Introduction to Dysphagia
Swallowing (also called deglutition) is a complex process that involves the propulsion of food bolus from the oral cavity to the stomach via the pharynx and esophagus while protecting the airway and minimizing the residue. This is accomplished by the coordination of over 30 nerves and muscles. Any disruption in the normal functioning of these elements can lead to significant pathology (1).
Dysphagia is defined as the impairment or difficulty in swallowing. It has both objective and subjective aspects. Dysphagia is common but is usually underreported. It is an important symptom pointing towards some underlying disease that should be addressed. It may be due to mechanical obstructive causes or motility disorders leading to impaired swallowing and may affect the patient’s quality of life (2).
Early diagnosis of the underlying disease and proper management is necessary to improve the quality of life and reduce morbidity and mortality rates. In this brief overview of dysphagia, we will discuss the definition, causes, pathophysiology, and management of dysphagia.
Definition of Dysphagia
Dysphagia is defined as impairment or difficulty in swallowing, leading to a delay in the movement of the food bolus from the oral cavity to the stomach (2). It can be objective or subjective. In the subjective aspect of dysphagia, there is a feeling of impaired or difficulty swallowing associated with pain (odynophagia). While the objective aspect is based on the investigations and evaluation, which may show hindrances to the transit of food bolus even if there is no subjective feeling of dysphagia present (3).
In every case of dysphagia, both of these aspects are important as the sensation of delay or dysphagia may be lost partially in some patients while it may also be enhanced or diminished through sensory neural dysfunction (3).
Dysphagia is a common symptom but is usually underreported. The prevalence of dysphagia also depends upon the underlying disease, advancing age, and place of assessment (i.e., community vs. hospital).
In the United States, 10% to 20% of people of age 50 and above experience dysphagia once in their lifetime. This number increases with an increase in age, and prevalence rises to 40% in people over 60. Almost 30% to 60% of people in nursing homes have dysphagia (4).
The underlying disease is also an important factor in determining the prevalence of dysphagia. In patients with a history of unilateral hemispheric stroke, dysphagia usually ranges from 19% to 81% (5). The prevalence rates increase in cases of brainstem stroke or bilateral hemispheric stroke (6). It is important for the clinician to consider dysphagia while managing these patients as it may lead to aspirational pneumonia and pulmonary complications, which in turn, lengthens the hospital stay.
Dysphagia is also associated with intubation and intensive care units (ICU), especially patients who experience the symptoms after extubation. According to a study, the prevalence of post-extubation dysphagia can range from 3% to 62%. Similarly, a retrospective cohort study has shown that the prevalence of dysphagia may rise up to 84% in post-extubated patients (7, 8).
Idiopathic achalasia may also present with associated dysphagia. The prevalence of achalasia is approximately 10.82 per 100,000 people per year (9).
Dysphagia can be classified on the basis of the location of etiology. It can be oropharyngeal, esophageal, esophagogastric, and para-esophageal dysphagia. Moreover, some systemic diseases can also manifest dysphagia during the course of the disease. These causes are as follows:
The causes of oropharyngeal dysphagia can be further divided into three main groups:
Neurological causes: These include cerebrovascular accidents (CVA) such as hemispheric or brainstem stroke leading to post-stroke dysphagia. Cranial nerve nuclei involvement in CVA also plays a role in this. Parkinson’s disease is also an important cause of dysphagia that is due to basal ganglia lesions. Furthermore, central nervous tumors, degenerative cervical spine disease, supranuclear palsy, multiple sclerosis, and amyotrophic lateral sclerosis can also present with dysphagia. (3, 5, 6, 10)
Muscular causes: Myasthenia gravis is the most important muscular disease leading to dysphagia. Other diseases include Duchene muscular dystrophy (DMD) and polymyositis. (11, 12)
Anatomical causes: Any obstructive disease that prevents the transit of food bolus from the oropharynx to the esophagus can lead to dysphagia. These include goiter (large enough to cause an obstruction), Zenker diverticulum, the fusion of cervical vertebrae, and tumor of the upper esophagus or esophageal web. (3)
It can be due to impaired motility of the esophagus (motility disorders) or obstructive disorders.
