FAQs from the Motor Speech Committee | IALP : International Association of Communication Sciences and Disorders (IALP) FAQs from the Motor Speech Committee – IALP : International Association of Communication Sciences and Disorders (IALP)

FAQs from the Motor Speech Committee

Frequently Asked Questions

Target audience: General public, adults

A Acquired Motor Speech Disorders:

Dysarthria and Apraxia of Speech

(Joseph R. Duffy)

What are acquired motor speech disorders?

Motor speech disorders are a group of speech problems due to neurologic abnormalities. The abnormalities can be present at birth or become evident when a child begins to speak, but in many cases they emerge later in life in association with acquired neurologic injury or disease. Two broad types of motor speech disorders are recognized — apraxia of speech and dysarthria. Apraxia of speech reflects an impaired ability to plan or program movements for speech. In contrast, dysarthria is a broad category of speech difficulties that reflect abnormalities that can include weakness, incoordination, spasticity, involuntary movements, or reduced movements. By definition, motor speech disorders are problems of speech production, not problems of language or thinking.

What are the main symptoms of acquired motor speech disorders?

The characteristics of acquired motor speech disorders vary as a function of specific type and severity. In general, apraxia of speech is associated with distortions of sounds and syllables and reduced rate and melody or flow of speech. The affected speaker and listeners often have a sense that muscles are not being given the right directions for the accurate production of sounds or syllables (for more detail, see FAQs for acquired apraxia of speech).

In contrast, the abnormalities associated with dysarthria often include one or a combination of the following: abnormal voice quality (for example, strained or breathy); abnormal resonance or tone (usually excessive nasal quality); distortion or “slurring” of speech sounds; abnormal speech rate (usually too slow but sometimes too fast); and abnormal speech rhythm (for example, too little or too much variation in pitch or loudness). In dysarthria, the affected speaker and listeners have a sense that while the correct plan for speech is there, it cannot be carried out because of underlying weakness, lax or excessive muscle tone, incoordination, or involuntary movements.

How are motor speech disorders diagnosed?

Acquired motor speech disorders are typically diagnosed by highly trained and skilled speech-language pathologists. Diagnosis usually relies on detection of speech abnormalities during conversational speech, reading, repetition of words and sentences, and performance on speech-like tasks such as vowel prolongation and rapid repetition of speech sounds. Observations of the size, strength, symmetry, and steadiness of speech structures (jaw, lower face, tongue, palate, larynx), and movements of those structures on non-speech tasks can be important, but diagnosis depends primarily on recognition of specific combinations or patterns of speech abnormalities. These patterns help determine if a motor speech disorder is present and the specific type of motor speech disorder. Speech-language pathologists sometimes use instrumental acoustic and physiologic measures to assist in diagnosis, but at this time those measures are confirmatory as opposed to primary diagnostic tools in most cases.

What are the typical causes of acquired motor speech disorders?

Motor speech disorders can be caused by a wide variety of neurologic diseases. Stroke, traumatic brain injury, and frequently occurring neurodegenerative diseases such as Parkinson’s disease and amyotrophic lateral sclerosis are among the most frequent causes. However, they can also be associated with less common neurologic conditions. A motor speech disorder can be the first or the only sign of common or uncommon neurologic diseases. Thus, the diagnosis of a particular type of motor speech disorder can help localize neurologic disease and contribute to medical diagnosis.

Are there treatments for acquired motor speech disorders? If so, what are those treatments?

Yes, there are a large number of treatment approaches that can help people with acquired motor speech disorders. Decisions about the most appropriate approaches depend on the severity of the problem, the specific type of motor speech disorder (for example, apraxia of speech or a specific type of dysarthria), and the affected person’s specific communication needs and preferences. Treatment choices also are influenced by whether the underlying neurological problem is stable or chronic, and whether it is expected to improve or worsen in the short or long term.

Some treatment approaches focus on reducing or eliminating the underlying impairment, whereas other approaches work to compensate for difficulties that likely will not resolve or may worsen. Some individuals benefit from medications or surgeries that are designed to manage the underlying neurologic disease, such as medications for Parkinson’s disease or myasthenia gravis, or laryngeal surgery for vocal fold paralysis. Some people benefit from medical or prosthetic interventions, such as Botox injection for spasmodic dysphonia or the fitting of a palatal lift prosthesis for individuals with significant weakness of the soft palate.

