Oropharyngeal dysphagia in Parkinson's disease: potential utility of speech acoustic analysis in detection and evaluation of swallowing impairment progression.

Aim of the study: This study aimed to evaluate the utility of speech acoustic analysis as a tool for diagnosing dysphagia in Parkinson's disease.

Clinical rationale for the study: Swallowing impairment is a common and potentially life-threatening symptom of Parkinson's disease (PD). Fiberoptic endoscopic examination of swallowing (FEES), considered the gold standard for dysphagia diagnosis, is often inaccessible in everyday clinical practice. Many studies highlight the link between speech and swallowing impairment in PD patients. Evaluating possible correlations between speech acoustic parameters and the presence or severity of dysphagia in PD could potentially indicate speech acoustic parameters for use in a non-invasive screening tool for swallowing impairment in PD patients.

Material and methods: This study included 40 patients with a clinical diagnosis of PD aged from 36 to 82 years. The disease duration varied from 1 to 25 years. All study participants were treated with oral medications, allowing them to achieve and maintain the best possible performance status. All study participants underwent a subjective and objective neurological examination, speech acoustic analysis, which was performed based on a standardized speech recording, and FEES, according to a specific study protocol. The obtained results were analyzed statistically.

Results: The presence of oropharyngeal dysphagia was confirmed among 92.5% of the analyzed patients. The FEES findings described in this study are consistent with the specific pattern of swallowing impairment characteristic of PD. The obtained results indicate the existence of multiple statistically significant correlations between the FEES findings and speech acoustic analysis parameters. The most important speech acoustic parameters in terms of swallowing impairment evaluation include the phonation time, efficiency coefficient, average efficiency, energy modulation depth, standard deviation of the length of the interval between segments, standard deviation of the length of the intervals between segments in the speech disfluency test, unharmonic-to-harmonic ratio (U2H), Yanagihara coefficient (YG), 1/Q, residual-to-harmonic ratio (R2H), and amplitude irregularity (APQ).

Conclusions: Speech acoustic analysis could be useful in everyday clinical practice for performing non-invasive dysphagia screening tests in PD patients, especially when an endoscopic examination is unavailable. Results obtained in the study require further validation in larger cohorts. However, if confirmed, this tool could be used to identify patients who potentially require an invasive examination of swallowing for individualized dysphagia management.