Quality of Life After Botulinum Toxin Injection in Patients With Adductor Spasmodic Dysphonia; a Systematic Review and Meta-analysis

Abstract

Introduction: Adductor spasmodic dysphonia is an extremely disabling voice disorder that negatively impacts a patient's quality of life (QOL). We performed a systematic review to determine if Botulinum Toxin (BT) injections improved voice related QOL in patients with this disorder.

Methods: PubMed, EMBASE, Web of Science, Cochrane Library, ProQuest, and Scopus from 2000, to and including November 1st, 2018, were searched. We identified randomized controlled trials, controlled trials, and observational studies of the effects of BT injections on the QOL in patients with adductor spasmodic dysphonia. The two authors, separately and individually chose the studies based on inclusion criteria, assessed study quality, and relevant extracted data.

Results: Nine studies used the Voice Handicap Index (VHI). The results showed significant changes pre- to post-BT injection (SMD = -0.357; 95% CI: -0.579, -0.136; z = 3.16; P = 0.002; I-squared = 0.000%). Five studies used the Voice-Related QOL; their results also showed a significant improvement pre- to postinjection (SMD = -2.99; 95% CI: -3.27, -1.32; z = 4.61; P < 0.001; I-squared = 87%). Three other studies used other, shortened versions of the VHI, VHI-10. They also showed significant results (SMD = -0.145; 95% CI: -0.349, 0.06; z = 1.38; P = 0.17; I-squared = 0.000).

Conclusion: BT injections positively affect patients' QOL. However, patients' QOL scores may never be normalized, in line with perceptual voice quality and acoustic parameters.

Keywords: Adductor Spasmodic Dysphonia; Botulinum toxin injection; Laryngeal dystonia; Quality of life; Voice disorder.