Childhood Apraxia of Speech

See the Assessment section of the Apraxia of Speech (Childhood) Evidence Map for pertinent scientific evidence, expert opinion, and client/caregiver perspective.

Screening

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 assessment or referral to other professional services. For a more detailed list of screening components, see the Screening section of ASHA’s Practice Portal page on Speech Sound Disorders: Articulation and Phonology.

To date, there are no available CAS-specific standardized screening tools. In addition, CAS may not be identified during screening because the diagnosis sometimes results from observations made over the course of treatment.

Comprehensive Assessment

Children who are suspected of having CAS on the basis of screening results should be referred to an SLP for a comprehensive assessment.

Consistent with the World Health Organization’s (WHO) International Classification of Functioning, Disability and Health (ICF) framework (ASHA, 2016a; WHO, 2001), a comprehensive assessment is conducted to identify and describe

  • impairments in body structure and function, including underlying strengths and weaknesses in speech sound production and verbal/nonverbal communication;
  • co-morbid deficits or conditions, such as developmental disabilities, medical conditions, or syndromes;
  • limitations in activity and participation, including functional communication, interpersonal interactions with family and peers, and learning;
  • contextual (environmental and personal) factors that serve as barriers to or facilitators of successful communication and life participation; and
  • the impact of communication impairments on quality of life of the child and family.

See ASHA’s International Classification of Functioning, Disability, and Health (ICF) for examples of assessment data consistent with ICF for various clinical disorders.

Assessment is accomplished using a variety of standardized and nonstandardized measures and activities. See ASHA’s resource on assessment tools, techniques, and data sources. Keep in mind that standard scores cannot be reported for assessments that are not normed on a group representative of the individual being assessed.

SLPs take into account cultural and linguistic speech differences across communities. They select assessments that are culturally and linguistically sensitive, taking into consideration current research and best practice in assessing speech sound disorders in the languages and/or dialect used by the individual (see, e.g., McLeod, Verdon, & The International Expert Panel on Multilingual Children’s Speech, 2017). See ASHA’s Practice Portal page on Cultural Competence.

Comprehensive assessment for speech sound disorders typically includes a case history, oral mechanism examination, speech sound assessment, and language assessments, if indicated.  For details, see the Comprehensive Assessment section of ASHA’s Practice Portal page on Speech Sound Disorders: Articulation and Phonology. See also ASHA’s Practice Portal pages on Spoken Language Disorders and Written Language Disorders.

A comprehensive oral mechanism examination includes a motor speech assessment. This 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.

A key consideration in the motor speech assessment is an evaluation of movement accuracy. Using a variety of tasks, the SLP looks 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 the Signs and Symptoms section of this page).

Examples of 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 single syllable, bisyllable, multisyllable, phrase, and sentence levels; and
  • sequential and alternating movement repetitions (e.g., [papapa] and [pataka]; Thoonen, Maassen, Gabreëls, & Schreuder, 1999; Thoonen, Maassen, Wit, Gabreëls, & Schreuder, 1996).

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 sounds (Velleman, Huffman, & Mervis, 2012). In preschool children, consistency and accuracy of repetitions are likely to be more useful performance indicators than repetition rate (Williams & Stackhouse, 1998, 2000).

Assessment should include performance across multiple contexts (e.g., spontaneous vs. elicited vs. imitated utterances), as results can vary by context. 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 when 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; Strand & McCauley, 2019). Using dynamic assessment procedures, the clinician can provide cues (e.g., gestural or tactile cues) to better judge the child’s 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;
  • identification of factors that might contribute to the speech disorder;
  • recommendations for intervention that relates to overall communication adequacy, including AAC measures, as needed;
  • diagnosis of a spoken language (listening and speaking) disorder;
  • identification of literacy (reading and writing) 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 support (e.g., response to intervention [RTI]) in the child’s school to support speech and language development; and
  • 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; an
    • a geneticist if the child’s medical or family history suggests the possibility of a neurobehavioral disorder of genetic origin (e.g., fragile X syndrome, Rett syndrome, dysmorphology).

Cultural and Linguistic Considerations

In children who speak more than one language, CAS will influence production across all languages; however, errors may be manifested differently in each language.

SLPs consider the variation in vowel systems across languages and the number of vowels within a language when evaluating error patterns. Some languages have a greater number of vowel phonemes than other languages, and this may influence intelligibility and/or the overall frequency of errors.

In languages where 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 to produce these words. In languages with a higher frequency of single-syllable words, CAS may be more likely to manifest in vowel errors and inconsistent consonant production in the early stages of speech development.

Word and syllable structure (e.g., frequency of consonant clusters) in a language may also influence errors. For example, English has many one-syllable words with final consonants and consonant clusters. In children with CAS, this may result in more frequent cluster reduction, final consonant deletion, and unstressed syllable deletion.

In tonal languages, which rely on changes in intonation to change the meaning of a word, CAS may have an increased impact on intelligibility and error frequency.

The following may be observed in children with CAS who speak more than one language:

  • They may rely on earlier mastered sounds across all languages spoken.
  • They may appear to favor or use one language over another, but the difference may be due to the relative ease of the phonemic inventory and word structure in that language rather than an indication of language choice or dominance.

See Considerations When Working With a Bilingual Child With CAS (Portland State University, n.d.). See also ASHA’s Practice Portal pages on Bilingual Service Delivery and Cultural Competence.

Diagnosing CAS

Diagnosis Under 3 Years Of Age

Diagnosis of CAS in children under 3 years of age 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; and
  • the possibility that changes in speech occurring during the first 3 years (e.g., due to developmental maturation, social and linguistic peer exposure, and/or the beneficial effects of treatment) may alter the diagnostic label.

Retrospective analyses of home videos suggest some early indicators of CAS below the age of 3 years (Overby & Caspari, 2015). More recent data suggest that consonant development of children between birth and age 3 years who were later diagnosed with CAS may be different than that of children with other types of speech sound disorders and children who are typically developing. Differences include less vocalizations overall, fewer consonants, a less diverse phonetic repertoire, and later consonant acquisition (Overby, Caspari, & Schreiber, in review). However, given the preliminary nature of these data and the need for more research (e.g., longitudinal studies from infancy), diagnosis below age 3 years 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."

Differential Diagnosis

A number of instruments have been proposed for use in assessing the speech motor planning and programming skills considered to represent the core deficits in CAS; however, the rigor of their psychometric characteristics has been called into question (see, 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; Strand & McCauley, 2019).

CAS Versus 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; Shriberg et al., 2017). In addition, 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 (e.g., imprecise consonant, inconsistent pitch or loudness, inappropriate or aberrant stress patterns). 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. Polysyllabic production accuracy, along with an assessment of diadochokinetic rates, may be sufficient to identify CAS and rule out dysarthria (Murray, McCabe, Heard, & Ballard, 2015). Several maximum-performance tasks may also help differentiate CAS from (spastic) dysarthria or establish the presence of both (Thoonen et al., 1996, 1999).

Less commonly, but on occasion, there is a need to differentiate between apraxia and dysfluency (stuttering, cluttering), given that there can be some overlap in symptoms (Byrd & Cooper, 1989). Also, similar to children without motor speech disorders, children who are suspected of having CAS may go through periods of disfluency (Byrd & Cooper, 1989). See ASHA’s Practice Portal page on Childhood Fluency Disorders for more information about fluency.

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 Versus 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 in order 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.

See ASHA’s Practice Portal pages on Bilingual Service Delivery and Cultural Competence .

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 that a child has made before making a definitive diagnosis (Davis & Velleman, 2000; Strand, Shriberg, & Campbell, 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.

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