The DVD debate - Afasic

Article updated 10 July 2017

As we have seen with the SLI Debate, terminology in the field of paediatric speech and language therapy can be a problematic issue. The term DVD (Developmental Verbal Dyspraxia) has been widely used for some time, but has always raised questions. Is it an appropriate term to use for children? Is it ever an accurate diagnosis? Does it even exist?

Over the next few months, we will be featuring a number of contributions from a range of experts with differing viewpoints. In the first article (below) Sean Pert argues that, in most cases, the term ‘Inconsistent Phonological Disorder’ (IPD)  more accurately describes children’s difficulties.

In the second article (added on 10 July 2017) Pam Williams and Hilary Stephens share their vast experience in the DVD field.

Do leave a comment to let us know what you think.

12 comments on “The DVD (Developmental Verbal Dyspraxia) Debate

  1. Very dated, old, research references used to explain the issues.
    No mention of Auditory Processing Disorder (APD) which can be a major cause of phonological processing problems.
    There needs to be a multi – discipline approach to the multiple issues that can cause these types of issues. And using more recent international research regarding multiple languages, and speech acquisition.

    • The age of research is not relevant here; many seminal papers are old. It is only relevant if the papers are peer reviewed and the findings of the papers quoted here have not been disproven. In fact, they have stood the test of time and are therefore strong evidence.
      APD is itself a highly controversial diagnosis; and I note that you are a researcher in this field.
      As an NHS therapist for more than twenty years I always worked in a team with specialist teachers, educational psychologists, paediatricians and other professionals.
      I am also an advisor for the Royal College of Speech and Language Therapists on bilingualism and have published one of the few assessments in a language other than English. The research team showed that both the categories of speech disorder and the interventions worked with children who spoke languages other than English and bilingual/multilingual children.

  2. I find this analysis extraordinary and unhelpful. What is to be gained by questioning whether something that can be defined by a group of features exists, where there are children that clearly fit within the feature list and there is very specific published therapy treatment approach that is shown to benefit those children (NDP3)? The features are clearly outlined in the RCSLT policy statement I don’t get why you would bunch these children in with a broader group of children who have lesser difficulties and then recommend an approach for treatment that is less suitable for the children with the more severe disorder. Or are you trying to suggest the Core Vocabulary approach is as valuable for the children who display all the features of Verbal Dyspraxia and that your belief is group therapy doing Core Vocabulary approach is as valuable for those children as one to one therapy with a specialist at delivering the NDP3 programme? I can assure you my child made no progress in group therapy where the focus was on pronouncing words and then came on significantly working with the specialist speech therapist on a one to one breaking down speech into the individual sounds and working on sequencing these back into words. It is ludicrous to suggest working on Core Vocabulary is going to fix a child who struggles with almost every sound and sequencing these back into words. Ours are children with severe speech disorder and your analysis reads like a propaganda sheet for justification why services should be cut for this group of children. Given that these children are already incredibly vulnerable and getting the services that they need for them is already hugely difficult and even with the right approach it can take years for these children to overcome their difficulties, I’m really worried that your suggested approach could cost children their opportunity to learn to speak and I worry about Afasic promoting this view.

    • Hi Hayley,
      Just to reiterate that Afasic is not promoting this view. As we make clear, we are hosting a debate on the subject and hope to include a range of views from experts with varying opinions. Thank you for your robust contribution and we would encourage other parents, therapists and any other interested party to let us know what they think.

    • A list of diagnostic features means that children are diagnosed by exclusion (If it’s not X or Y then it must be Z). This was the approach used in Specific Language Impairment (SLI) diagnosis and this has been shown to be highly problematic and diagnosis by exclusion has now been rejected by the research community, with the SLI diagnosis changed to Developmental Language Disorder (DLD). We should therefore be very wary of a diagnostic label which uses a cluster of features, especially when such small numbers of children are involved.
      There was not room in the article to explore the issues you raise; Group therapy has been consistently shown to be as effective as individual therapy in speech and language therapy. This doesn’t mean that there isn’t a place for individual therapy, just as in school, children benefit from both individual and group activities for learning. The delivery method is thought to be less important than the content.
      Individual experiences are important and I am so pleased that your child has made progress. However, the article is aimed at the assessment of all children with speech sound difficulties and how speech and language therapists arrive at a diagnosis.
      I have always supported services for children, being a speech and language therapists working in the NHS, and the article is based on the evidence we have.
      I wrote the article precisely because children may be missing out on the correct diagnosis and therefore the correct treatment.

