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Dysarthria is a condition where a person may have slurred speech and difficulty speaking due to weak muscles or damaged nerves in the diaphragm, lips, tongue, or vocal cords. It may begin developing in the womb or shortly after birth, can be caused by other conditions such as cerebral palsy or muscular dystrophy, or can be found in adults after a stroke, tumors, or MS.

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As you get to know more about the field of speech-language pathology you'll increasingly realize why SLPs are required to earn at least a master's degree. This stuff is serious - and there's nothing easy about it.

In 2016 the National Institute on Deafness and Other Communication Disorders reported that 7.7% of American children have been diagnosed with a speech or swallowing disorder. That comes out to nearly one in 12 children, and gets even bigger if you factor in adults.

Whether rooted in psycho-speech behavioral issues, muscular disorders, or brain damage, nearly all the diagnoses SLPs make fall within just 10 common categories...

Types of Speech Disorders & Impediments

Apraxia of Speech (AOS)

Apraxia of Speech (AOS) happens when the neural pathway between the brain and a person's speech function (speech muscles) is lost or obscured. The person knows what they want to say - they can even write what they want to say on paper - however the brain is unable to send the correct messages so that speech muscles can articulate what they want to say, even though the speech muscles themselves work just fine. Many SLPs specialize in the treatment of Apraxia .

There are different levels of severity of AOS, ranging from mostly functional, to speech that is incoherent. And right now we know for certain it can be caused by brain damage, such as in an adult who has a stroke. This is called Acquired AOS.

However the scientific and medical community has been unable to detect brain damage - or even differences - in children who are born with this disorder, making the causes of Childhood AOS somewhat of a mystery. There is often a correlation present, with close family members suffering from learning or communication disorders, suggesting there may be a genetic link.

Mild cases might be harder to diagnose, especially in children where multiple unknown speech disorders may be present. Symptoms of mild forms of AOS are shared by a range of different speech disorders, and include mispronunciation of words and irregularities in tone, rhythm, or emphasis (prosody).

Severe cases are more easily diagnosed, with symptoms including inability to articulate words, groping for sound positions, off-target movements that distort sounds, and inconsistency in pronunciation.

Stuttering - Stammering

Stuttering, also referred to as stammering, is so common that everyone knows what it sounds like and can easily recognize it. Everyone has probably had moments of stuttering at least once in their life. The National Institute on Deafness and Other Communication Disorders estimates that three million Americans stutter, and reports that of the up-to-10-percent of children who do stutter, three-quarters of them will outgrow it. It should not be confused with cluttering.

Most people don't know that stuttering can also include non-verbal involuntary or semi-voluntary actions like blinking or abdominal tensing (tics). Speech language pathologists are trained to look for all the symptoms of stuttering, especially the non-verbal ones, and that is why an SLP is qualified to make a stuttering diagnosis.

The earliest this fluency disorder can become apparent is when a child is learning to talk. It may also surface later during childhood. Rarely if ever has it developed in adults, although many adults have kept a stutter from childhood.

Stuttering only becomes a problem when it has an impact on daily activities, or when it causes concern to parents or the child suffering from it. In some people, a stutter is triggered by certain events like talking on the phone. When people start to avoid specific activities so as not to trigger their stutter, this is a sure sign that the stutter has reached the level of a speech disorder.

The causes of stuttering are mostly a mystery. There is a correlation with family history indicating a genetic link. Another theory is that a stutter is a form of involuntary or semi-voluntary tic. Most studies of stuttering agree there are many factors involved.

Because the causes of stuttering are largely unknown the treatments are mostly behavioral. Triggers often precede a stuttering episode, and SLPs can help people recognize and cope with these triggers ahead of time.

Dysarthria

Dysarthria is a symptom of nerve or muscle damage. It manifests itself as slurred speech, slowed speech, limited tongue, jaw, or lip movement, abnormal rhythm and pitch when speaking, changes in voice quality, difficulty articulating, labored speech, and other related symptoms.

It is caused by muscle damage, or nerve damage to the muscles involved in the process of speaking such as the diaphragm, lips, tongue, and vocal chords.

Because it is a symptom of nerve and/or muscle damage it can be caused by a wide range of phenomena that affect people of all ages. This can start during development in the womb or shortly after birth as a result of conditions like muscular dystrophy and cerebral palsy. In adults some of the most common causes of dysarthria are stroke, tumors, and MS.

As an SLP there's not much you can do about muscle damage, and even less you can do about nerve damage. So for treatments you'll focus on managing the dysarthria symptoms through behavior changes. This can include helping a person slow down when they're speaking, breath training, and exercising the muscles that are involved in speech.

Lisping

A lay term, lisping can be recognized by anyone and is very common.

Speech language pathologists provide an extra level of expertise when treating patients with lisping disorders . They can make sure that a lisp is not being confused with another type of disorder such as apraxia, aphasia, impaired development of expressive language, or a speech impediment caused by hearing loss.

SLPs are also important in distinguishing between the five different types of lisps. Most laypersons can usually pick out the most common type, the interdental/dentalised lisp. This is when a speaker makes a "th" sound when trying to make the "s" sound. It is caused by the tongue reaching past or touching the front teeth.

Because lisps are functional speech disorders, SLPs can play a huge role in correcting these with results often being a complete elimination of the lisp. Treatment is particularly effective when implemented early, although adults can also benefit.

