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AUTHOR AND EDITOR INFORMATION
Section 1 of 11  
Author: Segun T Dawodu, MD, FAAPMR, FAANEM, CIME, DipMI(RCSed), Former Clinical Instructor, Mount Sinai Medical School, Current Director, Pain and Injuries Rehabilitation Services, PMRehab Pain & Sports Medicine Associates
Segun T Dawodu is a member of the following medical societies: American Academy of Physical Medicine and Rehabilitation, American Association of Neuromuscular and Electrodiagnostic Medicine, American College of Sports Medicine, American Medical Association, American Medical Informatics Association, Association of Academic Physiatrists, International Society of Physical and Rehabilitation Medicine, and Royal College of Surgeons of England
Editors: Everett C Hills, MS, MD, Medical Director, Rehabilitation Hospital, Assistant Professor of Orthopaedics and Rehabilitation, Orthopaedics and Rehabilitation, Penn State Milton S. Hershey Medical Center; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Richard Salcido, MD, Chairman, Erdman Professor of Rehabilitation, Department of Physical Medicine and Rehabilitation, University of Pennsylvania School of Medicine; Kelly L Allen, MD, Consulting Staff, Department of Physical Medicine and Rehabilitation, Lourdes Regional Rehabilitation Center, Our Lady of Lourdes Medical Center; Consuelo T Lorenzo, MD, Consulting Staff, Department of Physical Medicine and Rehabilitation, Alegent Health Care, Immanuel Rehabilitation Center
Author and Editor Disclosure
Synonyms and related keywords:
swallowing disorders, dysphagia, difficulty swallowing, deglutition disorders
Swallowing disorders, or dysphagia, is a general term used to describe the inability to move food from the mouth to the stomach. This condition should be differentiated from any other disorder that prevents transfer of food to the mouth or food beyond the stomach. Feeding disorder, which is the inability to get food to the mouth, and gastric outlet obstruction, the inability of food to pass from the stomach into the small intestine, should be differentiated from swallowing disorders. An average of 10 million Americans are evaluated for swallowing disorders annually. Many causes have been identified for dysphagia, and they are discussed later in this article.
ANATOMY AND PHYSIOLOGY OF NORMAL SWALLOWING
Normal swallowing can be divided into the following 3 phases:
- Oral phase, which involves oral preparatory phase and oral transit phase
- Pharyngeal phase
- Esophageal phase
Oral phase
This phase is divided into the following 2 parts:
- Oral preparatory phase
- This phase involves movement of the mandibular and labial musculature in the process of mastication with the food formed into a bolus and held anterolaterally against the hard palate by the tongue.
- This process requires the taste, temperature, touch, and proprioception senses for formation of a bolus of the right size and consistency.
- Oral transit phase
- This segment of the swallowing process involves manipulation of the bolus formed in the preparatory stage in the central portion of the tongue and then pushing it toward the pharynx posteriorly with a sequential anterior-to-posterior tongue elevation to trigger the pharyngeal reflex as the bolus enters the pharyngeal phase.
- This process requires that a labial seal be maintained to prevent food from leaking from the mouth and a buccal musculature tension to prevent food from getting into the recess between the mandible and cheek.
- This segment of the swallowing process is a voluntary phase controlled by the cerebral cortex through the corticobulbar tracts.
Pharyngeal phase
This phase, a reflex action in which the bolus moves through the pharynx, takes place in less than one second. The initiation of the process starts at the anterior faucial arch, preventing interruption of the posterior movement of the bolus. This action leads to retraction of the tongue and elevation and complete retraction of the velum, leading to velopharyngeal closure, which prevents material from entering the nasal cavity.
This stage is followed by pushing of the bolus further into the pharynx toward the cricopharyngeal sphincter by the pharyngeal constrictor muscles. The larynx prevents material from entering the airway by closing at the level of the true vocal cords, false vocal folds, and epiglottis-aryepiglottic folds. The phase ends with the elevation of the larynx itself, which also helps in the cricopharyngeal opening by stretching that region. This action is followed by relaxation of the cricopharyngeal muscle, allowing the bolus to pass into the esophagus.
Esophageal phase
This final phase of the swallowing process is under the control of the brain stem and the myenteric plexus. A peristaltic wave beginning in the pharynx pushes the bolus sequentially from the cervical esophagus down through the esophageal-gastric sphincter into the stomach.
