Developmental verbal dyspraxia

Shula Burrows (BSc; MSc; MRCSLT), Consultant speech and language therapist, clinical lead. Nuffield Paediatric Speech Clinic.

Developmental verbal dyspraxia (DVD), also known as childhood apraxia of speech (CAS) is a motor speech disorder and it is a subgroup of the diagnostic category called, speech sound disorder.

DVD impairs a child’s ability to plan, sequence and produce precise articulatory movements for speech. Children with DVD have difficulties with accuracy, timing and speed of speech production in the absence of damage to the muscles. The core deficit in developmental verbal dyspraxia is in motor planning of speech production. The cause of DVD is yet unknown. DVD can cooccur with other developmental disorders.

At the Nuffield Paediatric Speech Clinic, we offer a tertiary level service where the children are referred for an assessment and diagnosis of their speech.

Below, is an exert from a brief conversation with a child, aged 5 years, 10 months with DVD:

Jack: “This is a big hospital.”

Jack’s pronunciation of the utterance was heard as : [ di i a bi ho i pel ]

SB: “Yes, it is. Tell me more about your visit to the farm.”

Jack: “I like animals. I saw a caterpillar, no, no a caterpillar.”

Jack’s pronunciation of the utterance was heard as:

[ I lie a mels. I saw a tatiar no no tapetipa ].

SB: “Let’s say it together ‘caterpillar’.”

Jack: “Ye,[ ta a pi ar ]”

It would have been much harder to understand Jack’s message out of context. His speech contains many omissions of sounds, substitutions, and glottal stops. Sequencing of sounds and syllables within words are difficult for him and there is a distorted, almost jerky, quality in the rhythm of his speech with the rate of speech being quite slow. Imitation of the target word, does not improve his accuracy of production.

Identification of DVD:

Detailed assessment of speech output is essential for diagnosis. The importance of case history cannot be emphasised enough. Receptive and expressive language and phonological skills need to be assessed, in order to look at the child’s communication holistically. DVD is a speech disorder; differential diagnosis cannot be made in children who are without any verbal output.

What signs do we look for?

From the case history

• Frequently described by parents as “quiet baby”, did not vocalise very much
• Delayed babble
• Limited range of sounds used in babble
• Late to produce first recognisable words
• Stay at single word level for a long time
• Late to produce two–word joining ( my teddy, more bubble )
• Unintelligible speech
• Feeding difficulties, sensitive to certain textures, messy eater food gets smudged over face (current or past)
• Oromotor difficulties in imitating lip and tongue movements and sequencing these
• Drooling (current or past)
• Difficulties with blowing and sucking
• May have generalised gross motor and fine motor dyspraxia; may have an additional diagnosis of Developmental Coordination Disorder
• Comprehension of spoken language is reported to be in advance of expression
• Frustration due to unintelligible speech
• Positive family history of speech and/or literacy difficulties.

Signs to look for in speech assessment:

Diagnostic signs of DVD have been controversial for a long time.

Based on the Royal College of Speech and Language Therapists policy statement on DVD the 3 core signs on which there is consensus are:

• Inconsistent errors on consonants and vowels in repeated productions (child repeats the same word differently each time)
• Lengthened and disrupted coarticulatory transitions between syllables and sounds (Jack’s speech shows many examples of difficulties in moving from one syllable to the next smoothly and accurately)
• Inappropriate prosody, especially at lexical or phrase level. For example, placing the stress on the wrong syllable or placing equal stress on all syllables

In addition to these clinical experience and research literature highlight the following speech features:Vowel distortions

• A limited range of consonants and vowels, especially compared with the language levels of the child
• Omissions of sounds
• Substitutions of sounds
• Unusual substitutions which do not necessarily follow a developmental pattern
• Overuse of one sound, known as “favourite articulation”, child may replace a wide range of consonants, for example, (b,t,d,s,sh) by [g]
• Reduced accuracy and rate in sequencing of words and syllables, for example, “say digger 5 times”
• Increased number of errors with increased word length and complexity of utterance
• Glottal stop insertions and substitutions
• Imitation does not improve accuracy of production (Jack could not imitate caterpillar)
• Unintelligible speech
• Oromotor difficulties affecting ability to make movements of lips and tongue.

Treatment: 

DVD is treatable. Treatment approaches which are based on Motor Learning Principles, for example, Nuffield Dyspraxia Programme, would be appropriate. Phonological skills should be monitored and included in therapy to build accurate phonological representations in vocabulary. Children with DVD require regular, direct speech therapy, delivered by a speech and language therapist. Long breaks in therapy between courses do not help generalisation of targets and leads to slow progress.

Teaching assistants require training to carry out speech practice effectively with dyspraxic children. Frequent practice helps to stabilise the newly learned speech sounds and/or words. Repetitive drilling helps motor patterns to become automatic.

Educational consequences of DVD:

Most children with DVD attend mainstream schools. Educational difficulties which are frequent can be summarised as follows