Abstract
Adductor spasmodic dysphonia (AdSD) is a focal dystonia predominantly involving the laryngeal adductor muscles. AdSD is reported to be a largely non-progressive neurological disorder, though fluctuations in symptom severity do occur. Repeated laryngeal onabotulinumtoxinA (BTX-A) injections are the primary management for AdSD. A number of studies have demonstrated long-term dose stability as evidence of this long-term disease stability. A retrospective review was performed on all patients undergoing BTX-A injections for AdSD from April 1994 to September 2013 by a single laryngologist at a tertiary referral laryngology center. Patient demographics, injection doses, use of diazepam and/or lidocaine, and self-reported vocal function were recorded. Multiple linear regression analyses were performed. 83 patients underwent a total of 1,168 injections over 19 years. The mean starting dose was 2.35 MU (0.79 SD). The mean long-term dose was 2.36 MU (0.79 SD). After adjusting for confounders, the change in the relative dose of BTX-A, with every year elapsed since initial dose was 0.13% (95% confidence interval -0.31 to 0.57%), p = 0.568. BTX-A dose is stable over time in our large cohort of patients treated with bilateral thyroarytenoid injections for AdSD.
Highlights
Repeated laryngeal onabotulinumtoxinA (BTX-A) injections are the primary management for Adductor spasmodic dysphonia (AdSD)
Spasmodic dysphonia is a chronic, adult-onset neurological disorder that results in involuntary muscle spasms of the vocal folds during task-specific speech [1]
First described by Blitzer et al [2] in the 1980s, this treatment modality is the primary management strategy recommended by the American Academy of Otolaryngology-Head and Neck Surgery for spasmodic dysphonia [3]
Summary
Spasmodic dysphonia is a chronic, adult-onset neurological disorder that results in involuntary muscle spasms of the vocal folds during task-specific speech [1]. Adductor spasmodic dysphonia (AdSD) is the most common subtype occurring in at least 80% of patients with spasmodic dysphonia. It is characterized by spasms of the adductor laryngeal muscles including the thyroarytenoid (TA), interarytenoid, and the lateral cricoarytenoid (LCA) muscles [2]. Temporary management of symptoms is the current standard treatment for AdSD. This can be done by serial laryngeal onabotulinumtoxinA (BTX-A) injections under electromyography guidance in the awake, outpatient setting. First described by Blitzer et al [2] in the 1980s, this treatment modality is the primary management strategy recommended by the American Academy of Otolaryngology-Head and Neck Surgery for spasmodic dysphonia [3]. The natural progression of symptoms involves a period of breathiness with or without dysphagia starting 24–48 h after the BTX-A injection which is followed by a period of symptomatic improvement and eventual return of AdSD symptoms [4]
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