Spasmodic dysphonia (SD) can be difficult to diagnose, and affected patients often see multiple physicians over many years before receiving a correct diagnosis.
In this study, questionnaires were sent to physicians who examined and treated patients with SD over a one-year period from 2012 to 2013. The questions included the number of SD patients seen within the past year, the characteristics of the disorder (medical history, symptoms and laryngeal findings) and the differential diagnosis. The questionnaires were sent to 91 university hospitals and voice clinics nationwide, of which 55 facilities (60.4%) responded.
The findings of the investigation are summarized below.
The total number of patients seen within the past one year was 894. Adductor SD was confirmed in 856 patients (95.7%), while abductor SD was detected in 37 patients (4.1%). The ratio of the adductor SD to abductor SD was consistent with that found in the literature. The results in this study revealed several common characteristic findings in the medical history, symptoms and laryngeal findings of the patients. In particular, the presence of hyperfunctional dysphonia, psychogenic dysphonia, and essential tremors should be used to distinguish SD. Assessing such characteristics may improve the ability to accurately diagnose SD. In addition, the use of screening questions, voice therapy, and lidocaine block were reported as differential diagnosis methods in this study.