Current practices in the management of adductor spasmodic dysphonia

Adductor spasmodic dysphonia (ADSD) is a focal dystonia treated most commonly by chemodenervation of the thyroarytenoid (TA) muscles with botulinum toxin. Currently, there are no consensus guidelines regarding this treatment and the management of ADSD. The objective of this study was to assess current practice patterns among physicians who treat ADSD.

A cross-sectional survey study was conducted regarding treatment choices and specific technical aspects of injection technique and botulinum toxin use. The study population consisted of laryngologists from the Canadian Society of Otolaryngology-Head and Neck Surgery and laryngologists obtained from the American Laryngological Association member database and the American Academy of Otolaryngology-Head and Neck Surgery Neurolaryngology Study Group.

An overall response rate of 13% was achieved, with a high absolute number of physicians who manage ADSD responding (n = 37). Most respondents treat ADSD by injecting botulinum toxin type A (Botox) through the cricothyroid membrane submucosally at a mode starting dose of 2.5 units per TA muscle using electromyographic guidance with or without fibre-optic laryngoscopy every 3 to 4 months, with the frequency of reinjection being based on patient symptomatology. There is much variability with regard to starting injection dose, alternate treatments for ADSD, unilateral versus bilateral injections, and guidance technique. Most physicians (36 of 37) share one vial among more than one patient, and some (7 of 37) freeze a reconstituted vial that has remaining toxin for reuse at a later time.

There is considerable variability in treatment practices for the management of ADSD. Further study is warranted to define an optimal therapeutic paradigm.