Assessment section of the Childhood Apraxia of Speech Evidence Map for pertinent scientific evidence, expert opinion, and client/caregiver perspective.
Screening is conducted by an SLP whenever a speech sound disorder is suspected or as part of a comprehensive speech and language evaluation for a child with communication concerns. The purpose of the screening is to identify those who require further speech-language/communication assessment or referral to other professional services. For a more detailed list of screening components, see the
assessment section of speech sound disorders: articulation and phonology. To date, there are no CAS-specific standardized screening tools available. In addition, CAS may not be identified during screening, as the diagnosis is sometimes the result of observations made over the course of treatment.
Children suspected of having CAS based on screening results are referred to an SLP for a comprehensive assessment. The assessment takes into account cultural and linguistic speech differences across communities.
Assessment is accomplished using a variety of measures and activities, including both standardized and nonstandardized measures, as well as formal and informal assessment tools. SLPs select assessments that are culturally and linguistically sensitive and ensure that standardized measures used in assessment show robust psychometric properties that provide strong evidence of their quality (Dollaghan, 2004).
Comprehensive assessment for speech sound disorders typically includes
- case history,
- oral mechanism examination,
- hearing screening,
- speech sound assessment (single-word testing and connected-speech sampling),
- spoken language assessment and literacy assessment, as indicated.
comprehensive assessment section of speech sound disorders: articulation and phonology.
A comprehensive oral mechanism/motor speech examination is critical for differentiating CAS from childhood dysarthria and other speech sound disorders and for identifying both oral apraxia and apraxia of speech—either of which may occur in the absence of the other. See McCauley and Strand (2008) for a discussion of nonverbal oral and speech motor performance assessment tools.
For children suspected of having CAS, a key consideration in the comprehensive assessment is an evaluation of movement accuracy. Differential performance on the pairs of tasks and across tasks of varying complexity may indicate motoric difficulty with speech. Examples of these tasks include
- nonspeech articulatory postures (e.g., smile) and sequences (e.g., kiss-smile) versus speech sounds and words;
- well practiced/automatic versus volitional speech (for children who are older and/or have some speech);
- speaking tasks that require single postures versus sequences of postures (e.g., single sounds such as [a] vs. words, such as [mama]);
- speech production at the syllable, single-word, bisyllable, multisyllable, phrase and sentence levels;
- sequential/alternating movement repetitions (e.g., [papapa] versus [pataka], formerly called diadochokinesis; Thoonen, Maassen, Wit, Gabreëls, & Schreuder, 1996).
The SLP evaluates the child's performance on these tasks for the presence of consensus features and other clinical characteristics of CAS to help identify the presence of motor-based planning and speech difficulties (see
signs and symptoms).
In preschool children, consistency and accuracy are more likely to be useful performance indicators than repetition rate (Williams & Stackhouse, 1998, 2000). Sequencing errors may consist of inaccuracies, inconsistency (i.e., not producing the same sound or syllable in each repetition—whether correct or not), or mis-ordering (Velleman, Huffman, & Mervis, 2012).
Assessment should include performance across multiple contexts, as observations during spontaneous versus elicited versus imitated utterances may result in different performance. Fluidity (smoothness), rate, consistency, lexical stress, and accuracy should be monitored, as there may be trade-offs among these variables (e.g., the child's productions might be smoother if speaking rate is slow vs. rapid).
Dynamic assessment is important for differential diagnosis of CAS and for determining severity and prognosis (Strand, McCauley, Weigand, Stoeckel, & Baas, 2013). Using dynamic assessment procedures, the clinician can provide cues (e.g., slowed rate, gestural or tactile cues) to better judge the speech production and to determine how much cueing is necessary to facilitate performance.
Assessment may result in
- diagnosis or provisional diagnosis of CAS or diagnosis of other speech sound disorder (e.g., articulation and/or phonological disorder);
- description of the characteristics and severity of the disorder;
- recommendations for intervention that relates to overall communication adequacy, including augmentative or alternative communication measures as needed;
- identification of factors that might contribute to the speech disorder;
- diagnosis of a spoken language (listening and speaking) disorder;
- identification of literacy problems;
- monitoring of literacy learning progress in students with identified speech sound disorder by SLPs and other professionals within the school setting;
- recommendations for a multi-tiered system of supports, such as
response to intervention (RTI) services in the schools, to support speech and language development;
- referral to other professionals as needed, including
- an occupational therapist for nonspeech, sensory-motor, or fine motor issues;
- a physical therapist if gross motor skills or overall muscle tone are of concern;
- a pediatric neurologist if neurological indicators (e.g., potential seizure activity, tremors, or imbalance) are present;
- a geneticist if the child's medical or family history suggests the possibility of a neurobehavioral disorder of genetic origin (e.g., fragile X, Rett syndrome, dysmorphology).
Cultural and Linguistic Considerations
In bilingual children, CAS will influence production across all languages; however, errors may be manifested differently in each language.
SLPs consider the variation in complexity of vowels across languages when evaluating error patterns. Some languages have a greater number of vowel phonemes than other languages, and this may influence the overall frequency of errors and/or the impact on intelligibility.