The process of swallowing is organized with sensory input from receptors in the base of the tongue, soft palate, faucial arches, tonsils, and the posterior pharyngeal wall, which then is transmitted to the swallowing center located within the pontine reticular system through the facial (VII), glossopharyngeal (IX), and vagus (X) cranial nerves. Information from the swallowing center then is conveyed back to the muscles that help in swallowing through trigeminal (V), facial (VII), glossopharyngeal (IX), vagus (X), and hypoglossal (XII) cranial nerves, with the trigeminal, hypoglossal, and nucleus ambiguus constituting the efferent levels.
The act of swallowing usually interrupts the expiratory phase of ventilation, while the completion of expiration occurs when swallowing ends. In situations where the swallowing is initiated during the inspiratory phase of ventilation, a brief expiration ensues after completion of swallowing.
PATHOPHYSIOLOGY OF SWALLOWING DISORDERS
Abnormalities of swallowing could be secondary to defects in any of the stages of swallowing enumerated above.
Aspiration: Passive entry of any food item into the trachea (eg, during inhalation), although the term often is used to denote any entry of a bolus into the trachea in any manner
Penetration: Active entry of any food item into the trachea (eg, during swallowing), although the term often is used to denote the entry of any bolus into the laryngeal vestibule
A lesion in the cerebral cortex or the brain stem can cause swallowing disorders in the following ways:
- Decrease in range of motion (ROM) of muscles of mastication and bolus propulsion, especially those responsible for buccal, labial, and lingual strength and the cricopharyngeus
- Decreased sensation
- Delayed or absent pharyngeal swallowing and reductions in pharyngeal peristalsis
- Delayed or absent laryngeal adduction and elevation
- Location of specific sites of lesions does not show correlation with findings on the CT scan or MRI.
Abnormality at the oral stage
- Pocketing of food in the mouth, circumoral leakage, and early pharyngeal spill can occur with weakness and poor coordination of the lips, cheeks, and tongue.
- Aspiration of food, especially during inhalation, can occur before pharyngeal swallowing due to premature pharyngeal spillage.
- Weak posterior tongue can lead to abnormal tongue thrusting.
- Changes in mental status with cognitive deficits also may affect the initiation of swallowing, increasing the tendency to pocket food in the lateral sulci, leading to possible aspiration.
Abnormality at the pharyngeal stage
- Dysfunction or abnormalities of the soft palate and superior pharynx can lead to nasopharyngeal reflux (eg, cleft palate) following uvulectomy
- Defect in thyrohyoid and palatopharyngeal muscles function and hyoid bone elevation can lead to reduced laryngeal and pharyngeal elevation leading to aspiration.
- Pharyngeal constrictor weakness can lead to accumulation of food residue in the valleculae and preform sinus that then could be aspirated after swallowing.
- Impaired relaxation, distensibility, fibrosis, hyperplasia, or hypertrophy of the cricopharyngeus can lead to improper coordination of swallowing.
Abnormality at the esophageal phase
- Achalasia can lead to reduced gastroesophageal junction relaxation or absent esophageal peristalsis.
- Zenker diverticulum can lead to swallowing difficulty with possible nocturnal aspiration of residue in the diverticulum.
- Other defects in the wall of the esophagus or in the external structures (eg, in the hilar lymph nodes) can lead to dysfunction in the propulsion of the bolus within the esophagus on to the stomach (eg, esophageal webs, rings, strictures; intraluminal obstruction from solids) and in weak esophagopharyngeal peristalsis due to scleroderma or other conditions.
CLINICAL EVALUATION OF SWALLOWING
History and physical examination
When obtaining the patient's history and performing the physical examination, the physician should inquire about onset, duration, timing, associated factors, and progress of the symptoms. The following are symptoms and signs that should suggest possible dysphagia:
- Difficulty in initiating swallowing
- A feeling of obstruction as if food has become stuck in the throat
- Voice change
- Difficulty with chewing or weakness of muscles of mastication
- Pocketing of food in the mouth
- Globus sensation or pain in the hypopharynx
- Coughing after eating
- Drooling
- Impairment gag reflex and ability to clear bolus, cough, and breathing
- Nasal regurgitation
- Inappropriate breathing or speaking while swallowing
- Weight loss
- Recurrent pneumonia
- Other associated factors/symptoms
- General weakness
- Mental status changes
- Weight loss and malnutrition
- Relevant past medical history, including the following:
- Recent stroke
- Neuromuscular disease
- Hypertension
- Diabetes mellitus (DM)
- Thyroid disease
- Cancer
- Nephropathic cystinosis
- Dementia
- Recent injection of botulinum toxin (could lead to swallowing difficulties within 3 d)
- Traumatic brain injury (TBI)
- Medications that may be associated with swallowing disorders include the following:
- Nitrates
- Anticholinergic agents
- Calcium tablets
- Calcium channel blockers
- Aspirin
- Iron tablets
- Vitamin C
- Antipsychotics (eg, olanzapine [Zyprexa])
- Tetracycline
A thorough physical examination should include the following:
- General examination, including weight and vital signs
- Full head and neck examination, focusing on cranial nerve functions, dentition, palate, tongue, and pharynx
- Laryngoscopy may be needed to evaluate the supraglottis further, as well as the vallecular area. Neck masses, thyroid, and bruits should be checked. Structural integrity of the hyoid and larynx also should be checked.
