43.Oral Motor Training

Explanation

The aim of this module;

1. Learners can understand how the oral moto training is important.
2. Learners can understand the oral motor training techniques.

In this module, we cover the significance of oral motor training as an element of indirect training, as well as the techniques used in oral motor training. Many of the techniques conventionally used in indirect training were not based on sufficient evidence. This led to many practitioners using exercises for the mouth and other such classical training techniques with little supporting evidence that run counter to the theory of exercise physiology. However, training to improve neuromuscular function must be based on such theory, namely, the 3 major principles of overload, specificity, and reversibility and the 5 major general rules of progression, comprehensiveness, awareness, individuality, and continuity (repeatability).

Although there is still insufficient evidence today, some evidence has been accumulated recently. Also, very little high-quality research was conducted on the association between the effects of oral function training and swallowing function in the past, but recent studies are now showing that oral function training does promote improvement in swallowing function. Most techniques for oral motor training were developed to treat dysarthria (Murry et al., 2006), so technical books on dysarthria are very useful references on techniques for oral motor training

Explanation

The mouth is the entrance to the digestive tract. It is an internal cavity enclosed by the lips at the anterior aspect, the cheeks on the exterior, the hard and soft palates at the superior aspect, and the tongue and interior surface of the mandible at the inferior aspect. At the posterior aspect, it connects to the pharynx via the fauces. Oral motor training primarily refers to training of the tongue, lips and cheeks (lower part of the face), and mandible.

Impairments in oral structures cause impairment in the preparatory and oral stages of the 5-stage model of eating and swallowing. Specifically, they cause difficulties with taking food or drink into the mouth, mastication, bolus formation, bolus retention, and bolus transport, and these difficulties can cause aspiration and choking. So, oral motor training is primarily aimed at improving voluntary motor functions involved in the actions that occur from the mouth to the pharynx, including those actions mentioned above.

Tooth loss and poorly fitted dentures can also cause difficulties with mastication and bolus formation, but these problems require dental treatment. We do not cover such treatments in this module.

Explanation

Here is key evidence of the effects of tongue training. Robbins et al. (2005, 2007) had healthy elderly adults perform tongue presses against resistance using the Iowa Oral Performance Instrument (IOPI) in an 8-week training program consisting of 30 repetitions per session, 3 sessions per training day, and 3 training days per week, and they found that the program was effective. In their program, they gradually increased the load of isometric exercise by setting the resistance at 80% of maximal muscle strength so that the load would increase as muscle strength increased. Swallowing function also improved through the program, and the volume of the tongue measured by MRI increased by an average of 5.1%.

The same group also had stroke patients perform tongue presses against resistance using the IOPI in an 8-week program consisting of 10 repetitions per session, 3 sessions per training day, and 3 training days per week, and they also found that the program was effective. As in the other program, they gradually increased the load of isometric exercise by setting the resistance at 80% of maximal muscle strength so that the load would increase as muscle strength increased. Swallowing function also improved.

Yeates et al. (2008) had patients with dysphagia (with various primary diseases) perform tongue presses against resistance using the IOPI in a program consisting of 60 repetitions per session, 1 session per training day, and 2-3 training days per week, and they found that this program also improved swallowing function. Like Robbins et al., they used isometric exercises.

In Nishio' s study (2006), healthy adults performed tongue presses, tongue protrusions, and lateral movement exercises against resistance in a 4-week program consisting of 10 repetitions per session, 3 sessions per training day, and 3 training days per week. Effects of these exercises were evaluated using the IOPI. He found that all exercises significantly improved muscle strength. He also noted the importance of using a bite block designed for speech and voice therapy to hold the mandible in place during tongue exercises, as significant improvement in muscle strength was seen with the technique. This is because in tongue press exercises in particular, the mandible tends to compensate for inadequate tongue movement if the mandible is not held in place.

