From the Guidelines
Dysarthria is associated with a wide range of neurological conditions, including stroke, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis (ALS), cerebral palsy, brain tumors, traumatic brain injury, Huntington's disease, myasthenia gravis, and progressive neurological disorders like progressive supranuclear palsy and multiple system atrophy, as these conditions affect the muscles used for speech and can lead to impaired speech production due to articulation, phonation, resonance, prosody, and/or respiration deficits related to muscle weakness, abnormal tone, and/or incoordination 1.
Neurological Conditions Associated with Dysarthria
The following neurological conditions are associated with dysarthria:
- Stroke, which can damage brain areas controlling speech muscles
- Parkinson's disease, where reduced dopamine causes muscle rigidity and slowness
- Multiple sclerosis, due to demyelination of nerve fibers
- Amyotrophic lateral sclerosis (ALS), which causes progressive motor neuron degeneration
- Cerebral palsy, resulting from early brain development abnormalities
- Brain tumors that compress speech-related neural pathways
- Traumatic brain injury affecting speech control centers
- Huntington's disease, with its characteristic involuntary movements
- Myasthenia gravis, which weakens muscles due to autoimmune attack at neuromuscular junctions
- Progressive neurological disorders like progressive supranuclear palsy and multiple system atrophy
Diagnosis and Treatment Planning
Dysarthria manifests differently depending on which part of the nervous system is affected, with symptoms ranging from slurred speech to changes in voice quality, rhythm, or volume 1. The specific speech characteristics often provide clues about the underlying neurological condition, which helps in diagnosis and treatment planning. A certified speech and language pathologist normally performs the evaluation and treatment of communication disorders, including dysarthria, and 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, to decrease isolation, and to meet the patient’s wants and needs 1.
From the Research
Neurological Conditions Associated with Dysarthria
Dysarthria is a motor speech disorder that can be associated with various neurological conditions, including:
- Parkinson's disease 2, 3, 4
- Stroke 2
- Traumatic brain injury 2
- Amyotrophic lateral sclerosis (ALS) 2, 4, 5
- Cerebral palsy 2, 3, 6
- Multiple sclerosis 4
Types of Dysarthria
There are six major types of dysarthria, each associated with distinct underlying neuropathology:
- Flaccid dysarthria: associated with lower motor neuron impairment 3
- Spastic dysarthria: associated with damaged upper motor neurons linked to the motor areas of the cerebral cortex 3
- Ataxic dysarthria: primarily caused by cerebellar dysfunction 3
- Hyperkinetic dysarthria: related to a disorder of the extrapyramidal system 3
- Hypokinetic dysarthria: related to a disorder of the extrapyramidal system 3
- Mixed dysarthria: associated with damage in more than one area, resulting in speech characteristics of at least two groups 3
Impact of Dysarthria on Communication
Dysarthria can have a profound effect on communication, leading to difficulties with speech quality and intelligibility, and can be a frequent symptom of many neurological conditions 2, 3, 4, 5, 6. Speech and language therapy can be used to encourage effective communication and improve intelligibility 3.