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Dysarthria

Original Editor - Jacintha McGahan
Top Contributors - Jacintha McGahan, Uchechukwu Chukwuemeka, Kim Jackson, Vidya Acharya, Alexandra Stead and Nupur Smit Shah

Introduction

Dysarthria is a class of neurogenic speech disorders defined by abnormalities in the strength, speed, range, stability, tone, or accuracy of movements required for breathing, phonation, resonance, articulation, or prosodic speech production.[1] These movement impairments are the result of sensorimotor deficits such as paresis or paralysis, incoordination, involuntary movements, and abnormal muscle tone (either increased or decreased).[1] Dysarthria may have a detrimental impact on speech intelligibility, naturalness, or both. It is vital to acknowledge that people with dysarthria often retain normal cognitive abilities and intelligence. Dysarthria frequently coexists with other neurological illnesses, such as dysphagia, language abnormalities, and cognitive impairment, necessitating thorough multidisciplinary evaluation and treatment.[1]

The video below also summarises dysarthria

[2]

Relevant Anatomy

Speech Centre in the Brain

Dysarthria results from disturbances in neural pathways that affect speech and motor function.[1] Speech production needs intact upper motor neuron circuits, lower motor neurons, and coordinated operation across several brain areas.[3]

Upper Motor Neuron Pathways

The corticobulbar tract originates in the motor cortex and travels through the internal capsule, brainstem, and pons to innervate cranial nerve nuclei that control the speech musculature.[4] Because most speech activities are redundant due to bilateral corticobulbar innervation, unilateral upper motor neuron injuries usually result in milder dysarthria than bilateral damage.[1] Bilateral corticobulbar tract injury causes spastic dysarthria, increased muscular tone, and hyperreflexia.[5]

Lower Motor Neuron Pathways

Lower motor neurons send signals from brainstem motor nuclei to speech muscles via cranial nerves V, VII, IX, X, XI, and XII.[6] Lower motor neuron lesions cause flaccid dysarthria, defined by weakness, diminished muscle tone, and hyporeflexia.[6] Peripheral nerve injury to these cranial nerves reduces respiratory, laryngeal, velopharyngeal, and articulatory function.[6]

Subcortical and Cerebellar Systems

The basal ganglia regulate movement speed and force; malfunction results in hypokinetic or hyperkinetic dysarthria.[1] The cerebellum governs movement timing and rhythm via links to motor pathways; cerebellar injury results in ataxic dysarthria and incoordination.[4] Brainstem regions control phonation by integrating respiratory and laryngeal functions.[7]

Progressive Neurodegeneration

Neurodegenerative diseases cause broad dysfunction throughout interconnected motor networks, including the motor cortex, basal ganglia, brainstem, and cerebellum, resulting in complicated dysarthria patterns.[8]

Aetiology and Pathophysiology

Dysarthria is caused by nervous system injury that impairs motor control of speech-related muscles.[9] Neurological injury disrupts the brain circuits that control the complex movements of speech-producing tissues such as the face, lips, tongue, pharynx, and upper respiratory tract.[9] The specific pattern of dysarthria is determined by the location and nature of the neurological lesions.[10]

Dysarthria is caused by neurological disorders, which include:[1]

Incidence and Prevalence

The prevalence of dysarthria varies considerably depending on the underlying neurological condition. Recent epidemiological data indicate that dysarthria occurs across multiple neurological populations with significant functional impact.[10][11]

Stroke

Stroke represents the leading cause of acquired dysarthria in the adult population, with dysarthria occurring in approximately 25% to 40% of acute stroke survivors,[9] although estimates vary from 8% to 60% depending on stroke severity and assessment timing.[10]

Parkinson's Disease

Parkinson's disease results in dysarthria affecting approximately 70% to 100% of patients at some point during disease progression, with speech impairment increasing in prevalence as the condition advances.[1]

Multiple sclerosis

Multiple sclerosis demonstrates dysarthria in approximately 44.9% of patients, with considerable variability based on disease stage and duration.[11]

Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis frequently presents with dysarthria as an initial symptom in up to 30% of patients, with virtually all patients developing dysarthria in later disease stages.[1]

Clinical Presentation

Dysarthria types are classified according to the anatomical site of neurological injury and the pattern of motor speech dysfunction. Understanding the dysarthria type is critical for effectively tailoring intervention options, and the classifications are:[1][5]

Flaccid dysarthria

Flaccid dysarthria is caused by lower motor neuron dysfunction affecting the peripheral nervous system, characterised by weakness or paralysis of speech musculature. The hallmark features include imprecise consonant articulation, hypernasality, and reduced loudness.

