Utility of Unified Spasmodic Dysphonia Rating Scale for Adductor Type Laryngeal Dystonia (AdLD)

The Unified Spasmodic Dysphonia Rating Scale (USDRS) was developed in 1997 to standardize evaluation of adductor-type laryngeal dystonia (AdLD) but has been sparsely utilized since then. The goal of this study was to explore the descriptive value and contemporary relevance of the USDRS in characterizing AdLD by examining its relationships with established patient-reported, clinician-perceptual, and acoustic measures.

Patients with stable-dose, botulinum toxin-A (BtxA)-responsive AdLD presented to a tertiary laryngology center for follow-up BtxA injections. USDRS, PROMs (Voice Handicap Index-10, Dyspnea Index, OMNI-Vocal Effort Scale, and Communicative Participation Item Bank-10), and voice recordings were obtained. Acoustic analysis was completed, and voice-specialized speech-language pathologists blindly rated voices using the Consensus Auditory Perceptual Evaluation-Voice (CAPE-V). Descriptive statistics compared each measurement with USDRS results.

Forty-four patients (mean age 58.4 years) were evaluated in this study. The USDRS demonstrated significantly lower variance than all other clinician- and patient-reported outcomes as well as acoustic analysis. Comparison of overall USDRS score to other outcome measures demonstrated statistically significant, positive correlations: USDRS versus VHI-10 (R = 0.451, p = 0.002), Overall Severity (R = 0.482, p = 0.004), and Strain (R = 0.487, p = 0.004), respectively.

The USDRS exhibited restricted variability relative to VHI-10, CAPE-V, and CPP-S and did not appear to add information beyond these measures; therefore, it may be limited for monitoring treatment response in AdLD patients.