44.Training for velopharyngeal closure, pharyngeal constriction, and laryngeal closure

Explanation

Velopharyngeal closure, pharyngeal constriction, and laryngeal closure are particularly important in the series of movements that occur during the pharyngeal stage of swallowing. As such, impairment of these functions causes various problems, including aspiration. In this module, we look at exercises to address velopharyngeal insufficiency, poor pharyngeal constriction, and impaired laryngeal closure, and cover the theoretical foundations of those exercises and how to perform them. We also cover points to note when performing these exercises because there are some techniques that are widely known as exercises for training local muscle groups but actually have little evidence of any effect on swallowing.

Explanation

Velopharyngeal closure (VPC) during swallowing refers to the movement in the pharyngeal stage､ during which the soft palate and superior pharyngeal constrictor muscles contract, resulting in the tight contact between the two structures. VPC obstructs the passageway between the nasal cavity and pharynx. Impairment of this movement is believed to cause regurgitation of bolus into the nasal cavity. As we can see in the figure, when a healthy person swallows, the base of tongue and the pharyngeal wall approach each other at the top the bolus as it enters the pharynx, and help to propel the bolus downward. Therefore, regurgitation of the bolus into the nasal cavity is not always caused by the impaired soft palate movement, but rather can be caused by insufficient contact between the base of the tongue and the pharyngeal wall.¹

The velopharynx closes not only during swallowing but also during sucking, blowing, vomiting, and speech production, which is why non-swallowing movements have been traditionally used for the purpose of improving VPC during swallowing. However, much still remains unclear how much VPC improvement during swallowing can be expected when the muscles of the soft palate and pharynx are strengthened by repeated non-swallowing movements.

Explanation

Here we see the main exercises that engage muscles involved in velopharyngeal closure. Note, however, that there is still little evidence that any training exercises for VPC during non-swallowing movements improve VPC during swallowing. Also note that speech production is rarely used in swallowing training because speech production does not demand VPC as strong as needed for swallowing,² and the movement pattern of the soft palate during speech is reported to be different from that during swallowing.³ Because of this, speech production exercises are not included in this list.

Explanation

1. Continuous positive airway pressure (CPAP)²
One resistance exercise technique adapts CPAP, a treatment for sleep apnea syndrome, to VPC training. One protocol proposed consists of a continuous 8-week training program where resistance to muscles involved in VPC is gradually increased by continuously sending positive airway pressure through the nose using a CPAP device.⁴ This method has been shown to be effective in increasing muscle strength.^4,5

Explanation

Here we see VPC exercises that are performed by blowing air or using the arms in pushing and pulling movements.⁶ These exercises are widely used because their incorporation of everyday movements makes them easy to perform, although there is some doubt over whether they actually improve VPC during swallowing.

Nevertheless, blowing (exhaling through the mouth) serves as practice to improve respiratory function and intraoral pressure, and pushing and pulling promote laryngeal closure (as explained later), so they may be effective depending on the purpose of training. However, blowing exercises can cause hyperventilation if overdone. Also, exercises that involve exertion of considerable force should be performed with care in patients with hypertension or heart disease because they can cause blood pressure to increase.

Explanation

One method that promotes muscle contraction through icing of the soft palate. It is an adaptation of Nishio's method for facilitating neuromuscular function by icing.⁷

Ask patients to open their mouth wide, place a frozen cotton swab or ice stick against the soft palate to stimulate it, and ask them to voluntarily lift the soft palate after the stimulation. This method was originally designed to improve VPC during speech production, but it is believed to be applicable to swallowing as well if patients swallow rather than speak after soft palate stimulation. The optimal number of repetitions and frequency of training are unclear, but Nishio's program consisted of 5-10 repetitions per session, 2-3 sessions per training day, and 5 training days per week. This method is contraindicated in patients who have a strong gag reflex or are hypersensitive to cold.

Explanation

The pharyngeal wall plays 3 roles in the pharyngeal stage of swallowing. Particularly importantly, pharyngeal constriction (i.e., contact between the base of the tongue and the pharyngeal wall) is the source of swallowing pressure. Insufficient contact between these 2 structures prevents generation of enough force to push the bolus downward, which leads to retention of the bolus in the pharynx (reduced pharyngeal clearance), aspiration, and regurgitation.

Explanation

The pharyngeal constrictor muscles are not voluntary muscles, which is why it was long believed that they could not be targeted in intentional constricting exercises. So, in traditional practice, soft palate-lifting exercises were mainly performed to address velopharyngeal insufficiency, and tongue-retracting exercises were mainly performed to address insufficient contact between the base of the tongue and the pharyngeal wall. Today though, the tongue-hold swallow has been proposed as a potential way to improve movement of the pharyngeal wall (i.e., increased anterior bulging of the pharyngeal wall on videofluorographic examination of swallowing).^8,9 The tongue-hold swallow is performed by swallowing while holding the anterior portion of the protruded tongue between the anterior teeth. Other names for this exercise include the tongue-hold maneuver and Masako maneuver. Unfortunately, there are still no exercises that can facilitate continuous downward constriction of the pharyngeal wall.

