Diagnosis of Oropharyngeal Dysphagia

Accurate diagnosis of the specific oral or pharyngeal motor impairment in each patient is the crucial first step in management of oropharyngeal dysphagia. The patient's external symptoms may include coughing or throat clearing, or obvious increased effort for swallow or repeated swallows on one bolus if there is difficulty generating adequate pressure on the bolus to propel it efficiently through the oral cavity or pharynx. It is important to note, however, that approximately 50% of patients who aspirate do not cough or give any external sign of food or liquid entering the airway. The patient's history, medical diagnosis, and other characteristics can assist the clinician in pointing toward the specific swallow abnormality in the oral cavity or pharynx. Generally, however, an instrumental imaging study of the oral cavity and pharynx, particularly the pharynx, is necessary in order to accurately identify the muscle or muscles that are damaged.

Diagnostic Imaging Studies

Diagnostic imaging procedures for the oral cavity and pharynx should be done to determine the specific types of motor disorders present followed by the introduction of treatment strategies in order to evaluate their effectiveness. There are two primary diagnostic procedures used to assess the oral cavity and pharynx during swallow: videoendoscopy and videofluoroscopy.^{2, 22, 23, 24, 25} Videoendoscopy has the advantage of providing no x-ray exposure to the patient and being portable. However, there are several disadvantages to this procedure including the inability to visualize the oral aspects of the swallow and the inability to visualize the critical aspects of the pharyngeal stage of swallow including tongue-base motion, laryngeal elevation, and upper esophageal sphincter.^{23, 24} However, the portable nature of the endoscopic equipment can make it a choice by clinicians for use in nursing homes and intensive care units, where it may not be easy to transport a patient to a radiologic suite in acute care.

In contrast, the use of videofluoroscopy enables the clinician to visualize all aspects of the oral and pharyngeal stages of swallow except vocal fold closure during the pharyngeal swallow.^{23, 24} However, the oral stage can be examined in detail, as can pharyngeal triggering and the majority of the motor aspects of the pharyngeal stage of swallowing. In either case, the clinician should utilize a consistent protocol as each patient is examined in order to compare one individual to another, normal subjects to dysphagic patients, and a patient to him- or herself over time. The protocol should include a sampling of bolus volumes and viscosities, because both variables can significantly affect the timing and organization of the normal oropharyngeal swallow and the disordered swallow. For example, the volume of the bolus can significantly change bolus transit times, that is, bolus movement through the oral cavity and pharynx as well as the duration and width of upper esophageal sphincter opening and airway closure. The most typical protocol utilized during videofluoroscopy involves presentation of 1, 3, 5, or 10 mL of thin liquids, cup-drinking of thin liquids, straw-drinking of thin liquids, 3 mL of pudding-thick barium, and one quarter of a Lorna Doone cookie coated with barium pudding to be chewed so that mastication can be visualized.² At least two swallows of each of these bolus types is given in order to gain a clear understanding of motor control of the oral cavity and pharynx for deglutition. If a physiologic or anatomic disorder is observed, the clinician should identify that disorder and, if aspiration results or if there is significant residue after the swallow, the clinician should introduce one or more treatment strategies to examine their immediate effectiveness in improving the patient's swallow. All of the treatment procedures described below except exercise programs can be introduced and evaluated for effectiveness during the radiographic study.^{1, 3, 26, 27}

Treatment for Disorders of the Oropharyngeal Swallow

Treatment strategies in the oral cavity and pharynx are generally behavioral in nature, because this is a mechanism that does not respond well to surgical procedures^{28, 29, 30} and for which no drugs have been identified to improve any or all swallow disorders.^{1, 31, 32}

Postures

Treatment procedures often begin with postural changes, which affect the direction and speed of bolus flow through the mouth and pharynx.³ There are five postural procedures that can impact specific aspects of the swallow as shown in Table 1. The change in posture does not normalize the motor disorder but rather compensates for it, is generally used only temporarily, while spontaneous recovery can take effect, or while sensory stimulation or exercise programs can improve the swallow.