Most often, however, treatment is behavioral. For some, the primary focus is on modifying speech through consistent vigorous speech practice that, for example, improves loudness or phrasing, or accuracy and precision of speech movements. Other people benefit from learning strategies that will make speech more comprehensible even if speech itself will not change. For example, the understandability of speech can often be improved if speaking rate is slowed in specific ways, if the speaker points to the first letter of each spoken word on a letter board, or if the speaker and their listeners learn to consistently speak face-to-face, reduce noise or distraction, and identify the topic before beginning a conversation. In many cases, combinations of treatment strategies are necessary for optimal improvement of spoken communication. And, when speech is severely impaired, alternative means of communication, such as electronic devices with or without synthesized speech, may be necessary to ensure effective communication.

Which disciplines are involved in motor speech disorders diagnosis and treatment?

Although many disciplines are involved in diagnosis and helping to manage the consequences of brain injury and neurologic disease, the diagnosis and treatment of motor speech disorders typically relies on the unique skills of experienced speech-language pathologists. Although many people working in related medical disciplines can reliably identify the presence of a motor speech disorder, a skilled assessment is necessary to identify the specific type of motor speech disorder and the most appropriate avenues for its management. In some cases collaboration among health care disciplines is essential, especially if medical, surgical, or prosthetic treatments are appropriate considerations (for example, laryngeal surgery or prosthesis construction to improve vocal fold or palatal functions for speech). And, in many cases, optimal use of speaker and listener strategies to maximize the affected person’s ability to communicate requires a team effort that includes the affected individual and his or her co-workers and significant others, a speech-language pathologist, and other health care providers.

Apraxia of Speech in adults

(Malcolm R. McNeil)

What is Apraxia of Speech (AOS)?

AOS is a phonetic-motoric disorder of speech production caused by brain damage that produces inefficient or impaired translations of language (phonological representations) into commands for carrying out intended speech movements. AOS is, by definition, not a language disorder although it most often co-occurs with aphasia, a condition resulting in disordered language and also caused by damage to brain structures closely associated with those that cause AOS.

What are the main symptoms?

AOS causes distortions in the production of sounds and syllables and in the melody or flow of speech (prosody). Prosodic distortions commonly include slowed speech rate (including prolonged sounds and increased time between sounds and syllables), and perceived equal stress particularly on multi-syllable words. Other frequently identified behaviors such as effortful productions and inconsistency of productions may be present but do not appear to contribute to the unique clusters of behavior necessary for identifying AOS.

How is AOS diagnosed?

AOS is currently diagnosed by highly trained and skilled speech-language pathologists. The differential diagnosis of AOS from phonological disorders associated with aphasia is challenging and a number of acoustic and kinematic (movement and other physiological measures), along with perceptual measures is sometimes used to help in the diagnosis. AOS can only be diagnosed by the identification of complex patterns of disordered speech characteristics and not by the presence or absence of particular features. This pattern is necessary because most of the perceived identifiable characteristics are shared with other linguistic and motor speech production disorders; but they occur in unique patterns. While listening by trained clinicians is the gold-standard or the clinically accepted method for diagnosing AOS, research is under way to assess combine perceptual, acoustic and physiologic methods for improved accuracy and reliability of diagnoses. While AOS often also co-occurs with oral nonspeech apraxia, it cannot be diagnosed by the presence of this similar but dissociable disorder.

What is the typical onset and etiology?

The onset of acquired AOS is associated with the onset of injury to the brain used for planning and programming movements for speech. It can be present immediately after the onset of the injury or its features can sometimes only be detected after other consequences of the brain injury (e.g., consciousness, attention or language disorders) have resolved sufficiently for the individual to begin to attempt communication through speech.

The most common etiology for AOS is stroke, although anything that causes focal (e.g. tumor or surgical intervention) or diffuse (penetrating or closed-head traumatic or infections) brain injury can cause AOS. Additionally, a progressive form of AOS associated with dementia has received considerable attention in recent years.

Are there treatments for AOS? If so, what are those treatments?

There are effective treatments that reduce the quantity of speech impairments and improve the quality of speech of persons with AOS. Without exception, those that have sufficient evidence to be recommended are those that involve behavioral, long-term, repetitive practice driven interventions. While instruments are frequently used to aid in the treatment such as metronomes, acoustic displays and kinematic imaging instruments, the careful selection and sequencing of speech targets and the structured hierarchies of treatment goals are essential to efficacious interventions.

Which disciplines are involved in AOS diagnosis and treatment?

While many disciplines are involved in the consequences of brain injury (e.g. diagnosis and treatment of stroke or traumatic brain injury such as neurology, neuropsychology, physical therapy, nutrition, etc.), the diagnosis and treatment of AOS typically relies on the unique knowledge and skills of highly trained and experienced speech-language pathologists.