  3. After reading Dr Perts article and reasons for debate, i thought i would put my views on this. My Child had great Difficulty to say T,D,N sounds, for approx 2 years he had core vocabulary therapy, which did NOT help. After 2 years, there was no improvement. They chose words he liked, one of them Helicopter, where he could not say T but there was a K sound in it as well. We visited the Nuffield and was provided with help, and in a relatively short time, they changed his articulation. He learned to lift his tongue up whilst making sounds. So According to DR Pert my childs difficulties did not exist at all!!! This is an extremely sad article which can upset many a parents who have witnessed first hand, how Verbal Dyspraxia affects their child.

    • I am so pleased that your child made progress.
      The article is based on research and highly specialist clinical practise over twenty years. I completely accept that your child had the difficulties you describe. I simply think we need to think about these difficulties in a different way. The approaches outlined do not exclude articulation work, and it is important to understand that speech disorders may include several levels of breakdown in the speech system. This might include difficulty producing sounds physically (articulation) and difficulty using sounds in words (phonology). I do carry out articulation work if a child is not stimulable (cannot produce the individual sounds). This would not prevent phonology work in addition if detailed assessment showed that there were difficulties at several levels. This is what I would suspect in your child’s case. When teaching my students I emphasise detailed assessment, leading onto therapy or therapy combination approaches. One of the motivations for this article is that speech and language therapists often only have the training or resources or time to try only one approach.
      I am not detracting from your family’s experience. I have worked with many many children with very severe speech difficulties and know how distressing this is. However, I am challenging current thinking so that the profession and researchers can find the best way to help children with these difficulties, so that the children can recover more quickly.

  4. Hi,
    Thanks for your response. I think if you are aiming a paper at parents of children, you need to make it understandable and useful to those parents. Here, what I think you are trying to say is that some children who present with some of the features of what has been categorized as DVD actually have IPD and that a proportion of those can be helped just as well with group therapy focusing on core vocabulary method. But, you haven’t identified how to distinguish those children and what your report actually says is that verbal dyspraxia probably doesn’t exist and kids who present with those features will definitely get just as good outcomes if they have group therapy focusing on core vocabulary only. The fact that you were restricted in the length of the paper from clarifying that you actually do believe that there is a place for individual therapy – as you have now explained that you do – is precisely what makes it dangerous. It would be interesting to hear more on when you believe individual therapy is useful. I’m presuming you would agree for children who have significant difficulties with oral-motor co-ordination including making the speech sounds in the first place would benefit from individual therapy. This, of course, is encompassed in the group of children we are considering here. I have responded below to the two main points on definition and group therapy at the end of this email below.

    I’m not trying to be difficult in challenging you, I just have been through the journey of trying to get services for a child who presents with DVD and I know that in cost cutting climate, articles like yours will be used as dangerous evidence why individual therapy isn’t necessary. Moreover, if you are teaching clinicians not to look for the more severe symptoms of problems with motor planning and to address them in groups only working on core vocabulary, then I have big concerns that children will not receive the services that they need to overcome the disorder. Likewise, I also know it’s crazy hard as a parent to find the right path for your child. I have a support group (with 650 members) on Facebook for families who present with features of verbal dyspraxia, so whilst I am writing from my own personal experience, I am fully aware of other people’s journeys and struggles. These parents all do everything they can trying to get the right support for their children with very difficult routes to services and anything given to parents which further confuses the issue without clear and helpful guidance on what they need to best support their children is, in my view, worrying and unhelpful.

    Thank you for taking time to respond to my points.
    Kind regards

    1) Problem with Diagnosis: A list of diagnostic features which are present, does not mean that children are diagnosed wholly by exclusion (otherwise wouldn’t by that rationale, all syndromes fall under that criteria) Both the RCSLT policy statement and the ASHA cover the difficulty in definitions, however both acknowledge that DVD does exist as a subset of SI where there is a core impairment in planning and/or programming spatiotemporal parameters of movement sequences resulting in errors in speech sound production and prosody. Moreover, that there is broad consensus that those planning difficulties result in: (a) inconsistent errors on consonants and vowels in repeated productions of syllables or words, (b) lengthened and disrupted co-articulatory transitions between sounds and syllables, and (c) inappropriate prosody, especially in the realization of lexical or phrasal stress. The RCSLT policy statement goes further to helpfully list other likely to be present difficulties. So, it is possible to broadly categorize these children, which of course is what clinicians and specifically the Nuffield has successfully been doing with its treatment programme and assessment tool for years.