Experts recommend professional SLP intervention if a child has reached the age of four and still has an interdental/dentalised lisp. SLP intervention is recommended as soon as possible for all other types of lisps. Treatment includes pronunciation and annunciation coaching, re-teaching how a sound or word is supposed to be pronounced, practice in front of a mirror, and speech-muscle strengthening that can be as simple as drinking out of a straw.

Lisps usually develop during childhood, and children will often outgrow an interdental or dentalised lisp on their own.

Spasmodic Dysphonia

Spasmodic Dysphonia (SD) is a chronic long-term disorder that affects the voice. It is characterized by a spasming of the vocal chords when a person attempts to speak and results in a voice that can be described as shaky, hoarse, groaning, tight, or jittery. It can cause the emphasis of speech to vary considerably. Many SLPs specialize in the treatment of Spasmodic Dysphonia.

SLPs will most often encounter this disorder in adults, with the first symptoms usually occurring between the ages of 30 and 50. It can be caused by a range of things mostly related to aging, such as nervous system changes and muscle tone disorders.

It's difficult to isolate vocal chord spasms as being responsible for a shaky or trembly voice, so diagnosing SD is a team effort for SLPs that also involves an ear, nose, and throat doctor (otolaryngologist) and a neurologist.

After diagnosis SLPs can have a role helping with coaching to optimize voice production, and can be particularly effective in mild cases of SD. This especially includes working on breathing control techniques to maintain a stead flow of air from the lungs.

Cluttering

Have you ever heard people talking about how they are smart but also nervous in large groups of people, and then self-diagnose themselves as having Asperger's? You might have heard a similar lay diagnosis for cluttering. This is an indication of how common this disorder is as well as how crucial SLPs are in making a proper cluttering diagnosis.

A fluency disorder, cluttering is characterized by a person's speech being too rapid, too jerky, or both. To qualify as cluttering, the person's speech must also have excessive amounts of "well," "um," "like," "hmm," or "so," (speech disfluencies), an excessive exclusion or collapsing of syllables, or abnormal syllable stresses or rhythms.

The first symptoms of this disorder appear in childhood. Like other fluency disorders, SLPs can have a huge impact on improving or eliminating cluttering. Intervention is most effective early on in life, however adults can also benefit from working with an SLP.

Treatment methods include delayed audio feedback, syllable articulation and annunciation coaching, playing games that involve rapid word retrieval, practicing pausing and phrasing in sentences, and increasing a clutterer's own self-awareness of what they are doing, such as through video recording.

Muteness - Selective Mutism

There are different kinds of mutism, and here we are talking about selective mutism. This used to be called elective mutism to emphasize its difference from disorders that caused mutism through damage to, or irregularities in, the speech process.

Selective mutism is when a person does not speak in some or most situations, however that person is physically capable of speaking. It most often occurs in children, and is commonly exemplified by a child speaking at home but not at school.

Selective mutism is related to psychology. It appears in children who are very shy, who have an anxiety disorder, or who are going through a period of social withdrawal or isolation. These psychological factors have their own origins and should be dealt with through counseling or another type of psychological intervention.

Diagnosing selective mutism involves a team of professionals including SLPs, pediatricians, psychologists, and psychiatrists. SLPs play an important role in this process because there are speech language disorders that can have the same effect as selective muteness - stuttering, aphasia, apraxia of speech, or dysarthria - and it's important to eliminate these as possibilities.

And just because selective mutism is primarily a psychological phenomenon, that doesn't mean SLPs can't do anything. Quite the contrary.

SLPs can play an important role through working with selectively mute children to create a tailored behavioral treatment program and address speech and language disorders - such as stuttering - that may be contributing to psychological factors like excessive shyness.

Aphasia

The National Institute on Neurological Disorders and Stroke estimates that one million Americans have some form of aphasia.

Aphasia is a communication disorder caused by damage to the brain's language capabilities. Aphasia differs from apraxia of speech and dysarthria in that it solely pertains to the brain's speech and language center.

As such anyone can suffer from aphasia because brain damage can be caused by a number of factors. However SLPs are most likely to encounter aphasia in adults, especially those who have had a stroke. Other common causes of aphasia are brain tumors, traumatic brain injuries, and degenerative brain diseases.

In addition to neurologists, speech language pathologists have an important role in diagnosing aphasia. As an SLP you'll assess factors such as a person's reading and writing, functional communication, auditory comprehension, and verbal expression.

Because the field of brain damage repair is in its infancy, your role as an SLP is to help with coping methods and strategies. The brain is a remarkable organ, and sometimes when one part gets damaged another part will try and pick up the slack. That means you can also try working on activities to improve the language skills that have been affected by the brain damage - sometimes this can have an effect.

Speech Delay - Alalia

A speech delay, known to professionals as alalia, refers to the phenomenon when a child is not making normal attempts to verbally communicate. There can be a number of factors causing this to happen, and that's why it's critical for a speech language pathologist to be involved.

The are many potential reasons why a child would not be using age-appropriate communication. These can range anywhere from the child being a "late bloomer" - the child just takes a bit longer than average to speak - to the child having brain damage. It is the role of an SLP to go through a process of elimination, evaluating each possibility that could cause a speech delay, until an explanation is found.

Approaching a child with a speech delay starts by distinguishing among the two main categories an SLP will evaluate: speech and language.

Speech has a lot to do with the organs of speech - the tongue, mouth, and vocal chords - as well as the muscles and nerves that connect them with the brain. Disorders like apraxia of speech and dysarthria are two examples that affect the nerve connections and organs of speech. Other examples in this category could include a cleft palette or even hearing loss.