Spastic dysarthria

This arises from bilateral upper motor neuron pathology, causing increased muscle tone and hyperactive reflexes alongside speech disturbance. Speech characteristics include imprecise consonants, slow speech rate, reduced loudness and a strained, strangled vocal quality.

Ataxic dysarthria

Ataxic dysarthria is characterised by cerebellar system dysfunction, which causes incoordination and affects speech production. Irregular articulatory breakdowns, slurred speech, and an irregular speech rhythm with varying volume and pitch are among the most noticeable characteristics.

Hypokinetic dysarthria

Hypokinetic dysarthria is caused by basal ganglia dysfunction, which is most typically seen in Parkinson's disease and other parkinsonian syndromes. Characteristic traits include a low or breathy voice, monotone speaking, difficulties commencing phonation, stuttering, imprecise articulation, limited facial expression, and facial and neck muscle rigidity.

Hyperkinetic dysarthria

Hyperkinetic dysarthria is likewise caused by basal ganglia dysfunction, but it is linked to involuntary movement abnormalities. Speech characteristics include slurred or sluggish speech, voice tremor, shortness of breath while speaking, weariness from extended speaking, and varying loudness.

Unilateral upper motor neuron (UUMN) dysarthria

This is triggered by unilateral lesions of the upper motor neuron pathways, and it often manifests as a milder form of speech impairment than spastic dysarthria.

Mixed dysarthria

Mixed dysarthria develops when injury affects numerous levels of the neurological system, resulting in characteristics of many dysarthria categories.

Undetermined dysarthria

Undetermined dysarthria refers to presentations that have dysarthria-like symptoms but do not clearly fall into current diagnostic groups.[10]

Click here for more overview on Dysarthria and diagnosis[12]

Differential Diagnosis

Accurate distinction among different neurogenic speech and language disorders is required for effective intervention planning. Dysarthria must be differentiated from an apraxia of speech, aphasia, and other speech-language disorders.

Some dysarthria types may have surface symptoms in common with apraxia of speech, complicating the diagnosis. A crucial distinguishing aspect is the presence or absence of weakness or spasticity.[13] Unless there is concurrent dysarthria, apraxia of speech does not cause muscle weakness or spasticity.[1] Speech apraxia is a problem with motor planning rather than execution.[14] Aphasia and dysarthria are separate neurological abnormalities. Aphasia impairs language understanding and expression in both spoken and written forms, while dysarthria affects the muscular execution of speaking solely; language formulation and understanding are unaffected.[10] Assessing written language helps differentiate these conditions.

Moreover, speech and language therapists (SLT) must take cultural and linguistic aspects into account when assessing speech patterns. Variations in accent and dialect ought never to be interpreted as pathological speech disorders.[10]

Diagnostic Procedures

A comprehensive assessment of dysarthria includes both detailed speech evaluation and a study of the speech motor system. Physiotherapists working in multidisciplinary settings could assist with initial screening and motor function assessment, but an SLT should provide the definitive diagnosis and comprehensive speech analysis.[10]

Also, non-speech oral motor examination analyses of structures and functions that facilitate speech production, including cranial nerve examination (CN V, VII, IX, X, XI, XII), muscle tone assessment during rest and non-speaking activities, and evaluation of oral motor movements, add positively to dysarthria diagnosis.[15]

In addition, formal assessment of dysarthria necessitates the use of established outcome measures that assess speech intelligibility, motor function, and functional communication abilities [16]. Some of the outcome measures utilised are:

  • PATA and PATAKA examinations asking patients to repeat bisyllabic statements as many times as they can manage under specific time limits. This provides objective measurements of articulation rate and motor control.[17]
  • The Boston Diagnostic Aphasia Examination includes repeated articulation of specific words, which is graded using preset standards.[18]
  • Also, the Cookie Theft Picture Description Task, a part of the Boston Aphasia Examination, could be used as a standalone. This challenges patients to describe a scenario, with grading based on the number of understandable words uttered, providing a functional assessment of communication effectiveness.[19]
  • The Assessment of the Intelligibility of Dysarthric Speech test entails recording and assessing standardised speech samples for intelligibility.[20]

