Childhood Apraxia of Speech
Childhood Apraxia of Speech is a childhood speech disorder. It is NOT the same as “Apraxia” or “Dyspraxia” in adults who have had strokes or head injuries. Children with dyspraxia (or apraxia – both terms are as “correct” as any of the others listed below) have the capacity to say speech sounds but have a problem with motor planning. They have difficulty making the movements needed for speech, voluntarily.
Dyspraxia can be mild, moderate or severe. It can apparently resolve with appropriate therapy, in that the person’s speech sounds acceptable, though the underlying deficit probably remains forever. Alternatively, it can persist for a lifetime, in the form of very little speech and / or very difficult to understand speech, despite a great deal of appropriate therapy.
Dyspraxia in children is known by various names:
apraxia of speech
developmental apraxia of speech [DAS]
childhood apraxia of speech [CAS]
suspected childhood apraxia of speech [sCAS]
developmental verbal dyspraxia [DVD]
developmental articulatory dyspraxia [DAD]
On close reading of the literature, all the CAS ‘names’ seem to mean the same thing when it comes to looking at the actual symptoms or features of the child’s speech production, mouth movements and slow progress acquiring speech. The most commonly used names for it are probably: developmental apraxia of speech [DAS], developmental articulatory dyspraxia [DAD], and developmental verbal dyspraxia [DVD]. Childhood Apraxia of Speech [CAS] is an insurance friendly newcomer that has rapidly currency in the United States in recent years, and in the contemporary research literature where the terms CAS and sCAS are used and preferred.
In general each of these terms refer to children who have the capacity (the neuro-muscular wherewithal, if you like) to say speech sounds but who have a problem with motor planning. Messages from the brain, intended to tell the speech mechanism (larynx, lips, tongue, palate and jaw) what movements to make to produce speech, do not occur easily for children with dyspraxia. This difficulty comprises both a motor planning problem AND a difficulty ‘retrieving’ speech sounds and patterns when they are required.
The characteristic speech of such children includes differences in the rhythm and timing (prosody or ‘melody’) of speech and inconsistent speech sound errors. The distinguishing characteristic of apraxia of speech is that it is a problem with motor speech planning and programming, with NO weakness, paralysis or poor co-ordination of the speech mechanism.
It is probably safe to say that that whether researchers or clinicians call the disorder DAS/CAS/sCAS, DAD or DVD, they would ALL agree that the features outlined above are characteristic of the speech problem they are studying, assessing or treating.
It is also probably true to say that whatever term is being used to name the problem, experienced clinicians at the ‘grass roots’ level will be drawing on a very similar range of therapy techniques and activities.
All of which begs the question: so why call the problem by different names? There are at least five main THEORIES that attempt to explain the basis of developmental apraxia.
(1) It is due to an auditory processing problem
(2) It is a very specific ‘specific language impairment’ affecting language acquisition at the sound-syllable-prosody level
(3) It is due to an organisational problem with sequencing the movements required for speech
(4) It is due to a difficulty with making volitional (pre-planned, if you like) movements for speech production
(5) It is due to various combinations of these factors.
Importantly, these are THEORIES that are currently being formulated and tested by speech scientists. The fact is, we do not yet have a watertight explanation for dyspraxia.
Many clinicians and researchers actually working with children in the “apraxia population” who use the terms DAS and DAD tend to be those who veer towards the “motor based” explanation.
Those who use the term DVD tend towards a “language based” explanation. Some clinicians use the terms DAS and DVD interchangeably. Some, who embrace the probability that the problem might be “linguistic” and “motor” in origin use DVD/DAS.
Those who use the term CAS are probably au fait with the current research literature and current thinking about the disorder.
Then again, there are clinicians who use terms such as these because they have dropped into their clinical vernacular, in which case the term used does not reflect a particular theoretical orientation
The characteristics of Childhood Apraxia of Speech
To recapitulate, the distinguishing characteristic of childhood apraxia of speech is that it is a problem with motor speech planning and programming, with NO weakness, paralysis or poor co-ordination of the speech mechanism.
Some authorities believe that the primary difficulty children with dyspraxia have is with volitional (voluntary) movements of the speech production mechanism.