Other evidence about tongue exercises comes from authors such as Lazarus et al. (2003), van den Steen et al. (2018), and Yano et al. (2019). If a bite block is not used, the tongue muscle strength may not be accurately measured. The values may also include the muscle strength of the mandible.

Explanation

Depending on the severity of the patient's condition, we can use passive exercises, active assistive exercises, active exercises, or resistance exercises in functional training of the tongue. Recent research has emphasized that whichever mode of exercise is selected, we should carry out a multifaceted program that includes (1) tongue protrusions, (2) tongue elvation, and (3) lateral movement exercises to avoid problems with angle specificity and to enhance the effects of training (Nishio, 2019).

For passive tongue exercises, the clinician wraps the tongue in moist gauze and firmly grip it while the client completes each exercise. For passive and active assistive exercises, a mirror is placed in front of the client to provide visual feedback and help them re-learn the sensation of gross motor movements outward, upward, and to the side. For active assistive exercises, the client is helped by the clinician using a tongue depressor or their fingers.

Explanation

As movement of the mandible tends to compensate for inadequate tongue movement in tongue press exercises, we must hold the mandible in place using a bite block designed for speech and voice therapy. Compensatory movement of the mandible makes improvement in tongue muscle function less likely because it prevents proper tongue muscle contraction. Recent advances in neuroscience suggest that exercises with constraint of compensatory movement may promote reorganization of the central nervous system in the brain.

We should have a suitable number of bite blocks available, and they must be sterilized before use with each patient. Sterile disposable bite blocks for speech and voice therapy are now available as well (Interuna Publishers).

Explanation

Resistive exercises for strengthening the muscles also consist of outward protrusion of the tongue, tongue presses, and lateral movement exercises. For protrusion exercises, have patients open their mouth, place a tongue depressor between the maxillary and mandibular incisors to apply manual resistance, and have them forcefully protrude their tongue outward. To directly evaluate tongue muscle strength while conducting training, we can wear disposable gloves and directly apply resistance to the tongue using gauze instead of using a tongue depressor.

As with the other exercises, when doing tongue press exercises, we must hold the mandible in place using a bite block designed for speech and voice therapy. Have patients open their mouth, push a tongue depressor down on the upper surface of the tongue to apply manual resistance, and have them forcefully lift the body of the tongue against that resistance. For lateral movement exercises, apply manual resistance by pushing a tongue depressor against one side of the tongue slightly away from the midline (on the side patients will move the tongue) and then have patients forcefully move their tongue to the side against that resistance. As with protrusion exercises, we may also wear disposable gloves and directly apply resistance to the tongue using gauze instead of using a tongue depressor.

We should change the amount of resistance we apply with the tongue depressor depending on each individual patient's muscle strength. The overload principle is important, but it is difficult to set the load precisely. Recent research on muscle strengthening indicates that exerting 80% of maximal strength is ideal for exercises of the arms and legs as well as the tongue. However, precise load setting is not realistic for tongue training. A realistic approach is probably to always encourage maximal contraction. Pushing against the tongue depressor should be sustained for 3-5 s. Each session should consist of one set of 10 repetitions, and 3 sets should be performed a day if possible.

Another exercise is where we insert our fifth finger (little finger) at the corner of the mouth on the paretic side, pull the corner toward the cheek to apply resistance, and have patients close their lips against that resistance. We can also have them suck on the fifth finger inserted at the corner of their mouth.

Explanation

It is recommended to perform tongue presses by placing the IOPI mentioned earlier between the palate and the anterior or middle tongue and having patients push upward against the bulb with the tongue due to the additional feedback effects of this method. In this case as well, we can expect greater improvement in tongue motor function if the mandible is held in place using a bite block designed for speech and voice therapy. When the IOPI's tongue bulb is connected to the main unit, the instrument measures the pressure applied against the bulb in kilopascal units (kPa) and displays the measurement on the main unit's LCD screen. The IOPI is also useful in the lip closure exercises described later in this module.

