Dysarthria: what is it, causes, symptoms, treatment, prognosis

What is dysarthria?

Dysarthriabelongs to the category of neurogenic speech disorders characterized by an abnormality of strength, speed, accessibility, stability, tone, or accuracy of movements necessary for breathing, phonetic, resonator, articulatory or prosodic features of speech creativity.

These abnormalities are the result of one or more sensorimotor problems, including weakness or paralysis, impaired coordination of movements, involuntary movements or excessive, decreased or inconsistent muscle tone. Dysarthria can negatively affect speech intelligibility, speech realism, or both. It must be remembered that some people with dysarthria may have normal intelligence. Dysarthria can coexist with other neurogenic disorders of speech, cognitive function, and swallowing.

Signs and symptoms

A child or adult with dysarthria may have:

• Slurred, nasal, or hoarse speech
• tense and hoarse voice;
• very loud or quiet speech;
• problems with speaking in the correct rhythm, with frequent hesitation;
• gurgling or monotonous speech;
• difficulty moving the tongue and lips;
• difficulty swallowing (dysphagia), which can lead to persistent salivation.

As a result of these problems, a person with dysarthria can be difficult to understand. In some cases, patients can only pronounce short phrases, separate words, or not make intelligible speech at all.

Dysarthria does not affect intelligence or understanding, but a person with the condition may also have problems in these areas. Speech problems can also affect social interaction, employment, and education.

Causes and risk factors

There are many potential causes of dysarthria. These include toxic, metabolic, degenerative diseases, traumatic brain injury, thrombotic or embolic stroke. Here are the most common causes that can lead to dysarthria:

• Congenital neurological causes:cerebral palsy, Arnold-Chiari malformation, congenital pseudobulbar paralysis, syringomyelia, syringobulbia.
• Degenerative diseases:amyotrophic lateral sclerosis (BASS), Parkinson's disease, progressive supranuclear palsy, cerebellar degeneration, corticobasal degeneration, multiple systemic atrophy, Friedreich's ataxia, Huntington's disease, olivopontocerebellar atrophy, spinocerebellar ataxia, ataxia-telangiectasia.
• Demyelinating and inflammatory diseases:multiple sclerosis, encephalitis, Guillain-Barré syndrome and related autoimmune diseases, meningitis, multifocal leukoencephalopathy.
• Infectious diseases:acquired immunodeficiency syndrome (AIDS), Creutzfeldt-Jakob disease, shingles, infectious encephalopathy, central nervous system tuberculosis, poliomyelitis.
• Neoplastic diseases: tumors of the central nervous system; tumors of the brain, cerebellum, or brainstem; paraneoplastic degeneration of the cerebellum.
• Other neurological conditions: hydrocephalus, Meige's syndrome, myoclonic epilepsy, neuroacanthocytosis (chorea-acanthocytosis), radiation necrosis, sarcoidosis, epilepsy, Tourette's syndrome, chorea of ​​pregnant women.
• Toxic / metabolic diseases: alcoholic addiction (alcoholism), botulism, carbon monoxide poisoning, central pontine myelinolysis, heavy metal or chemical poisoning, hepatocerebral degeneration, hypothyroidism, hypoxic encephalopathy, lithium poisoning, Wilson-Konovalov disease.
• Injuries: traumatic brain injury, chronic traumatic encephalopathy, neck injury, neurosurgical / postoperative injury, skull fracture.
• Vascular diseases:stroke (hemorrhagic or non-hemorrhagic), Moyamoy disease, anoxic or hypoxic encephalopathy, arteriovenous malformations.

Incidence and prevalence

• Stroke. It is estimated that 8–60% of stroke patients have dysarthria.
• Traumatic brain injury. Approximately 10-65% of patients with post-traumatic brain injury suffer from dysarthria.
• Parkinson's Disease: It is estimated that dysarthria affects approximately 70-100% of patients who have had Parkinson's disease.
• Multiple sclerosis: 25% and 50% of patients with multiple sclerosis develop dysarthria at some stage in the course of the disease.
• Amyotrophic lateral sclerosis: dysarthria can be considered an initial symptom in up to 30% of patients with this disease, and in all patients with this disease, dysarthria develops at later stages.

