Delayed initiation of the pharyngeal swallow: normal variability in adult swallows

The purpose of this investigation was to determine bolus head timing and location relations with the onset of hyoid movement at the initiation of the pharyngeal swallow and at the onset of swallow-related apnea.

Bolus head timing and location and the timing of swallow-related apnea were recorded from frame-by-frame analyses of 5-ml single liquid swallows using dual-modality videofluoroscopy and nasal airflow recordings in 82 consecutive, healthy volunteers. The presence, depth, and response to airway entry were also recorded and related to the bolus head location and the onset of hyoid movement.

The majority of participants-80% on at least 1 trial-produced the onset of hyoid movement at pharyngeal swallow initiation after the bolus head passed the posterior angle of the mandible. There was a trend in older participants for later onset of hyoid movement and onset of apnea relative to bolus head arrival at the posterior angle of the mandible.

Although entry of the bolus head into the pharynx prior to hyoid movement may result in a threat to the laryngeal airway, these data demonstrate that a "delay" by itself cannot be assumed to indicate a disordered swallow without coexisting impairments of swallowing physiology.