INVITED REVIEW ARTICLE

https://doi.org/10.5005/jp-journals-10001-1525
International Journal of Head and Neck Surgery
Volume 13 | Issue 1 | Year 2022

Pharyngeal Dysphagia

Jaykumar R Menon

Director, Dr. Jaykumar’s Laryngology Group, Thiruvananthapuram, Kerala, India

Corresponding Author: Jaykumar R Menon, Dr. Jaykumar’s Laryngology Group, Thiruvananthapuram, Kerala, Phone: +91 9846011740, e-mail: jkrmenon@rediffmail.com

ABSTRACT

Pharyngeal dysphagia may be due to different etiologies. But the commonest causes are neurological, and secondary to head and neck cancer treatments. Various stages of pharyngeal phase of swallowing can be affected. Understanding the pathophysiology and managing accordingly is the key to success. Proper history taking, clinical and instrumental evaluation are the important methods to diagnose the dysfunction. Flexible endoscopic evaluation of swallowing (FEES) and Video fluoroscopy (VFS) are the most commonly used instrumental evaluation techniques. Management includes alternative methods of swallowing, prevention of aspiration, swallowing therapy and interventional management.

How to cite this article: Menon JR. Pharyngeal Dysphagia. Int J Head Neck Surg 2022;13(1):55-61.

Source of support: Nil

Conflict of interest: None

Keywords: FEES, Pathophysiology of dysphagia, Pharyngeal dysphagia, Swallowing therapy, VFS

INTRODUCTION

Dysphagia or difficulty taking in oral feeds not only affects nutrition, but can affect a patient’s quality of life. Many systemic and local diseases affect the swallowing mechanisms adversely. Until recently, this was almost a neglected branch of medicine. This article aims to explain the mechanism of oropharyngeal dysphagia, review diagnostic modalities, and discuss management strategies.

PHYSIOLOGY OF SWALLOWING

The swallowing act can be divided into four phases:

Each phase is complex in its own right and involves a coordinated series of muscular actions, but none more than the pharyngeal phase.

The oropharyngeal phase starts with the retraction of the tongue base and the palatoglossal folds prevent the reentry of the bolus to the oral cavity. The hypoglossal nerves and pharyngeal plexus are very important in this particular step. Nasopharyngeal regurgitation is prevented by the palatopharyngeus and musculus uvulae acting together, with pharyngeal plexus again forming the neurological support. Suprahyoid muscles pull the larynx under the umbrella of the retracting tongue base. This is mediated by the mandibular division of trigeminal nerve (the anterior belly of digastric and mylohyoid), facial nerve (the posterior belly of digastric and stylohyoid), and C1 through ansa hypoglossi (geniohyoid and thyrohyoid) is the first mechanism.1,2 The larynx is also protected by the sphincteric closure of aryepiglottic folds, ventricular bands, and the true vocal cord, all dependent on the integrity of the recurrent laryngeal nerves. Retroversion of the epiglottis, more mechanical than neuromuscular, also adds to the protection. Sensation mediated by the internal branch of the superior laryngeal nerve is of great importance if the above-mentioned motor activities need to take place at the appropriate time.

Once the bolus is in the laryngopharynx, it needs to be transferred to the esophagus. This is done by the sequential squeezing by the thyropharyngeus and relaxation of the cricopharyngeus. The pharyngeal plexus is responsible for the former, while central inhibition mediated by the Recurrent Laryngeal nerve controls the latter. Cricopharyngeal relaxation is triggered by the stretch provided by the laryngeal elevation. The larynx closes during the act of pharyngeal transit and respiration restarts with the expiratory phase. All these complex mechanisms need a high level of coordination. This is brought about by a network of neurons in the Brainstem, known as the Central Pattern Generator (CPG).2,3 This network interconnects inspiratory, expiratory, and apneustic nuclei as well as nuclei of the various cranial nerves involved in the act of swallowing.

