Dysarthria
Synonyms and keywords: Motor Speech Disorder

# Overview
Dysarthria is a motor speech disorder caused by a neurological deficit resulting in weakening or paralysis of the muscles responsible for speech formation. The term dysarthria is derived from New Latin. Dysarthria may be classified according to presentation of symptoms into 7 subgroups. Neurological deficit in CNS and/or PNS causes weakness and/or paralysis of muscles responsible for speech. Dysarthria must be differentiated from other motor speech disorders like apraxia and developmental verbal dyspraxia. Incidence and prevalence is not fully established. Dysarthria affects men and women equally. There are no established risk factors for dysarthria. There is insufficient evidence to recommend routine screening for dysarthria. Common complications of dysarthria include social distancing, irritability, and depression. Detailed history and examination are important to identify the cause and to classify dysarthria. There are no CT scan findings associated with dysarthria. However, it provides a detailed image of CNS to help identify the underlying cause of the speech problems. Treatment includes exercises and techniques to adjust speech rate, strengthen muscles of articulation, increase breath support, improve articulation, safe chewing and swallowing, avoiding conversations when feeling tired, repeat words and syllables, and techniques to deal with the frustration while speaking.

# Historical Perspective
- The term dysarthria is derived from New Latin.
- 'Dys' means dysfunctional/impaired and 'arthr' means joint/vocal articulation.
- Tradiationally, dysarthria has been defined as disorders of oral speech resulting from lesions within the nervous system.
- Recently, dysarthria includes speech disorders resulting from problems in muscular control of speech formation.

# Classification
- Dysarthria may be classified according to presentation of symptoms into the following: 

# Pathophysiology
- Dysarthria is a motor speech disorder, marked by poor articulation caused by neuromuscular impairment.
- Neurological deficit in CNS and/or PNS causes weakness and/or paralysis of muscles responsible for speech.
- Following subsystems contribute to speech formation, impairment of these subsystems results into poor perceptual speech:
Respiration
Phonation
Resonance
Prosody
Articulation
- Respiration
- Phonation
- Resonance
- Prosody
- Articulation

# Causes
Common causes of dysarthria  include:

# Differentiating Dysarthria from other Diseases
- Dysarthria must be differentiated from other motor speech disorders like apraxia and developmental verbal dyspraxia.
- Apraxia is a neurological disorder where there are abilities and motivations to form speech but the patient cannot due to neurological deficit.
- Development verbal dyspraxia lacks muscle weakness and is characterized by the developmental inability to motor plan volitional movement for the production of speech. Links to the FOXP2 gene have been identified.

# Epidemiology and Demographics
- Incidence and prevalence is not fully established.
- Disease based prevalence of dysarthria is as following:
Stroke: Approximately 8%60% of individuals with stroke present with dysarthria.
Parkinson's disease: Approximately 70%100% of individuals develop dysarthria.
Multiple sclerosis: 25% and 50% of individuals with multiple sclerosis present with dysarthria at some point.
Amyotrophic lateral sclerosis: Approximately 30%-100% depending on the stage of the disease.
Traumatic brain injury: Approximately 10%65% of individuals with traumatic brain injury develop dysarthria.
- Stroke: Approximately 8%60% of individuals with stroke present with dysarthria.
- Parkinson's disease: Approximately 70%100% of individuals develop dysarthria.
- Multiple sclerosis: 25% and 50% of individuals with multiple sclerosis present with dysarthria at some point.
- Amyotrophic lateral sclerosis: Approximately 30%-100% depending on the stage of the disease.
- Traumatic brain injury: Approximately 10%65% of individuals with traumatic brain injury develop dysarthria.
- There is no racial predilection to dysarthria.
- Dysarthria affects men and women equally.

# Risk Factors
- There are no established risk factors for dysarthria.

# Screening
- There is insufficient evidence to recommend routine screening for dysarthria.

# Natural History, Complications, and Prognosis
- Common complications of dysarthria include social distancing, irritability, and depression.
- Prognosis varies depending on the severity of underlying disease and response to speech therapy.

# Diagnosis

## Diagnostic Study of Choice
- There are no established criteria for the diagnosis of dysarthria.
- Detailed history and examination are important to identify the cause and to classify dysarthria.
- Speech assessment should be conducted by a speech-language pathologist to identify perceptual speech and subsystem involvement.

## History and Symptoms
- Signs and symptoms of dysarthria vary, depending on the underlying cause and the type of dysarthria.
- Patient may present with slow or rapid speech, nasal speech, uneven or monotone, slurred speech and/or abnormal speech volume or rhythm.

## Physical Examination
- Physical examination varies depending on the underlying cause of dysarthria.

## Laboratory Findings
- There are no diagnostic laboratory findings associated with dysarthria. Laboratory findings defer on the basis of the underlying cause.

## Electrocardiogram
- There are no ECG findings associated with dysarthria.

## X-ray
- There are no x-ray findings associated with dysarthria.

## Echocardiography or Ultrasound
- There are no echocardiography/ultrasound findings associated with dysarthria.

## CT Scan
- There are no CT scan findings associated with dysarthria. However, it provides a detailed image of CNS to help identify the underlying cause of the speech problems.

## MRI
- There are no MRI findings associated with dysarthria. However, it provides a detailed image of CNS to help identify the underlying cause of the speech problems.

## Other Imaging Findings
- There are no other imaging findings associated with dysarthria.

## Other Diagnostic Studies
- There are no other diagnostic studies associated with dysarthria.

# Treatment

## Medical Therapy
- Treatment is focused on achieving independent daily living for the patients.
- A speech language pathologist assist in improving respiration, phonation, resonance, prosody and/or articulation using various techniques.
- These treatment includes exercises and techniques to adjust speech rate, strengthen muscles of articulation, increase breath support, improve articulation, safe chewing and swallowing, avoiding conversations when feeling tired, repeat words and syllables, and techniques to deal with the frustration while speaking.
- If dysarthria is severe, another possible technique includes using a computer or flip cards to communicate more effectively.
- Augmentative and alternative communication (AAC) is used by speech language pathologist to supplement or replace natural speech.
- Lee Silverman voice treatment(LSVT) focuses on increasing vocal loudness and is found to be effective in patients with Parkinson's disease.
- Pitch Limiting Voice Treatment (PLVT) increases loudness without increasing pitch.
- Treat the underlying cause and slowing progression of the disease-causing motor speech dysfunction.

## Surgery
- Surgical intervention is not recommended for the management of dysarthria.

## Primary Prevention
- There are no established measures for the primary prevention of dysarthria.

## Secondary Prevention
- There are no established measures for the secondary prevention of dysarthria.