Motility disorders: Ineffective esophageal motility, Achalasia, spasm of the lower esophageal sphincter (LES), or scleroderma can lead to dysphagia. (13)
Obstructive disorders: These include esophageal stricture or Schatzki ring, esophageal tumor, and eosinophilic esophagitis. (14)
It occurs when there is a hindrance to the transmission of food from the esophagus to the stomach through the lower esophageal sphincter. Achalasia is the most important cause to this respect, which occurs due to a non-relaxing lower esophageal sphincter. Other causes include tumors of the distal third of the esophagus and mass lesions of the gastric cardia. (15)
This type of dysphagia occurs when a mass or lesion (aortic aneurysm or tumor) outside of the esophagus causes physical impingement or infiltration of the esophageal wall leading to obstruction and dysphagia. (10)
Some systemic diseases can also manifest dysphagia during the course of the disease, such as rheumatoid arthritis, CREST syndrome, systemic lupus erythematosus, and mixed connective tissue disorders. Several drugs such as opioids, tricyclic antidepressants, antipsychotics, potassium supplements, bisphosphonates, NSAIDs, and alcohol can also cause dysphagia as their side effect.
The pathophysiology of dysphagia depends upon the underlying disease. It can be oropharyngeal, esophageal, esophagogastric, or para-esophageal dysphagia.
In old age, dysphagia can occur due to impaired salivary production leading to difficulty in swallowing, age-related changes in muscle and jaw strength, dental problems, and changes in the threshold of laryngeal elevation. Loss of elasticity of the upper esophageal sphincter can also cause delayed oropharyngeal phase and dysphagia. (16, 17)
In patients with neurological disorders such as cerebrovascular accidents (CVA) or stroke (cerebral or brainstem), dysphagia can manifest due to dysfunction of voluntary control of mastication, leading to delayed transit of bolus. This is especially important in the oropharyngeal phase of swallowing.
Cortical lesions of the brain involving the precentral gyrus lead to the loss (partial or complete) of facial muscles and tongue movements. It can also be associated with impaired pharyngeal peristalsis leading to dysphagia.
Brainstem strokes are significantly associated with dysphagia compared to the others due to the involvement of cranial nerves emerging from the brainstem. The patient may also have sensory loss over the mouth, tongue, and cheeks, along with uncontrolled loss of coordination of pharyngeal swallow, laryngeal elevation, and glottis closure. (18)
In the case of muscular disorders such as polymyositis, Duchene muscular dystrophy (DMD), and other myopathies, voluntary control of the muscles of swallowing is lost due to muscle spasms and inflammation which, in turn, causes difficulty in passing food bolus causing dysphagia. (19)
Physical obstruction of the passage of food bolus by a tumor, stricture, or any mass is also an important cause of dysphagia. This includes Zenker diverticulum, esophageal web, Schatzki ring, or carcinomas of the esophagus. These cause mechanical obstruction to food bolus leading to dysphagia.
It is important to note here that dysphagia caused by mechanical obstruction is usually gradual, and the patient has more difficulty in taking solid foods than liquids (which develops later). This characteristic is significant to differentiate it from motility disorders in which both solid and liquid dysphagia occurs at the same time. (3, 20)
Motility disorders of the esophagus are also important in causing dysphagia. In these diseases, dysphagia develops due to irregular movements of muscles of the esophagus and impaired peristalsis. Achalasia is the most important differential, which occurs due to increased tone and non-relaxing of the lower esophageal sphincter. This prevents the passage of food bolus from the esophagus to the stomach, causing dysphagia. Both liquid and solid dysphagia develop simultaneously in motility disorders differentiating it from mechanical obstruction. (3, 15)
Para-esophageal dysphagia develops due to any mass or tumor outside of the esophagus pushing it to the extent that the transit of food bolus is disturbed. This includes aortic aneurysm, lung carcinoma, and enlarged lymph nodes or thyroid. These cause physical impingement on the esophageal wall leading to obstruction. (21)
History and Associated Signs and Symptoms
Completely history of dysphagia is important in the diagnosis of the underlying disease. This should include duration, onset, pattern, aggravating, and relieving factors. The history given by the patient is then co-related with other clinical features. This varies from patient to patient, depending on the disease.