The other major category SLPs will evaluate is language. This relates more to the brain and can be affected by brain damage or developmental disorders like autism. There are many different types of brain damage that each manifest themselves differently, as well as developmental disorders, and the SLP will make evaluations for everything.

Once the cause or causes for the speech delay are identified then the SLP can go to work treating and monitoring the child. For many speech-language disorders that cause a speech delay, early intervention and evaluation by an SLP can make a huge difference.

Issues Related to Autism

While the autism spectrum itself isn't a speech disorder, it makes this list because the two go hand-in-hand more often than not.

The Centers for Disease Control and Prevention (CDC) reports that one out of every 68 children in our country have an autism spectrum disorder. And by definition, all children who have autism also have social communication problems.

Speech-language pathologists are often a critical voice on a team of professionals - also including pediatricians, occupational therapists, neurologists, developmental specialists, and physical therapists - who make an autism spectrum diagnosis.

In fact, the American Speech-Language Hearing Association reports that problems with communication are the first detectable signs of autism. That is why language disorders - specifically disordered verbal and nonverbal communication - are one of the primary diagnostic criteria for autism.

So what kinds of SLP disorders are you likely to encounter with someone on the autism spectrum?

A big one is apraxia of speech. A study that came out of Penn State in 2015 found that 64 percent of children who were diagnosed with autism also had childhood apraxia of speech.

A study published in the National Center for Biotechnology Information out of Harvard Medical School cites muteness, involuntarily repetition of another person's vocalizations (echolalia), and unusual inflection and tone (prosody) as also being characteristics of people on the autism spectrum, especially children. It points out that in general language abilities are impaired or delayed at an early age.

This basic primer on the most common speech disorders offers little more than an interesting glimpse into the kind of issues that SLPs work with patients to resolve. But even knowing everything there is to know about communication science and speech disorders doesn't tell the whole story of what this profession is all about. With every client in every therapy session, the goal is always to have the folks that come to you for help leave with a little more confidence than when they walked in the door that day. As a trusted SLP, you will build on those gains with every session, helping clients experience the joy and freedom that comes with the ability to express themselves freely. At the end of the day, this is what being an SLP is all about.

Ready to make a difference in speech pathology? Learn how to become a Speech-Language Pathologist today

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10 Most Common Speech Impediments & Language Disorders

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As you dive into speech-language pathology, you learn about all types of speech disorders. Here are the top 10 most common language disorders

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Dysarthria has a wide range of symptoms, from slurred or slow speech to rapid, incohesive speech. People with dysarthria may be monotone. They may struggle with speaking too quietly or loudly, and even may speak with uneven cadence and volume. All of this comes from the inability to move the tongue and facial muscles.

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Overview

Dysarthria occurs when the muscles you use for speech are weak or you have difficulty controlling them. Dysarthria often causes slurred or slow speech that can be difficult to understand.

Common causes of dysarthria include nervous system disorders and conditions that cause facial paralysis or tongue or throat muscle weakness. Certain medications also can cause dysarthria.

Treating the underlying cause of your dysarthria may improve your speech. You may also need speech therapy. For dysarthria caused by prescription medications, changing or discontinuing the medications may help.

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Symptoms

Signs and symptoms of dysarthria vary, depending on the underlying cause and the type of dysarthria. They may include:

Slurred speech

Slow speech

Inability to speak louder than a whisper or speaking too loudly

Rapid speech that is difficult to understand

Nasal, raspy or strained voice

Uneven or abnormal speech rhythm

Uneven speech volume

Monotone speech

Difficulty moving your tongue or facial muscles

When to see a doctor

Dysarthria can be a sign of a serious condition. See your doctor if you have sudden or unexplained changes in your ability to speak.

Causes

In dysarthria, you may have difficulty moving the muscles in your mouth, face or upper respiratory system that control speech. Conditions that may lead to dysarthria include:

1. Amyotrophic lateral sclerosis (ALS, or Lou Gehrig's disease)

2. Brain injury

3. Brain tumor

4. Cerebral palsy

5. Guillain-Barre syndrome

6. Head injury

7. Huntington's disease

8. Lyme disease

9. Multiple sclerosis

10. Muscular dystrophy

11. Myasthenia gravis

12. Parkinson's disease

13. Stroke

14. Wilson's disease

Some medications, such as certain sedatives and seizure drugs, also can cause dysarthria.

Complications

Because of the communication problems dysarthria causes, complications can include:

Social difficulty. Communication problems may affect your relationships with family and friends and make social situations challenging.

Depression. In some people, dysarthria may lead to social isolation and depression.

Show references

1. Daroff RB, et al., eds. Bradley's Neurology in Clinical Practice. 7th ed. Elsevier; 2016. https://www.clinicalkey.com. Accessed April 10, 2020.

2. Dysarthria. American Speech-Language-Hearing Association. https://www.asha.org/public/speech/disorders/dysarthria/. Accessed April 6, 2020.

3. Maitin IB, et al., eds. Current Diagnosis & Treatment: Physical Medicine & Rehabilitation. McGraw-Hill Education; 2020. https://accessmedicine.mhmedical.com. Accessed April 10, 2020.

4. Dysarthria in adults. American Speech-Language-Hearing Association. https://www.asha.org/PRPPrintTemplate.aspx?folderid=8589943481. Accessed April 6, 2020.

