Aerodynamic-induced Effects of Artificial Subglottic Stenosis on Vocal Fold Model Phonatory Response.
Benjamin A Hilton, Scott L Thomson
PMID 36496305WHAT IT FOUND
Aerodynamic effects of subglottic stenosis on voice remain minimal until obstruction exceeds 80 to 90 percent.
Grade I and II stenoses likely do not alter voice quality through airflow changes alone. Clinical voice issues at lower grades may stem from other factors.
Key findings
01Onset sub-stenosis pressures remained consistent until 80 to 90 percent obstruction, then increased sharply, with the highest obstruction requiring 34 to 56 percent more pressure than the baseline.
02High-frequency noise components became significant by 80 percent obstruction, while fundamental frequency and flow resistance only showed significant changes beyond 80 to 90 percent obstruction.
03The study suggests that Grade I and Grade II stenoses (0 to 70 percent obstruction) are unlikely to introduce aerodynamic disturbances sufficient to alter phonatory output.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study used synthetic silicone models, which do not replicate human tissue properties or the dynamic changes in stiffness that may occur with real stenosis. The device could not test obstructions below 36 percent due to material deformation, leaving lower-grade stenoses unexamined in this specific setup. Vibration of the stenotic sleeve itself was not quantified, though the authors expected it to be minor. There was variability between the three model pairs, and some fatigue or deformation occurred during the long testing sessions. The study isolated aerodynamic effects, ignoring other potential contributors to voice change like laryngeal inflammation or surgical scarring.
Declared interests
No conflicts of interest or funding sources were reported in the provided text.
The easy way to misread this
Do not assume that Grade I or Grade II subglottic stenosis causes voice changes purely through aerodynamic obstruction. This study suggests that significant aerodynamic effects on voice only occur at very high obstructions (above 80 percent), so mild voice symptoms in lower-grade stenosis likely have other causes.