In case of malignancy, there will be associated loss of appetite, weight loss, and chronic history of symptoms. However, in post-stroke dysphagia, the onset is sudden, associated with weakness of either half of the body. Muscular disorders such as Duchene muscular dystrophy and polymyositis may present with the spasm or weakness of other muscles of the body along with dysphagia. (3, 10)
The comparison of the onset of liquid dysphagia and solid dysphagia is also important as it allows the clinician to differentiate between mechanical obstruction and motility disorders. In case of mechanical obstruction, solid dysphagia appears earlier as the patient may still be able to tolerate liquid foods. While in motility disorders, liquid and solid dysphagia occurs simultaneously. (3, 10)
Initially, a swallowing evaluation should be done by the speech pathologist. But, it has significant observer variability, and some diseases can be missed. (22)
A barium swallow can be done to check the extent of obstruction (if present) and aspiration. This is relatively cheap and can be done easily as it requires less expertise. It can be used for achalasia, Zenker diverticulum, and other causes. (23)
Esophageal manometry can also be done in cases of achalasia and esophageal spasm. (24)
The gold standard test for the evaluation of dysphagia is fiberoptic endoscopic evaluation of swallowing (FEES) and videofluoroscopic swallowing study. It can visualize the oropharyngeal and esophageal pathways and also allows the clinician to take a biopsy of the mass (if present). Moreover, it can also be used for surgical procedures such as surgical myotomy and other endoscopic procedures. In this way, FEES can prove to be very helpful in patients with dysphagia. (24)
CT-scan head & neck, and chest can be done to rule out malignancy if the patient presents with weight loss, anorexia, and chronic history of dysphagia. (3, 23)
Dysphagia should be evaluated and treated effectively as it significantly affects the lifestyle of patients. The management depends upon the underlying disease. This includes lifestyle modifications, medications, and surgical procedures.
Lifestyle modifications include:
- Dietary modifications (Use of soft foods which are easy to ingest)
- Decreasing bolus size according to the patient’s capability of swallowing
- Chin-tuck, head turn, and supraglottic maneuver to prevent aspiration
Medications can be used in some cases, such as dysphagia caused by myasthenia gravis and Parkinson’s disease can be treated with anticholinesterase inhibitors and L-Dopa respectively. Achalasia also improves when treated with medications such as nitrates, calcium channel blockers, and endoscopic botulinum toxin injections. (3, 10)
Surgical interventions may be needed in case of Zenker diverticulum, esophageal strictures, achalasia (non-responsive to medication), esophageal tumor, or aortic aneurysm. Esophageal tumors may also need further radiotherapy and chemotherapy along with the surgery.
Dysphagia associated with stroke usually recovers with the passage of time, usually after one to two weeks.
Those patients who fail to respond to these treatment options are selected for a gastrostomy tube or feeding tube insertion. (3, 10)
Prognosis and Complications
The prognosis of dysphagia depends upon the underlying disease. Post-stroke dysphagia may improve spontaneously in one to two weeks. While in Parkinson’s disease, it has a poor prognosis without medications. While achalasia, esophageal webs, and tumors might need surgical interventions.
The most important complications of dysphagia include aspiration pneumonia, malnutrition, and dehydration due to decreased intake. Moreover, the lifestyle of the patient is also affected. (3)
The author does not report any conflict of interest.
This information is for educational purposes and is not intended to treat disease or supplant professional medical judgment. Physicians should follow local policy regarding the diagnosis and management of medical conditions.
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Dr. Muhammad Daniyal Haider is a general physician who continuously seeks for platforms to serve the community and utilize his knowledge and abilities to improve the health
system. Dedication to the cure of diseases and, more importantly, prevention and
awareness of people about these diseases is the goal. He is a general physician, author
and a calligrapher. He is passionate about research projects, latest guidelines and
techniques which can lead to a better approach to the patient’s condition.