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EBP Compendium: Summary of Systematic Review

Supported in part by a grant from the National Institutes of Health
Botox Treatment in Adductor Spasmodic Dysphonia: A Meta-Analysis

Boutsen, F., Cannito, M. P., et al. (2002).
Journal of Speech, Language, and Hearing Research, 45, 469–481.

Indicators of Review Quality:

The review addresses a clearly focused question Yes
Criteria for inclusion of studies are provided Yes
Search strategy is described in sufficient detail for replication No
Included studies are assessed for study quality No
Quality assessments are reproducible No

Description: This is a descriptive review and meta-analysis of studies assessing the effects of botulinum toxin type A for the treatment of adductor spasmodic dysphonia. Although involvement of speech-language pathology was not reported, a number of short term and long term perception outcomes were included.

Question(s) Addressed:

Question not specifically stated.

Population: Individuals with adductor spasmodic dysphonia.

Intervention/Assessment: Injection of botulinum toxin

Number of Studies Included: 30

Years Included: 1988-1999



  • Treatment
    • Voice
      • "Although the data indicate moderate overall improvement as a result of Botulinum toxin treatment, they also suggest significant variation across patients, measurements, and treatment conditions" (p. 469).
      • A number of methodological limitations and lack of standardization in treatment protocol warrant caution when interpreting the results. 

Keywords: Spasmodic Dysphonia, Voice Disorders

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Added to Compendium: December 2011

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