In languages in which multisyllabic word productions are common early in development, CAS may manifest as metathesis, coalescence, syllable deletion, and other word-level errors due to the longer motor plan required for production. In contrast, CAS may be more likely to manifest in vowel errors and inconsistent consonant production in the early speech development of children in language environments with a higher frequency of single-syllable words, such as English.
Word and syllable structure, including frequency of consonant clusters, in a given language may also influence errors. For example, English has many one-syllable words with final consonants and consonant clusters, which may result in high levels of cluster reduction, final consonant deletion, and unstressed syllable deletion for children with CAS.
- Reliance on earlier mastered sounds may be noted across all languages spoken by a child.
- Productions may appear to be more common in one language than the other for bilingual children with CAS, but the difference may be due to the relative ease of the phonemic inventory and word structure in a given language, rather than an indication of language choice or dominance.
See also Considerations
When Working with a Bilingual Child with CAS.
Diagnosis Under 3 Years Of Age
Diagnosis of CAS in children under 3 is challenging for a variety of reasons, including
- the potential presence of developmental disabilities and/or comorbid conditions;
- the lack of a single validated list of diagnostic features that differentiates CAS from other types of childhood speech sound disorders (e.g., those due to phonological-level deficits or neuromuscular disorder);
- the fact that some primary characteristics of CAS (e.g., word inconsistency, a predominant error pattern of omission, etc.) are characteristic of emerging speech in typically developing children under the age of 3 years;
- the lack of a sufficient speech sample size for making a more definitive diagnosis;
- the challenge of sorting out inability versus unwillingness to provide a speech sample or to attempt a speech target;
- the possibility that changes occurring prior to age 3 (e.g., developmental maturation, social and linguistic peer exposure, and beneficial effects of therapy) may alter the diagnostic label.
Preliminary research using retrospective analyses of home videos suggests some early indicators of CAS below the age of 3 (Overby & Caspari, 2012, 2013). However, given the preliminary nature of these data and the need for more research (e.g., longitudinal studies from infancy), diagnosis below age 3 is best categorized under a provisional diagnostic classification, such as "CAS cannot be ruled out," "signs are consistent with problems in planning the movements required for speech," or "suspected to have CAS."
A number of instruments have been proposed for use in assessing the speech motor planning and programming skills considered to represent the core deficit in CAS; however, the rigor of their psychometric characteristics has been called into question (e.g., McCauley & Strand, 2008).
Dynamic assessment can be used as a method for examining both the question of differential diagnosis and the value of particular types of cues (Strand et al., 2013).
CAS vs. Speech Delay or Other Speech Sound Disorders
Many of the behaviors and signs associated with CAS are also found in children with more broadly defined speech sound disorders (McCabe et al., 1998). Additionally, it is important that the diagnosis of CAS not be based solely on the severity of a child's speech sound disorder, as this may result in overdiagnosis.
Differentiating CAS from some types of dysarthria presents a significant challenge, because these disorders can share several speech, prosody, and voice features. For example, vowel distortions can be a result of oral hypotonicity or dysarthria, especially if the error is made in isolation and not influenced by connected speech.
Less commonly, but occasionally, there is a need to differentiate between apraxia and dysfluency (stuttering, cluttering), given that there can be some apparent overlap in symptoms (Byrd & Cooper, 1989). Also, like children without motor speech disorders, children suspected of having CAS may go through periods of disfluency (Byrd & Cooper, 1989).
In rare cases, CAS can co-occur with dysarthria or fluency disorders; therefore, it may not be an "either-or" diagnosis. Further, the child's limited speech sound system may mask these other diagnoses.
CAS vs. Speech Characteristics Typical of Dual or Second Language Learners or Speakers of Dialects of English That Are Unfamiliar to the Clinician
It is important to differentiate potential features of CAS from differences noted in typical dual or second language acquisition, as well as those noted in dialectal variants of English. A child's complete language system must be considered to appropriately distinguish differences from disorders.
In bilingual children, normal processes of second or dual language acquisition may be confused with features of CAS. For example, syllable reduction or deletion in specific word positions may vary by dialect or language. Expected prosody and stress patterns may not be present due to these differences. Children may also demonstrate inconsistent error patterns for phonemes in a new language that are not present in their primary language or are allophones in their primary language. For example, /l/ and /r/ are allophones in some languages, and children may have difficulty accurately and distinctly producing these phonemes in English.
bilingual service delivery.
Response to Treatment
Disorders with similar symptoms (e.g., CAS vs. severe phonological disorder vs. severe articulation delay) may not be distinguishable from one another without treatment. During treatment, the clinician has the opportunity to document the rate and amount of progress a child has made before making definitive conclusions regarding the diagnosis (Davis & Velleman, 2000; Strand et al., 2003). In these cases, a provisional diagnostic classification (e.g., "suspected of having CAS") can serve as a working diagnosis during the period of treatment. The working diagnosis can be used until a definitive diagnosis can be made.