| Description |
Laryngeal dystonia (LD) is a focal dystonia that affects one body part, the larynx, with symptom onset during volitional activities, such as speech production. Essential tremor of the voice (ETv) is another neurogenic voice disorder with similar clinical characteristics to LD, making differential diagnosis challenging for clinicians. We studied the potential for incorporating systematic testing utilizing a signature characteristic of dystonia, "sensory tricks." The goal of this pilot study was to compare clinical symptomatology with and without administration of sensory tricks in individuals with LD, ETv and normal controls (NC). The LD group was hypothesized to exhibit reduced speech symptomatology under all or some of the sensory trick conditions, whereas the ETv and normal control groups were expected to exhibit unchanged symptomatology under all sensory trick conditions. Five participants for each speaker group (LD, ETv, and NC) completed audio recordings of sustained phonation and connected speech tasks under four sensory conditions: 1) delayed auditory feedback (DAF), 2) vibrotactile stimulation (VTS), 3) nasoendoscopic scope placement with (ENDO+A), and 4) without (ENDO-A) topical anesthesia. Seven naïve listeners completed ratings of voice quality of the participants using a paired comparison paradigm between the control and each sensory condition. Participant self-report of vocal effort ratings and average Smoothed Cepstral Peak Prominence (CPPS) values were obtained across conditions for comparison. This study's iv preliminary findings demonstrated that LD and ETv both exhibited modified speech symptomatology under the sensory conditions. The VTS condition worsened symptoms for both voice disorder groups as indicated by CPPS measures as well as listener and vocal effort ratings. The DAF condition worsened symptomatology according to listener and vocal effort ratings; however, CPPS measures suggested improved voice quality for both voice disorder groups. The ETv group additionally demonstrated slightly greater speech aberrance during both nasoendoscope conditions based on listener ratings. Although the outcomes of this pilot study did not support the proposed hypotheses, several compelling questions were raised requiring additional research to clarify salient sensorimotor features of LD and ETv symptomatology. Current findings will guide future work investigating the clinical utility of sensory conditions to distinguish between LD and other voice disorders. |