Table 1: Postures: the change in pharyngeal dimensions or gravity's effect on food flow^{26, 56, 57}

• Full size table

Heightening Sensory Input

A second set of treatment strategies involves heightening sensory input.^{20, 33} These procedures are generally used for patients with a delay in triggering the pharyngeal swallow, which is a sensory disorder rather than a motor one. Such strategies as changing bolus volume, changing bolus viscosity, or introducing boluses of a strong taste including sour boluses or carbonated boluses can heighten and facilitate faster triggering of the pharyngeal swallow. The more that we understand the way in which normal swallow physiology changes systematically with bolus characteristics, the more we will be able to use this information to understand swallowing disorders and understand the patient with specific oral and pharyngeal swallowing disorders.

Exercise Programs Including Swallow Maneuvers

Another classification or type of rehabilitation technique for the motor disordered dysphagic patient is an exercise program. There are a number of exercises for specific muscles or muscle groups in the oral cavity and pharynx that can be effective in remediating specific swallowing disorders. They may take 2 weeks to 2 months to take effect. For patients with weakness in facial and labial muscles, resistance and range-of-motion exercises can be very helpful. Range-of-motion exercises typically involve moving the target structures to their furthest extension, holding the extended position with effort for 1 second, and then releasing it. Such exercises can be used for the lips and facial muscles as well as lingual muscles. Resistance exercises in which a tongue blade or instrument such as the Iowa Oral Pressure Instrument is pushed against the tongue while the tongue attempts to resist are also known as strengthening exercises. These exercises can be quite effective in improving tongue strength and coordination. Recently, data have been presented illustrating that increasing tongue strength will be applied immediately to the act of swallowing with no transitional therapy.³⁴ These exercises are useful in many patients with generalized lingual weakness and in normal elderly individuals who lose tongue strength from aging. They are not appropriate for patients with motor neuron disease, as they only cause additional fatigue. There have been no exercises defined as consistently effective for improving velopharyngeal closure for swallowing.

Tongue-base exercises are quite different from lingual tongue exercises. Although the lingual tongue is generally elevating during swallow and its contact to the palate is moving posteriorly, the tongue base is retracting on a horizontal plane during swallow. Three exercises have been found to be helpful for the tongue base³⁵: (1) pulling the tongue straight back in the mouth to its maximum position and hold with effort for 1 second, (2) gargling and holding the tongue in its retracted position for 1 second, and (3) yawning and holding the tongue in the most posterior position for 1 second. Clinicians can assess the extent of tongue-base motion with these procedures during videofluoroscopy and identify the one that results in greatest movement. Repeating "ka/ ka/ ka" or "ga/ ga/ ga" is not an exercise for the tongue base, because it results in vertical movement of the back of the tongue rather than horizontal movement of the base of the tongue.

An exercise to improve laryngeal and hyoid upward forward motion to open the upper esophageal sphincter is the Shaker exercise.^{36, 37, 38} In this exercise, patients lie on their back on a bed or the floor and elevate their head to see their toes while keeping their shoulders against the bed or floor. They then hold the head up for 1 minute, followed by 1 minute of rest. After three repetitions of 1 minute with the head lifted and 1 minute of rest, patients are instructed to lift their head to see their toes and let it down 30 times. This exercise is not appropriate for patients with significant arthritis or damage to their neck.

Swallow Maneuvers

Swallowing maneuvers are generally voluntary controls applied to a specific movement used during swallow.^{39, 40, 41} There is very little exercise designed to improve pharyngeal wall activity other than the tongue-holding maneuver, which involves holding the tongue tip between the teeth gently but firmly and swallowing with the oral tongue in that position. Holding the tongue in this position pulls the tongue forward, forcing the glossopharyngeal fibers (the lowest fibers) of the superior constrictor to contract more strongly, resulting in a greater bulge at the portion of the posterior pharyngeal wall.^{42, 43} This is an exercise and cannot be used to eat, because the maneuver makes it more awkward to trigger a pharyngeal swallow with the oral tongue in that position.

