The Mayo Clinic Spasmodic Dysphonia Experience: A Demographic Analysis of 686 Patients

Abstract

Objectives: (1) Review demographic data collected over a 23-year experience of 686 patients with spasmodic dysphonia (SD) who have been treated with onabotulinum toxinA (onaBTX-A). (2) Compare demographic trends surrounding SD with previously published data. Methods: A retrospective chart review was conducted. A total of 686 patients with SD were treated with 6345 onaBTX-A injections at Mayo Clinic Arizona between 1989 and 2013. Demographic data were compiled and analyzed. Patients were subdivided based on type of SD, presence of vocal tremor (VT), and presence of neurologic disorders. Family history of neurological disorders was also recorded. Results: In 686 patients, 432 patients were female (63.0%) and 254 patients were male (37.0%). A total of 630 patients (91.8%) were of the adductor type (AdSD) and 56 patients (8.2%) were of the abductor type (AbSD). AdSD patients noted symptom onset and began injections at an older age than AbSD patients (52.5; 60.6 years vs 43.7 years; 50.0 years, respectively). A total of 374 patients (54.5%) had VT, with 355 AdSD patients and 19 AbSD patients. A total of 45 patients (6.6%) had other movement disorders, such as blepharospasm (1.5%), torticollis (2.3%), limb dystonia (1.0%), or oromandibular dystonia (1.8%). Family history of SD was positive in 4 patients (0.6%) and of other dystonias in 9 patients (1.3%). Conclusions: Spasmodic dysphonia is a chronic and potentially disabling laryngeal dystonia resulting from disrupted motor control of the laryngeal musculature during phonation. This large series adds new insight and contributes to the current literature regarding the clinical scope and nature of SD.