- Lungs should be checked for rales/crepitations, wheezes, rhonchi, air entry, and other abnormalities.
- Thorough neurologic examination, looking at mental status and cranial nerves (especially V, VII, IX, X, and XII)
- Muscle strength, reflexes, coordination, gait, and functional status to complete the neurologic examination
DIAGNOSTIC EVALUATION OF SWALLOWING
History and physical examination alone may not be adequate to make a diagnosis in silent aspiration. Further diagnostic tests include the following:
- Videofluoroscopic swallowing study (VFSS) is the criterion standard. This test is performed with the modified barium swallow. The VFSS evaluates the pharyngeal phase of the swallowing process, using different consistency of the barium and allowing for evaluation of the effect of different maneuvers in preventing aspiration.
- Fiberoptic endoscopic evaluation of swallowing (FEES) is used to evaluate any structural abnormalities in the nasopharynx, laryngopharynx, and hypopharynx, especially in patients who cannot be transported to the radiology suite for the VFSS.
- Transnasal esophagoscopy is especially useful for esophageal diverticula, tumor, or other conditions.
- Ultrasonography evaluates soft tissue dynamics during the oral and pharyngeal phases, looking at tongue function and laryngeal/hyoid elevation. Ultrasonography is useful in diagnosing childhood tongue incoordination and could be combined with FEES to diagnose extramural and submucosa lesion that could be undetected by FEES alone.
- Electromyography (EMG) is of limited use clinically and is used mainly in research to evaluate individual myoelectric function.
- Scintigraphy entails having the patient swallow a Tc-99m sulfur colloid bolus to label oral secretions and subsequently obtaining neck and chest images to detect aspirations. The advantage of this test is in quantification of aspiration, identification of silent aspiration of saliva, and determination of the rapidity and completeness of aspirated materials. Scintigraphy also can be combined with 24-hour pH manometry to check the cause of chest pain between esophageal and possible cardiac factors.
- Manometric fluoroscopy is manometry combined with VFSS to check the pressure gradient of the pharynx and the pharyngoesophageal junction.
- Cervical auscultation allows assessment of pharyngeal swallow by listening to stereotypical sounds using the stethoscope. This test might be a useful bedside tool, especially in the absence of other diagnostic tools.
- Blood tests, including thyroid-stimulating hormone, vitamin B-12, creatine kinase, especially in neurogenic dysphagia
- Other tests (eg, CT scan, MRI of the head and neck, chest x-ray, pulmonary function tests to evaluate other possible associated causal factors).
The above enumeration of tests is not exhaustive, and the need for further tests may be based on the need to follow up on other associated findings during initial evaluation. Consultations and further evaluations by an ear, nose, and throat (ENT) surgeon and speech language therapist also may be necessary.
TREATMENT OF SWALLOWING DISORDERS
The goals of treatment are (1) to maintain adequate nutritional intake and (2) to maximize airway protection.
Rehabilitation therapy
Rehabilitation therapy is the main stay of dysphagia management and allows for safe swallowing. Rehabilitation requires the cooperation of the patient and the ability of the patient to understand and follow commands. Typical therapy programs involve the following components:
- Oral feeding with consistency modifications - Dysphagia diets
- Dysphagia diet 1 - Thin liquids (eg, fruit juice, coffee, tea)
- Dysphagia diet 2 - Nectar-thick liquids (eg, cream soup, tomato juice)
- Dysphagia diet 3 - Honey-thick liquids (ie, liquids are thickened to a honey consistency)
- Dysphagia diet 4 - Pudding-thick liquids/foods (eg, mashed bananas, cooked cereals, purees)
- Dysphagia diet 5 - Mechanical soft foods (eg, meat loaf, baked beans, casseroles)
- Dysphagia diet 6 - Chewy foods (eg, pizza, cheese, bagels)
- Dysphagia diet 7 - Foods that fall apart (eg, bread, rice, muffins)
- Dysphagia diet 8 - Mixed textures
Thickened liquids increase oropharyngeal control. A diet of chopped or pureed foods decreases difficulties with mastication.
