Patient-Perceived Vocal Effort in Adductor Laryngeal Dystonia (ADLD): Order of Evaluation Tasks Matter

Objective: Adductor laryngeal dystonia (ADLD) is characterized by a strained, effortful voice. Consequently, evaluation methods often include patient perception of vocal effort. Different measures for capturing perceived vocal effort include the OMNI Vocal Effort Scale (OMNI-VES) and visual analog scales. The OMNI-VES instructs speakers to provide ratings of effort “when using their voice today”. In the original validation study, OMNI-VES scores were obtained prior to making speech recordings. Results showed that OMNI-VES scores were only weakly related to voice-related quality of life and were not related to clinician measures of voice severity. Recently, several groups have recommended that perceived vocal effort be measured immediately following a vocal activity. The purpose of this study was to examine the relationship between the OMNI-VES and a visual analog scale (VE-VAS) when both ratings were obtained immediately after a voice production task. A second purpose was to evaluate the relationships of these scales with other voice measures.

Methods: Fifty-five individuals diagnosed with ADLD (9 M, 46 F) participated. Speakers receiving Botox injections (n=52) were recorded at the end of their cycle. Immediately after providing speech recordings, speakers rated vocal effort using a 100mm visual analog scale, which included instructions to anchor their ratings to the vocal task. Speakers then completed the OMNI-VES using the standard instructions. They also completed the Voice-Related Quality of Life (V-RQOL) scale. Four experienced speech-language pathologists rated speech samples for overall severity of dysphonia using 100 mm VAS (SLP-OS).

Results: There was a strong, statistically significant correlation (r = 0.81, p < .001) between OMNI-VES scores and patient-rated vocal effort using a VAS (VE-VAS). Moderate correlations were found between patient-reported measures of vocal effort and the V-RQOL (OMNI-VES vs. V-RQOL: r = -0.43; VE-VAS vs. V-RQOL: r = -0.35). Clinician-rated measures of overall severity were similarly and moderately related to both patient-reported measures of vocal effort (r = 0.57, SLP-OS vs. OMNI-VES; r = 0.55, SLP-OS vs. VE-VAS).

Conclusions: When patient-reported measures of vocal effort are performed directly after a vocal activity, they are moderately related to voice-related quality life as well as clinician-rated measures of voice severity in ADLD.