Children with CAS, if they are able to talk, usually make very variable articulation errors, their speech is slow, it seems very effortful to an onlooker, and there is a lot of ‘trial and error’ involved in trying to make particular sounds. The rhythm of speech usually seems wrong to the listener, and the child seems to put the emphasis in all the wrong spots (that is, there is something obviously unusual about their prosody).
The key features that alert a speech-language pathologist to the possibility of a CAS diagnosis in a young child are these:
- The child may have no words, very few words, or up to 100 to 200 words in their vocabulary. They are unlikely to be attempting to make more than a handful of 2-word combinations.
- Some give the impression of struggling to talk, exhibiting trial and error attempts to say words, accompanied by great frustration.
- Many use self-taught signs and gestures to augment communication, which may include a lot of ingenious body language and facial expression. They MAY use a lot of mime and gesture to communicate. Some augment signs and gestures with a repertoire of sound-effects (car noises, and the like) to good effect.
- Their speech has several of these characteristics:
- Words, in general, are not clearly spoken, though there may be remarkable exceptions such as a very clear (and useful!) ‘no’. Examples of this lack of clarity might include ‘ball’ being pronounced as ‘or’ and ‘knee’ being pronounced as ‘dee’.
- Speech errors affect vowels as well as consonants. For instance, ‘milk’ might be pronounced ‘mih’, ‘muh’ or ‘meh’.
- Inconsistency is evident, with the same word being pronounced in several different ways (e.g., ‘me’ pronounced as ‘ee’, ‘dee’, ‘bee’ ‘nee’, or ‘mee’). This is called token-to-token variability.
- Sounds that are used in some words are omitted from other words. I knew a child who could say ‘p’ TWICE in the word ‘Poppi’ (her grandfather) but who pronounced both ‘happy’ and ‘puppy’ as ‘huh-ee’.
- When asked to imitate speech sounds, sound effects (e.g., car noises: brm-brm etc) or words, the child does not seem to know where to start.
- They may have unusual intonation, pausing and stress patterns.
- They may not seem to know where to “put” nasal resonance.
- Many of these children can UNDERSTAND LANGUAGE at a more advanced level than their limited speech would suggest. This is sometimes called the Receptive-Expressive gap.
- They MAY not be able to easily copy mouth movements (i.e., non-speech movements) as well as their age-peers, and they may be (understandably!) reluctant to imitate speech movements and words.
Referred to as a ‘controversial’ diagnosis
Having said that CAS or sCAS is a motor speech disorder, it is important to note that it is a somewhat controversial diagnosis, with some authorities seeing it as a purely motor speech disorder with no ‘language’ (linguistic) component; others seeing it as a linguistically based disorder; others seeing it as a combination of these two; with yet another group doubting its very existence as a diagnostic entity!
My own position is that childhood apraxia of speech does exist, as a complex disorder and that no two children with it will be precisely the same. It can range from mild to severe. Some children with CAS appear to have a motor planning / programming problem with little or no accompanying language component. In my clinical experience this is a rarity. Most appear to have a motor planning / programming difficulty combined with associated linguistic difficulties, particularly phonological problems and difficulties with expressive grammar and syntax. I do not see these language difficulties as part of the CAS, but as difficulties that commonly occur alongside the CAS.
While the idea of a purely linguistic, or phonological basis (that is, no motor planning component) for DVD is intriguing, to date there is no convincing research data to support such a view.
There is no actual AGE at which CAS can be diagnosed for sure. It is more to do with STAGE than age.
SLP’s often have CAS on their ‘short-list’ of probable diagnoses for children who are late talkers with difficult-to-understand-speech (especially if they have feeding difficulties and sensory integration issues too) but we cannot be really sure until the child has plenty to say, or, at the very least, is making many speech attempts.
Ideally, the SLP has to be in a position to do a detailed speech and language assessment that includes analysing speech movements, speech sounds, speech patterns and speech rhythms. To be able to do this the child has to be attempting to say lots of words.
SLP colleagues and I have made diagnoses of CAS in children who had vocabularies of between 100 and 200 words, and who ranged in age from 2;3 to 4;6. We also know of several children for whom a clear diagnosis of DAS was not possible until after the age of 7.
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