Dysarthria refers to a group of neurogenic speech disorders characterized by "abnormalities in the strength, speed, range, steadiness, tone, or accuracy of movements required for breathing, phonatory, resonatory, articulatory, or prosodic aspects of speech production" (Duffy, 2013, p. 4).
These abnormalities are due to one or more sensorimotor problems—including weakness or paralysis, incoordination, involuntary movements, or excessive, reduced, or variable muscle tone (Duffy, 2013).
Dysarthria can adversely affect intelligibility of speech, naturalness of speech, or both. It is important to note that intelligibility can be normal in some speakers with dysarthria. Dysarthria may also co-occur with other neurogenic language, cognitive, and swallowing disorders.
The predominant framework for differentially diagnosing dysarthria is based on a perceptual method of classification (Darley, Aronson, & Brown, 1969a, 1969b, 1975). This method relies primarily on the auditory perceptual attributes of speech that point to the underlying pathophysiology. The perceptual attributes are used to characterize the dysarthrias and, along with pathophysiological information, can help identify underlying neurologic illness.
The primary types of dysarthria identified by perceptual attributes and associated locus of pathophysiology (Duffy, 2013) are as follows:
Although dysarthria is present in many neurologic diseases, its true incidence and prevalence is not fully known. Estimates and ranges vary based on the location of lesion, the nature and course of the underlying condition, and the assessment criteria used. Estimates of the prevalence of dysarthria associated with some common neurologic conditions are as follows:
Signs and symptoms of dysarthria include perceptual speech characteristics and physical signs that vary by dysarthria type (see Distinguishing Perceptual Speech Characteristics and Physical Findings by Dysarthria Type). Dysarthria can alter speech intelligibility and/or speech naturalness by disrupting one or more of the five speech subsystems—respiration, phonation, articulation, resonance, and prosody.
Perceptual speech characteristics are grouped below by the subsystem that contributes most to the feature, recognizing that it is difficult to associate some characteristics with specific subsystems. For example, reduced loudness may be a laryngeal problem for some individuals and a respiratory problem for others. In addition, due to the interactive nature of the speech subsystems, disruptions in one subsystem can have an impact on others. For example, impairments in respiration, phonation, articulation, and/or resonance may be responsible for prosodic deficits.
Physical signs may include the following:
Many neurologic illnesses, diseases, and disorders—both acquired and congenital—can cause dysarthria. Listed below are examples of some specific etiologies, grouped into broad categories (Duffy, 2013).
Speech-language pathologists (SLPs) play a central role in the screening, assessment, diagnosis, and treatment of persons with dysarthria. The professional roles and activities in speech-language pathology include clinical services (diagnosis, assessment, planning, and treatment); education, administration, and research; and prevention and advocacy. See ASHA's Scope of Practice in Speech-Language Pathology (ASHA, 2016b).
The following roles are appropriate for SLPs:
As stated in the Code of Ethics (ASHA, 2016a), SLPs who serve this population should be specifically educated and appropriately trained to do so. SLPs who diagnose and treat dysarthria must possess skills in the differential diagnosis and management of motor speech disorders. They must have specialized knowledge of
Screening for dysarthria is pass/fail. It does not provide a diagnosis or a detailed description of the severity and characteristics of speech deficits associated with dysarthria but, rather, identifies the need for further assessment.
Screening may result in recommendations for
Assessment of individuals with suspected dysarthria should be conducted by an SLP using both standardized and nonstandardized measures (see assessment tools, techniques, and data sources).
The goal of the dysarthria assessment is to
See, for example, Duffy (2013) and Lowit and Kent (2010).
The severity of the disorder does not necessarily determine the degree of disability. Speech-related disability will depend on the communication needs of the individual and the comprehensibility of his or her speech in salient contexts.
Consistent with the World Health Organization's (WHO) International Classification of Functioning, Disability, and Health (ICF) framework (ASHA, 2016b; WHO, 2001), the assessment identifies and describes
See Person-Centered Focus on Function: Dysarthria [PDF] for an example of assessment data consistent with ICF.
The assessment process includes consideration of the individual's hearing and vision status. This may include hearing screening, inspection of hearing aids, and provision of an amplification device, if needed. If the individual wears corrective lenses, these should be worn during the assessment.
The assessment section below is not prescriptive—it outlines the components of a very thorough exam. Some components may not be applicable in all clinical settings.