Several other swallow maneuvers are helpful in improving specific muscle activities in the pharynx. They can be utilized during swallows and, therefore, during eating. The supraglottic swallow is designed to close the airway voluntarily at the level of the true vocal folds.^{14, 44} Patients are instructed to hold their breath gently before and during the swallow and to cough when the swallow is completed to clear any residue. The super-supraglottic swallow is designed to close the entrance to the airway before and during the swallow by again holding the breath but this time while bearing down. Bearing down increases muscle effort and closes not only the true vocal folds but also the false vocal folds.^{44, 45} The arytenoid cartilages are pulled more anteriorly during a super-supraglottic swallow, causing narrowing of the region above the false cords. This procedure is generally used in patients who have undergone laryngeal surgeries such as a supraglottic laryngectomy.

A third swallow maneuver is the effortful swallow. During the effortful swallow, patients are asked to squeeze hard with all of the muscles in their mouth and their throat.⁴⁶ This increased effort results in greater pressure during swallow and, therefore, better oral tongue and tongue-base movement and less pharyngeal residue. This maneuver can be utilized during eating, though patients may tire more quickly during a meal.

The fourth swallow maneuver is the Mendelsohn maneuver, designed to improve hyolaryngeal elevation and forward movement during the swallow, thereby opening the upper esophageal sphincter more widely and longer to facilitate the clearance of the bolus into the esophagus.^{47, 48} There are several directions that can achieve the Mendelsohn maneuver. The first is to ask patients to swallow several times and feel with their muscles (not their hand) the degree of lifting in their neck by their voice box. When they can perceive that their voice box does lift during swallow, they are asked to swallow again, and as their voice box elevates, to grab it with muscles—not their hand—and to hold their larynx up for an extra few seconds. The effort of holding the larynx up generally increases the extent and duration of laryngeal elevation, thereby opening the upper esophageal sphincter longer and wider. Although this is generally an exercise, it can be utilized to improve upper esophageal sphincter opening during food swallows.

A second set of directions for this maneuver involves asking patients to feel as they swallow to see if they can perceive that a squeeze occurs during swallow, which is the point at which the tongue base, pharyngeal wall, and larynx all come together. Patients can be instructed to "hold the squeeze" for several seconds. It is at that point that the larynx is most elevated and that elevation can be increased with effort.

Intraoral Prostheses

The development of an intraoral prosthetic to lower the hard palate to meet the tongue that is restrictive in bulk or range of motion can have a major effect on the efficiency or safety or the oropharyngeal swallow.^{49, 50, 51} These prosthetics are designed individually, usually by the maxillofacial prosthodontist and a speech-language pathologist.

Experimental Treatment Procedures

There have been a number of experimental procedures described recently for improvement of motor control of swallow. None of these procedures has any experimental evidence to support its effectiveness. These procedures include myofascial release, designed to release any scar tissue or connective tissue inhibiting movement of structures in the pharynx; neuromuscular electrical stimulation (NMES), designed to improve the strength of muscle contraction during swallow; and deep pharyngeal neuromuscular stimulation (DPNS), designed to utilize reflexive activity in the pharynx to improve swallow. The rationale for many of these procedures and their effectiveness are unclear. These types of procedures should be utilized with care until efficacy data are clearly identified.

Diet Change

Changing a patient's diet can eliminate some of the effects of dysphagia such as aspiration.

Thickened Liquids

In the past 10 years, thickening liquids to nectar or honey consistencies has become popular to manage aspiration of thin liquids in a wide range of patients, particularly those in nursing homes and other residential facilities.⁵² Unfortunately, the data to support the efficacy of these procedures is not strong and the use of thickened liquids can reduce the patient's quality of life and hydration. The ongoing clinical trial mentioned earlier, when completed in 2006, should provide us with a great deal more data on the true effectiveness of nectar and honey consistency liquids in contrast to chin-down posture for patients with dementia and/or Parkinson's disease.

Studies have shown that heightening sensory input in the form of strong taste (sour) or carbonation may improve some motor characteristics of the swallow.^{19, 53} Much more research on the effects of bolus characteristics is needed to understand which motor disorders can be affected by various bolus characteristics.^{19, 20}