Overview
This lecture covers hyperkinetic dysarthria, its causes, mechanisms, symptoms, and specific movement disorders that result in excessive involuntary movements affecting speech.
Definition and Misconceptions
- Hyperkinetic dysarthria is caused by excess involuntary movement, not by speaking quickly or excess muscle tone.
- "Hyper" means increased/excess; "kinetic" means movement.
- Do not confuse with hypokinetic dysarthria (too little movement, e.g., Parkinson's).
Causes of Hyperkinetic Dysarthria
- Common causes: Huntington's disease (hereditary), tardive dyskinesia (from certain neuroleptics), Tourette's syndrome, trauma, and medication-induced dyskinesia.
- Parkinson’s disease can cause hyperkinetic features if overmedicated (excess levodopa leads to dyskinesias).
Mechanism and Brain Structures
- Hyperkinetic dysarthria arises from dysfunction in the basal ganglia, which regulate movement through complex pathways.
- Some circuits suppress movement, others excite it; imbalance can cause excess movement.
Clinical Features and Affected Speech Systems
- Speech may be normal but is disrupted by superimposed involuntary movements.
- Most commonly affected: jaw, tongue, face; can involve neck, trunk, and respiratory muscles.
- The disorder doesn’t produce a unique speech sound but is identified by the presence of involuntary or compulsive movements during speech.
Types of Hyperkinetic Movement Disorders
- Dystonia: Sustained muscle contractions; can affect speech muscles (e.g., jaw, tongue, larynx).
- Spasmodic Dysphonia: Dystonia of the larynx, causing abnormal vocal fold movement (breathy or strained voice).
- Tardive Dyskinesia: Involuntary facial/tongue movements from psychiatric medications; impacts eating and speech.
- Chorea: Rapid, irregular, dance-like involuntary movements (e.g., Sydenham’s chorea).
- Tics (Tourette’s): Sudden, irresistible movements or vocalizations that are voluntarily suppressible but often uncontrollable.
Key Terms & Definitions
- Hyperkinetic dysarthria — Speech disorder due to excessive involuntary movement.
- Dystonia — Sustained muscle contractions causing abnormal postures.
- Chorea — Quick, irregular, involuntary movements.
- Tardive dyskinesia — Involuntary oral/facial movements from long-term neuroleptic use.
- Spasmodic dysphonia — Voice disorder from involuntary laryngeal muscle contractions.
- Tics — Sudden, repetitive movements or sounds, often temporarily suppressible.
Action Items / Next Steps
- Review the table of movement disorder definitions as referenced in the lecture.
- Watch the recommended videos for visual examples of each movement disorder.
- Check out additional lectures on other types of dysarthria for comparison.