Explanation

When we compare the lateral view of the videofluorographic images with and without the tongue-hold (normal swallow vs. tongue-hold swallow), we can see increased anterior bulge of the pharyngeal wall during the tongue-hold swallow. The tongue-hold swallow, in which a person swallows while holding the tongue between the anterior incisors, works to pull the pharyngeal wall out anteriorly. As such, repetition of this maneuver as an exercise can be expected to improve pharyngeal wall movement. However, no data have been obtained about the therapeutic effects of this exercise or the optimal dose of the exercise.

The tongue-hold swallow, which inhibits tongue movement, should be done only for training purposes, and not for eating and drinking purposes. When performing and teaching this exercise, we need to take due care to ensure that patients understand the purpose correctly.⁹

Explanation

Laryngeal closure during the laryngeal stage of swallowing is a strong protective function which happens at 3 levels: the epiglottic, the supraglottic, and the glottic levels. The supraglottic level refers to the closure of the laryngeal vestibule, which appears as contact between the base of the epiglottis and the arytenoid cartilage on lateral videofluorographic images during swallow evaluation.

Explanation

Closure at the epiglottic level occurs through inversion of the epiglottis. However, the epiglottis is not a structure that actively inverts.¹⁰ In reality, movements of the surrounding structures are essential to epiglottic inversion. To promote epiglottic inversion during the pharyngeal stage of swallowing, we need exercises that promote retraction of the base of the tongue, anterior movement of the hyoid bone, elevation of the larynx, and contact between the base of the tongue and the pharyngeal wall to generate swallowing pressure (i.e., to create the force that propels the food bolus downward). Refer to other applicable modules of this e-learning program for more specifics about these exercises.

Explanation

Closure of the supraglottic space (laryngeal vestibule) is the most robust and important level of laryngeal closure. Even if the epiglottis does not invert, aspiration will not occur if supraglottic space closure is sound.

The following closing exercises (1) to (3) should be repeated for about 5 minutes at a time, 5-10 times per day.¹

Hold the breath for 1 s, exert force, and exhale.
Push down on the chair you are sitting on and exhale while maintaining that force for a few seconds.
Then, pull up on the chair and exhale while maintaining that force for a few seconds.

These exercises require exerting a large amount of force, so we must carefully consider their suitability in patients with hypertension or heart disease. Laryngeal lifting exercises must also be performed if the insufficient closure at the supraglottic level is due to reduced laryngeal elevation.

Explanation

Vocal exercises to promote coming together (adduction) of the vocal cords are used in training for closure at the glottic level.¹

Exercises (1) and (2) below should be performed in sets of 3 repetitions, 5-10 times per day.

While using one hand to push down on the chair you are sitting on, make an "aah" sound in as clear of a voice as possible 5 times.
Next, make an "aah" sound while forcing the vocal cords together (glottal stop) 5 times.

Another option is to do vocal exercises while doing the pushing/pulling movements on velopharyngeal closure exercises described earlier. To give an example, one exercise involves sitting in a chair and making a continuous vocalization while using both hands to pull up on the chair. At first, a strong "aah" sound should be made with a glottal stop, and next it should be made in as clear of a voice as possible 5-10 times. Finally, an exercise involving taking a deep breath, holding it, and then coughing as strongly as possible should be added. This exercise should also be repeated 5-10 times.

References

1. Michi K, Michiwaki Y (translation):Logemann Swallowing Disorders. Japanese translated version of Evaluation and treatment of swallowing disorders. Ishiyaku Publishers, p26, 2000.
2. Nishi M. Standard textbook in dysarthria. Ishiyaku Publishers, p156-158, 2007 (Japanese).
3. Tachimura T: Velpharyngeal dysfunction. Pathophysiology, diagnosis, treatment. Ishiyaku Publishers, pp105-107, 2012 (Japanese).
4. Kuehn, D. P. & Moon, J. B.: Levator veli palatine muscle activity in relation to intraoral air pressure variation.Journal of Speech, and Hearing Research, 37, 1260-1270, 1994.
5. Hara H, Tachimura T, Koh H, Morimoto C, Hirata S, Yoneda M, Wada T: Change in Nasalance by Continuous Positive Airway Pressure (CPAP) Therapy for Hypernasal Speech (Japanese), Journal of Japanese Cleft Palate Association, 23:28-35, 1998.
6. Medical review committee of Japanese Society of Dysphagia Rehabilitation: Summary of swallowing treatment 2014ver (Japanese) . The Japanese Journal of Dysphagia Rehabilitation 18(1):55-89, 2014.
7. Nishio M: Principle and practice : Vol. 3. Interuna Publishers, p81-822006 (Japanese)
8. Fujiu, M., Logemann, J. A. & Pauloski, B. R.:Increased postoperative posterior pharyngeal wall movement in patients with anterior oral cancer: Preliminary findings and possible implications for treatment.American Journal of Speech-Language Pathology, 4, 24-30,1995.
9. Fujiu, M., & Logemann, J. A.:Effect of a tongue-holding maneuver on posterior pharyngeal wall movement during deglutition. American Journal of Speech-Language Pathology, 5, 23-30, 1996.
10. Kaneko T (translation):UPDATE of swallowing mechanism. Japanese translated version of Clinical anatomy & physiology of the swallow mechanism, Ishiyaku publishers, pp58-62, 2006.

Recommended reading

1. Saitoh E & Ueda K eds:Dysphagia Rehabilitation 3rd edition. Ishiyaku Publishers, 2016.