PATHOPHYSIOLOGY OF PHARYNGEAL DYSPHAGIA

Velopharyngeal Incompetence

We have already seen that closure of the velopharyngeal port by the soft palate is the first step in the pharyngeal phase. Neurological and neurosurgical conditions causing involvement of the vagus nerve and pharyngeal plexus can wreak havoc with this mechanism. Brainstem stroke and surgeries like decompression of the foramen magnum are well known to produce this malady. In head and neck cancer treatment, this may be brought about by either intentional or inadvertent sacrifice of the nerve supply to the palatal muscles. Resection of the soft palate in tumors of the oropharynx and radiotherapy to the nasopharynx also can make the soft palate incompetent.

Absent/Inefficient/Infrequent Laryngeal Elevation

Anterior and superior movement of the hyolaryngeal complex, not only makes the larynx safe under the tongue base but also stimulates the cricopharynx to relax by stretching it. As this movement is brought about by the thyrohyoid and suprahyoid muscles, neurological or neurosurgical conditions like brain posterior circulatory stroke, cerebellopontine angle surgery, and high spinal injuries and tumors can critically affect this most important component of the pharyngeal phase.3 Extensive head and neck cancer surgery with removal of suprahyoid musculature and its nerve supply, the floor of mouth resection, and radiotherapy causing fibrosis in this area can also create significant restrictions to the laryngeal elevation.

Inefficient Laryngeal Closure

Epiglottis plays a significant role in diverting the bolus stream to the two pyriform fossae. It also closes the laryngeal inlet like a closet lid. Partial or complete epiglottic resection obviously will result in suboptimal laryngeal protection and diversion of the food bolus. Even though recurrent laryngeal nerve injury alone is unlikely to produce significant and persistent aspiration, a high vagal injury with involvement of superior laryngeal nerves also creates a lot of swallowing and penetration-aspiration problems. For the same reason, Brainstem lesions and surgery are likely to affect this vital step.

Partial laryngectomies like vertical partial, supraglottic partial, and Supracricoid partial laryngectomies are known to adversely affect the sphincteric mechanism of the larynx. In supraglottic partial laryngectomy, there is the added problem of loss of sensation of the supraglottic larynx, due to the sacrifice of the superior laryngeal nerve. Supracricoid laryngectomy, where the suprahyoid epiglottis is retained (Cricohyoidoepiglottopexy), fares better when compared to cricohyoidopexy, where the whole epiglottis is removed.4

Inefficient Thyropharyngeal Contraction

If thyropharyngeus is paralyzed on one side, it can result in stasis of the food bolus in the pyriform fossa on the affected side. Pathologies affecting the nuclei of cranial nerves IX, X, and XI, such as neurosurgery or stroke, are likely to cause this dysfunction. Resection of the posterior pharyngeal wall of the hypopharynx in tumors limited to the posterior pharyngeal wall sometimes produces incapacitating dysphagia, due to the lack of thyropharyngeal contraction.

Cricopharyngeal Dysmotility

Cricopharyngeus is quite a unique muscle, as it is in a stage of tonic contraction except during swallowing. Its nerve supply is from a branch of the recurrent laryngeal nerve, which is cholinergic in nature. So the method by which it relaxes during the act of swallowing is thought to be due to central inhibition. Whatever is the mechanism, the key to successful swallowing is its proper relaxation at the appropriate time. Cricopharyngeal dysfunction may be primary or secondary. Secondary cricopharyngeal dysmotility is due to the lack of elevation of the larynx and its causes have been elaborated.5 Primary cricopharyngeal dysmotility is caused by problems in its neurological control. The lateral medullary syndrome commonly affects the proper functioning of the cricopharyngeus and causes dysphagia of varying severity (Fig. 1).

Fig. 1: Cricopharyngeal spasm in VFS seen in a case of lateral medullary syndrome

One special condition to be mentioned is idiopathic cricopharyngeal spasm or a cricopharyngeal bar (Fig. 2).6 This usually occurs in middle-aged people, though rarely reported in children and infants. This is actually an improperly timed contraction-relaxation of the thyropharyngeus-cricopharyngeus complex. This results in simultaneous contraction of both thyropharyngeus and cricopharyngeus and is later likely to lead to the development of a pulsion diverticulum, known as a pharyngeal pouch or Zenker’s diverticulum (Fig. 3).