Childhood dysarthria

(Angela Morgan)

What is childhood dysarthria?

The term ‘dysarthria’ is restricted to speech disorders with a neurogenic origin, ie., speech disorders resulting from damage to the central or peripheral nervous system. Dysarthria in children may occur due to neurogenetic disorders, metabolic disorders, congenital brain damage or later acquired brain injury. It results from damage to the brain pathways responsible for controlling movement. As for adults (pg.1), dysarthria in children is associated with abnormalities such as weakness, incoordination, spasticity, involuntary movements, or reduced movements of the speech mechanism (ie., lips, tongue, jaw, cheeks, soft palate, larynx, respiratory system). Dysarthria does not include speech disorders associated with structural defects (eg., cleft palate, malocclusion, etc.), psychological disorders (eg., psychogenic aphonia) or cognitive-linguistic disorders (eg., aphasia, phonological disorder, developmental language disorder).

What are the main symptoms?

Similarly to adult dysarthrias as noted above (pg.1), the key features of childhood dysarthria include one or a combination of the following: abnormal voice quality (for example, strained or breathy); abnormal resonance (usually excessive nasality); abnormal tone; distortion or “slurring” of speech sounds; abnormal speech rate (usually too slow but sometimes too fast); and abnormal speech rhythm (for example, too little or too much variation in pitch or loudness). In dysarthria, the affected child and listeners have a sense that while the correct plan for speech is there, it cannot be carried out because of underlying weakness, lax or excessive muscle tone, incoordination, or involuntary movements. This is in contrast to childhood apraxia of speech (CAS) (see below), a disorder of planning and coordinating the movements for speech, such that speech production is highly variable. It is important to note that some children however, particularly those with Cerebral Palsy or neurogenetic syndromes, experience dysarthria co-morbid with CAS. Dysarthria may also co-occur with other acquired or developmental disorders (eg., language impairment).

How is childhood dysarthria diagnosed?

Childhood dysarthria is diagnosed by speech-language pathologists. Diagnosis relies on an oral exam of neuromuscular function and structure and an assessment of speech production. The oral exam assesses the symmetry, size and positioning of oral structures (eg., jaw malocclusion, micrognathia, macroglossia), strength, and range, rate and smoothness of movements of the articulators (lips, tongue, jaw, cheeks, larynx, soft palate). Most critically, diagnosis depends on a clinician’s perception of neuromuscular speech errors (as outlined above under symptoms) during conversation and also reading aloud in literate children. Tasks such as sound prolongation (saying /ah/, /s/, /z/ aloud for as long as possible) or rapid repetition of speech sound sequences (eg., saying /pa-ta-ka/ as quickly and clearly as possible) inform specific areas of speech breakdown to aid in differential diagnosis and to generate appropriate treatment targets. Differential diagnosis between dysarthria, CAS and structural deficits can be challenging in neurogenetic conditions where these conditions may co-occur (eg., is the child’s excessive or ‘hyper’ nasality due to velopharyngeal incompetence associated with structural deficits, limited neuromuscular control or even poor speech planning (CAS) where children can’t mark oral vs nasal contrasts accurately and consistently). In some instances further instrumental assessment is required to aid differential diagnosis, such as nasometry, nasendoscopy.

What are the typical causes of childhood dysarthria?

The most common etiology for childhood dysarthria is Cerebral Palsy, the most common form of childhood disability. Other common etiologies include neurogenetic syndromes, metabolic disorders, brain tumours (mainly of the posterior fossa region of the brain), stroke, traumatic brain injury, neurodegenerative diseases and epilepsy disorders.

Are there treatments for childhood dysarthria? If so, what are those treatments?

Current recommended treatments for childhood dysarthrias rely on modifying speech through intensive speech practice. The chosen treatment plan depends entirely on an individual child’s speech deficits, severity of disorder and the neuromuscular deficits or physiological profile underlying those errors. Parents/care-givers and significant others in the child’s life (eg., teachers) should also be consulted in the management plan, particularly in relation to developing functionally relevant and salient communication goals. Where appropriate, older children who are cognitively able should also be consulted to provide input into their therapy plan.

Current treatment approaches advocate intensive therapy delivery as being the most efficacious. These interventions have been trialed on children with Cerebral Palsy, the most commonly affected population with dysarthria. Very few studies have examined the efficacy of interventions for childhood dysarthrias associated with acquired brain lesions, neurogenetic or metabolic disorders. Where children are largely non-verbal, with severe to profound dysarthric presentation, alternative communication supports may be required to facilitate effective communication.

