Differential diagnosis of adductor-type spasmodic dysphonia, vocal tremor, and muscle tension dysphonia

Individuals with vocal tremor or muscle tension dysphonia may exhibit symptoms similar to those with adductor-type spasmodic dysphonia, and vice versa. Incorrect diagnosis of these disorders may lead to inappropriate treatment choices that delay relief of an individual's symptoms. Current methods for diagnosis of muscle tension dysphonia, adductor-type spasmodic dysphonia, and vocal tremor use perceptual judgments across such parameters as phonatory breaks during speech, stability of voice during sustained voicing, and observation of laryngeal behaviors with imaging. The search for objective measures to differentiate these disorders has not met with success. Recent investigations demonstrate promise for developing quantifiable diagnostic methods using acoustic and aerodynamic evaluation of patients. Imaging techniques may also be quantified using an examination protocol implemented to elicit laryngeal behaviors typical for each of these voice disorders. This article discusses the the findings of quantitative methods used to differentiate adductor-type spasmodic dysphonia, muscle tension dysphonia, and vocal tremor from each other or from normal controls.