Identification of symptoms for spasmodic dysphonia and vocal tremor: a comparison of expert and nonexpert judges

Spasmodic dysphonia is a rare voice disorder that is most successfully treated by injection of botulinum toxin (i.e., BOTOX) into the affected laryngeal muscles. BOTOX is currently available for use by professionals outside of metropolitan voice centers who may be unfamiliar with this rare disorder. Patients may seek assessment and treatment locally from clinicians who are unfamiliar with the speech symptoms for adductor-type (ADSD) or abductor-type (ABSD) spasmodic dysphonia. Although these disorders have been described in the literature, the symptoms have not been well defined and may appear similar to those of vocal tremor or muscle tension dysphonia (MTD). Thus, patients with spasmodic dysphonia might not be easily identified by local clinicians for treatment. The purpose of the current study was to determine whether voice clinicians with infrequent exposure to patients with spasmodic dysphonia could learn to identify speech symptoms for ADSD and ABSD comparable to voice clinicians with extensive experience with these disorders. The ratings of five nonexpert judges were compared to the ratings obtained from three expert judges. The results of this study demonstrated that nonexpert judges could be trained to identify the speech symptoms associated with ADSD, ABSD, and vocal tremor. While the nonexpert judges tended towards false positive judgements for the speech symptoms of interest, the overall speech symptom profiles for each type of voice disorder appeared comparable to those obtained from the expert judges. The symptom identification scales used, therefore, have potential for use by clinicians unfamiliar with these disorders for correctly identifying persons with symptoms of ADSD and ABSD. Educational objectives: Readers will be able to (1) define the predominant speech symptoms reflective of the voice disorder categories of ABSD, ADSD, and vocal tremor; and (2) describe the methods utilized in a new perceptual training protocol for teaching clinicians how to identify predominant speech symptoms associated with the voice disorder categories of ABSD, ADSD, and vocal tremor.