Fig. 2: Focal impression on the posterior aspect of the esophagus at the level of C5-6 on VFS in a case of idiopathic cricopharyngeal spasm

Fig. 3: Barium entering a pharyngeal pouch (black arrow) on VFS

Radiotherapy to the region of cricopharynx can cause dysfunction of the cricopharynx, especially if the dose is more than 60 G.7 Postcricoid, cricopharyngeal and posterior pharyngeal wall malignancies are more likely to develop cricopharyngeal stenosis and dysfunction than tumors of the pyriform fossa. Rarely intraluminal, intramural, and extraluminal neoplasms like leiomyoma can cause obstruction to the pharyngeal phase. Postcricoid web in Plummer-Vinson syndrome is a well-described entity and needs to be treated carefully, as it has the potential to turn malignant (Fig. 4). Occasionally large osteophytes can impinge upon the posterior pharyngeal wall and cause swallowing disturbance. A retroesophageal goiter also can trouble the swallowing act occasionally.

Fig. 4: Pooling of food in the right pyriform sinus on FEES

In addition to the above-mentioned causes, chronic neurodegenerative conditions like parkinsonism and motor neuron diseases should be kept in mind and searched for in unexplained dysphagia, irrespective of the phase involved.

CLINICAL FEATURES

Usually, the symptoms give a clue to the diagnosis. If there is nasal regurgitation, chances are that there is velopharyngeal incompetence, though occasionally it may be secondary to a cricopharyngeal dysfunction. Multiple attempts to swallow, usually suggest a problem with laryngeal elevation or cricopharyngeal dysmotility. Penetration and aspiration produce cough. If a cough happens immediately after the act of swallowing, chances are that patient has laryngeal incompetence, either unilateral or bilateral. A delayed cough suggests a hypopharyngeal dysfunction because the residual bolus passes on to the glottis which opens a little later for breathing. The absence of coughing doesn’t always suggest normal swallowing, since, in sensory paralysis, the patient may be aspirating, but showing no discomfort at all. This is an extremely serious condition, which if not detected early, can turn to be catastrophic. A pharyngeal dysphagia patient may also have other laryngeal dysfunction symptoms like hoarseness and breathing difficulty.

DIAGNOSIS

A good history of both the primary condition as well as the swallowing dysfunction will give clues to the possible diagnosis. Examination of the neck, oral cavity, oropharynx, and cranial nerves add to the necessary information for a proper diagnosis. In addition, watching the act of swallowing will give valuable tips regarding not only the diagnosis but also the possible therapeutic and feeding options. It is a good practice to make use of a stethoscope by auscultating over the neck to identify possible stenosis, and over the chest to look for signs of aspiration and the general status of the lower respiratory tract. Many patients can be confidently cleared for starting oral feeds after clinical evaluation. But when there is any doubt regarding the integrity of the swallowing mechanism, and when the patient clearly fails to swallow normally, instrumental evaluation is indicated. There are many instrumental evaluation methods, of which flexible endoscopic evaluation of swallowing (FEES) and modified barium swallow (MBS) or video fluoroscopy (VFS) are the most commonly used ones.

Flexible Endoscopic Evaluation of Swallowing (FEES)

The advantage of FEES is that structural and physiological assessment of the palate, pharynx, and larynx can be done, and documented too. Consequently, even the swallowing techniques to be adopted can be determined. It will also assess the salivary aspiration that may be happening, and the cough sensitivity and efficiency. Ideally, this is to be done with a flexible laryngoscope with a suction port, though a transnasal esophagoscope also may be used if available. Pediatric scopes do not have a suction channel; in this case, a suction catheter can be introduced through the other nostril for simultaneous suction.

In the first level, the anatomy and the sensation of the laryngopharynx are assessed.

