges in a diagnosis of CAS in young children is the lack of a “gold standard”, that is, a characteristic that, when present, means that there is little doubt that the diagnosis should be CAS. At present, the diagnostic criteria used in research vary from study to study (Davis, Jakielski, & Marquardt, 1998; Shriberg, Aram, & Kwiatkowski, 1997; Strand, 2002) as researchers strive to find a feature or set of features that could become that gold standard. Clinicians in the field have devised their own diagnostic schemes that differ from one person or location to the next. Additional pitfalls will be discussed below.

For some young children, there is a potential to arrive at “diagnosis by default.” What happens? This occurs when a child has not begun talking when expected, or is not learning to produce sounds and words at the expected rate. Parents will report that a physician or SLP decided that their child had CAS because they determined the child had age-expected understanding of language but was not yet talking or was not yet intelligible. Why might this be of concern? As noted above, we don’t yet have a foolproof means for identifying children at risk for CAS or for language disorder versus late talking. When a child is not yet speaking, it may not be possible to evaluate their ability to produce and sequence sounds and syllables. Without that information, we cannot determine or rule out the possible contribution of motor planning and programming for speech. Thus, it is not possible to make a conclusive diagnosis of CAS.

Some clinicians may use a checklist approach to determining the diagnosis. In an interesting exercise, Karen Forrest (2003) asked clinicians at a workshop to list three characteristics they considered to be indicative of CAS. The result was a list of 50 different characteristics! What happens? SLP’s who use a checklist approach may rely more heavily on some characteristics than others, or may base their diagnosis on the total number of characteristics they see in a child. Why might this be of concern? Based on Forrest’s compilation, the characteristics used by clinicians are diverse and even contradictory. They include behaviors that could suggest a severe articulation or phonological disorder or dysarthria as well as CAS. The use of such variable criteria could mean the same child would receive a different diagnosis depending on how many, and which, characteristics a given clinician used for their diagnosis.

Another issue of concern is over-reliance on standardized tests. There are several published tests developed for the purpose of assessing oral motor and motor speech skills. What happens? There are large differences in the number of items that focus on evaluating oral structures, oral movements, and motor speech skills from one of these tests to another. The complexity of tasks and types of judgments to be made by the evaluator also vary widely. Few of these measures are intended for use with very young children (Strand & McCauley, 2003). Why might this be of concern? Here again, whether or not a child is given a diagnosis of CAS may depend on which test is used because of the important differences in what is being measured and how it is measured. In addition, it can be very difficult to evaluate oral motor and motor speech skills reliably in children who may not be developmentally ready for the type of tasks currently used to assess these skills.

Yet another issue is reliance on tests that are inadequate for making a diagnosis of CAS. Often, school systems or insurers require standardized test scores to qualify a child for therapy. One of the potential clinical indicators of CAS is a discrepancy between receptive and expressive language. What happens? Clinicians may rely on standardized language scores and/or a standardized, single-word articulation test in order to satisfy the eligibility requirements. Why might this be of concern? CAS is not a language disorder; language testing contributes useful information to diagnosis but does not rule in/rule out CAS because it is possible to have a co-occurring language delay or disorder. Standardized, single-word tests of articulation do not systematically challenge a child’s speech motor system, meaning that a child may obtain a score that does not represent their intelligibility in connected speech, where the breakdown related to CAS may be more evident.

So, what are we to do? The short answer is that SLP’s have an obligation to provide competent evaluation and treatment. A full diagnostic assessment for CAS integrates information from a variety of measures (that may include both standardized tests and spontaneous samples of speech and language) as well as other tasks that may include: examination of the physical structures used for speech; evaluation of automatic and volitional control of the oral structures for both nonspeech activities and speech; identification of error patterns and whether they change as speaking tasks become more complex; and consideration of prosody (the “melody” of speech). However, a child’s age or physical or developmental abilities may preclude completion of all the tasks by which the diagnosis of CAS may be made with confidence. There may be times when “possible CAS” is the closest we can come to a diagnosis, monitoring maturation and progress over time to come to what will hopefully be the “right” diagnosis.

References

Davis, B.L., Jakielski, K.J., & Marquardt, T.P. (1998). Developmental apraxia of speech: Determiners of differential diagnosis. Clinical Linguistics and Phonetics, 12, 25-45.

Forrest, K. (2003). Diagnostic criteria of developmental apraxia of speech used by clinical speech-language pathologists. American Journal of Speech Language Pathology, 12, 376-380.

Olswang, L.B., Rodriguez, B., & Timler, G. (1998). Recommending intervention for toddlers with specific language learning difficulties: We may not have all the answers, but we know a lot. American Journal of Speech Language Pathology, 7, 23-32.

Shriberg, L.D., Aram, D.M., & Kwiatkowski, J. (1997a). Developmental apraxia of speech: I. Descriptive and theoretical perspectives. Journal of Speech and Hearing Research, 40, 254-272.

Strand, E. (2002). Childhood apraxia of speech: suggested diagnostic markers for the younger child. Childhood Apraxia of Speech Research Symposium, Phoenix, AZ.

Strand, E., & McCauley, R. Assessment of children’s oral and speech motor skills: A review. Presented to the American Speech Language and Hearing Association, Chicago, IL, 2003. ASHA, 8, 2003, p. 202.


[Ruth Stoeckel, MA, CCC-SLP, from Rochester, Minnesota, is a clinical therapist and evaluator at Mayo Clinic and a doctoral student at the University of Minnesota. She has experience working as a therapist and independent consultant in the schools, private practice, and clinic. Ms. Stoeckel is a member of the professional advisory board of the Childhood Apraxia of Speech Association of North America (CASANA) and presents at both local and national levels on a variety of topics. Her areas of special interest include childhood motor speech disorders, cochlear implants, and autism.]

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