PMC10468693_01
VFSS in Case 2 showing the oral preparatory (left) and pharyngeal (right) phases.
Black arrow indicates dorsum of the tongue; white arrow indicates posterior wall of
the pharynx. In the pharyngeal phase, the dorsum of the tongue was pulled downward and
backward to press against the posterior wall of pharynx and to close the
hypopharyngeal space.
prm-8-20230026-g001.jpg
PMC10468693_01_prm-8-20230026-g001.jpg
fig_001
In all cases, the tongue was elevated in the oral phase and the dorsum of the tongue was pulled inferoposteriorly to contact and press against the posterior wall of the pharynx to generate positive pressure, propelling the bolus into the upper esophagus in the pharyngeal phase as previously reported as compensatory behavior (Fig. 1 showing Case 2).,,) No pharyngeal residue was observed in each case.
Definition of onset and completion of volitional swallowing according to
swallow-related muscle activities in Case 2. M0 is defined as the time of the first
electromyographic activity upon initiating swallowing, M1 is the time at which the
main muscles are activated, and M2 is the time to return to baseline.
prm-8-20230026-g002.jpg
PMC10468693_01_prm-8-20230026-g002.jpg
fig_002
In all cases, the tongue was elevated in the oral phase and the dorsum of the tongue was pulled inferoposteriorly to contact and press against the posterior wall of the pharynx to generate positive pressure, propelling the bolus into the upper esophagus in the pharyngeal phase as previously reported as compensatory behavior (Fig. 1 showing Case 2).,,) No pharyngeal residue was observed in each case. We defined the onset of swallowing (E1) as M1-0.4 s and the completion of swallowing as M2 to analyze the event-related EEG signals (Fig. 2), as in previous studies.,,) The time intervals were determined as follows: