Evaluation of voice quality in adductor spasmodic dysphonia before and after botulinum toxin treatment

Abstract

In this prospective study, the efficacy of botulinum toxin (Botox) injections in patients with adductor spasmodic dysphonia (AdSD) was assessed by 3 different modalities: perceptual and acoustic analyses and subjective self-assessment. This was done by comparing AdSD patients' pretreatment and posttreatment values and comparing these values with those of normal control speakers. In contrast to most other studies, the posttreatment status was defined as the optimal voice quality as judged by the patient. The aim of the study was to assess to what extent Botox injections actually improve voice quality and function. The AdSD subjects rated a significantly improved voice quality and function after Botox treatment. However, the results were never within normal limits. Perceptually, the characteristic and severely impaired AdSD voice improved, but another "type" of pathological voice was detected after Botox treatment. Acoustic analyses demonstrated a significant improvement, as well. Nevertheless, the "optimally" treated AdSD voice still remained significantly deviant as compared to normal voice production. Currently, Botox injection is the therapy of first choice for AdSD. Although significant improvement could be measured in our study perceptually, acoustically, and subjectively, the optimal voice that was achieved never fully matched normal voice quality or function.