The Mayo Clinic Arizona Spasmodic Dysphonia Experience: A Demographic Analysis of 718 Patients

Objective: Analyze demographic data collected over a 25-year experience of 718 patients with spasmodic dysphonia (SD) who have been treated with botulinum toxin-A (BoNT-A) and compare our data with previously published studies. Methods: Seven hundred eighteen patients with SD were treated with 6621 BoNT-A injections at Mayo Clinic Arizona between 1989 and 2014. All patients were treated by the same physician team. Background demographic data for each patient were recorded. Results: Of 718 patients, 557 patients were female (77.6%). Six hundred sixty of 718 (91.8%) patients had adductor SD (AdSD), and 58 of 718 (8.1%) patients had abductor SD (AbSD). Average age of onset was 51 years. Of 718 patients, 378 (52.6%) had vocal tremor (VT); VT was present in 54.4% of AdSD patients and 32.1% of AbSD patients. Thirty-seven of 718 (5.2%) patients had other dystonias, including cervical dystonia (2.3%), blepharospasm (1.4%), limb dystonia (1.1%), and oromandibular dystonia (0.3%). A positive family history of SD was present in only 6 of 718 patients (0.8%) and of other dystonias in 11 of 718 patients (1.5%). Conclusions: Spasmodic dysphonia is a chronic and potentially disabling focal laryngeal dystonia. The Mayo Clinic Arizona SD experience compares to prior reports and reveals a female preponderance, onset in middle age, infrequent hereditary pattern, high co-occurrence of VT, and low co-occurrence of other dystonias.