What are the types of dysarthria?

Types of Dysarthria

Dysarthria is classified into six major types based on the underlying neurological damage: flaccid, spastic, ataxic, hypokinetic, hyperkinetic, and mixed dysarthria. 1

Classification Based on Neuroanatomical Damage

1. Flaccid Dysarthria

• Neurological basis: Lower motor neuron impairment
• Characteristics: Weak articulation, hypernasality, breathy voice quality, reduced loudness
• Common causes: Peripheral nerve damage, myasthenia gravis, Guillain-Barré syndrome

2. Spastic Dysarthria

• Neurological basis: Upper motor neuron damage (bilateral)
• Characteristics: Strained-harsh voice quality, slow rate of speech, imprecise consonants, hypernasality
• Common causes: Bilateral stroke, multiple sclerosis, amyotrophic lateral sclerosis

3. Ataxic Dysarthria

• Neurological basis: Cerebellar dysfunction
• Characteristics: Irregular articulatory breakdowns, excess and equal stress on syllables, distorted vowels
• Common causes: Cerebellar stroke, multiple sclerosis, cerebellar tumors, alcoholic cerebellar degeneration

4. Hypokinetic Dysarthria

• Neurological basis: Basal ganglia damage (extrapyramidal system)
• Characteristics: Reduced loudness, monotone, monopitch, short rushes of speech, imprecise consonants
• Common causes: Parkinson's disease and related disorders 2

5. Hyperkinetic Dysarthria

• Neurological basis: Basal ganglia damage (extrapyramidal system)
• Characteristics: Irregular breakdowns in articulation, abnormal prosody, variable rate
• Common causes: Huntington's disease, dystonia, chorea

6. Mixed Dysarthria

• Neurological basis: Multiple neurological areas affected
• Characteristics: Features of at least two types of dysarthria
• Common causes: Multiple system atrophy, amyotrophic lateral sclerosis, Wilson's disease 3

Clinical Features and Assessment

Speech Subsystems Affected

• Respiratory: Abnormal breathing patterns affecting speech
• Laryngeal: Voice quality disturbances (hoarseness, breathiness)
• Velopharyngeal: Hypernasality or hyponasality
• Oral-articulatory: Imprecise consonants, distorted vowels

Diagnostic Challenges

• Studies show poor accuracy (35%) and low inter-observer agreement in classifying dysarthria types based on perceptual analysis alone 4
• Experienced neurologists and trainees both struggle with identifying specific dysarthria types without additional clinical context
• Formal assessment by speech-language pathologists using standardized tools is recommended for accurate classification

Clinical Significance

Impact on Quality of Life

• Dysarthria affects approximately 20% of stroke patients 5
• Can significantly impact social participation, psychological well-being, and quality of life
• May lead to social isolation, depression, anxiety, missed work, and lifestyle changes

Relationship to Underlying Conditions

• Can be an early indicator of neurological disease
• May present as part of a complex of symptoms in conditions like:
  • Multiple system atrophy (mixed dysarthria with hypokinetic, ataxic, and spastic components) 3
  • Parkinson's disease (hypokinetic dysarthria)
  • Cerebellar disorders (ataxic dysarthria)
  • Motor neuron disease (mixed, often flaccid and spastic)

Management Considerations

• Speech and language therapy is recommended for individuals with dysarthria 5
• Treatment should target the specific speech subsystems affected
• Communication partner training is effective in improving communication activities 5
• Augmentative and alternative communication approaches may be necessary as the condition progresses

Common Pitfalls in Diagnosis

• Confusing dysarthria with aphasia (dysarthria affects speech production while language processing remains intact)
• Failing to distinguish between different types of dysarthria, which can lead to missed diagnostic opportunities
• Relying solely on perceptual analysis without considering the broader neurological context
• Not recognizing mixed dysarthria patterns that may indicate specific neurological conditions

Understanding the specific type of dysarthria can provide valuable diagnostic information about the location and nature of neurological damage, guiding both diagnosis and treatment approaches.