Authors: Fisher KV, Scherer RC, Guo CG, Owen AS
Title: Longitudinal Phonatory Characteristics after Botulinum Toxin Type A Injection
Source: Journal of Speech and Hearing Research 1996 39(5): 968-980
Year: 1996
Research Design: Single Case Design

Following Botulinum Toxin Type A injection, glottal competency of an adductor spasmodic dysphonia patient is thought to vary over a wide range. This study quantifies variability in laryngeal adduction for one such patient over a 10-week period. Analyses of kinematic and aerodynamic measures were used to track the voice weekly. The measures included the electroglottographic waveform width (EGGW50), nondimensional electroglottographic slope quotient (SLQ), glottal flow open quotient (FOQ), dc glottal flow, and nondimensional glottal peak quotient (FPQ). The results suggested that change in degree of glottal adduction over time can be observed even when vocal instability is present within each recording session. Perceptual ratings of vocal quality (breathy to present) were related to the laryngeal measures. The coefficient of variation for EGGW50 and the percentage of dichotic phonations reached minima during sessions with predominantly breathy and hypoadducted phonation. The methods used in the study show potential to aid decisions about dose level and sources of perceptual adductor spasmodic dysphonia symptoms for a given patient.

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