    2) Group therapy: You state conclusively that group therapy has been shown to be as effective as individual therapy in speech and language therapy for this group of children. The reference that you quote, however, appears to have been discredited – having selected only 13 studies of speech and language therapy out of several hundred, the studies considered were based almost exclusively on studies of 2-3 years olds which were widely divergent in method and duration (and only addressed those children with primary speech and language difficulties, whilst we know for e.g., that those with DVD tend to have motor and other associated difficulties as a rule rather than exception). To hold this as a model for the efficacy of treatment for children with DVD completely distorts the study and is dangerously misleading those families whose children will need significant one to one input from a specialist therapist to make gains. (see for more discussion on this research).

    The ASHA cites the below recommendation for therapy for DVD.

    Dosage refers to the frequency, intensity, and duration of service and the culmination of those three variables (Warren, Fey, & Yoder, 2007). Treatment dosage for CAS is consistent with principles of motor learning (McNeil, Robin, & Schmidt, 1997). Given the need for repetitive production practice in motor speech disorders like CAS, intensive and individualized treatment is often stressed. A number of research studies support the need for three to five individual sessions per week versus the traditional and less intensive one to two sessions per week (Hall et al., 1993; Skinder-Meredith, 2001; Strand & Skinder, 1999). For younger children, the frequency and length of sessions may need to be adjusted; shorter, more frequent sessions are often recommended (e.g., Skinder-Meredith, 2001).”

    They recommend group for language and pragmatic skills but individual sessions for motor skills.

  5. Dear Hayley,

    Many thanks for continuing the debate. Many researchers and practitioners do not engage in difficult debates and I think this exchange is vital. We may not always agree, but be assured that my aim is to improve the assessment, diagnosis and care of children with speech disorder.

    You make a leap from diagnosis to therapy delivery; the article is aimed at parents and generalist therapists at the start of the diagnostic journey and for such children ‘dynamic assessment’ where therapy is tried and the child’s response is an important way of diagnosing, especially with respect to complex conditions. This has long been used to assess bilingual children (where no normative data is available) and is now recommended for assessing children with suspected developmental language disorder (DLD, previously specific language impairment, or SLI). See

    In addition, research has consistently shown that there is a place for group therapy, and that is is at least as effective as one-to-one therapy. This doesn’t mean that there isn’t a place for one-to-one therapy, but that, especially at the start of therapy children may benefit from learning symbols etc. in a group setting. This makes sense as people talk to other people in pairs and groups, and children need to generalise skills to their peers in the playground and school, as well as socially. Social interaction is perhaps the most powerful motivator for children to use language. However, this is a red herring!

    The main point is that DVD is a highly controversial diagnosis. The group/individual/care pathway debate is another debate entirely and is to do with resources and the evidence base around delivery of therapy. We should debate this, but I suggest this is another debate for Afasic to look at away from the diagnostic/treatment debate.

    I understand your concerns re: commissioning of services, but DVD is a misnomer, and unless we differentiate children into the correct diagnostic categories, they may receive the wrong treatment. DVD is the only speech and language therapy label where confusingly both aetiology (the underlying cause) and the presenting difficulty (speech difficulties) are mixed up together. Dyspraxia is an adult acquired label, meaning that if you say a child has DVD you are saying that they have, or are like an adult with a motor cortex lesion, which is clearly nonsense. The article’s main thrust is that the vast majority of speech sound disorders are psycholinguistic and not physical in nature. The DVD label is firmly in the motor speech/physical camp, and without ruling out Inconsistent Phonological Disorder, I cannot agree with. To jump directly to DVD seems to miss a step in the diagnostic process.

    1) Diagnosis by exclusion is not conclusive and you helpfully raise the point of syndromes. DVD, in common with other controversial diagnoses (see the SLI/DLD debate recently) are not an aetiology, i.e. they are not ‘present’ or ‘not present’, there is a spectrum or cluster of symptoms. To provide an analogy, people with Down’s syndrome have a genetic difference which can be identified without doubt, the aetiology; people with Down’s syndrome have a range of learning difficulties and speech and language difficulties (the presenting speech and language diagnosis). No two people with Down’s syndrome are the same, but the aetiology is uncontroversial.