Prosody—use of variations in pitch, loudness, and duration to convey emotion, emphasis, and linguistic information (e.g., meaning, sentence type, syntactic boundaries); speech naturalness reflects prosodic adequacy
Speech Intelligibility—the degree to which the listener (familiar/unfamiliar) understands the individual's speech; typically reported as a percentage of words correctly identified by a listener
Comprehensibility—the degree to which the listener understands the spoken message, given other information or cues (e.g., topic, semantic context, gestures) to enhance communication; typically reported as percentage of words correctly identified by a listener
Efficiency—the rate at which intelligible or comprehensible speech is communicated; typically reported as the number of intelligible or comprehensible words per minute
Other components of the assessment may include a review of the following, which may lead to further, in-depth assessment of these areas:
Assessment may result in the following outcomes:
Given the overlap in speech characteristics and other deficits across the dysarthrias, it may be difficult to determine dysarthria type, particularly when the underlying etiology is unknown (Fonville et al., 2008; Van der Graaff et al., 2009; Zyski & Weisiger, 1987). However, there are a number of distinguishing speech characteristics and physical findings that can be useful in making a differential diagnosis. See Distinguishing Perceptual Speech Characteristics and Physiologic Findings by Dysarthria Type.
Listed below are characteristics and comparisons often used to distinguish dysarthria from apraxia of speech (AOS). Some dysarthria types (e.g., ataxic, hyperkinetic, and unilateral upper motor neuron) share some characteristics with AOS and can be difficult to distinguish (Bislick, McNeil, Spencer, Yorkston, & Kendall, 2017; Duffy, 2013).
For more information about AOS, see ASHA's Practice Portal page on Acquired Apraxia of Speech.
Aphasia affects language comprehension and expression in both spoken and written modalities; dysarthria affects only speech production.
When an individual has both dysarthria and aphasia, and verbal expression is significantly impaired, the clinician will need to determine if the problem is motor based or language based—or some combination of the two.
Intelligibility and speech naturalness can be significantly compromised by dysarthria; however, delays during speech and/or attempts by the speaker to revise content might indicate language expression problems associated with aphasia. In such cases, it may be necessary to assess written language expression as well as oral and written language comprehension to make a definitive diagnosis. If deficits are found in these modalities, it is likely that language problems are contributing to verbal expression difficulties (Duffy, 2013). For more information about aphasia, see ASHA's Practice Portal page on Aphasia.
When selecting screening and assessment tests, the SLP considers the influence of cultural and linguistic factors on the individual's communication style and the potential impact of impairment on function. Variations in dialect should be taken into consideration before marking phonemes in error if they were not part of the client's repertoire or dialect prior to injury or disease.
The assessment is conducted in the language(s) used by the person with dysarthria, with the use of interpretation services as necessary. See ASHA's Practice Portal pages on Collaborating With Interpreters, Transliterators, and Translators and Bilingual Service Delivery.
Appropriate accommodations and modifications must be made to the testing process to reconcile cultural and linguistic variations. Comprehensive documentation includes descriptions of these accommodations and modifications. Scores from standardized tests should be interpreted and reported with caution in these cases.
Treatment is individualized to address the specific areas of need identified during assessment. It is provided in the language(s) used by the person with dysarthria—either by a bilingual SLP or with the use of trained interpreters, when necessary. See ASHA's Practice portal page on Collaborating With Interpreters, Transliterators, and Translators.
Consistent with the WHO's ICF framework (WHO, 2001), the goal of intervention is to help the individual achieve the highest level of independent function for participation in daily living.
Intervention is designed to
For individuals with dysarthria, treatment focuses on facilitating the efficiency, effectiveness, and naturalness of communication (Rosenbek & LaPointe, 1985; Yorkston et al., 2010).
See Person-Centered Focus on Function: Dysarthria [PDF] for an example of functional goals consistent with ICF.
Treatment can be restorative (i.e., aimed at improving or restoring impaired function) and/or compensatory (i.e., aimed at compensating for deficits not amenable to retraining).
Restorative approaches focus on improving
Compensatory approaches focus on
Treatment is not always restorative or compensatory. Sometimes, it is directed at preserving or maintaining function, such as when an individual has a slowly progressing degenerative disease.
Below are brief descriptions of treatment options for addressing dysarthria. This list is not exhaustive, and the inclusion of any specific treatment does not imply endorsement from ASHA.
Treatments are grouped into (a) those that directly target the speech-production subsystems and (b) other treatment options, including communication strategies, environmental modifications, AAC, and medical/surgical interventions by other specialists.
Treatment selection depends on a number of factors, including the severity of the disorder, natural history and prognosis of the underlying neurologic disorder, the perceptual characteristics of the individual's speech and his or her communication needs, patient and family preference and engagement, and the presence and severity of co-occurring conditions (e.g., aphasia, cognitive impairment, or apraxia of speech). One or more of these co-occurring conditions might affect the individual's insight into communication limitations, ability to implement compensatory strategies such as conversational repair, or ability to benefit from some treatment approaches.