5. Drugs that cause dysarthria. IBM Micromedex. https://www.micromedexsolutions.com. Accessed April 10, 2020.

6. Lirani-Silva C, et al. Dysarthria and quality of life in neurologically healthy elderly and patients with Parkinson's disease. CoDAS. 2015; doi:10.1590/2317-1782/20152014083.

7. Signs and symptoms of untreated Lyme disease. Centers for Disease Control and Prevention. https://www.cdc.gov/lyme/signs_symptoms/index.html. Accessed April 6, 2020.

8. Neurological diagnostic tests and procedures fact sheet. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Neurological-Diagnostic-Tests-and-Procedures-Fact. Accessed April 6, 2020.

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This condition affects muscles used for speaking. Speech therapy and treating the underlying cause may improve speech.

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County Durham & Darlington NHS Foundation Trust

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A person with dysarthria may be suffering from damage to the nerves or muscles in one's face and/or throat. Those damages may stem from injuries, illnesses or neuromuscular conditions. Illnesses like MS, Parkinson's, Dementia, Lyme disease, ALS, or a stroke may cause dysarthria later on in life. Some medications may cause symptoms of dysarthria as well.

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What is dysarthria?

Dysarthria (pronounced "dis-AR-three-uh") is a motor speech disorder that makes it difficult to form and pronounce words. Motor speech disorders occur when damage to your nervous system prevents you from fully controlling parts of your body that control speech, like your tongue, voice box (larynx) and jaw. Dysarthria makes it challenging to speak so that others can understand you.

Dysarthria can be developmental or acquired:

Developmental dysarthria happens due to brain damage during fetal development or at birth. For example, cerebral palsy can cause dysarthria. Children tend to have developmental dysarthria.

Acquired dysarthria happens as a result of brain damage later in life. For example, a stroke, a brain tumor or Parkinson's disease can lead to dysarthria. Adults tend to have acquired dysarthria.

People with dysarthria understand language. They know what they want to say and how to say it. It's just that muscle weakness makes speaking difficult.

What are the types of dysarthria?

There are six categories of dysarthria. They're grouped based on the specific part of your nervous system affected. Dysarthria may result from damage to various parts of your nervous system, including your brain and spinal cord (central nervous system) and the network of nerves that carry signals throughout your body ( peripheral nervous system).

Flaccid dysarthria results from damage to the lower motor neurons. The lower motor neurons are part of your peripheral nervous system. With flaccid dysarthria, your speaking may sound breathy and nasal.

Spastic dysarthria results from damage to the upper neurons on one or both sides of your brain. The upper neurons are part of your central nervous system. Your speaking may sound strained or harsh.

Ataxic dysarthria results from damage to the part of your brain called the cerebellum. Your cerebellum helps coordinate muscle movement. You may have trouble pronouncing vowels and consonants, and you may have difficulty placing emphasis on the right parts of a word when you're speaking.

Hypokinetic dysarthria results from damage to the part of your brain called the basal ganglia. The basal ganglia is a structure inside your brain that helps your muscles move. Hypokinetic dysarthria is associated with slow ("hypo"), monotone, rigid-sounding speech.

Hyperkinetic dysarthria also results from damage to your basal ganglia. It's associated with fast ("hyper") sounding and often unpredictable speech.

Mixed dysarthria includes a mix of two or more of the other five types. It's the most common type of dysarthria.

How common is dysarthria?

Dysarthria is more common in people with certain neurological conditions, such as:

Amyotrophic lateral sclerosis (ALS): Up to 30% of people with ALS (Lou Gehrig's disease) have dysarthria.

Multiple sclerosis (MS): Around 25% to 50% of people with MS get dysarthria at some point.

Parkinson's disease: Dysarthria affects 70% to 100% of people with Parkinson's disease.

Stroke: About 8% to 60% of people with stroke have dysarthria.

Traumatic brain injury: Some 10% to 65% of people with traumatic brain injury have dysarthria.

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Dysarthria (Slurred Speech): Symptoms, Causes & Treatment

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Dysarthria makes it difficult to control and coordinate your speaking muscles. Learn more about causes and common treatments, like speech therapy.

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Treatment and Implementation in the Classroom

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Treatment and Implementation in the Classroom

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Dysarthria is not a curable condition, but it can be treated to better help the person retain their speech. Speech-language pathologists and physicians work in tandem to assess and execute treatment for the person with dysarthria. Treatment can come from rehabilitating the muscles in the face, using effective communication strategies, and possibly even surgery. The most important part of working with a student with dysarthria is making sure you have an effective communication method with them. Do not single them out and speak to them like they can't hear you. The student's disability does not prevent them from hearing you, speak to them like any other student. It's frustrating to not be able to get a point you're trying to make understood, so being patient is also key as you may have trouble in the beginning trying to understand them. A student with this disability would help other students learn good and effective communication methods with not only the student but each other. This would also teach them empathy and kindness.

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Continuing Education Activity

Dysarthria is a neuromotor disorder that results from abnormalities in speed, strength, accuracy, range, tone, or duration required for speech control. Decreased speech intelligibility characterizes the disorder. The content of the spoken language remains intact, so the patient can write and comprehend spoken and written language. Dysarthria is a motor speech disorder seen with many neurological causes. This activity reviews the main subtypes, evaluation, management of dysarthria, and the role of the interprofessional team in evaluating and improving patient care.

Objectives:

Identify the different subtypes of dysarthria.