- Compensatory strategies to reduce the risk of aspiration include the following:
- Chin tuck: The patient holds the chin down, increasing the epiglottic angles, and pushes anterior laryngeal wall backward, thereby decreasing the airway diameter.
- Head rotation: The ipsilateral pharynx is closed, forcing the food bolus to the contralateral pharynx while cricopharyngeal pressure is decreased.
- Head tilt: This technique guides the bolus to the ipsilateral pharynx using the effect of gravity.
- Supraglottic swallow: This technique involves simultaneous swallowing and breath-holding, closing the vocal cords and protecting the airway. The patient thereafter can cough to expel any residue in the laryngeal vestibule. The Valsalva maneuver may be used to maximize vocal cord closing.
- Mendelsohn maneuver: This maneuver is a form of supraglottic swallow in which the patient mimics the upward movement of the larynx by voluntarily holding the larynx at its maximum height to increase the duration of the cricopharyngeal opening.
- Exercise and facilitation techniques
- Exercises are used to increase muscle tone and augment pharyngeal swallow. These techniques are geared especially toward ROM, coordination and strengthening of muscles of the jaw, lips, cheek, tongue, soft palate, and vocal cords.
- Biofeedback techniques are used to re-educate muscles affected in facial palsy and disorders of articulation. This includes electromyography (EMG) feedback in which surface electrodes are placed over the anterior neck, for example. Visual feedback is obtained in VFSS while experimenting with head positions and swallowing maneuvers.
- Thermal stimulations can be performed in which icing of the anterior faucial arches may help to decrease delay of pharyngeal swallow.
- Medical interventions
- Botulinum toxin type A is injected endoscopically into the gastroesophageal sphincter and upper esophagus to decrease tone. This could be very useful in cricopharyngeal spasms causing dysphagia.
- Diltiazem can aid in esophageal contractions and motility, especially in the disorder known as the nutcracker esophagus.
- Glucagon is used in disimpacting esophageal bodies; diazepam also is used sometimes. No major study has proven their effectiveness.
- Cystine-depleting therapy with cysteamine is the treatment of choice for patients with dysphagia due to pretransplantation or posttransplantation cystinosis.
- Nitrates can be recommended, especially Isosorbide dinitrate in achalasia.
- Endoscopic and surgical interventions
- Esophageal dilatation in achalasia, strictures, and webs
- Cervical osteophyte resection
- Cricopharyngeal myotomy for upper esophageal spasm
- Zenker diverticula resection on suspension
- Esophageal resection and reanastomosis
- For paralyzed vocal cords, Teflon injection or reversible vocal cord medialization can be performed.
- Microsurgical techniques to help in swallowing with improvement in biotechnology are on the horizon.
- Cuffed tracheostomy sometimes is performed to protect the airway in recurrent pneumonia.
- Laryngectomy or laryngotracheal diversion also may be indicated, as for tracheostomy, and often is performed as a permanent palliative measure when all else has failed.
- See other recommendations on nonoral feedings for procedures to help feeding.
- Nonoral feedings
- Parenteral alimentation and IV fluid replacement should be prescribed to meet caloric and fluid requirements. The necessary caloric/fluid needs must be calculated to meet the patient's daily needs.
- Esophagostomy is needed in patients in whom other placements may not be possible and to help in the control of pharyngeal secretions.
- Nasogastric (NG) tubes are convenient for the short term, but their use is limited by complications including regurgitation, irritation, bleeding, and discomfort. H2-blocker or proton-pump inhibitors should be given as prophylaxis to prevent some of the above complications.
- Gastrostomy can be placed by percutaneous endoscopic means (PEG), allowing for continuous or bolus feedings. Risks are the same as mentioned above, and reflux prevention is performed by feeding the patient in a vertical position, using H2-blockers to decrease gastric pH, Chlorpromazine or Maxolon to facilitate gastric emptying, and proton-pump inhibitor to decrease gastroesophageal reflux.
- Jejunostomy may be indicated in patients with known reflux and aspiration. This procedure is performed under general anesthesia and could involve continuous or bolus feeds.