Explanation

In Japan, JMS Co., Ltd. began selling a tongue pressure measurement device that resembles the IOPI in 2011. This accelerated tongue pressure research in Japan. Takei Scientific Instruments Co., Ltd. also began selling a tongue muscle dynamometer in 2010. This dynamometer easily measures muscle strength exerted during tongue training using a normal tongue depressor and displays it as a numerical value. It can measure force exerted by tongue movement at all different angles.

Explanation

We discussed load earlier in this module, but there is no clear consensus about the appropriate load and frequency for muscle strength training in patients with neuromuscular disorders due to stroke or other such causes. However, the trend in recent years has been to emphasize the need for intensive and frequent rehabilitation for neuromuscular disorders. It is believed that a relatively high frequency of 5-7 sessions per week is necessary to have a chance to achieve neuroplasticity. That is why self-directed training is necessary.

Patients can easily do any self-directed training exercise if they are simply given equipment such as a bite block and tongue depressor. If they are doing resistance exercises, they should be instructed to use their own fingers to apply the load. If they can't their arms, they should ask a caregiver or family member to help.

It is also important to emphasize in self-directed exercise that (1) compensatory mandibular movement should be constrained by holding the mandible in place with a bite block designed for speech and voice therapy and (2) perform the exercises while looking in a mirror to get visual feedback on whether they are performing the exercises properly.

Explanation

Here we see key evidence regarding the effects of facial training. Hägg et al. (2008) had patients with post-stroke dysphagia perform lip closure exercises against resistance using an acrylic oral screen in a 5-week or longer program consisting of 3 repetitions per session in 3 daily sessions and found that this program significantly improved both lip muscle strength and swallowing function. They reported that lip muscle strength increased after training even in patients with facial nerve palsy.

Nishio (2006) had healthy adolescents perform lip closure exercises against resistance in a 4-week program consisting of 10 repetitions per session, 3 sessions per training day, and 3 training days per week. When he analyzed IOPI measurements, he found that the program significantly increased muscle strength. He also noted the importance of holding the mandible in place using a bite block designed for speech and language therapy in lip exercises, as he achieved significant improvement in muscle strength with the technique. This is because in lip closure exercises in particular, the mandible compensates for inadequate lip movement if the mandible is not held in place.

Explanation

Studies by Okubo et al. (2012), Abe et al. (2012), Onoda et al. (2012), and Takakura et al. (2012) have demonstrated the clinical effectiveness of facial constraint-induced (CI) therapy. CI therapy is an important method for facial muscle training and will be described in detail later in this module.

Explanation

In training of the lips and cheeks, as with functional training of the tongue, we can use passive exercises, active assistive exercises, active exercises, or resistance exercises depending on the severity of the client's condition. Whichever mode of exercise we select, a lip exercise program should consist of (1) pulling the lips to the side while making an /e/ sound, (2) pucker while making an /o/ sound, and (3) closing the lips while making an "mm" (/m/) sound.

Explanation

When performing exercises of the lips and cheeks (ie.., the lower face), almost all patients does not use the paretic side of their lower face. This causes them to do the exercises using the non-paretic side only (ie, the normal side). Consequently, muscle strength in the paretic side will not improve and will actually decrease, with the normal side getting even stronger. So, the exercises will not be effective unless movement of the normal side is constrained. Such movement must always be forcibly constrained in every exercise in order to focus on the paretic side.

This approach that aims to improve motor function in the affected side by constraining use of the normal side while focusing on exercises for the affected side is called constraint-induced movement therapy (CI therapy, or CIMT). CI therapy is supported by a high level of evidence. Large randomized controlled trials by Wolf et al. (2006, 2008) established the efficacy of CI therapy, and it was designated a Grade A (highly recommended) therapy in the 2009 edition of the Japanese Guidelines for the Management of Stroke (Joint Stroke Guidelines Committee, 2010).

