Laryngeal and Vocal Instability during Phonation and Breathing in Elderly individuals with and without Parkinson’s Disease

OBJECTIVE: To investigate the presence and the correlation of vocal tremor and laryngeal instability from the same moment in elderly individuals with and without diagnosis of Parkinson’s Disease (PD) during phonation and breathing.

METHODS: Nasolaryngoscopy recordings from 27 elderly with PD and 27 age and gender-matched controls, from an existing database were analyzed. The videos were muted and edited to isolate segments during breathing and sustained vowel phonation. The extracted audio underwent auditory-perceptual analysis to assess vocal tremor, conducted by two judges who were blinded to the subjects’ group assignments. To ensure reliability, 20% of the audio and video samples were re-evaluated, yielding consistent intra-judge agreement (Kappa > 0.8). Auditory-perceptual assessment of vocal tremor and visual evaluation of laryngeal instability were rated on a 0-2 scale, where 0 = absence, 1 = discreet presence, and 2 = evident presence. Each recorded segment (breathing/phonation) was scrutinized for the palate, base of the tongue, pharyngeal wall, arytenoids, epiglottis, and laryngeal vertical movements. Data analysis employed the Mann-Whitney test and Spearman correlation, with a significance level set at p < 0.05.

RESULTS: Compared to neurologically healthy elderly subjects, elderly individuals with PD exhibited increased instability in the pharyngeal wall (p = 0.034) and laryngeal vertical movements (p = 0.004). Comparing the moments of phonation and breathing, both groups had greater instability in the arytenoids during breathing (p < 0.001). During phonation, the PD group showed increased instability in the pharyngeal wall (p = 0.048) and laryngeal vertical movements (p = 0.038). Vocal tremor was perceived by the judges in approximately 60% of the individuals in both groups, and displayed a weak correlation with laryngeal instability in the arytenoids (p = 0.006), pharyngeal wall (p = 0.049), and vertical movements (p = 0.006).

CONCLUSION: Laryngeal and vocal instability are complex aspects. While tremor is most expected in Parkinson’s disease at rest, it remains a little understood behavior. This study, which analyzes both voice and laryngeal movement simultaneously, leads to the conclusion that despite individuals with Parkinson's disease presenting more movement in the larynx, there is no difference in their voice compared to individuals without the disease.