A 70-year old man comes to the office due to persistent aspiration. Two weeks ago, he had a stroke that impacted his speech, voice, and swallowing. Modified barium swallow study reveals aspiration of liquids without nasal regurgitation. Aspiration is ameliorated when the patient flexes his neck to put his chin to his chest during swallowing. This maneuver is most likely augmenting which of the following airway-protective mechanisms?
Normal swallowing involves a complex sequence of voluntary and reflexive processes that move food from the mouth to the esophagus while preventing it from entering the airway (ie, aspiration). Three main airway-protective movements occur during normal swallowing:
Displacement of the larynx superiorly and anteriorly under the base of tongue, which allows food to be directed into the more posteriorly located esophagus
Tilting of the epiglottis to block the airway
Closing of the glottis by adduction of the vocal folds
Because of the complexity of swallowing, patients who sustain strokes often have persistent dysphagia and/or aspiration. If a neurologic deficit cannot be corrected, behavioral modifications can sometimes improve the safety of swallowing. A chin-tuck maneuver (ie, flexion of the head and neck during swallowing) sometimes helps. The maneuver seems to decrease the distance from the hyoid bone to the larynx (simulating elevation of the larynx), as well as to narrow the distance of the laryngeal entrance, leading to decreased aspiration.
(Choice A) The first phase of swallowing is the oral preparatory phase, in which food is chewed and mixed with saliva to form a controlled bolus. Although impaired mastication can lead to poor bolus formation, flexion of the head and neck does not generally change the mechanics of mastication.
(Choice B) Elevation of the soft palate primarily prevents food from entering the nasopharynx rather than the larynx.
(Choice C) Contraction of the base of tongue occurs during the pharyngeal phase of swallowing and pushes the bolus posteriorly into the pharynx. Head and neck flexion could potentially worsen this function by increasing the distance that the base of tongue has to contract and by increasing the anterior force on the tongue due to gravity.
(Choice E) Although adduction of the vocal folds is an important airway-protective mechanism, head and neck flexion would not alter vocal fold movement.
Educational objective:
The most important airway-protective movements during swallowing are the anterior/superior displacement of the larynx, the tilting of the epiglottis to block the airway, and vocal fold adduction. A chin-tuck maneuver can be helpful in some patients with aspiration by simulating the airway-protective movement of the larynx.