Background: Electromyography (EMG)-guided botulinum injection is recommended in clinical practice guideline for spasmodic dysphonia. However, other alternative techniques have been practiced in absence of EMG machine. Comparison of the techniques is limited in the literatures.

Objectives: This study aimed to compare the effectiveness of treatment between the EMG-guided technique and the endoscopic-guided technique in adductor spasmodic dysphonia.

Methods: Five patients who were diagnosed with adductor spasmodic dysphonia (AdSD) were enrolled and then randomized into two groups. Patient data (before and after treatment) were collected. The outcome measurement included voice analysis, voice handicap index (VHI), duration aspiration, duration of breathiness, mean effective duration, and satisfaction score (visual analog scale). The difference between the pretreatment data and the posttreatment data at 1 and 3 months was compared.

Results: The mean effective duration between of the EMG group and the endoscopic group was not significantly different. There were no significant differences in voice analysis differences in the EMG group and the endoscopic group after botulinum toxin injection 1 month and 3 months after treatment. There were no significant differences in adverse effects between the two groups in both durations of breathiness and duration of aspiration. No significant difference in satistactions score among two groups was observed.

Conclusion: Botulinum toxin injection under endoscopic guidance is a feasible technique for the treatment of adductor spasmodic dysphonia in the context of lack of EMG equipment. Additionally, endoscopic guidance is a simple and inexpensive device, composed of materials at hand in every otolaryngology unit. However, we suggest that the optimal injection technique would be determined by surgeon training, equipment availability, and preferences.