Differential Diagnosis of Adductor Spasmodic Dysphonia and Muscle Tension Dysphonia Using Phonatory Break Analysis

Objectives: Muscle tension dysphonia (MTD) can masquerade as adductor spasmodic dysphonia (ADSD) leading to diagnostic confusion. Intraword phonatory breaks have been offered as the sine qua non of ADSD, however, little is known regarding the presence of phonatory breaks in MTD. This investigation assessed the diagnostic worth of acoustic analysis of phonatory breaks as a possible objective test to distinguish ADSD from MTD. Study Design: Case-control comparison. Methods: Voice samples from patients with confirmed ADSD (n = 41) and MTD (n = 59) were analyzed acoustically to determine the presence, frequency, and duration of phonatory breaks-defined as complete interruption of phonation within a word. Estimates of sensitivity, specificity, positive and negative predictive value, and likelihood ratios were calculated to determine the precision and worth of phonatory break analysis as a clinical diagnostic test. Results: 1) Individuals with ADSD showed a significantly higher number of phonatory breaks as compared with MTD. 2) All measures of diagnostic precision varied according to both duration and frequency of phonatory breaks, with separation of males and females leading to different diagnostic test performance results. Conclusions: The results suggest that phonatory break analysis offers promise as an objective test to distinguish ADSD from MTD, with respectable diagnostic precision, especially among men. Automation of the acoustic analysis procedure should be explored.