Which disciplines are involved in the diagnosis and treatment of childhood dysarthria?

Highly trained speech-language pathologists are required to conduct the diagnosis and treatment of childhood dysarthrias. The list of possible additional health professionals involved in the care of a child with dysarthria depends on the primary neurological etiology of the child and any other co-morbid health needs. Given the neuromuscular involvement in this population, typically affecting gross motor systems as well as the more focal speech system, most children with dysarthria will require support from a physiotherapist to ensure the child has appropriate trunk and postural support. Speech treatment will not be effective until adequate trunk, head and neck stability is established.

Readings and resources



Childhood Apraxia of Speech (CAS) / Developmental Verbal Dyspraxia (DVD)

(Ben Maassen)

What is Childhood Apraxia of Speech (CAS) / Developmental Verbal Dyspraxia (DVD) ?

Childhood apraxia of speech (CAS), which is equivalent to developmental verbal dyspraxia (DVD), is a speech disorder in young children, that shows some similarities with acquired apraxia of speech (AOS) in adults, but also some crucial differences. Like AOS, CAS is a disorder of planning and coordinating the movements for speech, such that the speech intelligibility is highly variable. In severe cases even daily caregivers have difficulty to understand the child. Unlike AOS, however, CAS can be a disruptive factor in the normal process of speech and language acquisition. Typical speech development starts from babbling and is built on much practice in producing early words and brief utterances. Not being able to express themselves in a normal manner, the child with CAS runs the risk to stay behind in the acquisition of the sound system and the vocabulary of the language. This results in a clinical picture that shows overlap with other speech-sound disorders which complicates the diagnosis and therapeutic management of CAS. ‘Pure’ CAS is rare, exclusion criteria such as poor phonological development should not be applied, because these can co-occur with CAS. Importantly, speech perception develops normally, such that, in general, children with CAS show normal receptive language functions.

What are the main symptoms?

The main symptoms are either limited speech production or speech that is difficult to understand, in severe cases even for parents or daily caregivers. Speech production tend to be variable and inconsistent, and also can be restricted with respect to the sound patterns (phonemes, syllables, words) in the child’s repertoire. Typically, children with CAS tend to produce some daily used and overlearned phrases quite well, which contrasts with the poorly intelligible spontaneous, voluntary speech. Not only within children, but also between children symptoms tend to show much variability. Due to this variability, CAS tends to be resistant to regular speech therapy. Over the years, CAS tends to normalize to a large extent, but the inconsistency and poor intelligibility in some cases remain an obstacle for fluent communication.

How and when is CAS diagnosed? What are the typical causes of CAS?

CAS is typically diagnosed around the age of 3 years or later, depending on the amount of speech production. Severely restricted production at age 2 to 4 years can be a sign of CAS, but is not a very specific sign, in that restricted production can also occur in a diversity of other developmental disorders related to language and cognition (such as specific language impairment (SLI), autism spectrum disorders, or neurogenetic syndromes). There is a common misunderstanding that CAS always leads to severe speech difficulties; also mild to moderate forms of CAS can be found. For most cases of CAS, no clear etiology can be determined (idiopathic form). However, CAS has also been identified in quite a few neuro-genetic syndromes and some diseases that are assumed to affect the central nervous system, such as galactosemia. For most of these etiologies no curative treatment is available.

Are there treatments for CAS? If so, what are those treatments?

There is no single, evidence based speech treatment for CAS, but many approaches can be successful to some extent. The main issue is, that children with CAS need much more practice than typically developing children to acquire simple motor patterns for producing speech sounds and more complex patterns for producing syllables and words. Hence the characteristic resistance to therapy. Due to their speech impairment however, rather than practicing more than typically developing children, children with CAS tend to practice a whole lot less. Structured and efficient treatment must be applied to compensate for this. Treatment programs are based on imitating normal speech development, reflected in the order and structure of to be acquired speech utterances. Treatment and management of CAS typically requires many years; in most cases treatment is concentrated in the years of Kindergarten and early primary school.

Which disciplines are involved in the diagnosis and management of CAS?

CAS is primarily diagnosed and treated by a speech-language pathologist (SLP). Aim of the assessment by the SLP is to determine firstly to what extent speech motor planning difficulties underlie the complex speech symptoms, and secondly what the possible consequences for speech intelligibility and speech-language development are. These are the major starting points for proposing a therapeutic plan. Task of the SLP is also to arrange the management plan, that includes the involvement of parents, care-givers, and teachers.