Management

Current dysarthria management relies on evidence-based, multidisciplinary approaches that are customised to the patient's dysarthria type, underlying cause, and functional communication goals.[1] Speech and language therapists lead specific treatments, with physiotherapy providing respiratory and motor control training.[10]

Speech and Language Therapy Interventions

Speech and language therapists use a variety of therapeutic techniques, such as behavioural interventions aimed at speech production subsystems, compensatory measures that improve functional abilities, conversation partner training, and counselling.[21][22]

Recent randomised controlled trials have shown that communication-oriented group therapy for non-progressive dysarthria improves both functional speech and communicative involvement.[22] Also, non-speech oromotor exercises (NSOMEs), which include tongue and lip exercises, have been used for many years to manage dysarthria. Nevertheless, current evidence suggests that NSOMEs have limited efficacy in enhancing actual speech output outcomes.[23][24] The video below shows some visuals on oromotor exercise.

[25]

Respiratory and Aerodynamic Interventions

Dysarthria typically includes respiratory dysfunction that impairs breath support for speaking. Physiotherapists and speech-language therapists work together to implement respiratory interventions such as postural optimisation, preparatory breathing techniques, optimal breath grouping training, expiratory muscle strength exercises, inspiratory muscle strength training, maximal vowel prolongation exercises, and controlled exhalation exercises.[1]

Recent research supports the usefulness of respiratory muscle training in dysarthria therapy.[26] Stroke survivors who received combined inspiratory and expiratory respiratory muscle training showed significant improvements in respiratory muscle strength and dysarthria severity.[27]

Technology-Enhanced Interventions

Emerging evidence strongly supports technology-based approaches to dysarthria rehabilitation. Smartphone-based speech therapy apps have demonstrated significant efficacy in enhancing speech intelligibility, articulation, and quality of life in persons with post-stroke dysarthria.[28] Remote speech therapy delivery via telehealth platforms is effective for people with Parkinson's disease, improving quality of life and speech quality while putting less strain on patients than in-person treatment.[29] Artificial intelligence and machine learning techniques have emerged as promising tools for objective dysarthria assessment and severity categorisation, with the potential to improve diagnostic accuracy and reliability over traditional subjective assessments.[30][31]

Pharmacological and Neuromodulation Management

Dopaminergic medicines in Parkinson's disease may enhance speech when speech impairment is associated with disease motor symptoms. Recent systematic reviews suggest that repetitive transcranial magnetic stimulation (rTMS) may be beneficial for dysarthria in Parkinson's disease. However, more studies are needed.[32]

Augmentative and Alternative Communication

Augmentative and alternative communication (AAC) systems are critical communication tools for people suffering from severe dysarthria. High-tech AAC systems use speech-generating equipment with synthetic or digitised voice output, whereas low-tech choices include communication boards.[33][1]

Prognosis and Recovery

Recovery and improvement in dysarthria are determined by a variety of factors, including the natural history of the underlying illness, the timing and intensity of intervention, and individual prognostic factors.[10] [1] Dysarthria caused by nonprogressive illnesses such as stroke may recover spontaneously in the acute period, with systematic intervention improving functional outcomes.[9] Progressive neurodegenerative disorders often cause slow speech degradation, with management concentrating on maintaining communicative function and timely augmentative and alternative communication adoption.[34]

Summary

Dysarthria is a motor speech problem that necessitates proper diagnosis and tailored, evidence-based treatment. A multidisciplinary intervention that includes speech and language therapy, physiotherapy, and emerging technology can improve communication function and quality of life. Early intervention in nonprogressive conditions, as well as timely deployment of augmentative and alternative communication in progressive conditions, helps to maintain functional outcomes over time.