Determine the etiology of dysarthria in common neurological disorders.

Implement a comprehensive initial history, physical, and speech evaluation for patients with dysarthria.

Apply best practices for the interprofessional team to achieve the overall goals of holistic individualized treatment to facilitate communication, decrease isolation, and improve patient outcomes.

Access free multiple choice questions on this topic.
Introduction

Dysarthria is a neuromotor disorder that results from abnormalities in speed, strength, accuracy, range, tone, or duration required for speech control.[1] Decreased speech intelligibility characterizes the disorder. The content of the spoken language remains intact, so the patient can write and comprehend spoken and written language. Anarthria is the severe form in which there is a complete loss of motor speech production.[2]

Speech is a complex neuromuscular phenomenon achieved through the smooth coordination of 5 subsystems: respiration, phonation, resonance, articulation, and prosody.[3] Muscular dysfunction affecting any of these subsystems causes impairments in audibility, naturalness, intelligibility, and communication efficiency. Dysarthria profoundly affects the patient and their families, as communication is integrally related to expressing personality and social relationships. Since there is overlap in the functioning of the muscles, feeding and swallowing difficulty in patients with dysarthria is common.

Etiology

Various neurological disorders can cause dysarthria. Dysarthria can arise from disorders at various locations of the neuroaxis, including the cerebral cortex, basal ganglia, cerebellum, cranial nerve nuclei, or peripheral nerves, and from a primary motor disorder of the tongue, larynx, and pharynx.

Mayo Clinic Classification (commonly used - groups dysarthria based on the location)[4]

Etiopathological Causes

1. Infections: Creutzfeldt-Jakob disease, acquired immune deficiency disease.

2. Vascular disorder: Ischemic and hemorrhagic strokes, arterio-venous malformations.

3. Neoplasm: Primary and metastatic brain tumors.

4. Demyelinating: Multiple sclerosis, Guillain-Barre disease.

5. Degenerative: PD, progressive supra nuclear palsy, corticobasal degeneration, multiple system atrophy, Huntington disease (HD), ataxia telangiectasia.

6. Trauma: TBI, chronic traumatic encephalopathy, cerebral palsy.

7. Toxic: Heavy metal poisoning (Minamata disease due to methylmercury poisoning can cause dysarthria), alcohol, drugs

8. Genetic: Sensory ataxic neuropathy, dysarthria, and ophthalmoparesis (SANDO) due to a mutation in the gene encoding the mitochondrial DNA polymerase gamma enzyme (POLG1)[5][6]

In addition to the neurological causes, nonneurological causes, such as cleft lip or palate and laryngeal tumors, also cause difficulty with articulation. However, the condition is not termed dysarthria if it stems from nonneurological causes.

Epidemiology

The exact incidence of dysarthria is not known, and incidence varies based on the underlying cause. About 90% of patients with PD develop dysarthria during the illness. In ALS patients, dysarthria may predate limb weakness by about 3 to 5 years; dysarthria affects about 70% of patients with limb weakness.[7][8]

In one study evaluating stroke patients, 28% had both aphasia and dysarthria, and 24% had dysarthria only. In a study of children with neuromuscular diseases, the prevalence of dysarthria was 31.5%.[9] It is estimated that 10 to 60% of patients with TBI have dysarthria.[10]

Pathophysiology

The motor control of speech occurs at multiple levels. The cranial nerve nuclei receive cortical supply through the corticobulbar tract. All other cranial nerves are innervated bilaterally except for the lower face, which receives contralateral innervation. The facial nerve terminates in 5 branches; the branches that contribute to the muscles of speech are the buccal, mandibular, and, to an extent, cervical. The glossopharyngeal nerve (IX), through the stylopharyngeal nerve, innervates the stylopharyngeus muscle and, through the pharyngeal branches, innervates the muscles of the pharynx.[11]

Through the pharyngeal branches, the vagus nerve innervates the pharyngeal muscles, which elevate the palate and cause pharyngeal constriction. The glossopharyngeal nerve provides a sensory supply to the stylopharyngeus, which elevates the pharynx during speech. The cricothyroid muscle supplied by the vagus' superior laryngeal branch is the vocal cords' chief tensor. The recurrent laryngeal nerve separates the vocal cords and opens the glottis through the posterior cricoarytenoids, closes the glottis through lateral cricoarytenoids, and relaxes the vocal cords through the vocalis.

Hypoglossal nerve nuclei originating in the medulla provide motor branches to the tongue, supplying the intrinsic and extrinsic muscles (except the palatoglossus).

Suprahyoid muscles: These influence tongue movements by altering the position of the hyoid bone.

1. C1 fibers supply the geniohyoid muscle.

2. The trigeminal nerve supplies the mylohyoid muscle and the anterior belly of the digastric muscle.

3. The facial nerve supplies the stylohyoid muscle and posterior belly of the digastric muscle.

In the neuromuscular junction, acetylcholine produced in the presynaptic nerve terminal binds to receptors, ultimately creating an endplate potential strong enough to propagate action potential over the surface of the skeletal muscle membrane, resulting in muscle contraction. In myasthenia gravis, various autoantibodies interrupt these processes resulting in dysarthria and other symptoms.[12]

History and Physical

Multiple neurological conditions cause dysarthria, so the natural course and clinical features can differ. The presentation can be acute in patients with acute ischemic stroke, whereas it can be delayed in neurodegenerative diseases like ALS.