Classification

Different types of dysarthria have been described depending on the location of the neurological damage;

• Sluggish: associated with conditions of the lower motor system of neurons and / or muscles, for example, with damage to the peripheral nervous system (PNS). Differs in the difficulty of pronunciation of consonants.
• Spastic: associated with bilateral diseases of the upper motor neuron system. Patients may have speech problems, muscle weakness, and abnormal reflexes.
• Ataxic: associated with conditions causing disruption of the cerebellar control unit. Symptoms of slurred speech and poor coordination are observed.
• Hypokinetic: is associated with disorders of the control block of the basal ganglia, for example, stroke caused by neurodegenerative diseases such as Parkinson's and Huntington's disease. Manifested in a low, hoarse or monotonous voice, difficulty in beginning sentences, stuttering or slurred speech, difficulty in pronunciation consonants, stiffness or lack of movement of the face and neck, difficulty swallowing, which can lead to drooling and tremors, or muscle spasms.
• Hyperkinetic: associated with disease of the control unit of the basal ganglia. Symptoms include slurred or slow speech, trembling voice, dyspnea or fatigue while talking, muscle cramps, and tremor, involuntary convulsive or hesitating movements, or atypical muscle tone.
• Unilateral upper motor neuron: associated with unilateral disorders of the upper motor (motor) neuron system.
• Mixed: a mixture of different types of dysarthria (for example, spastic-ataxic; sluggish-spastic).
• Uncertain: the observed signs correspond to dysarthria, but do not relate to any of the identified types of dysarthria.

Diagnostics

To diagnose dysarthria, the doctor asks the patient about the symptoms and performs a physical exam. Speech therapists are often helpful in diagnosing the disease. The practitioner can also do the following:

1. Asking the person to do a few simple tasks, such as blowing out a candle, biting their lower lip, and sticking out their tongue: observing the person performing these tasks helps the practitioner assess the strength and movement of the muscles involved in speech.
2. Ask the person to repeat words and sentences, sing and count: Observing the patient making sounds helps the practitioner identify speech problems, such as shortness of breath and choppy speech.

Standardized brain function tests (neuropsychological examinations) can be performed by a neuropsychologist or speech therapist. Neuropsychological diagnostics also helps practitioners plan treatment and determine the likelihood of recovery.

Imaging tests such as computed tomography (CT) or magnetic resonance imaging (MRI) are done to help determine the cause.

Other tests may be performed depending on the suspected cause. These tests may include blood and urine tests, lumbar puncture (lumbar puncture), electroencephalography (EEG), electromyography, and nerve conduction studies.

Treatment

Articulation problems resulting from dysarthria are treated by speech pathologists (speech therapists) using a variety of techniques. The methods used depend on the effect of dysarthria on articulator control. Traditional therapies are aimed at correcting disturbances in speed (articulation), prosody (appropriate emphasis and intonation that are affected, for example, by apraxia of speech, damage to the right hemisphere of the brain, etc.), intensity (loudness of the voice, impaired, for example, with hypokinetic dysarthria such as Parkinson's disease), resonance (the ability to alter the vocal tract and resonant spaces for correct speech sounds) and phonation (control of the vocal cords for proper voice quality and respiratory ventilation paths). These treatments usually include exercises to increase strength and control the articulatory muscles (which may be flaccid and weak or overly tense and difficult to move), as well as using alternative speaking techniques to improve the speaker's intelligibility (how well someone's speech is understood peers).

There are several skills that it is important for a speech therapist to teach a patient; safe chewing and swallowing techniques, avoiding talking when tired, repeating words and syllables again and again to learn the correct mouth movements, as well as methods of dealing with frustration during conversation. Depending on the severity of dysarthria, there is another opportunity - to learn how to use a computer or open cards for more effective communication.

More modern techniques based on the principles of motor learning, such as Lee Silverman's voice treatment (LSVT method), speech and language therapy, and in particular LSVT method, can improve vocal and speech function in disease Parkinson's. In Parkinson's disease, it is necessary to retrain speech skills by creating new generalized motor programs and attach great importance to regular practice through peer / partner support and self-government. The regularity of the practice and the timing of its use are the main problems in the treatment according to the principle of motor learning as they can determine the likelihood of generalizing new motor skills and therefore the effectiveness of the treatment.

Forecast

The prognosis of dysarthria depends on the nature of the lesion; the prognosis is poor in neurodegenerative disorders and better in stroke.