  • Velopharyngeal closure

  • Pooling of secretions in the pharynx

  • Laryngeal elevation—white out phase on monitor

  • Vocal fold function.

    • Eee-sniff maneuver

    • Breath-holding maneuver— Patient’s ability to close supraglottis and protect airway

    • Vocal fold position.

  • Pharyngeal squeeze maneuver (PSM): The patient says a forceful “eee” sound and the degree of pharyngeal muscular contraction and narrowing of the pyriform sinus during voluntary forceful adduction of the vocal folds is noted.

  • Ability to clear secretions by coughing.

  • Laryngeal adductor response (LAR): The sensation of the larynx is tested with the tip of the laryngoscope. The LAR is a brainstem mediated airway protective reflex, the afferent component is internal branch of the superior laryngeal nerve and the efferent arc is the recurrent laryngeal nerve.

  • In the second level, food is administered and the laryngopharynx is visualized through the scope during the act of swallowing.

    • If LAR is present and PSM is absent then only water is given for testing.

    • If PSM is present and LAR is absent then only semisolids are given for testing.

    • If both are absent, then ice chips which will enhance the sensory information to the patient and will cause lesser harm if aspirated are given to the patient.

    • The presence of abundant secretion in the laryngeal vestibule or a non-protective cough can be contraindications to an examination with a bolus.

    • The tip of the scope is kept at the level of the base of the tongue and observation of swallowing is done for the following:

      • Premature spillage: Loss of bolus into the pharynx before the initiation of swallow

      • Swallowing white-out: The oropharyngeal stage is not visible endoscopically when the swallowing reflex starts, because the endoscope will be in contact with the base of the tongue, the epiglottis and the bolus itself.

      • Penetration: Passage of material into the laryngeal inlet

      • Aspiration: Passage of material below the vocal cord

      • Pooling of food.

If the remains of the bolus are abundant at the end of the swallow, particularly in cases of cricopharyngeal spasm, they might penetrate the larynx and cause aspiration (post-swallowing inhalation) (Fig 5).

Fig. 5: Barium swallow showing the indentations (arrow) of the proximal esophagus indicating web Plummer-Vinson syndrome (2)

Video Fluoroscopy (VFS)

Video fluoroscopy is still considered the gold standard in the diagnosis of swallowing disorders, though of late, the hazard of radiation exposure has compelled many clinicians to reduce its use. Its advantage over FEES is its ability to assess all the phases of swallowing, as well as the ability to quantify the aspiration, due to the side-on view, as compared to the end-on view provided by FEES.8 Rosenbek et al. described an 8-point penetration-aspiration scale based on videofluoroscopic data that fulfills this purpose (Fig. 6 and Table 1).9

Table 1: Eight-point penetration-aspiration scale
1. Material dose not enter the airway
2. Material enters the airway, remains above the vocal folds, and is ejected from the airway
3. Material enters the airway, remains above the vocal folds, and is not ejected from the airway
4. Material enters the airway, contacts the vocal folds, and is ejected from the airway
5. Material enters the airway, contacts the vocal folds, and is not ejected from the airway
6. Material enters the airway, passes below the vocal folds, and is ejected into the larynx or out of the airway
7. Material enters the airway, passes below the vocal folds, and is not ejected from the trachea despite effort
8. Material enters the airway, passes below the vocal folds, and no effort is made to eject.

Fig. 6: Barium swallow showing aspiration

Other Investigations

A pharyngeal manometer can be used to understand the inferior constrictor dysmotility in far more detail.10 A two-channeled electromyography (EMG) simultaneously assesses the thyropharyngeus and cricopharyngeus muscles, and this gives more information regarding the individual and combined dysfunction of the thyropharyngeus-cricopharyngeus complex. A pH meter is used to assess the acidic and nonacidic reflux, and scintigraphy can pick up microaspirations.

