Pressure and Timing Differences Between Volitional and Non-Cued Saliva Swallows Measured with Pharyngeal High-Resolution Manometry.
Maryann N Krasko, Corinne A Jones, Michelle R Ciucci and 1 others
Volitional swallows produce significantly higher pressures than non-cued saliva swallows in the velopharynx, tongue base, and upper esophageal sphincter, but not in the hypopharynx.
For SLPs reading pharyngeal manometry, the two swallow types are not interchangeable in those regions.
Key findings
1Volitional swallows generate significantly higher maximum pressure in the velopharynx (d = 0.65) and tongue base (d = 0.2907), and a higher tongue base pressure integral (d = 0.5423), than non-cued saliva swallows.
2UES post-closure pressure was higher (d = 0.4081) and nadir relaxation duration was longer (d = 0.5438) during volitional swallows, while no significant differences appeared in the hypopharynx for any measure.
3Sex and cervical vertebral size (C2-C4) did not significantly affect any pressure or timing measure, despite males having significantly larger vertebrae.
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What it does not show
The 'spontaneous' swallows may not be purely reflexive — the authors state they cannot rule out cortical involvement, so this is not a clean voluntary-versus-reflexive comparison. Saliva volume during non-cued swallows was never measured; the 2 mL bolus was chosen to approximate it, but the true volume is unknown and likely variable. Only one bolus volume (2 mL) was tested for volitional swallows, despite evidence that volume significantly affects pressure and timing. All participants were healthy with no swallowing or neurological disorders, so findings may not apply to dysphagic populations. Single-centre study; the exact reason each non-cued swallow was triggered is unknown.
The easy way to misread this
Do not read this as a clean comparison between voluntary and reflexive swallowing — the authors explicitly state they cannot establish whether the 'spontaneous' swallows involved any cortical contribution, and saliva volume was never objectively measured. The comparison is between a cued 2 mL bolus swallow and an uncued swallow of unknown volume, not between two well-defined physiological states.
Summarised by AI from the full paper, without a clinician reviewing it. Check it against the source before it changes what you do. Read it on PubMed →