Resources

American Speech-Language-Hearing Association

Speech and Language Therapy-UK

References

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 Duffy JR. Motor Speech Disorders: Substrates, Differential Diagnosis, and Management. 4th ed. St. Louis: Elsevier; 2019.
  2. ↑ Theresa Richard-Medical SLP. What is Dysarthria and How to Manage It? Ways to Assess Dysarthria. Available from: http://www.youtube.com/watch?v=y-CU-t6dbw0[last accessed 29/08/2026]
  3. ↑ Fiorella ML, Ballini L, Lavermicocca V, Ragno MS, Restivo DA, Marchese-Ragona R. Dysphagia and Dysarthria in Neurodegenerative Diseases: A Multisystem Network Approach to Assessment and Management. Audiol Res. 2026;16(1):9.
  4. ↑ 4.0 4.1 Fiorella ML, Ballini L, Lavermicocca V, Ragno MS, Restivo DA, Marchese-Ragona R. Dysphagia and Dysarthria in Neurodegenerative Diseases: A Multisystem Network Approach to Assessment and Management. Audiol Res. 2026;16(1):9.
  5. ↑ 5.0 5.1 Zimmerman EE, Samuels MA, Kirshner HS, Misulis KE. Neurologic Localisation and Diagnosis: Differential Diagnosis by Complaint-Based Approach. 1st ed. St. Louis: Elsevier; 2022.
  6. ↑ 6.0 6.1 6.2 Patestas MA, Meyer AJ, Gartner LP. A Textbook of Neuroanatomy. 3rd ed. Hoboken: Wiley; 2024.
  7. ↑ Park J, Choi S, Takatoh J, Zhao S, Harrahill A, Han BX, et al. Brainstem control of vocalisation and its coordination with respiration. Science. 2024;383(6687):eadi8081.
  8. ↑ Ogawa K, Akimoto T, Hara M, Fujishiro M, Nakajima H. Clinical study of six patients with pure dysarthria and dysarthria-(Central) facial nerve palsy/isolated central facial nerve palsy caused by extracerebellar infarction. Neurol Clin Neurosci. 2024; 12: 100-107.
  9. ↑ 9.0 9.1 9.2 9.3 Lin LX, Yao SY, Chen Q, Du MQ, Kang XH, Jiang DY, et al. Stroke-associated dysarthria. Front. Neurol. 2025;16:1629640.
  10. ↑ 10.0 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 American Speech-Language-Hearing Association. Dysarthria in Adults. Available from: https://www.asha.org/practice-portal/clinical-topics/dysarthria-in-adults/ [accessed 26 August 2026].
  11. ↑ 11.0 11.1 Smyrni V, Giannopapas V, Kitsos DK, Stavrogianni K, Chasiotis AK, Papagiannopoulou G, et al. Prevalence of dysarthria in the multiple sclerosis population: A systematic review and meta-analysis. Mult Scler Relat Disord. 2025;98:106458.
  12. ↑ Louis Kroon. Dysarthria. Available from: http://www.youtube.com/watch?v=WzwMEOJtYQg[last accessed 30/08/2026]
  13. ↑ Allison KM, Cordella C, Iuzzini-Seigel J, Green JR. Differential Diagnosis of Apraxia of Speech in Children and Adults: A Scoping Review. J Speech Lang Hear Res. 2020;63(9):2952-2994.
  14. ↑ Mohamadi O. Childhood Apraxia of Speech: From the First Motor Planning and Execution to Video Modelling During the Home Quarantine Period. Int Arch Commun Disord. 2020; 3:015
  15. ↑ Clark HM, Solomon NP. Muscle tone and the speech-language pathologist: Definitions, neurophysiology, assessment, and interventions. Perspectives on Swallowing and Swallowing Disorders (Dysphagia). 2012 Mar;21(1):9-14.
  16. ↑ Lancheros M, Friedrichs D, Laganaro M. What Do Differences between Alternating and Sequential Diadochokinetic Tasks Tell Us about the Development of Oromotor Skills? An Insight from Childhood to Adulthood. Brain Sci. 2023;13(4):655.
  17. ↑ Boscato N, Hayakawa H, Iida T, Costa YM, Kothari SF, Kothari M, et al. Impact of oral motor task training on corticomotor pathways and diadochokinetic rates in young healthy participants. J Oral Rehabil. 2022; 49(9):924-934.
