Cognitive Load Contributes to Perception of Vocal Effort in Adductor Laryngeal Dystonia Patients

Vocal effort is a widely measured outcome in the treatment of laryngeal dystonia. Although it is known to be multifaceted with both physical and psychological contributors, the most frequently used vocal effort scales in laryngeal dystonia are limited to capturing its physical components. In this study, we hypothesized that the cognitive workload associated with speaking, assessed by the mental subscale of the NASA Task Load Index (NASA-TLX), would show positive correlations with the perception of vocal effort, as measured by the OMNI Vocal Effort Scale (OMNI-VES), in adductor laryngeal dystonia (ADLD) patients.

ADLD patients scheduled for Botox treatment at a single tertiary care center were identified and prospectively enrolled. Patients completed the NASA-TLX, an assessment of task-related workload with six subscales, and the OMNI-VES just prior to, 1 week following, and 4-6 weeks following Botox administration.

Twenty five patients completed measures for all timepoints. All NASA-TLX subscales, including mental demand, physical demand, temporal demand, performance, effort, and frustration, correlated with OMNI-VES (p < 0.05) on multilevel bivariate regression. On multilevel multivariate regression, both mental and physical demand correlated with OMNI-VES (p < 0.05) with coefficients of 0.036 and 0.032, respectively.

Both cognitive load and physical effort associated with speaking, as measured by the NASA-TLX, contributed to the perception of vocal effort in ADLD patients. Understanding vocal effort and its contributing factors is important to tracking and understanding ADLD treatment outcomes.