47.Indirect Training for the Pharyngeal Stage: UsingThermal Tactile Stimulation, Shaker Exercise, and Medical Devices

Explanation

Pharyngeal stage disorders and exercises

Disorders in the pharyngeal stage of the eating and swallowing process directly leads to aspiration and is a core problem in dysphagia.
Two problems occur during the pharyngeal stage:
(1) poor triggering of the swallowing reflex (pharyngeal swallow) and
(2) insufficient movements following the swallowing reflex.
These problems result in a time lag between transporting the bolus down into the pharynx and triggering the swallowing reflex, and this lag causes residue of the bolus in the pharynx and consequently aspiration (before, during, and after swallowing).

Explanation

Thermal tactile stimulation: Overview

Thermal tactile stimulation is a technique used to facilitate the swallowing reflex by stimulating the back of the oral cavity (particularly the anterior faucial pillars) with a lightly applied chilled stimulator.
Other names besides thermal tactile stimulation include thermal stimulation, tactical-thermal application, cold stimulation, thermal-tactile stimulation of the anterior faucial pillars, and ice massage of the throat.

Explanation

Mechanism of action and indications

Mechanism of action: The swallowing reflex is facilitated by thermal and tactile stimulation of the anterior faucial pillars and other structures of the posterior oral cavity. If a frozen cotton swab is used as the stimulator, the small amount of cold water produced by melting of the ice on contact with the mouth provides additional gustatory/chemical stimulation. Compound stimuli are more effective than a single stimulus.^1,2 Even though we still don't understand many aspects of the neurophysiological mechanism of action, these stimuli facilitate the swallowing reflex by increasing the sensitivity of sensory receptors. Another theory is that compound peripheral sensory inputs reduce the threshold for activation of the swallowing centers in the brain.
Indications: This treatment is indicated for patients with a delayed swallowing reflex. It's recommended for patients who are only having indirect training and are not yet using food, as well as patients who have started direct training.

Explanation

Specific methods

Ask patients to open their mouth. Use a chilled stimulator to stimulate the anterior faucial pillars by lightly applying pressure from the base of the pillar toward the middle, and repeat this motion several times. After stimulation, if they can follow instructions, ask them to close their mouth and dry swallow. Apply the next stimulus after the swallowing reflex.
If using this exercise in direct training, have patients take food into their mouth after applying the cold stimulus and swallow the food.
We usually apply the stimulus to the anterior faucial pillars. However, the same response occurs with stimulation of other structures, including the back of the tongue, the soft palate, and the posterior pharyngeal wall. There is no clear empirical data indicating whether the effects differ depending on the number of stimulus applications per session,² the frequency of sessions, or the duration of the training program.⁶ Adjust variables such as the location of stimulus application and the number of applications depending on each patient's response.

Explanation

Tool (stimulator)

We generally use a chilled direct laryngoscope (child's size 00) as the stimulator, but we can also use a small metal spoon with a long handle or a frozen water-filled syringe. In some cases, we can use a cotton swab dipped in water or lemon-flavored water and frozen.

Explanation

Precautions and contraindications

Thermal tactile stimulation may not be feasible in patients with a strong gag reflex because it involves stimulating the faucial pillars. Patients with a strong bite reflex may be injured if they bite on the stimulator. In either of these cases, adjust stimulus application in steps. Patients with a strong bite reflex require adjustments such as wrapping soft cushioning around the handle of the stimulatory tool.
Patients with severe dysphagia who are at high risk of aspiration and have previously aspirated saliva are highly likely to aspirate saliva during this exercise. So, provide oral care before starting the exercise to ensure good oral hygiene. Also, be sure that excess water (melted ice) doesn't enter the pharynx when using a frozen cotton swab.

Explanation

Effects

Thermal tactile stimulation can have immediate effects.^4,5 In patients with a delayed swallowing reflex, the pharyngeal stage of swallowing takes place more quickly immediately after stimulation. However, there's no clear evidence as to whether long-term training shortens swallowing reflex latency.^5,6

Explanation

Shaker exercise: Overview

Shaker exercise: An indirect training exercise proposed by the physician Reza Shaker.
Some patients with disorders in the pharyngeal stage can't lift the hyoid bone and larynx sufficiently forward and upward. This results in bolus residue in the pharynx and aspiration. The Shaker exercise is designed to reduce residue in the lower pharynx and aspiration by strengthening the suprahyoid muscles responsible for lifting the hyoid bone and larynx and promoting opening of the upper esophageal sphincter (UES).^7,8
It is also called the head raising exercise because the suprahyoid muscles are strengthened by lifting the head.