  18. ↑ Castro N, Hula WD, Ashaie SA. Defining aphasia: Content analysis of six aphasia diagnostic batteries. Cortex. 2023;166:19-32.
  19. ↑ Bunker LD, Berube SK, Neal V, Kelly L, Kelly C, Meier EL, et al. Discourse Measures From the Modern Cookie Theft Picture Description Are Sensitive to Mild Communication Deficits Not Captured by the Western Aphasia Battery-Revised Aphasia Quotient. Am J Speech Lang Pathol. 2025;34(3):1100-1120.
  20. ↑ Mitchell C, El Kouaissi S, Duncan-Zaleski M, Bowen A, Conroy P, Whelan BM, et al. How do we measure dysarthria after stroke? A systematic review to guide the core outcome set for dysarthria. BMJ Open. 2025 May 23;15(5):e099662.
  21. ↑ Campbell P, Rooney S, Nicoll A, Brady MC, Smith CH, Deane KHO, et al. Speech and language therapy interventions for speech problems in Parkinson's disease. Cochrane Database Syst Rev. 2022; 2022(6): CD015009.
  22. ↑ 22.0 22.1 Masoud V, Baumgaertner A. Communication-oriented group therapy for non-progressive dysarthria: A randomised controlled trial in an inpatient setting. Int J Speech Lang Pathol. 2025; 27(4):589-604.
  23. ↑ Mackenzie C, Muir M, Allen C, Jensen A. Non-speech oro-motor exercises in post-stroke dysarthria intervention: a randomised feasibility trial. Int J Lang Commun Disord. 2014; 49(5):602-17.
  24. ↑ Weismer G. Oromotor Nonverbal Performance and Speech Motor Control: Theory and Review of Empirical Evidence. Brain Sciences. 2023; 13(5):768.
  25. ↑ Mister Clay. Video Model: oral motor exercises for speech therapy. Available from: http://www.youtube.com/watch?v=WgXwVlEi2JY[last accessed 29/08/2026]
  26. ↑ Liaw MY, Hsu CH, Leong CP, Liao CY, Wang LY, Lu CH, et al. Respiratory muscle training in stroke patients with respiratory muscle weakness, dysphagia, and dysarthria - a prospective randomised trial. Medicine (Baltimore). 2020;99(10):e19337. Erratum in: Medicine (Baltimore). 2020;99(17):e20194.
  27. ↑ Zhang YS, Zhang K, Huang L, Wei JS, Bi ZT, Haio JH, et al. The effects of respiratory muscle training on respiratory function and functional capacity in patients with early stroke: a meta-analysis. Eur Rev Aging Phys. 2024; 21(4).
  28. ↑ Kim Y, Kim M, Kim J, Song TJ. Smartphone-Based Speech Therapy for Poststroke Dysarthria: Pilot Randomised Controlled Trial Evaluating Efficacy and Feasibility. J Med Internet Res. 2024; 26:e56417.
  29. ↑ Maas JJL, de Vries NM, IntHout J, Bloem BR, Kalf JG. Effectiveness of remotely delivered speech therapy in persons with Parkinson's disease - a randomised controlled trial. EClinicalMedicine. 2024;76:102823.
  30. ↑ Merler M, Agurto C, Peller J, Roitberg E, Taitz A, Trevisan MA, et al. Clinical assessment and interpretation of dysarthria in ALS using attention-based deep learning AI models. NPJ Digit Med. 2025; 8(1):260.
  31. ↑ Remya MS, Ishwar P, Nedungadi P. A Hybrid Cross-Attentive CNN-BiLSTM-Transformer Network for Dysarthria Severity Classification. Sci Rep. 2025;15(1):42080.
  32. ↑ Chen K, Zhou S, Lu S, Qin Y, Li X, Li Y, et al. A systematic review of the efficacy of repetitive transcranial magnetic stimulation in treating dysarthria in patients with Parkinson's disease. Front. Aging Neurosci. 2025; 17:1501640.
  33. ↑ Elsahar Y, Hu S, Bouazza-Marouf K, Kerr D, Mansor A. Augmentative and Alternative Communication (AAC) Advances: A Review of Configurations for Individuals with a Speech Disability. Sensors (Basel). 2019;19(8):1911.
  34. ↑ Rong P, Heidrick L. An interpretable, clinically grounded framework for digital speech biomarker development in neurodegenerative diseases. Front. Digit. Health. 2026; 8:1794169.
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