Dysarthria is a collective term for a group of speech disorders that occur as a result of muscle weakness. People with dysarthria have neurological damage that weakens the muscles necessary for speech.
The neurological damage underlying dysarthria may occur as a result of a stroke, brain injury, or neurodegenerative disease.
Dysarthria shares many of its symptoms with other types of neurological disorders, such as aphasia, dysphasia, and apraxia.
Aphasia and dysphasia affect a person's ability to understand or produce language. These disorders result from damage to the language centers within the brain. Apraxia affects a person's ability to produce speech and results from damage to the part of the brain that plays a role in planning speech.
Dysarthria is a distinct speech disorder that specifically involves muscle weakness.
Read on to learn more about the causes, types, and symptoms of dysarthria, as well as the treatment options available.
Dysarthria occurs when damage to the nervous system weakens the muscles that produce speech sounds. It may affect the muscles in one or more of the following areas:
- upper respiratory tract
The neurological damage that causes dysarthria can occur due to:
- neurological conditions, such as epilepsy, amyotrophic lateral sclerosis (ALS), and Parkinson's disease
- brain tumors
- trauma from injuries to the head or neck, as well as repeated blunt force impacts to the skull
- inflammatory conditions, such as autoimmune diseases, encephalitis, and meningitis
- vascular conditions, such as stroke or Moyamoya disease
- exposure to toxic substances, such as alcohol, heavy metals, or carbon monoxide
People can develop different types of dysarthria depending on the location of neurological damage. We outline the different types of dysarthria below.
People with spastic dysarthria may have speech problems alongside generalized muscle weakness and abnormal reflexes.
Spastic dysarthria occurs as a result of damage to the motor neurons in the central nervous system (CNS). The CNS includes the brain and spinal cord.
The hallmark of flaccid dysarthria is difficulty pronouncing consonants. Damage to the peripheral nervous system (PNS) is responsible for this type of dysarthria. The PNS connects the brain and spinal cord to the rest of the body.
Flaccid dysarthria can result from any of the following:
Ataxic dysarthria causes symptoms of slurred speech and poor coordination.
This type of dysarthria can occur if a person sustains damage to the cerebellum. The cerebellum is the part of the brain responsible for receiving sensory information and regulating movement.
A malfunction in the brain's extrapyramidal system causes hypokinetic dysarthria. This system includes areas of the brain that coordinate subconscious muscle movements.
People with this condition may experience the following symptoms:
- a quiet, breathy, or monotone voice
- difficulty starting sentences
- a stutter or slurred speech
- difficulty pronouncing consonants
- rigidity or reduced movement in the face and neck
- difficulty swallowing, which can cause drooling
- tremors or muscle spasms
Hyperkinetic dysarthria occurs as a result of damage to parts of the brain that doctors refer to collectively as the basal ganglia. The basal ganglia play a role in various functions, including involuntary muscle movement.
Symptoms of hyperkinetic dysarthria include:
- slurred or slow speech
- shaky voice
- shortness of breath or fatigue while speaking
- muscle spasms and tremors
- involuntary jerking or flailing movements
- abnormal muscle tone
Damage to the basal ganglia can develop as a result of neurodegenerative diseases, such as Parkinson's and Huntington's.
According to the American Speech-Language-Hearing Association, dysarthria can affect one or more of the following five systems that speech involves:
- Respiration: Respiration moves air across the vocal cords, creating sounds that the mouth and nose shape into words.
- Phonation: This system uses airflow from the lungs plus vocal cord vibrations to produce speech sounds.
- Resonance: Resonance refers to the quality of speech sounds that the vocal tract produces.
- Articulation: This term means shaping sounds into recognizable words, which involves forming precise and accurate vowels and consonants.
- Prosody: The rhythm and intonation of speech that give words and phrases their meaning.
The five speech systems work together, meaning that impairment in one system can affect the others.
People who have dysarthria may experience one or more of the following symptoms:
- abnormally quiet or loud speaking voice
- monotonous tone
- rough, scratchy, or hoarse voice
- stuffy or nasal-sounding voice
- vocal tremors
- speech that is too fast or too slow
- distorted consonant and vowel sounds
As conditions that cause dysarthria also affect the nerves that control muscles, people with dysarthria may experience physical symptoms, such as:
- tremors or involuntary movements of the jaw, tongue, or lip
- overly sensitive or undersensitive gag reflex
- muscle wasting
People who have difficulty speaking can make an appointment to see a speech-language pathologist (SLP). SLPs are healthcare professionals who specialize in diagnosing and treating speech and language conditions.
As part of the diagnostic procedure, the SLP will review a person's medical history and ask about their current symptoms. They will also test a person's speech and language. They may ask a person to:
- stick out their tongue
- inhale and exhale
- make different consonant and vowel sounds
- read a few sentences out loud
- count out loud
An SLP or other healthcare professional may recommend one or more of the following tests to rule out other medical conditions:
- blood or urine tests
- imaging tests, including MRI or CT scans
- brain function tests
- electromyography, which tests muscle function
- brain biopsy
- spinal tap
The treatment for dysarthria varies depending on its type, underlying cause, and symptoms.
Some people develop dysarthria due to an underlying medical condition, such as an infection or exposure to a toxic substance. These individuals may notice improvements in their speech after they receive antibiotics or identify and eliminate the toxic compound.
An SLP may recommend exercises and techniques to help a person overcome speech difficulties. These may include:
- exercises to strengthen the muscles in the mouth, jaw, and throat
- breathing techniques to increase or decrease the volume of a person's voice
- techniques to address specific speech problems, such as teaching people to pause when talking to slow down their speech
People who have dysarthria may also improve their communication skills by practicing these techniques:
- maintaining eye contact with the listener
- having conversations in a quiet environment
- using gestures and facial expressions to convey meaning
- using different words to reiterate a message
- carrying a pen and notepad to communicate via written word, if necessary
The following tips can be helpful for people who want to communicate with someone who has dysarthria:
- reducing external distractions and finding a quiet, calm place to have a conversation
- watching the person as they speak
- asking for clarification when having trouble understanding something
- avoiding finishing the person's sentences or correcting errors
- speaking normally and clearly
Dysarthria is a speech disorder that occurs due to weakness in the muscles necessary for speech production.
People can develop dysarthria after a stroke, brain infection, or brain injury. Certain neurodegenerative diseases can also damage parts of the brain that control the muscles that speech involves.
Although dysarthria can make communication more complicated, an SLP can teach people how to improve their speaking ability. An SLP can also recommend strategies to aid conversation between a person with dysarthria and their communication partners.