Explanation

Mechanism of action

Mechanism of action: The food bolus is transported from the pharynx down the esophagus by downward pushing of the food bolus by pharyngeal constriction and simultaneous opening of the UES. The UES (cricopharyngeus/cricopharyngeal muscle) relaxes when the swallowing reflex is triggered. In addition to this, forward and upward movement of the hyoid bone and larynx causes passive extension of the cricopharyngeus and opening of the UES. The muscle groups responsible for forward and upward movement of the larynx include the suprahyoid muscles (geniohyoid muscle, mylohyoid muscle, and the anterior belly of the digastric muscle) and the thyrohyoid muscle. These muscle groups contribute to anterior flexion of the head when the hyoid bone and larynx are held in place. Therefore, head raises performed in the supine position can be used to strengthen these muscle groups.

Explanation

Specific methods

In the supine position, patients should raise their head without lifting the feet. Ensure that they can see their toe by only using the suprahyoid muscles.
A. Isometric exercise: Patients should maintain their head in the raised position for 1 min, then lower the head and rest for another 1 min. Repeat this sequence 3 times.
B. Isotonic exercise: Patients should raise and lower their head 30 times.

Explanation

Indications, contraindications, and effects

Indications: This exercise is indicated for various groups of patients, including patients with difficulty opening the UES due to problems with lifting the hyoid bone and larynx, patients with cerebrovascular disease (supratentorial or brainstem) as their primary disease, patients who have undergone radiation therapy, and elderly patients with dysfunctions due to disuse syndrome. To determine whether the Shaker exercise is indicated, confirm insufficient lifting of the hyoid bone/larynx and associated insufficient opening of the UES by videofluoroscopy or other instrumental assessments.
Contraindications:
This exercise is contraindicated in patients with restricted neck movement due to conditions such as cervical spondylosis or having an endotracheal tube. Because this exercise stresses the body, patients with concurrent hypertension or heart disease require risk management as is done for physical therapy.
Effects:
Shaker et al. randomly assigned 27 patients to either a group undergoing the Shaker exercise or a group with a sham exercise. They found that the Shaker exercise resulted in significant improvement in the UES opening, laryngeal elevation, and functional evaluation of swallowing.^7,8

Explanation

Other methods for strengthening suprahyoid muscle activity

Other training methods similar to the Shaker exercise have been proposed to strengthen the suprahyoid muscles to promote laryngeal elevation and UES opening.

1) Neck muscle strengthening by digital manipulation
Objective: To strengthen the neck muscles by anterior flexion of the head against resistance applied by digital manipulation
Methods: Have patients seated, while the therapist stands behind them. To apply resistance, the therapist places both their hands on the forehead of the patients and pulls their head backward. The patients then perform isometric or isotonic exercises against this resistance.
Evidence: Sugiura et al. found that this exercise improved hyoid elevation and reduced aspiration in 2 patients who had undergone surgery for head and neck tumors.⁹
Contraindications: Patients who should avoid neck strain due to a condition such as cervical spondylosis or having an endotracheal tube

2) Chin tuck against resistance (CTAR) exercise
Objective: To strengthen the suprahyoid muscles by anterior flexion of the head against resistance.
Methods: Place a rubber ball between the chin and sternum and instruct patients to press the rubber ball against the sternum with their chin.
Evidence: One study showed that the CTAR exercise stimulated suprahyoid muscles more specifically than the head raising exercise.¹⁰

3) Jaw opening exercise
Objective: To strengthen suprahyoid muscle activity by mouth-opening movements.
Methods: Have patients hold a maximal mouth opening position for 10 s and rest for 10 s. The patients repeat this sequence 5 times in a set. Perform 2 sets per day.¹¹
Evidence: Wada et al. found that upward displacement of the hyoid bone, the amount of the UES opening, and pharyngeal transit time improved significantly after 1 month of training in 8 patients with dysphagia.
Contraindications: Contraindicated in patients with a history of temporomandibular joint dislocation.

Explanation

Electrical stimulation therapy

This method is designed to strengthen relevant motor functions by excitation of nerves and muscles using an electrical current passed through the body. Various methods for using this therapy for dysphagia have been proposed and commercialized.

1) Therapeutic electrical stimulation (TES) of the suprahyoid muscles Electrical stimulation is used to strengthen muscles involved in the hyoid and laryngeal elevation.
Indications: Patients who have difficulties in elevating the hyoid bone and/or larynx due to cerebrovascular diseases and other reasons.
Methods: Electrical stimulation is delivered to the suprahyoid muscles (anterior belly of the digastric muscle/mylohyoid muscle and geniohyoid muscle) or the thyrohyoid muscle through the surface electrodes placed on the skin over the target muscles. Electrical stimulation can be applied at rest or timed to the triggering of the swallowing reflex.
Contraindications: Caution must be taken when using this method in patients with growing tumors or patients with an implanted electrical device such as a pacemaker.
Effects: A certain number of studies have shown that this method is effective.¹² However, various issues have also been pointed out, including that stimulation of the suprahyoid muscles is challenging due to their deep location from the skin, and that electrical stimulation is likely to activate the infrahyoid muscles as well due to their close anatomical locations.¹³
Devices with a biofeedback function in combination with electromyography are also commercially available.