Based on the Mayo classification, there are salient features of dysarthria[13] described below:

Flaccid: Speech is slow, with hypernasality and breathy vocal quality. One of the most common examples in clinical practice is idiopathic peripheral facial paralysis, in which the patient presents with facial paralysis and drooling. Another common cause is Guillain-Barre syndrome.

Spastic: Speech is harsh, with low pitch and constant errors. Speech evaluation shows hypernasality, reduced intelligibility, palatal elevation, and slow speech rate. Patients have signs of pseudobulbar palsy with dysphagia, hyperactive jaw jerk, and pseudobulbar affect. Patients with dysarthria-clumsy hand syndrome are noted to have facial weakness, dysarthria, and extremity dysmetria.[14]

Hypokinetic dysarthria: This is seen in PD due to the loss of dopaminergic neurons. Speech is monotone and poorly articulated and tends to be quiet. Delays in speech initiation mixed with rushing of words can be seen. Other characteristic signs, such as masked facial features, resting tremors, cogwheeling, and festinating gait, can be observed at the examination.

Hyperkinetic dysarthria: This is seen with basal ganglia lesions and associated hyperkinetic movement disorders, such as HD. Speech is harsh, with variation in loudness and rate of speech. There are occasional stoppages while speaking.

Ataxic dysarthria: This is commonly seen with disorders of the cerebellum or its connections. Speech has a "scanning" quality or irregular rhythm with the explosion of syllables. Prosody is impaired, with each syllable being pronounced slowly, and there is a pause after every syllable. There is decreased motor coordination manifested by axial and appendicular ataxia depending on the part of the cerebellum affected.

Mixed dysarthria: Two or more central nervous system components are affected in this type. This can be seen with ALS and multiple sclerosis. Speech is slow, prosody is disrupted, voice is strained, and there is marked hypernasality.

Evaluation

A thorough history and a detailed physical examination are crucial in evaluating patients presenting with dysarthria. A comprehensive initial speech evaluation is comprised of (1) history, (2) oral motor/speech mechanism exam, (3) screening of subsystems (respiration, phonation, articulation, resonance, and prosody), (4) perceptual assessment, and (5) intelligibility evaluation.

The water glass manometer test provides a gross assessment of pressure-generating capabilities for speech production. The patient must blow into a water-filled drinking glass with the straw secured at a certain depth inside the glass. If the patient can maintain a stream of bubbles for 5 seconds, breath support is adequate for most speech purposes. To be valid, the patient must maintain velopharyngeal closure and a tight lip seal around the straw.[15]

Perpetual assessment of speech helps observe the function of all speech subsets. This assessment provides insight into deficits and serves as a comparison tool. Passages such as "my grandfather" and "caterpillar passage" help assess perceptual speech.[16][17] These passages help evaluate the speech repertoire, examine the subsystems of speech, contemporary vocabulary, and simple syntax, and assess polysyllabic word form.

The Caterpillar Passage

"Do you like amusement parks? Well, I sure do. To amuse myself, I went twice last spring. My most MEMORABLE moment was riding on the Caterpillar, which is a gigantic roller coaster high above the ground. When I saw how high the Caterpillar rose into the bright blue sky, I knew it was for me. After waiting in line for thirty minutes, I made it to the front, where the man measured my height to see if I was tall enough. I gave the man my coins, asked for change, and jumped on the cart. Tick, tick, tick, the Caterpillar climbed slowly up the tracks. It went SO high I could see the parking lot. Boy, was I SCARED! I thought to myself, "There's no turning back now." People were so scared they screamed as we zoomed fast and faster along the tracks. As quickly as it started, the Caterpillar came to a stop. Unfortunately, it was time to pack the car and drive home. That night I dreamt of the wild ride on the Caterpillar. Taking a trip to the amusement park and riding on the Caterpillar was my MOST memorable moment ever!"

Speech Intelligibility Evaluation

Assessment of intelligibility in dysarthric speakers (AIDS), sentence intelligibility test (SIT), and word intelligibility test are used to assess speech intelligibility. AIDS is the most commonly used and comprises word and sentence tasks. The patient reads or imitates 50 unsystematically chosen words from 12 phonetically similar words for each word. In the sentence task, the patient reads or imitates two sentences each for 220 words. The sentences are chosen from a collection of 100 sentences of each length. The judge derives an intelligibility score based on the percentage of words transcribed accurately.

SIT is an improved Windows version of the sentence portion of AIDS. It examines the intelligibility of words and sentences and estimates efficiency by examining the rate of intelligible words per minute in sentences.

The onset and progression of dysarthria and associated neurological complaints, such as tremors, dysphagia, and gait instability, can provide clues for the diagnosis. A medication list review should include potential overdoses and exposure to toxins, such as alcohol and cocaine. Having the patient count from 1 to 100 can bring out respiratory muscle fatigue in myasthenia gravis. Counting numbers without interruption (1-30) is another bedside tool to assess respiratory status.[18] Sustaining an "ah" sound is a functional bedside test to assess laryngeal function.

