Change in Time-to-laryngeal-vestibule-closure Thin Liquids
Post treatment (4 weeks) compared to pre-treatment baseline
The time interval (in milliseconds) measured on a videofluoroscopic x-ray of swallowing between onset of the hyoid burst movement at the beginning of a swallow and achieving airway protection via closure of the laryngeal vestibule. The investigators will measure time-to-laryngeal-vestibule-closure across a series of 3 thin liquid swallows in videofluoroscopy. The participant's worst score (i.e. longest) across these 3 task repetitions will be recorded at each timepoint and the difference across timepoints will be calculated.
Change in Penetration-Aspiration Scale Score Thin Liquids
Post treatment (4 weeks) compared to pre-treatment baseline
The Penetration-Aspiration Scale is an 8-point ordinal scale, measured on a videofluorosopic x-ray of swallowing, which documents the depth of any airway invasion events, and the subsequent response to airway invasion (Rosenbek et al., 1996). The scale ranges from a minimum score of 1 (no airway invasion) to a maximum score of 8 (entry of material below the true vocal folds with no response and no ejection). Higher scores are worse. The investigators will measure penetration-aspiration across a series of 3 thin liquid swallows in videofluoroscopy. The participant's worst score (i.e. highest) across these three task repetitions will be recorded at each timepoint and the difference across timepoints will be calculated.
Change in Pharyngeal Area at Maximum Constriction Thin Liquids
Post treatment (4 weeks) compared to pre-treatment baseline
A videofluoroscopic measure of the degree of pharyngeal constriction during swallowing (i.e. maximum obliteration of the space in the pharynx). This measure is obtained from pixel-based measures of the unobliterated area of the pharynx on a lateral view x-ray image at the point of maximum constriction. The number of pixels is divided by an anatomical reference scalar defined by the squared length of the distance, in pixels, between the anterior inferior corners of the C2 and C4 cervical vertebrae on the same image. The investigators will measure pharyngeal area at maximum constriction across a series of 3 thin liquid swallows in videofluoroscopy. The participant's worst score (i.e. largest) across these three task repetitions will be recorded at each timepoint and the difference across timepoints will be calculated.
Change in Total Pharyngeal Residue Thin Liquids
Post treatment (4 weeks) compared to pre-treatment baseline
A videofluoroscopic measure of the amount of residue left behind in the pharynx after a swallow. This measure is obtained from pixel-based measures of the area of residue in the pharynx on a lateral view x-ray image at the end of the swallow. The number of pixels is divided by an anatomical reference scalar defined by the squared length of the distance, in pixels, between the anterior inferior corners of the C2 and C4 cervical vertebrae on the same image. The investigators will measure pharyngeal residue across a series of 3 thin liquid swallows in videofluoroscopy. The participant's worst score (i.e. largest) across these three task repetitions will be recorded at each timepoint and the difference across timepoints will be calculated.
Change in Time-to-laryngeal-vestibule-closure Mildly Thick Liquids
Post treatment (4 weeks) compared to pre-treatment baseline
The time interval (in milliseconds) measured on a videofluoroscopic x-ray of swallowing between onset of the hyoid burst movement at the beginning of a swallow and achieving airway protection via closure of the laryngeal vestibule. The investigators will measure time-to-laryngeal-vestibule-closure across a series of 3 mildly thick liquid swallows in videofluoroscopy. The participant's worst score (i.e. longest) across these 3 task repetitions will be recorded at each timepoint and the difference across timepoints will be calculated.
Change in Penetration-Aspiration Scale Score Mildly Thick Liquids
Post treatment (4 weeks) compared to pre-treatment baseline
The Penetration-Aspiration Scale is an 8-point ordinal scale, measured on a videofluorosopic x-ray of swallowing, which documents the depth of any airway invasion events, and the subsequent response to airway invasion (Rosenbek et al., 1996). The scale ranges from a minimum score of 1 (no airway invasion) to a maximum score of 8 (entry of material below the true vocal folds with no response and no ejection). Higher scores are worse. The investigators will measure penetration-aspiration across a series of 3 mildly thick liquid swallows in videofluoroscopy. The participant's worst score (i.e. highest) across these three task repetitions will be recorded at each timepoint and the difference across timepoints will be calculated.
Change in Pharyngeal Area at Maximum Constriction Mildly Thick Liquids
Post treatment (4 weeks) compared to pre-treatment baseline
A videofluoroscopic measure of the degree of pharyngeal constriction during swallowing (i.e. maximum obliteration of the space in the pharynx). This measure is obtained from pixel-based measures of the unobliterated area of the pharynx on a lateral view x-ray image at the point of maximum constriction. The number of pixels is divided by an anatomical reference scalar defined by the squared length of the distance, in pixels, between the anterior inferior corners of the C2 and C4 cervical vertebrae on the same image. The investigators will measure pharyngeal area at maximum constriction across a series of 3 mildly thick liquid swallows in videofluoroscopy. The participant's worst score (i.e. largest) across these three task repetitions will be recorded at each timepoint and the difference across timepoints will be calculated.
Change in Total Pharyngeal Residue Mildly Thick Liquids
Post treatment (4 weeks) compared to pre-treatment baseline
A videofluoroscopic measure of the amount of residue left behind in the pharynx after a swallow. This measure is obtained from pixel-based measures of the area of residue in the pharynx on a lateral view x-ray image at the end of the swallow. The number of pixels is divided by an anatomical reference scalar defined by the squared length of the distance, in pixels, between the anterior inferior corners of the C2 and C4 cervical vertebrae on the same image. The investigators will measure pharyngeal residue across a series of 3 mildly thick liquid swallows in videofluoroscopy. The participant's worst score (i.e. largest) across these three task repetitions will be recorded at each timepoint and the difference across timepoints will be calculated.