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EMG-Guided Versus Endoscopic-Catheter Botulinum Toxin Injection for Spasmodic Dysphonia
Sponsor: Chinese University of Hong Kong
Summary
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.
Official title: Randomized Controlled Trial of EMG-Guided Versus Endoscopic-Catheter Botulinum Toxin Injection for Spasmodic Dysphonia
Key Details
Gender
All
Age Range
18 Years - Any
Study Type
INTERVENTIONAL
Enrollment
17
Start Date
2026-10-21
Completion Date
2029-06-30
Last Updated
2026-10-26
Healthy Volunteers
No
Conditions
Interventions
Intervention A - Electromyography (EMG)-Guided BTX Injection
The patient is positioned comfortably with the neck slightly extended. Surface reference and ground electrodes are applied. After application of EMLA cream (lidocaine 2.5%/prilocaine 2.5%) and disinfection of the skin, a 27-gauge needle electrode connected to an EMG machine is introduced percutaneously through the midline of the cricothyroid membrane and angled superiorly and laterally toward the TA muscle. Correct placement is confirmed by characteristic bursts of motor unit activity on phonation. Once confirmed, BTX is injected. The whole procedure including post-operative observation takes approximately 90 minutes. Vital signs and oxygen saturations are monitored throughout the procedure.
Intervention B - Endoscopic Catheter BTX Injection
Following administration of topical anesthesia with 5% lidocaine/0.5% phenylephrine (Co-phenylcaine) nasal spray and topical Xylocaine laryngeal spray via working channel, a transnasal channel flexible bronchoscope is introduced. A sterile catheter needle is introduced via the working channel of the bronchoscope, and BTX is injected directly into the TA/LCA muscle and false cord under direct visualization. The whole procedure including post-operative observation takes approximately 90 minutes. Vital signs and oxygen saturations are monitored throughout the procedure.