RESUMEN
BACKGROUND AND OBJECTIVES: Botulinum toxin type A (BTX-A) injection is well known for its effectiveness in the treatment of "Spasmodic dysphonia". However, studies on the efficacy of BTX-A injection have not been attempted in Korea. Therefore, this study was carried out to investigate the effects of BTX-A. SUBJECTS AND METHOD: The study examined 12 female patients with 'adductor spasmodic dysphonia'. Objective assesments included aerodynamic analysis and electoroglottography (EGG) of each patient before and after BTX-A. Subjective assessments included using the Korean-version of Voice Handicap Index-30 (KVHI-30) and a patient self-rating scale. RESULTS: Aerodynamic analysis revealed that only maximum phonation time (MPT) was significantly shortened after the injection of BTX-A (p<0.05). In the EGG, the mean frequency distribution was significantly increased, while the mean amplitude and the mean closed quotient distribution were significantly decreased (p<0.05). The KVHI-30 and patient self-rating scale scores were significantly decreased (p<0.01) as well, demonstrating the effects of BTX-A on the quality of life. CONCLUSION: Our results show the effects of BTX-A objectively by comparing voice characteristics, which were measured through EGG before and after BTX-A injection, as well as by determining aerodynamic characteristics. The subjective self-assessment on the quality of life is significant as it may serve as a clinically relevant measure. This study may be helpful in elucidating treatment efficacy of BTX-A in many ways.