Detection of Swallow Kinematic Events From Acoustic High-Resolution Cervical Auscultation Signals in Patients With Stroke.
Atsuko Kurosu, James L Coyle, Joshua M Dudik and 1 others
PMID 30071198WHAT IT FOUND
In 35 stroke patients, several neck microphone features peaked within 0.1 seconds of key swallow X-ray events in at least 60% of swallows.
The study found timing links, not proof that the device diagnoses aspiration.
Key findings
01In 35 patients with stroke, 100 liquid swallows were analyzed; 11 swallows had aspiration and 57 had laryngeal penetration.
02Several acoustic signal features peaked within 0.1 seconds of key swallow events in at least 60% of swallows, including skewness maxima for all events.
03Lempel-Ziv complexity and entropy rate maxima were not observed within 0.1 seconds of any event, and peak frequency maxima did not meet the 60% cutoff.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
This was a preliminary analysis with 35 patients and 100 swallows, so the timing links need testing in a larger study. Patients' age, sex, and stroke lesion sites were not controlled, and these can affect swallowing and acoustic signals. The number of swallows per patient was not controlled, and exact bolus volume was not measured. Cup bolus volume, consistency, number of trials, and presentation order were set by the clinical SLP for the VFSS, not by the study. The study used only microphone signals; accelerometer signals were not compared in this report. Some swallow events could not be identified on the X-ray images and were excluded. The study found timing links between signal peaks and events, but it could not show whether a peak came from one event or from several overlapping movements. All participants were stroke patients suspected of dysphagia, so the results may not apply to healthy people or to patients without stroke.
Declared interests
The authors declared no conflicts of interest. The article metadata lists NIH extramural research support.
The easy way to misread this
Do not read the signal-event associations as evidence that cervical auscultation can replace VFSS or diagnose aspiration. This was a preliminary association study in 35 patients, and the authors say the source of the signals is unclear.