Explanation

Interferential current (IFC) devices
Stimulation at the sensory threshold level is performed by applying low-frequency interferential current at the body's surface to stimulate the nerves involved in swallowing . The objective is to facilitate the swallowing reflex by lowering the reflex threshold.

Indications: Patients with dysphagia with lesions/impairments in the central nervous system, such as cerebrovascular diseases, neuromuscular diseases, etc. are the candidates.
Effects: One study showed an immediate improvement in the pharyngeal stage of swallowing in patients with dysphagia following stroke and Parkinson's disease,¹⁴ and a randomized controlled study showed increased food intake and improved cough reflex.¹⁵

References

1. Sciortino K, Liss JM, Case JL, Gerritsen KG, Katz RC :Effects of mechanical, cold, gustatory, and combined stimulation to the human anterior faucial pillars, Dysphagia18(1) : 16-26 , 2003.
2. Kaatzke-McDonald MN, Post E, Davis PJ: The effects of cold, touch, and chemical stimulation of the anterior faucial pillar on human swallowing, Dysphagia, 11(3): 198-206, 1996.
3. Rosenbek JC, Roecker EB, Wood JL, Robbins J: Thermal application reduces the duration of stage transition in dysphagia after stroke, Dysphagia 11(4): 225-33, 1996.
4. Lazzara G, Lazarus C, Logemann JA: Impact of thermal stimulation on the triggering of the swallowing reflex, Dysphagia, 1 (2):73-77, 1986.
5. Rosenbek JC, Robbins J, Fishback B, Levine RL :Effects of thermal application on dysphagia after stroke, J Speech Hear Res, 34(6): 1257-68, 1991.
6. Rosenbek JC, Robbins J, Willford WO, Kirk G, Schiltz A, et al :Comparing treatment intensities of tactile-thermal application, Dysphagia 13(1):1-9, 1998.
7. Shaker R, Kern M, Bardan E, et al: Augmentation of deglutitive upper esophageal sphincter opening in the elderly by exercise: Am J Physiol,272(35): 1518-1522. 1997.
8. Shaker R, Easterling C, Kern M, et al: Rehabilitation of swallowing by exercise in tube-fed patients with pharyngeal dysphagia secondary to abnormal UES opening, Gastroenterology,122: 1314-1321. 2002.
9. Sugiura J, Fujimoto Y, Ando A et al. Effects of manual muscle strengthening exercise on swallowing function in post-operative head-neck cancer patients with dysphagia. The Japanese Journal of Dysphagia Rehabilitation 12 (1):69-74,2008.
10. Wai Lam Yoon ,Jason Kai Peng Khoo,Susan J. Rickard Liow : Chin Tuck Against Resistance (CTAR): New Method for Enhancing Suprahyoid Muscle Activity Using a Shaker-type Exercise. Dysphagia 29:243-248, 2014.
11. Wada S, Tohara H, Iida T et al: Jaw-Opening Exercise for Insufficient Opening of Upper Esophageal Sphincter, Arch Phys Med Rehabili, Vol(93):1995-1999,2012.
12. Carnaby-Mann GD, Crary MA : Examining the evidence on neuromuscular electrical stimulation for swallowing: a meta-analysis, Arch Otolaryngol Head Neck Surg, 133: 564-571, 2007.
13. Ludlow CL, Humbert I, Saxon K, et al : Effects of surface electrical stimulation both at rest and during swallowing in chronic pharyngeal dysphagia, Dysphagia, 22: 1-10, 2007.
14. Sugishita S, Imai T, Matui T, et al: Effects of Short Term Interferential Current Stimulation on Swallowing Reflex in Dysphagic Patients, International Journal of Speech & Language Pathology and Audiology 3:1-8,2015.
15. Maeda K, Koga T, Akagi J: Interferential current sensory stimulation through the neck skin improves airway defense and oral nutrition intake in patients with dysphagia : a double-blind randomized controlled trial, Clin Interv Aging,12:1879-86, 2017.

Recommended readings

1. Logemann JA: Evaluation and Treatment of Swallowing Disorders 2^nd ed. Pro-ed, Austin, Texas, 1998, pp.210-214.
2. The Society of Japanese Clinical Dysphagia Research:Rehabilitation for Dysphagia - Think and Practice 2^nd ed. Ishiyaku Publishers, Tokyo, 2008, pp.229-234.
3. Dysphagia Team of Seirei:Pocket Manual of Dysphagia 2^nd ed. Ishiyaku Publishers, Tokyo, 2003, pp.59-122.
4. Saitoh E, Ueda K:Dysphagia Rehabilitation 3^rd ed. Ishiyaku Publishers, Tokyo, 2016.