As noted earlier in this module, many studies in Japan have demonstrated the effectiveness of CI therapy for facial muscles in recent years. The therapy has been shown to be effective for both central and peripheral palsy. There were previously concerns about pathological synergic movements or facial contractures with CI therapy, but a recent series of studies on CI therapy for peripheral facial nerve palsy showed that it does not cause those issues. The importance of feedback in preventing pathological synergic movements has been recognized for some time, and so the lack of pathological synergic movements and facial contractures may be due in part to the fact that CI therapy for facial muscles emphasizes visual biofeedback.

To constrain movement of the normal side of the lower face, we stand behind patients and firmly hold the normal side of their lower face in place with our fingers for exercises that involve (1) pulling the lips to the side and (2) puckering the lips. Another option is to hold the non-paretic side of the lower face firmly in place with tape. For exercises that involve (3) closure of the lips, use a bite block to constrain compensatory mandibular movement. There is no point in doing lip closure exercises if the mandible is not held in place using a bite block.

It is also important to encourage patients to carefully watch movement of the affected side by looking at the synergic in front of them so that they learn the exercises.

Explanation

In resistive exercises for building lip muscle strength, insert the fifth finger (little finger) at the corner of the mouth on the paretic side, pull the corner toward the cheek to apply manual resistance, and have the patient close their lips against that resistance. During this exercise, we are applying resistance using the pad of the finger. We can also have patients suck as hard as they can on the finger inserted at the corner of the paretic side of their mouth. Do not forget to use a bite block to constrain compensatory mandibular movement. When selecting a bite block size, start with the smallest one and change to a larger one as function improves.

Other simple and practical exercises include (1) having patients maintain lip position against the resistance we exert when trying to pull out a tongue depressor wedged between the upper and lower lips and (2) the button-pull exercise, in which a button with dental floss or another such thread strung through the buttonholes is placed at the oral vestibule on the paretic side and clients close their lips and hold the button between them as we try to pull out the button.

Explanation

When performing CI therapy as self-directed training of the lips and cheeks, patients should constrain movement of the normal side of the lower face using the palm of their hand, and concentrate on moving the paretic side while facing a mirror for visual feedback.

Commercially available lip-closing devices for self-directed training include the Lift-Up, the Patakara, and Tojiro-kun, and the clinical effectiveness of these devices has been demonstrated (Nomiya, 2001). As noted earlier, patients tend to only move the normal side of the face, so they must be told to look in the mirror and focus on movement of the paretic side.

Explanation

Other techniques for training of the lower face include exercises with electromyographic feedback (EMG feedback), massage or relaxation, stretching, exercises to suppress pathological mirror movements, exercises involving coordinated movements, facial expression exercises, mime therapy with articulation exercises and other such exercises, articulation training, icing, and thermal therapy. In mime therapy as well, clients are instructed to look in a mirror and pay attention to movement of the affected side. Massage and stretching are considered effective for preventing and attenuating increases in muscle tone. Low-frequency electrical stimulation is no longer used today.

In articulation training, training of the lips and cheeks focuses on the bilabial consonants, namely, the /p/ and /b/ sounds. In this training also, instruct patients to look in a mirror and pay attention to symmetry or movement of the affected side. When performing articulation training to train the tongue, choose an appropriate target lingual sound. Humming is also useful for lip closure. Speech Rehabilitation Volume 1: Articulation Training (Interuna Publishers) is a widely used textbook on articulation training.

Explanation

Depending on severity of the condition, we can use passive exercises, active assistive exercises, active exercises, or resistive exercises in functional training of the mandible. Whichever mode of exercise is selected, the program should consist primarily of (1) mouth opening exercises and (2) mouth closing exercises.

In mouth-opening resistive exercises for building muscle strength, we apply manual resistance by pushing our finger or the palm of our hand against the base of the mandible and have clients open their mouth against that resistance. One mouth-closing resistive exercise is where we place a tongue depressor on top of the anterior teeth, apply resistance downward, and have clients close their mouth against that resistance. If they are missing their anterior teeth or have tooth pain there, apply manual resistance against the mandibular molars on both sides of the mouth and have them close their mouth against that resistance. Place a mirror in front of them for visual feedback as they perform the exercises.

