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Longitudinal phonatory characteristics after botulinum toxin type A injection
K V Fisher1, R C Scherer, C G Guo
1University of Oklahoma Health Sciences Center, Oklahoma City, USA. kfi663@nwu.edu
Journal of Speech and Hearing Research
|October 1, 1996
Summary
This study tracked voice changes in an adductor spasmodic dysphonia patient after Botulinum Toxin Type A injections. Findings show vocal quality fluctuations correlate with laryngeal adduction measures over time.
Area of Science:
- Laryngology
- Speech-Language Pathology
- Bioacoustics
Background:
- Adductor spasmodic dysphonia (AdSD) is a voice disorder characterized by involuntary muscle spasms in the larynx.
- Botulinum Toxin Type A injections are a common treatment, but vocal outcomes can vary significantly.
- Quantifying laryngeal dynamics post-injection is crucial for understanding treatment efficacy and patient variability.
Observation:
- This study monitored a single AdSD patient over 10 weeks following Botulinum Toxin Type A injection.
- Weekly kinematic and aerodynamic voice measures were collected to assess laryngeal adduction.
- Key acoustic and electroglottographic parameters included electroglottographic waveform width (EGGW50), slope quotient (SLQ), and glottal flow quotients (FOQ, FPQ).
Findings:
- Significant variability in laryngeal adduction was observed over the 10-week period, even with within-session vocal instability.
- Perceptual voice quality ratings (breathy to pressed) correlated with objective laryngeal measures.
- Minima in the coefficient of variation for EGGW50 and dichrotic phonations occurred during breathy, hypoadducted vocal states.
Implications:
- The study demonstrates that objective laryngeal measures can track changes in glottal function over time in AdSD patients.
- These findings suggest potential for using these methods to personalize Botulinum Toxin Type A dosage.
- Objective voice analysis may help identify the underlying causes of perceptual symptoms in AdSD, improving treatment strategies.