Salient Voice Symptoms in Primary Muscle Tension Dysphonia

Introduction: Patients with primary muscle tension dysphonia (pMTD) commonly report symptoms of vocal effort, fatigue, discomfort, odynophonia, and aberrant vocal quality (eg, vocal strain, hoarseness). However, voice symptoms most salient to pMTD have not been identified. Furthermore, how standard vocal fatigue and vocal tract discomfort indices that capture persistent symptoms-like the Vocal Fatigue Index (VFI) and Vocal Tract Discomfort Scale (VTDS)-relate to acute symptoms experienced at the time of the voice evaluation is unclear. Finally, correlations between voice symptoms and acoustic vocal quality are poorly understood. As such, the objectives of this study were to: (1) identify the most salient pMTD symptoms, (2) correlate the VFI and VTDS with acute voice symptom severity, and (3) better understand relationships between voice symptom experiences and vocal acoustics.

Methods: Thirty subjects (15 pMTD, 15 controls) rated their vocal effort, vocal fatigue, vocal tract discomfort, odynophonia, and vocal quality on separate 100 mm visual analog scales (VAS) and completed the VFI-Part1 and VTDS. Cepstral peak prominences (CPP) were obtained from voice recordings of sustained /i/ and the all-voiced consensus of auditory-perceptual evaluation of voice (CAPE-V) sentence.

Results: Patients with pMTD reported significantly higher severities of vocal effort (P < 0.0001), fatigue (P = 0.001), and discomfort (P = 0.0008) and scored significantly higher on both vocal indices (VFI-Part1: P < 0.0001; VTDS: P = 0.0056) compared to vocally healthy controls. Both indices had medium-to-high correlations with acute symptom severities in both groups. However, there were no significant differences between groups on odynophonia severity (P = 0.349), acoustic vocal quality (/i/: P = 1.00, CAPE-V: P = 0.228) or self-perceptual vocal quality (P = 0.141). There were also no significant relationships between vocal acoustics and patient symptoms or between vocal acoustics and standard vocal fatigue and vocal tract discomfort indices (P's > 0.05).

Conclusion: Somatosensory symptoms of vocal effort, vocal fatigue, and vocal tract discomfort are the most salient clinical features in patients with pMTD. Standard voice indices that capture more chronic symptoms can also reliably capture symptoms experienced at the time of the voice evaluation in patients with pMTD. Although odynophonia and aberrant acoustic vocal quality may be present in some patients with pMTD, they do not appear to be symptoms central to the condition. Because somatosensory experiences are more salient than vocal quality and vocal acoustics in pMTD, somatosensory symptoms of vocal effort, fatigue, and discomfort should hold more weight during the voice evaluation when pMTD is suspected.