Related Experiment Video
Updated: Aug 20, 2026
A Protocol for Comprehensive Assessment of Bulbar Dysfunction in Amyotrophic Lateral Sclerosis (ALS)
Published on: February 21, 2011
Perceptual analyses of spasmodic dysphonia before and after treatment
Michael P Cannito1, Gayle E Woodson, Thomas Murry
1School of Audiology and Speech Pathology, The University of Memphis, Memphis, Tenn, USA. mcannito@memphis.edu
Objective:
To evaluate expert listeners' perceptions of voice and fluency in persons with adductor spasmodic dysphonia (ADSD) before and after treatment with botulinum toxin type A (Botox), as a function of initial severity of the disorder (while controlling for patients' age at injection).
Design:
Simple before-and-after trial with blinded randomized listener judgments.
Setting:
Ambulatory care clinic at a single medical center.
Participants:
Forty-two consecutive patients with ADSD who underwent examination, with a 3- to 6-week follow-up, after initial botulinum toxin type A injection. There were also 42 age- and sex-matched healthy control subjects.
Interventions:
Injections of botulinum toxin type A into the thyroarytenoid muscle(s).
Main Outcome Measures:
Computer-implemented visual analog scaling judgments of voice quality and speech fluency made by expert listeners under psychoacoustically controlled conditions.
Results:
Response to botulinum toxin type A varied markedly as a function of pretreatment severity of ADSD. More severe initial symptoms exhibited greater magnitudes of improvement. Patients with mild dysphonia did not exhibit pretreatment to posttreatment change. Following treatment, voice and fluency remained significantly (P<.05) poorer in ADSD than in healthy speakers. Older patients exhibited less improvement than younger patients when the effect of initial severity was statistically controlled.
Conclusions:
Voice quality and fluency improved for most patients following treatment, but older patients and those with milder dysphonia exhibited the least optimal responses to the procedure. Patients who were profoundly impaired demonstrated the greatest amount of improvement. Computer-implemented visual analog scaling provided a reliable clinical tool for determining treatment-related changes in those with ADSD.