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EBP Compendium: Summary of Systematic Review

The Cochrane Collaboration
Botulinum Toxin for Treating Spasmodic Dysphonia (Laryngeal Dystonia): A Systematic Cochrane Review

Watts, C., Nye, C., et al. (2006).
Clin Rehabil, 20(2), 112-122.

Indicators of Review Quality:

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

Description: This is a systematic review of randomized controlled trials investigating botulinum toxin injection for adults with spasmodic dysphonia. Although not considered a treatment provided by speech-language pathologists, the authors found one study reporting improved physiological dimensions of voice (fundamental frequency, fundamental frequency range, perturbation, spectrographic analysis) after botulinum toxin treatment. However, due to the small number of studies found (N=1), no conclusions could be drawn about the effectiveness of this treatment for individuals iwth spasmodic dysphonia.

Question(s) Addressed:

Question not specifically stated.

Population: Adults whose primary diagnosis was adductor, abductor or mixed spasmodic dysphonia.

Intervention/Assessment: Any unilateral or bilateral injection of botulinum toxin into a muscle or muscles of the laryngeal mechanism. No restriction on dosage, number of treatments or time to outcome measurement was set. 

Number of Studies Included: 1

Years Included: 1966 - July 2003



"Due to the small number of studies available for this review, and the methodological differences inherent in the studies, generalizations regarding the degree and uniformity of effectiveness of botulinum toxin for all forms of spasmodic dysphonia or patients with different behavioral or clinical characteristics must be withheld at this point." (p. 119)

Keywords: Spasmodic Dysphonia, Voice Disorders

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The data in this systematic review were also published in:

Watts CCW, Whurr R, Nye C. Botulinum toxin injections for the treatment of spasmodic dysphonia. The Cochrane Database of Systematic Reviews 2004, Issue 3. Art. No.: CD004327. DOI: 10.1002/14651858.CD004327.pub2.

Added to Compendium: December 2011

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