    In contrast, Autistic Spectrum Disorder, Developmental Language Disorder and other conditions often have no obvious aetiology (underlying cause). We suspect a complex interaction of genetics and the environment, but this is yet to be firmly established. In such cases, diagnosis is problematic and so a multi-disciplinary team are involved, and there is often debate within that team about an individual child. In the case of DLD, the child’s language trajectory is now seen as crucial, i.e. their development over time, rather than ‘snapshot’ assessments on which clinicians used to rely until quite recently.

    So in conclusion, DVD is such a condition, where the aetiology is unclear (and the label misleading, as there is no motor cortex lesion), and the presenting condition varies from child-to-child. This is the very debate that this article is examining. Professionals need to be much clearer that we have no definitive way of diagnosing a range of conditions where the aetiology is unclear.

    2) Group therapy. As stated above, there is no research of which I am aware where group therapy has been shown to be less effective than one-to-one for speech and/or language intervention. More research needs to be undertaken, but studies are excluded from meta-analyses because they do not meet the criteria; this is a scientific and widely accepted way of comparing like with like. You may like Afasic to invite authors to explain how the evidence-base is collated and why such decisions are made.

    3) Dosage. I am so glad you highlighted this. I started to include this in my students’ studies as this is often overlooked. It is a relatively new area of research and not as straight forward as one would think; more therapy is sometimes not as effective as staggering therapy over time, and dosage is emerging as different for different groups of children.

    Therapy in the UK is often deficient when compared to the US. I quote some of the larger studies which support what you say, that the tradition six week block is not effective. I am not against higher dosage, and the service I ran provided therapy until the child met their therapy aims, not an arbitrary number of sessions. To limit sessions without considering the child’s needs and basing therapy on cost is rationing and this is what the NHS frequently does. I do not agree with rationing in this way. The problem we have, is that there is no firm research into all the different conditions encountered in a speech and language therapy practice.

    The article makes no comment on dosage (there was no space to do so) and indeed encourages parents to check that their child receives enough therapy. However, parents must be prepared to support therapy with home practice, and many parents are surprised that this is the case. I am sure you and your Facebook families are not in this category, but any practising SLT will tell you that families often need support and encouragement to practise outside of therapy sessions.

    Your references assume motor speech disorders and I reject that hypothesis, so I won’t comment further. I do not disagree that dosage is vital and my colleagues will tell you that I very much support more intervention that is typically offered. Again, this is a huge area which should encompass commissioners of services and Afasic could run articles on this aspect alone. However, diagnosis and dosage are not the same debate.

    I stand by my main point that more children would receive an evidence-based diagnosis if they received Core Vocabulary therapy initially (at a dosage which would be effective and in combination with therapy for any other presenting conditions), than if complex or persistent speech disorders are labelled as DVD (which currently they are, often without an inconsistency assessment).

    There is no doubt that speech disorders remain one of the most common childhood difficulties, and that we must work to address these difficulties. One of the main errors SLTs currently make is to fail to carry out an oral examination (to rule out cleft lip and palate etc.) and to fail to assess consistency of production. This is what my article addresses.

    The needs of children who do not respond to Core Vocabulary is the domain of another article and I do not claim to discuss this in the article. Such children may have motor disorders, but are these restricted to just speech? My experience with children with severe motor speech disorders is that they often have a general dyspraxia, affecting other aspects of fine and gross motor development. In this case, the DVD label is also not applicable as DVD implies no other difficulties and that the child only has difficulties with speech. I have found that a thorough assessment from an Occupational and/or Physiotherapist have often revealed subtle difficulties in areas other than speech.

    In any case, I am not saying children with severe and unexplained speech disorder do not require intensive and specialist help; they clearly do. What I am saying is that we must rule out inconsistency of speech production and other more generalised difficulties first.