Mouth opening is performed using the suprahyoid muscles, and these muscles are also important in lifting the hyoid bone during swallowing. Most of the suprahyoid muscles lift the hyoid bone when the mandible is held in place, and open the mouth by lowering the mandible when the hyoid bone is held in place. So, strengthening the suprahyoid muscles through mandibular mouth-opening resistive exercises may also improve lifting of the hyoid bone and larynx during the swallowing reflex.

Exercises involving forward and backward movement (protrusion and retraction) and lateral movement of the mandible can also be added if necessary.

Explanation

Most of the peripheral structures involved in movements required in speaking (eg, the lower half of the face, the mandible, the mouth, the pharynx, and the larynx) are also involved in swallowing movements. Studies have shown that dysarthria and dysphagia frequently present together due to these anatomical properties. In addition, if we look at the anatomical overlap in speech structures and swallowing structures, which is the cause of the high frequency of co-occurrence of speech disorders (dysarthria) and dysphagia, we can see that the impaired structures resemble each other as well. This finding created demand for a functional therapy that simultaneously addresses motor dysfunction in these structures when both disorders occur. The Movement Therapy Program for Speech & Swallowing in the Elderly (MTPSSE) was developed as a hybrid approach that reflects this perspective (Nishio; 2018, 2019). Results of a phylogenetic study by Nishio (2018) suggest that performing preventive interventions, therapy, and training for speech disorders (dysarthria) and dysphagia in parallel is both valid and can yield beneficial results for clients.

The MTPSSE program includes preventive interventions, therapy, and training for almost all speech and swallowing-related muscle groups, and its procedures are standardized. So, if the necessary exercises (sub-category) are selected from the MTPSSE therapy and training categories for each body part (major categories) based on problems identified by baseline assessment and the standardized procedures are followed, it should be easy to properly design a prevention and treatment plan, execute the plan, and achieve a relatively comparable degree of improvement.

Explanation

The MTPSSE simultaneously incorporates preventive and therapeutic approaches. It was developed with the expectation that it would be used not only in the acute, recovery, and maintenance stages of rehabilitation, but also in preventing clients from requiring nursing care. Generally, it is appropriate to use the preventive approach for clients who are healthy (independent), pre-frail, or frail and to use the therapeutic approach for patients with impairment. Its feature of handling adults across all these stages (healthy, pre-frail, frail, and impaired) makes the MTPSSE suited to modern comprehensive community care systems that provide integrated comprehensive support for medical, nursing, and preventive care.

Conventionally, dysphagia rehabilitation was performed only for people who already had developed impairment, was intended to improve function to address that impairment, and was performed in medical and nursing care settings. However, we should stand by the principle of prevention before impairment when trying to address dysphagia related to frailty and sarcopenia, and the relevant professionals must learn the preventive skills needed to follow that principle and feel a sense of responsibility for the community's health.

Specifically, MTPSSE to carry out preventive dysphagia rehabilitation should be used by programs that support community rehabilitation efforts as part of general programs to prevent residents from requiring nursing care, as well as visiting and outpatient short-term intensive preventive service programs offered as services to prevent residents from requiring nursing care and support them in their daily activities.

Explanation

The MTPSSE includes many novel techniques newly developed to enhance the program's clinical effects. One example is its tube training methods for various structures. Tube training has been shown to be effective in the fields of health and exercise science and rehabilitation medicine and is somewhat widely used, but the MTPSSE methods were the first to be developed for structures involved in swallowing. Tube training has many advantages, including that it enables resistance exercises at all kinds of angles, enables easy load adjustment, can be done easily with affordable equipment, and enables exercises to be conducted with different types of muscle contraction (concentric, eccentric, and isometric) as appropriate.

It is expectedd that the completion of the MTPSSE will greatly advance the field of rehabilitation of swallowing structures, including oral structures.

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