Effects of Botulinum Toxin on Pathophysiology in Spasmodic Dysphonia

• Published in: Annals of otology, rhinology & laryngology Vol. 109; no. 2; pp. 194 - 203
• Main Authors: Bielamowicz, Steven, Ludlow, Christy L.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Los Angeles, CA SAGE Publications 01.02.2000; Annals Publishing Compagny; SAGE PUBLICATIONS, INC
• Subjects: Adult; Biological and medical sciences; Botulinum Toxins, Type A - therapeutic use; Electromyography; Ent. Stomatology; Female; Humans; Laryngeal Muscles - drug effects; Laryngeal Muscles - physiopathology; Male; Medical sciences; Middle Aged; Non tumoral diseases; Otorhinolaryngology. Stomatology; Pharmacology. Drug treatments; Upper respiratory tract, upper alimentary tract, paranasal sinuses, salivary glands: diseases, semeiology; Voice Disorders - drug therapy; Voice Disorders - physiopathology; botulinum toxin; voice; larynx; Botox; electromyography; laryngology; spasmodic dysphonia; Human; Pathophysiology; Enzyme; Metalloendopeptidases; Spastic dysphonia; Peptidases; Bontoxilysin; Chemotherapy; Treatment; Hydrolases; ENT disease; Larynx disease; Biological effect
• ISSN: 0003-4894; 1943-572X
• DOI: 10.1177/000348940010900215

To determine the mechanism of symptom relief with treatment by botulinum toxin injection in persons with adductor spasmodic dysphonia (ADSD), we evaluated the effects of unilateral thyroarytenoid muscle injections on both injected and noninjected muscles in 10 subjects with ADSD, using electromyography on both sides of the larynx before and after treatment. The subjects' speech symptoms were reduced (p = .005) 2 weeks following injection, when the electromyographic study occurred. Muscle activation levels and the numbers of spasmodic muscle bursts decreased significantly (p ≤ .03) postinjection in both the injected and noninjected muscles. The reductions in laryngeal muscle bursts correlated with symptom reduction (r ≥ .7) in all muscles. Reductions in laryngeal muscle bursts did not relate to either absolute or normalized levels of muscle activity before or after botulinum toxin injection. The results suggest that changes in the central pathophysiology are responsible for changes in speech symptoms following treatment.