Types of Dysarthria: A Clinical Overview
A clinical overview of the types of dysarthria — the motor speech disorder classification by underlying pathology and characteristic speech features.
Dysarthria is a motor speech disorder caused by weakness, slowness, or incoordination of the muscles used for speech. It results from neurological impairment and is classified by the location and type of the underlying lesion. Knowing the types guides assessment, prognosis, and treatment planning.
What dysarthria affects
Depending on the subsystem involved, dysarthria can disturb respiration, phonation, resonance, articulation, and prosody. Listeners notice slurred or imprecise speech, changes in voice quality or pitch, altered rate or rhythm, and reduced intelligibility. The specific pattern points to the type.
The major types
The widely used Mayo classification, based on the underlying motor system affected, includes:
- Flaccid dysarthria: from lower motor neuron lesions. Speech features include breathiness, nasal emission, and imprecise consonants (e.g., from bulbar involvement).
- Spastic dysarthria: from bilateral upper motor neuron lesions. Speech is strained-strangled, slow, and effortful with reduced prosody.
- Ataxic dysarthria: from cerebellar involvement. Speech features include imprecise articulation, irregular articulatory breakdowns, and excess and equal stress.
- Hypokinetic dysarthria: associated with parkinsonism. Features include reduced loudness, monopitch and monoloudness, and rapid or rushed rate with reduced stress.
- Hyperkinetic dysarthria: associated with involuntary movements (e.g., dystonia, chorea). Speech features vary with the movement disorder.
- Mixed dysarthria: combinations of the above, common in conditions like multiple systems or amyotrophic lateral sclerosis (which can show combined upper and lower motor neuron signs).
- Unilateral upper motor neuron dysarthria: from a single-sided lesion, typically milder.
Assessment and goals
A speech-language pathologist assesses the subsystems (respiratory, laryngeal, velopharyngeal, articulatory) through perceptual, instrumental, and sometimes imaging methods. Treatment is tailored to the type and severity — targeting intelligibility, compensatory strategies, and, where appropriate, prosthetic or augmentative communication.
Documentation
Motor speech documentation should tie the type and severity to measurable functional goals. Use the ICD-10 lookup for the correct code and a treatment plan goal builder to specify measurable speech outcomes.