It can be important to sequence treatments. For example, respiration and phonation are usually targeted initially, but prosthetic management of velopharyngeal dysfunction may be needed first in order to achieve efficient and effective breathing and phonation for speech (Duffy, 2013; Yorkston et al., 2010).
Some treatments have benefits that extend to subsystems other than the one being targeted. For example, improving prosody can benefit naturalness and intelligibility (Patel, 2002; Yorkston et al., 2010), and increased loudness (vocal effort) may induce changes in articulation and resonance (Neel, 2009).
A variety of communication strategies can be used by the individual with dysarthria (speaker) and his or her communication partner to enhance communication when speech intelligibility or efficiency is reduced. These strategies can be used before, during, or after other treatment approaches are implemented to improve or compensate for speech deficits (see, e.g., Duffy, 2013).
Speaker strategies include
Communication-partner strategies include
Environmental modification involves identifying optimal parameters to enhance comprehensibility.
These parameters include
AAC involves supplementing or replacing natural speech and/or writing.
The two forms of AAC are
Other augmentative supports include voice amplifiers, artificial phonation devices (e.g., electrolarynx devices and intraoral devices), and oral prosthetics to reduce hypernasality.
See ASHA's Practice Portal page on Augmentative and Alternative Communication.
SLPs may refer the individual to a medical specialist to assess the appropriateness of, or need for, medical interventions.
These interventions can include, for example,
Not all individuals with dysarthria are candidates for treatment. Factors influencing decisions about treatment include the individual's communication needs, his or her motivation, and the presence of other deficits or conditions that can affect communication.
In neurodegenerative disease, treatment is often appropriate. The goal of treatment is to maximize communication at each stage of the disease, not to reverse decline (Duffy, 2013). This may include strategies to conserve energy and minimize fatigue.
Individuals with neurodegenerative diseases will need compassionate counseling to anticipate
Views of the natural aging process and acceptance of disability vary by culture. Cultural views and preferences may not be consistent with medical approaches typically used in the U.S. health care system. It is essential that the clinician demonstrate sensitivity to family wishes when sharing potential treatment recommendations and outcomes. Clinical interactions should be approached with cultural humility.
See the Service Delivery section of the Dysarthria Evidence Map for pertinent scientific evidence, expert opinion, and client/caregiver perspective.
In addition to determining the optimal treatment approach for an individual with dysarthria, the clinician considers service delivery variables—such as format, provider, dosage, timing, and setting—which may have an impact on treatment outcomes.
Format—refers to the structure of the treatment session (e.g., group and/or individual). Individual treatment may be most appropriate for learning new techniques and strategies. Group treatment provides opportunities to practice techniques and strategies in a naturalistic setting and receive feedback about their effectiveness in improving comprehensibility and overall communication.
Provider—refers to the person providing the treatment (e.g., SLP, trained volunteer, family member, caregiver). In addition to skilled treatment provided by the SLP, family members and other communication partners can be trained by the SLP to provide opportunities for practice, encourage the use of strategies like AAC, and give feedback about performance in functional settings.
Dosage—refers to the frequency, intensity, and duration of service. Dosage may vary depending on individual's type and severity of disease, energy level, motivation, and degree of community support. Individuals with dysarthria may benefit from frequent and intense practice consistent with the principles of motor learning to enhance retention of speech skills (Bislick, Weir, Spencer, Kendall, & Yorkston, 2012; Kleim & Jones, 2008; Maas et al., 2008).
Timing—refers to when intervention is initiated relative to the diagnosis. Early initiation of treatment may be beneficial for learning or relearning motor patterns; however, improvements in comprehensibility using communication strategies are possible at any point. Timing for introducing prosthetic management and/or AAC may vary with the setting, the individual's preferences, and the severity and stage of disease.
Setting—refers to the location of treatment (e.g., home, community-based). Individuals may benefit from a naturalistic treatment environment that incorporates a variety of communication partners to facilitate generalization and carryover of skills.
This list of resources is not exhaustive and the inclusion of any specific resource does not imply endorsement from ASHA.
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Content for ASHA's Practice Portal is developed through a comprehensive process that includes multiple rounds of subject matter expert input and review. ASHA extends its gratitude to the following subject matter experts who were involved in the development of the Dysarthria in Adults page:
The recommended citation for this Practice Portal page is:
American Speech-Language-Hearing Association. (n.d.). Dysarthria in Adults. (Practice Portal). Retrieved month, day, year, from www.asha.org/Practice-Portal/Clinical-Topics/Dysarthria-in-Adults/.