Acoustic Correlation with Dysphagia in Stroke Patients

Swallowing disorder or dysphagia is one of the common functional disorders in stroke survivors, and its early screening is important for reducing patient dependence, pneumonia incidence, mortality, and shortening the hospital stay. However, the commonly used methods to examine dysphagia, which include Toronto bedside swallowing screening test, volume viscosity swallowing test, and swallowing angiography screening/examination, are all invasive with the risk of aspiration. Here we have undertaken a detailed voice analysis on stroke patients with dysphagia by monitoring a series of acoustic parameters including maximum volume, maximum pitch, glottal noise excitation ratio, fundamental frequency perturbation, amplitude perturbation (Shimmer), maximum pronunciation time, irregularity, breath sound, overall severity, and voice disorder severity index. We show that all these acoustic parameters change significantly for the stroke patients with dysphagia compared with the healthy group as well as stroke group with no dysphagia, and the changes are correlated with the severity of pharyngeal residue especially for Shimmer and overall severity of the voice. Our findings suggest that voice analysis, which is quick and non-invasive, may give an important initial indication on the severity of dysphagia and cross-validate results from swallowing tests that clinicians may further pursue for a thorough diagnosis of dysphagia.