  6. It is wonderful to see the William’s and Stephens’ response and I very much welcome it. As a profession we are not used to debating controversial issues, and yet, as the DLD/SLI debate has shown, there is often much disagreement in defining complex developmental conditions.
    I have no doubt that there are children with the difficulties described, but how we differentiate disorders and how we label them is very important, as it leads to specific treatment pathways and current UK NHS rationing may threaten good outcomes for children with severe and/or complex speech disorders.
    The profession, and especially those using the DVD label have not justified why the term ‘dyspraxia’, a term borrowed from adult pathology is still used. We do not persist in using ‘developmental aphasia’ for comprehension problems, and as I have previously stated, DVD is one of the few labels to still appear to have a medical cause, when it is anything but clear what the aetiology is. Parents and other professionals are confused by the borders between generalised motor dyspraxia and dyspraxia affecting just speech production.
    It is worrying that DVD can be defined as part of other conditions, as the criteria for DVD was that is is specific to speech only. We should emphasis multi-disciplinary team working to identify speech disorders which might be part of a genetic syndrome, or other condition which affects more than just speech. Such children cannot be included in the current definition of DVD, but nevertheless still need expert help.
    In common with SLI, I would like to see the condition re-named to describe the condition, just like almost all current evidence-based speech and language therapy diagnoses. Even American researchers, who prefer motor speech theories of disorder over phonological, use two terms; ‘CAS’ and ‘DVD’. This is a prime time for the experts in this field to make the case for a more accurate and less controversial label for the condition, and clearly differentiate it from IPD.
    It is interesting that children with DVD appear to have literacy issues; How does a purely motor speech problem affect phonological development? The definitions of the disorder are linked to the opinion of experts in the field, which is in danger of being a circular argument. We need more research to show what differentiates children with DVD from other speech disorder sub-groups, and objective assessments to highlight this so children can be diagnosed and directed to the correct treatment pathway much more quickly. the areas which differentiate DVD from IPD highlighted by Williams and Stephens should be available in an objective assessment for SLTs to use. Dodd and her team produced the DEAP assessment to do precisely this, and it has proved extremely effective for highlighting children with IPD versus Phonological delay, Phonological disorder and Articulation disorder. Indeed, one of the motivations for the article was that I am aware that many generalist SLTs are not carrying out oral examinations, stimulabilty assessment (the ability to imitate individual sounds) or checking for consistency of word production, potentially leading to mis-diagnosis.
    There is not universal agreement about any model of speech disorder, but Dodd’s classification has been shown to be effective both in accurately describing speech disorders (they can be objectively defined, unlike DVD) and they lead the SLT onto evidence-based treatments. This is robust and reliable evidence that the model is valid, and this is why it is taught in many UK universities to student speech and language therapists.
    I look forward to a time when the condition is no longer questioned because it is objectively defined, there is an evidence-based test to easily differentiate it from IPD and other speech disorders, and it has a label which truly describes its nature, rather than borrowing from adult medical terminology.

  7. My child has developmental verbal
    dyspraxia and his speech only improved after specialist therapy. He could not articulate /K/G/W/L sounds and
    various others; although I am a trained teacher I could not have taught him these sounds. I am lucky that with my teaching background I am able to refer to papers and read them for myself and I have been able
    to read up on dyspraxia.

    You have written “The very existence of DVD has been questioned for more than a quarter of a century (Stackhouse 1992). Joy Stackhouse has since written many books and articles; in her 1992 paper she did not
    question the existence of dyspraxia . She refers to Guyette and Diedrich 1981. It is not accurate to quote Stackhouse like this. She then goes on in the same paper on to say : “This shows the unfolding and changing nature of the condition as new demands were made on the child. The defining characteristics of the condition will depend on the child’s developmental level…” She concludes that “Lack of a
    developmental perspective in the design of studies of the speech disordered children has hampered our understanding of the complex nature of the condition known as developmental verbal dyspraxia.” Stackhouse has NOT said DVD does not exist.

    I have found it incredibly sad that you have said “We know from various studies that IPD is more common than DVD ( if it exist at all)! From my experience of a child with verbal dyspraxia I totally disagree with you that parents are as effective as SLTs if the child truly has DVD rather than a delay. It was only when my son had focused, specialised SLT help that any difference was made to his articulation.

    For the focused, intensive, articulation of sounds therapy appropriate for VD (given by the Nuffield) could not be replicated by me or other parents.

    Evidence you refer to is from LAW Garrett and Nye 2005 . Law states “some of these results therefore need to be considered tentatively”.

    Children who improved with parental
    therapy may have had delay NOT dyspraxia or articulation difficulties.

    In the Law paper we do NOT know what the problem was with the children, they were not all dyspraxic.

    Kind regards, Sarah

  8. Dear Sarah,

    We cannot reach conclusions about treatment from individual experiences. The point of research is to see if therapeutic approaches work for any child with a particular disorder. I am not saying that other approaches, including articulation therapy don’t work. I am saying that children with severe speech disorders should try Core Vocabulary therapy prior to other approaches as this has proved effective for more children. Research systematically looks at different approaches between groups of individuals rather than individual experiences. This is why scientific knowledge is not based on individual experiences. Statistics show us that individual experiences vary, but it requires may individuals to reach statistical significance. This is not to doubt your experience, but science is not based on one outcome.

    The What Works? Database discusses the levels of evidence for this very reason.

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