In addition, depending on the hypothesized etiology and possible co-morbidity of CAS, other disciplines can be involved: physical therapy to assess general motor difficulties; ENT to assess hearing and speech perception; neurology to investigate possible underlying diseases; genetics to determine family history and heritability.

A comprehensive technical report and position statement in CAS has been published by the American Speech-Language-Hearing Association, and a policy statement by the Royal College of Speech Language Therapists.

American Speech-Language-Hearing Association. (2007). Childhood Apraxia of

Speech [Position Statement]. Available from www.asha.org/policy.

American Speech-Language-Hearing Association. (2007). Childhood Apraxia of

Speech [Technical Report]. Available from www.asha.org/policy.


Assessment and Outcome Measures

of Motor Speech Disorders.

(Pamela Enderby)

Why is it important to assess motor speech disorders?

It is important to distinguish between the different speech diagnoses as this relates to treatment approaches and prognosis. Identifying the nature of the condition and its severity will not only assist the speech and language pathologist in planning their intervention but can also contribute to the diagnosis of the underlying/causative medical diagnosis. For example a patient who is identified as having a hypokinetic dysarthria of slow onset may well have an extrapyramidal condition such as Parkinson’s disease. It is not uncommon for the speech disorder to be an early sign of such a condition when the neurologist may be uncertain of the underlying cause. Its identification may lead to more immediate medical treatment. Whereas the sudden onset of oral or verbal dyspraxia may be suggestive of a specific cortical lesion.

Using a standardised and psychometrically robust assessment of the dysarthria (e.g. Frenchay Dysarthria Assessment) will allow the therapist to identify the pattern of the features contributing to the disorder and aspects which are less affected which can help the therapist determine whether the dysarthria is: spastic, flaccid, hypokinetic, hyperkinetic, cerebellar or mixed. Additionally, a structured approach to the assessment will determine which features are contributing to reduced intelligibility or quality of the speech thus supporting the development of a focused treatment program.

Should one only assess the speech impairment?

No, whilst determining the nature of the speech problem is important there are many other aspects that need to be evaluated. These include: ability to communicate (use of all communication abilities such as gesture, facial expression et cetera); impact of the communication deficit on social participation (impact on education, employment, social engagement); the effect of the speech difficulty on general well-being of the patient as well as family members; the natural ability of the patient to repair communication interactions when they break down; the changing nature of the impairment over time (does speech get worse or is it more difficult in noisy situations?)

All of these dimensions need to be covered in order to consider the priorities of the treatment approach for the individual. Some patients will need to be introduced to augmentative and alternative communication aids and devices. These may be need to support communication in various settings (for example using a voice amplifier if the individual gets tired, using a speech app in certain situations to support speech). Choosing the right approach will depend not only on the characteristics and severity of the speech disorder but also the impact it is having on an individual’s life.

If the therapist determines that the individual or a family member is upset/distressed by the condition then emotional support and counselling may need to be included in the treatment package.

What is the difference between an assessment and an outcome measure?

Assessments can be used as outcome measures if they are used in the same way at the beginning of treatment and at the end. However, therapists commonly do not do assessments in this way and thus it is important to think of how one is going to judge the impact of therapy and monitor change over time. This is important not only for evaluating the effectiveness of the intervention but also in keeping the patient and those purchasing the treatment informed. It can also contribute to the body of evidence related to treatment such certain disorders. An outcome measure should cover all aspects which may be influenced by an intervention e.g. the severity of the speech deficit including changes to all aspects including: respiration, phonation, resonance, articulation, oral motor control, laryngeal function, intelligibility. It should also cover functional communication, impact on social participation and well-being.

What assessments and outcome measures should I consider for motor speech disorders?

The Communication Outcomes after Stroke Scale (COAST) and Carer COAST-They are designed to measure patient communication effectiveness from the point of view of patients themselves (COAST) and their carers (Carer COAST). The latter includes 5 items to explore impact on the carer’s own quality of life. http://www.psych-sci.manchester.ac.uk/actnow/outputs/resources/

Assessment of motor speech disorders Lowit, Anja and Kent, Raymond D (2011) Assessment of motor speech disorders. Plural Publishing, San Diego. ISBN 1597563676

Frenchay Dysarthria Assessment Enderby P, Palmer R. Second edition. Published by Pro ED.The second edition of Frenchay Dysarthria Assessment (FDA-2) includes new knowledge about motor speech disorders and their contribution to neurological diagnosis. This updated edition remains a well-established test for the measurement, differential description, and diagnosis of dysarthria. It can be used in international research, as well as all clinical settings. Norms are provided for ages 12 to 97.