Imaging techniques, such as computed tomography (CT) of the head and magnetic resonance imaging (MRI) of the brain, are helpful initial tools in evaluation. In patients suspected of neuromuscular junction disorders, electromyography (EMG) and nerve conduction studies (NCS) are indicated. CBC (complete blood count), basic metabolic profile (BMP), and urine drug screening are indicated based on history and pretest probability. If GBS is suspected, evaluation of pulmonary function (vital capacity and negative inspiratory force) is indicated.[18]

Speech Assessment Tools

Frenchay Dysarthria Assessment is one of the most commonly used commercially available tools for dysarthria assessment. It was initially devised in 1980 and revised in 2008. It incorporates a series of tasks used to identify the dysarthria subtype. Speech pathologists rate the patient's speech employing a 5-point scoring system on the following (a) reflexes, (b) respiration, (c) lips, (d)palate, (e) laryngeal, (f) tongue, and (g) intelligibility, (h) influencing factors.[19]

For subjective assessment, self-report questionnaires such as Living with Neurologically Based Speech Difficulties (Living with Dysarthria - LwD) may be used. The severity of dysarthria may not always correspond to the extent of perceived communicative difficulties.[20]

Treatment / Management

The overall goals of speech and language treatment are to facilitate the recovery of communication, to assist patients in developing strategies to compensate for communication disorders, and to counsel and educate people in the patient's environment on assistive communication supports to facilitate communication, decrease isolation, and meet the patient's wants and needs.

When developing the plan, it is essential to consider dysarthria's cause, severity, and underlying co-morbidities. Speech-language pathologists and physicians work together to formulate an individualized approach for the patient. Recent studies indicate that speech rehabilitation significantly improves speech in adults with stroke-related dysarthria and that interventions such as Lee Silverman Voice Treatment are effective for hypokinetic dysarthria in individuals with PD.[21][22]

Broadly, types of therapy could be grouped as follows:

Therapy targeting the speech-production subsystems

Environmental adaptations

Augmentative and alternative communication (AAC)

Medical/surgical interventions.

Targeting the Speech-Production Subsystems

Speech pathologists can target the five individual subcomponents that produce speech.

Lee Silverman Voice Treatment and Pitch Limiting Voice Treatment target phonation; the former is a program that improves loudness and intelligibility and has been widely studied in PD, while the latter increases vocal loudness without increasing pitch.[23][24] Articulation can be improved by increasing loudness, pausing, exaggerating articulation, and altering pitch variation. Respiratory muscle strength training supports breathing by altering posture to target respiration.

Communication Strategies

Providing feedback, clarifying, and encouraging are practical approaches for the partner. For the patient, setting up the conversation by gaining the partner's attention, slowing and repeating the phrases, and using nonverbal gestures, such as eye contact and facial expressions, are helpful strategies.

Speech supplementation, such as alphabet, syntactic, and topic, are helpful strategies. In alphabet supplementation, the speaker uses an alphabet board to identify the first letter of the spoken word. In topic supplementation, a phrase or cue word is uttered before speaking. Information about the grammar or word class is provided with each spoken word in the syntactic supplementation.

Behavioral communication intervention techniques such as biofeedback are shown to improve intelligibility. In stroke patients, biofeedback techniques increased the volume, decreased the speed, and improved the intelligibility.[25][26]

Environmental Adaptations

Setting up optimal environmental conditions to increase understandability includes ensuring a quiet conversation background, intimate seating, and face-to-face interaction.

Augmentative and Alternative Communication (AAC)

AAC may include low-tech aids, such as picture boards or pen and paper, or high-tech aids, such as smartphones, voice synthesizers, digital records, and speech-generating devices.[27]

Computer-based interventions offer an exciting step toward dysarthria management. Some examples are:

1. A mobile application for PD patients. It includes an assessment of the speech in addition to various other aspects of disease management[28]

2. Feedback and individual practice using computers were as effective as traditional therapy in patients with stable dysarthria[29]

3. Improvement in articulation and intelligibility was assessed in Virtual articulation therapy[30]

These small studies hold good promise for further expansion of computer-based interventions.

Medical/Surgical Interventions

Medical therapy should target the underlying neurological cause. In dysarthria arising from PD, therapy should focus on repleting dopaminergic therapy. The effects of PD drugs on dysarthria are variable. Subthalamic nucleus stimulation has some efficacy among surgical treatments, but speech intelligibility worsens, as with most surgical interventions in PD.[31] Improving spasticity in ALS with baclofen, tizanidine, and botulinum toxin type A has been tried.[8]

Laryngoplasty is an option if hoarseness is associated with recurrent laryngeal nerve palsy and does not improve with conservative management. Palatal lift improves resonance by surgically lifting the weak palate. Since the 2019 COVID pandemic, telehealth has become more relevant than ever. Telerehab (TR) is less expensive and equally effective in improving functional stroke outcomes, including speech, compared to traditional rehab.[32]

In another review of speech therapy administered via teletherapy in patients with PD, the patient reported overall increased satisfaction due to increased convenience and accessibility. Further research is needed, however, as the studies lacked double blinding, and there was heterogeneity in the protocol.[33]

Differential Diagnosis

The differential diagnoses for dysarthria include aphasia, apraxia of speech, and aphemia.

Apraxia, in general, is a dysfunction of a learned motor task. Patients need help initiating speech and transitioning between sounds; they speak through trial and error, and their errors are inconsistent. When patients are asked to repeat a phrase exactly, especially a polysyllabic word (eg, television), different errors are noted in each attempt. Isolated apraxia of speech is rare; it is usually seen with aphasia. Imaging might show lesions in the dominant insula and Broca's area.[34]

Aphasia is a language impairment. Depending on the location, language comprehension or production may be impaired. Patients also have difficulty writing and reading.[35]

Aphemia is a motor speech disorder resulting in near muteness. Patients have normal comprehension, reading, and writing.

