What Does Dysarthric Mean?
Dysarthric refers to a motor speech disorder resulting from paralysis, weakness, or incoordination of the speech musculature, causing slurred, imprecise articulation that affects speech intelligibility while language formulation and comprehension remain intact. 1, 2
Core Definition and Mechanism
Dysarthria is fundamentally a disorder of speech motor execution, not language processing. 1 The underlying problem involves impaired control of the physical mechanisms required to produce speech sounds, including:
- Respiration (breathing support for speech) 3, 2
- Phonation (voice production at the vocal folds) 3, 2
- Resonance (nasal vs. oral sound quality) 3, 2
- Articulation (precision of consonant and vowel formation) 3, 2
- Prosody (rhythm, stress, and intonation patterns) 3, 2
Clinical Presentation
When someone is dysarthric, their speech typically demonstrates:
- Slurred or imprecise articulation with sounds running together 3, 4
- Slow, labored speech production 4
- Reduced intelligibility ranging from mildly noticeable to completely unintelligible 3, 2
- Altered speech quality described as "thick tongue" or "porridge in the mouth" 4
- Variable loudness, pitch, or voice quality depending on which motor systems are affected 2
Critically, patients with dysarthria have preserved language abilities—their vocabulary, grammar, reading comprehension, writing, and understanding of spoken language remain intact. 4 This distinguishes dysarthria from aphasia, which is a language disorder affecting the ability to formulate or comprehend words and sentences. 1
Types and Underlying Causes
Dysarthria manifests in six major subtypes based on neurological localization 2:
- Flaccid dysarthria: Lower motor neuron damage 2
- Spastic dysarthria: Upper motor neuron damage affecting motor cortex 2
- Ataxic dysarthria: Cerebellar dysfunction 2
- Hypokinetic dysarthria: Extrapyramidal system disorders (e.g., Parkinson's disease) 2
- Hyperkinetic dysarthria: Extrapyramidal system with excessive movements 2
- Mixed dysarthria: Multiple system involvement 2
Common neurological conditions causing dysarthria include stroke, traumatic brain injury, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, and cerebellar disorders. 2, 5
Clinical Assessment
On the NIH Stroke Scale, mild to moderate dysarthria (score of 1) is characterized by slurred speech that remains intelligible to the listener, assessed by having the patient read standardized word lists. 3 Severe dysarthria (score of 2) renders speech unintelligible or the patient mute. 3
Comprehensive evaluation should systematically assess all motor speech subsystems through both perceptual rating and objective measures to identify the specific pattern and severity of impairment. 3
Impact and Management
Dysarthria profoundly affects quality of life, social participation, and psychosocial well-being disproportionate to the severity of the physiological impairment. 1, 3 Communication is integrally related to expressing personality and maintaining social relationships. 2
Speech and language therapy should be individually tailored to target the specific physiological support systems affected, including behavioral interventions for respiration, phonation, articulation, and resonance. 1, 3 Treatment may also incorporate augmentative and alternative communication (AAC) devices when intelligibility is severely compromised, along with communication partner training. 3