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Dynamic aspects of phonatory control in spasmodic dysphonia
Journal of Speech and Hearing Research
|June 1, 1987
Summary
Spasmodic dysphonia (SD) patients exhibit a laryngeal movement disorder. While laryngeal movement onset is normal, patients show a significant delay in achieving phonation, indicating impaired vocal fold adduction for speech.
Area of Science:
- Neurology
- Speech-Language Pathology
- Laryngology
Background:
- Spasmodic dysphonia (SD) is a chronic laryngeal movement disorder.
- Understanding the specific motor control deficits in SD is crucial for diagnosis and treatment.
Purpose of the Study:
- To investigate voluntary laryngeal movement control in patients with spasmodic dysphonia.
- To compare SD patients with healthy controls on speech tasks demanding varying laryngeal motor control.
Main Methods:
- Nine idiopathic chronic SD patients and 15 healthy controls performed speech tasks.
- Tasks assessed different degrees of dynamic and precise vocal fold movement control.
- Phonatory timing and reaction times for syllable production were measured.
Main Results:
- SD patients had increased phonatory off times.
- Maximum phonation time, phonatory on time, and frequency/intensity control were unaffected.
- Laryngeal movement onset was not delayed, but the interval between laryngeal movement onset and phonation onset was significantly increased in SD patients.
Conclusions:
- Spasmodic dysphonia involves a difficulty in achieving phonation onset, not in initiating laryngeal movement.
- The findings suggest a movement-control disorder affecting vocal fold adduction crucial for phonation initiation in SD.