MANAGEMENT

In any patient with dysphagia, the first concern is alternative feeding methods. Nutritional status has to be maintained at desirable levels either by enteral parenteral feeding.11 The different enteral feeding methods are nasogastric tube feeding, gastrostomy—either percutaneous endoscopic (PEG) or open and feeding jejunostomy (Fig. 7). Sometimes a nasojejunal tube positioning may be warranted. The selection of tube feeding has to be determined by the expected duration of alternative feeding and future treatment options. For example, if the expected period is more than 1 month, it is better to replace nasogastric tube feeding with either gastrostomy or jejunostomy. Similarly, in cases where a stomach pull-up is being planned, it would be sensible to go for a feeding jejunostomy rather than a gastrostomy. In rare circumstances, enteral feeding may not be possible or feasible. Then parenteral nutrition has to be considered. Occasionally a combined enteral plus partial parenteral nutrition may also be chosen.

Fig. 7: Percutaneous endoscopic gastrostomy

Swallowing Therapy

Swallowing therapy is the mainstay of treatment of swallowing disorders. There are two groups of swallowing therapy exercises namely, direct and indirect. In indirect swallowing therapy exercises are designed to strengthen the weakened muscles without any food being given. In direct swallowing therapy, oral feeds are started, but in a modified way, so that the difficulty in swallowing is reduced.

Velopharyngeal Incompetence

Palate strengthening exercises are balloon blowing, playing musical wind instruments, and blowing out candles. The direct swallowing therapy techniques consist of avoiding thin liquids, pinching the nose while swallowing, and chin tuck.

Absent/Weak/Infrequent Hyolaryngeal Excursion

Shaker exercise and chin tuck against resistance (CTAR) are excellent exercises to strengthen the suprahyoid musculature and consequently laryngeal elevation. In the Shaker exercise, the patient rests in a supine position and lifts his or her head to look at the toes. Neuromuscular electrical stimulation (NMES) helps by improving the sensory input of the oropharyngeal cavity, facilitating or restoring the oral or pharyngeal motor function, and achieving adequate laryngeal elevation.12 It can avoid the disuse of muscle dystrophy and strengthen the contraction of paralyzed oropharyngeal muscles (Fig. 8). Direct swallowing therapy in this scenario includes Mendelsohn’s maneuver and chin tuck (Fig. 9). The Mendelsohn maneuver is a method of intentionally holding the larynx when the larynx is elevated, so that activation of the suprahyoid muscles is induced.

Fig. 8: Electrodes placement for NMES

Fig. 9: Holding the larynx when it is elevated in Mendelssohn’s maneuver

Laryngeal Incompetence

Strengthening the incompetent hemilarynx can be done by push-pull exercise and half-swallow boom. In the half-swallow boom technique, the patient is asked to say ‘Boom’ while swallowing is in progress. This swallow procedure is known to maximize the closure of the larynx. Unilateral laryngeal incompetence can be successfully managed most of the time by supraglottic or super supra glottis swallowing techniques. In the supraglottic swallow technique, the patient is instructed to hold his or her breath just before swallowing, to close the vocal folds. The swallow is then followed immediately by a volitional cough. In super-supraglottic swallow, the patient is asked to hold one’s breath and bear down while swallowing, cough immediately after swallowing, and then swallow hard again before inhaling. Bilateral laryngeal incompetence is a different ball game altogether and is not amenable to swallowing therapy.

Thyropharyngeal Paralysis

Forcible phonation is a good stimulus to strengthen the weakened hemilarynx. Direct swallowing therapy techniques include head-turning to the paralyzed side so that the affected pyriform fossa is nearly obliterated, thus directing the bolus through the unaffected pyriform fossa in addition to effortful swallowing and avoiding a thick bolus of food.13 The thinner bolus does not require much squeezing effort from the thyropharyngeus muscle. In a bedridden patient, feeding should be given in a lateral lying position, with the normal side being down, thus utilizing gravity to direct the bolus through the normal side.