DIFFERENTIAL DIAGNOSIS AND PROGNOSIS
The possible causes of dysphagia need to be evaluated. Causes may include the following:
- Central nervous system disorders
- Stroke
- TBI
- Parkinson disease
- Alzheimer disease
- Amyotrophic lateral sclerosis
- Multiple sclerosis
- Brain tumors
- Guillain-Barré syndrome
- Huntington disease
- Central nervous system (CNS) infections
- Postpolio syndrome/muscular atrophy
- Neuromuscular junction disorders - Myasthenia gravis
- Muscular disorders may include the following myopathies:
- Muscular dystrophies
- Spinal muscular atrophy
- Poliomyelitis
- Polymyositis
- Dermatomyositis
- Neuropathic disorders may include the following neuropathies - Sensory neuropathies affecting the laryngeal nerves
- Endocrine disorders
- Secondary myopathies in Cushing syndrome, hyperthyroidism, and hypothyroidism
- Vitamin B-12 deficiency, leading to pseudobulbar palsy secondary to corticobulbar tract dysfunction
- Iatrogenic oropharyngeal dysphagia
- Medications produce effects due to a decrease in cognition or development of drug-induced myopathies. These medications include the following:
- CNS depressants
- Antipsychotics
- Corticosteroids
- Lipid-lowering agents
- Colchicine
- Aminoglycosides
- Anticholinergic drugs
- Surgeries leading to dysphagia may involve any part of the brain or brain stem, neck/oral/nasopharyngeal/laryngeal areas, or pharyngeal plexus during cervical fusion or carotid endarterectomy.
- Psychogenic dysphagia
- This diagnosis is one of exclusion.
- The condition is characterized by oral apraxia with intact speech and pharyngoesophageal and neurologic function.
- Associated psychiatric conditions include anxiety, depression, somatoform disorders, hypochondriasis, conversion disorders, or eating disorders.
- Instances of swallowed foreign bodies do occur (bezoars), especially in the mentally retarded, and this possibility also should be considered.
- Psychiatric evaluation and treatment often are needed.
- Esophageal disorders
- Motility disorders
- Diffuse esophageal spasms (DES)
- Achalasia (megaesophagus)
- Scleroderma
- Presbyesophagus
- Cricopharyngeal dysfunction
- Esophagitis
- Gastroesophageal reflux disease (GERD)
- Infectious esophagitis (eg, as in human immunodeficiency virus [HIV], herpes, Candidiasis)
- Radiation esophagitis, especially after radiation treatments of 4500 to 6000 rad over 6-8 weeks
- Medication-induced esophagitis may develop from enteric-coated nonsteroidal anti-inflammatory agents. Substances such as quinidine, potassium, vitamins, and FeSO4 also may produce esophageal injury.
- Structural disorders
- Zenker diverticulum at the upper esophagus or epiphrenic diverticula at the mid or distal esophagus
- Esophageal strictures, webs, or rings
- Schatzki rings
- Plummer-Vinson or Paterson-Kelly syndromes and hypopharyngeal webs with iron deficiency anemia
Neurogenic dysphagia is caused by neurologic disorders, in which the sensorimotor aspects of the oropharyngeal are affected. Diverticula and esophageal strictures, webs, or rings may lead to what could be termed neurogenic dysphagia that is present classically with symptoms of oropharyngeal dysphagia.
In conditions where recovery is possible (eg, TBI, stroke), the normalization of swallowing may take from 3 weeks to approximately 6 months or longer. Many patients tolerate normal oral caloric intake after 9 months following a stroke, while some may require partial or nonoral caloric supplementation. In patients who have sustained strokes, continued swallowing dysfunction after 6 months is associated with increased morbidity and mortality.
In static or progressive conditions (eg, neuromuscular disorders, postpolio syndrome), periodic evaluation of swallowing disorders is mandatory, especially with onset of new symptoms, and the appropriate changes (nonoral feeding techniques or new compensatory mechanism) should be considered.
Swallowing disorders are becoming a major source of disability. In the last decade, improvements have been made in the ways these disorders can be treated, especially the consequent malnutrition. With the available tests and management options, the prognosis for patients with swallowing disorders has improved.
The need for an understanding of the anatomy and physiology of the areas of the body affected is paramount in the diagnosis and management of swallowing disorders. Early involvement of other specialists, including ENT surgeons, nutritionists, gastroenterologists, general surgeons, and speech and language therapists, offers a good prognosis for the management of swallowing disorders.
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Swallowing Disorders excerpt Article Last Updated: Jan 26, 2007
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