EMG-Guided Versus Endoscopic-Catheter Botulinum Toxin Injection for Spasmodic Dysphonia

This randomized, controlled non-inferiority trial will compare two established botulinum toxin injection techniques for adductor spasmodic dysphonia: percutaneous electromyography-guided injection and transnasal endoscopic catheter-guided injection. The study will evaluate whether the endoscopic technique provides voice outcomes that are not inferior to the standard EMG-guided approach, while also assessing treatment-related adverse effects, procedural tolerability, and practical advantages such as direct visualization and suitability for patients with challenging neck anatomy.