Cricopharyngeal Dysmotility

Cricopharyngeal dysmotility, if secondary to absent laryngeal elevation, may respond well to the indirect swallowing therapy techniques described above for absent hyolaryngeal excursion. However, there are not many indirect swallowing therapy techniques for primary cricopharyngeal dysmotility apart from the local application of heat. Direct swallowing therapy would include chin tuck and large warm sour bolus.

Interventional Management

Interventional management includes a group of surgical interventions, for which the author prefers to use the term phaco-surgery, very much like phonosurgery.

Velopharyngeal Incompetence

Palatopexy using superiorly based palatopharyngeus flaps can be used to tighten the velopharyngeal port so as to improve the voice as well as swallowing (Fig. 10). Other surgeries like pharyngeal flap repair and posterior wall augmentation also may be used judiciously.

Fig. 10: Palatopexy; SP, soft palate; PPW, posterior pharyngeal wall. White asterix: Superiorly based pharyngeal flaps are raised on either sides and sutured transversely across the posterior pharyngeal wall

Absent Hyolaryngeal Excursion

Though sufficient evidence is missing, hyoidopexy (Fig. 11) (fixing the hyoid to the mandible and thyroid cartilage to hyoid) may be done on the basis that Mendelsohn’s maneuver improves swallowing.

Fig. 11: Hyoidopexy. Upper end of the sutures goes through holes drilled in the mandible. Lower sutures go through silastic bolsters on thyroid cartilage. Middle sutures are at the level of hyoid

Laryngeal Incompetence

Bilateral laryngeal incompetence almost always requires tracheostomy with a cuffed tube. A minority of patients may even require surgical procedures like laryngotracheal dysfunction, epiglottic oversew, and glottis closure. Though laryngectomy is described as the gold standard for the prevention of aspiration, this option is very rarely used.

Unilateral laryngeal incompetence not responding to swallowing therapy techniques should be treated by vocal cord medializing procedures like endoscopic or percutaneous injection laryngoplasty, medialization thyroplasty, and or arytenoid rotation.

Thyropharyngeal Paralysis

If this is the only pathology, usually surgical intervention is not warranted. However, if it occurs in conjunction with laryngeal incompetence and cricopharyngeal dysmotility, obliteration of the affected pyriform fossa (hypopharyngoplasty) may help to reduce the stagnation and consequent aspiration (Fig. 12).

Fig. 12: LEMG- guided botox injection for cricopharyngeal spasm

Cricopharyngeal Dysmotility

Cricopharyngeal dysmotility in Brainstem stroke generally recovers spontaneously, however, if the spontaneous recovery does not occur within 6 weeks to 3 months, intervention is indicated. Botulinum toxin injection into the cricopharyngeus under laryngeal EMG guidance or fluoroscopic control can give good results14 (Fig. 12). Those with long-standing dysfunction may benefit from cricopharyngeal myotomy—either endoscopic or external.15

Pharyngeal Pouch

Treatment of pharyngeal pouch includes external excision with cricopharyngeal myotomy, endoscopic stapling and myotomy (Dohlman’s operation) (Fig. 13), and diverticulo-esophagostomy.16 The latter operation is reserved for older patients with a high risk for anesthesia.

Fig. 13: Cricopharyngeal myotomy—Recurrent laryngeal nerve (Green arrow), cricopharyngeus (Black arrow)

Postcricoid Web

Postcricoid web in Plummer-Vinson syndrome requires endoscopic dilatation as well as aggressive treatment of iron-deficiency anemia. These patients should be under regular follow-up, to check for any malignant transformation.

Tumors and osteophytes should be surgically removed either endoscopically or externally depending upon the pathology, patient’s general condition, and surgeon’s expertise and experience.

CONCLUSION

Pharyngeal dysphagia is a spectrum of swallowing dysfunction, brought about by various illnesses, but predominantly neurological, neurosurgical and head and neck oncological causes. It can cause significant morbidity and mortality if left untreated. A systematic approach to diagnosis is to be followed. Most of them can be relieved of their dysphagia symptoms either completely or partially by suitable swallowing therapy exercises and techniques. A minority may require carefully chosen surgical procedures.

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