Prognosis

Dysarthria is described as chronic if persistent for greater than 5 years. Dysarthia is considered stable in patients with nonprogressive etiologies.

Recovery also appears to be dependent on the etiology. One study evaluating dysarthria following stroke showed recovery in about half of the patients.[36] No estimates of the long-term prognosis of various diseases are available. However, from various anecdotal reports, it is evident that dysarthria is progressive in most neurodegenerative diseases.

Functional Communication Measures (FCMs) refer to rating scales used to define an individual's functional abilities. They are seven-point rating scales, ranging from least functional (Level 1) to most functional (Level 7). They help measure a patient's functional communication and swallowing abilities throughout speech-language pathology intervention.

Complications

Speech difficulty can have a significant impact on the patient's psychosocial life. Patients report stigmatization, changes in self-identity, and social and emotional disturbances due to post-stroke dysarthria. In children, behavioral problems and lack of access to education can lead to decreased future employment opportunities. Tools such as the Dysarthria Impact Profile (DIP) are available to assess the psychosocial impact of dysarthria.[37] Given the possibility of far-reaching effects, timely intervention should be the goal.

Dysarthria Impact Profile is used to assess the psychosocial impact of dysarthria.[38] Patients report how their condition hinders them in multiple circumstances, such as talking to people they do not know and ordering a meal in a restaurant. The tool is used for outcome measurement and for planning interventions. Communicative Participation Item Bank (CPIB) is a self-reported tool designed for adults with various communication disorders; this tool has clinical and research applications.[39] Patients report how their condition hinders them in multiple circumstances, such as talking to people they do not know and ordering a meal in a restaurant.

Consultations

Speech and language pathologists

Physiatrist (physical medicine and rehabilitation)

Deterrence and Patient Education

When the patient or family first notices dysarthria, they should immediately bring it to the attention of an appropriate medical practitioner. Acute onset might be a symptom of stroke; hence, rapid evaluation in the hospital is warranted. If symptoms are progressive, patients are typically assessed by a primary care clinician and referred to specialists. Patient and caregiver strategies help during rehabilitation.[40]

Paying attention to the speaker, speaking in a quiet area with good lighting, repeating phrases that are not understood, and clarifying unclear statements by asking yes-or-no questions are some valuable strategies for caregivers. Patients should begin with one word or phrase before proceeding to complete sentences. Speaking slowly with frequent pauses helps ensure understanding. Frequently ensuring listeners understand and using pictures and writing are also helpful strategies. When tired and frustrated, dysarthria worsens. When necessary, using alternative methods of communication is warranted. Educating the listener about dysarthria improves recognition of the condition and their attitude toward the patients.[41]

Pearls and Other Issues

The International Classification of Functioning, disability, and Health (ICF) is a classification system of health and health-related conditions developed by the World Health Organization (WHO) and published in 2001. It is a framework that addresses functioning and disability related to a health condition within the context of the individual's activities and participation in everyday life.

The table below maps a patient with ataxic dysarthria due to a cerebellar stroke:

Enhancing Healthcare Team Outcomes

Dysarthria is among the most common neurological complaints and can arise from many primary neurological and nonneurological conditions. Collecting detailed history, including onset, progression, associated neurological symptoms, and collateral history from family and friends, is essential.

If dysarthria is a presenting symptom, extensive workup may be required to diagnose the underlying cause. Nurses are often the first to recognize speech difficulties in an inpatient who develops dysarthria and should inform the clinician and make recommendations for interventions. An interprofessional team, including a neurologist, physiatrist, nurses, and speech-language pathologist, must make the diagnosis and formulate a treatment plan. Social workers may assist in locating support groups and local resources for patients and families.

Conventional speech therapy and high-tech AAC devices can assist with functional communication when natural speech is not understandable. The Academy of Neurologic Communication Disorders and Sciences (ANCDS) and the American Speech-Language-Hearing Association (ASHA) published four practice guidelines between 2001-2004 to support the treatment of dysarthria. Various societies, such as the ANCDS, the National Parkinson's Foundation, the Multiple Sclerosis Society, and the ALS Association, have practical guidelines for managing patients with dysarthria.

The Speech-Language Pathology Medical Review Guidelines published by ASHA focus on specific components of the speech production process, such as improving muscle strength and control, reducing consonant imprecision, and improving respiration for producing an adequate voice. [Level 5] ASHA has an evidence maps section highlighting the most recent evidence-based research in dysarthria. Emerging evidence suggests TR improves costs and patient satisfaction compared to traditional in-person therapy. The study evaluated post-stroke patients' quality of life and motor, speech, and cognitive function.[32] [Level 1]

The prognosis of dysarthria depends on the cause. Proper consultation with specialists and education of family members and friends is required to optimize patient treatment and allow patients to regain their most significant level of independence. The treatment regimen is highly individualized and requires an extensive interprofessional team. Hence, prompt consultation with interprofessional specialists is recommended to improve outcomes.

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Disclosure: Dilip Kumar Jayaraman declares no relevant financial relationships with ineligible companies.

Disclosure: Joe M Das declares no relevant financial relationships with ineligible companies.

# data[].attributes.attachment_link.description
Dysarthria is a neuromotor disorder that results from abnormalities in speed, strength, accuracy, range, tone, or duration required for speech control.[1] Decreased speech intelligibility characterizes the disorder. The content of the spoken language remains intact, so the patient can write and comprehend spoken and written language.