Did You Know?
It is the collective work of more than 50 pairs of muscles and several nerves that allows us to eat food, and facilitates the passage of bolus (soft mass of chewed food) from the mouth to the stomach.
The term 'deglutition' refers to the complex process of swallowing, which in turn involves the passage of solid food or liquid from the mouth to the pharynx, and into the esophagus (food pipe). The epiglottis, which is a flap of cartilage covering the windpipe, shuts during the process of swallowing. If the epiglottis doesn't shut, food or liquid will go through the windpipe instead of the esophagus, thereby causing one to choke.
The term 'dysphagia' refers to a swallowing disorder where the affected individual experiences difficulty while swallowing. It should not be confused with odynophagia and the globus sensation. Odynophagia is derived from the Greek words 'odyno' and 'phagia', which mean pain and swallowing respectively. It is characterized by painful swallowing, whereas the globus sensation is the feeling of something being lodged in the throat. It must be noted that odynophagia may or may not occur with dysphagia.
Dysphagia is often observed in individuals affected by achalasia, which is an esophageal motility disorder. In people affected by achalasia, the esophagus is unable to facilitate the passage of food via peristalsis (wavelike muscle contractions of the digestive tract that move the food along), and the esophageal sphincter (LES) that is located between the esophagus and stomach doesn't relax fully. To help you understand this swallowing disorder in a better way, the three phases of swallowing have been briefly explained below.
The process of swallowing is divided into three phases, depending on the location of the bolus. These include the buccal phase (oral preparatory and transit), pharyngeal phase, and the esophageal phase.
In the oral preparatory phase, sensory impulses get transmitted, when the receptors in the mouth get stimulated with food approaching towards the mouth. The teeth masticate the food, thereby crushing it into a small mass. The tongue moves the food and mixes it with saliva. The tongue and the mandible (lower jaw) move till the food has been broken down to form a small mass called bolus. During this time, the airway is open and the mouth is closed with labial seal to prevent food from spilling out from the mouth. Nasal breathing continues in this phase. Thereafter, the bolus is positioned on the tongue for transport. In case of liquids, the liquid is kept between the hard palate in the front and the tongue in the oral cavity. It is kept between the midline of the tongue and the hard palate, as the tip of the tongue is elevated and contacts the anterior alveolar ridge. The liquid is then held on the floor of the mouth in front of the tongue, before it is spread throughout the oral cavity.
In the second phase of the oral transit, the tongue propels the bolus from the anterior to posterior towards the pharynx, by squeezing its midline against the hard palate. Tongue elevates to push the bolus at the back. The tip and the sides of the tongue contact to the alveolar ridge. If the food is thicker, the tongue divides the food after chewing, thereby taking a part of the food to form a bolus. The rest of the food stays on the side of the mouth, and is swallowed later. With the propulsion of food at the back, the sensory receptors in the oropharynx and tongue get stimulated. This triggers the pharyngeal swallow.
Impaired swallowing in this phase could be characterized by problems such as:
- Difficulty in chewing solid food.
- Difficulty in forming food into a bolus.
- Difficulty in moving the bolus to the back of the mouth.
In this phase, the velum or the soft palate elevates and retracts, and the velopharyngeal port closes to prevent bolus from entering the nasal cavity. The process of peristalsis (muscle contractions) of the pharynx is initiated, for picking up the bolus at the anterior faucial arch and moving it into and through the pharynx towards the cricopharyngeal sphincter that is located at the top of the esophagus. During this phase, the oropharynx closes, the larynx rises inside the neck, and the epiglottis moves to cover it. Nasal breathing stops so as to prevent pulmonary aspiration (passage of food or liquid into the lungs). Thereafter, the cricopharyngeal sphincter relaxes, and the upper esophageal sphincter opens to allow material to pass through the upper esophageal sphincter entirely. Thereafter, breathing starts.
Problems associated with this phase include:
- Passage of food or liquid into the throat before the triggering of automatic swallow, which can cause the food or liquid to come in contact with the vocal folds.
- Passage of food/liquid into the lungs.
The third phase, which is the esophageal phase, starts with the arrival and propulsion of the bolus through muscle contractions. Once the bolus has entered the esophagus, esophageal peristalsis and gravity are responsible for facilitating the passage of food towards the stomach. At the lower end of the esophagus lies the lower esophageal sphincter, which relaxes to allow the entry of food into the stomach. Thereafter, the process of digestion of the food begins.
Problems associated with this phase include:
- Abdominal pain
Damage to any of the structures involved in the swallowing process due to an injury or a medical condition could affect one's ability to swallow food, liquids, or even saliva. The damage to the esophagus is often the contributing factor for dysphagia or even odynophagia.
Dysphagia vs. Odynophagia
A person affected by dysphagia experiences the sensation of swallowed food being stuck in the lower neck or the chest. Since swallowing is a complex mechanism involving many anatomical structures, there can be several contributing factors for difficulty in swallowing. The conditions that might be responsible for causing difficulty in swallowing are categorized into oropharyngeal (related to the mouth or pharynx) and esophageal (related to the esophagus). The common causes of dysphagia include:
- Spastic motility disorders or problems with peristalsis
- Tumors of the esophagus or the pharynx
- Congenital abnormalities
- Bone spurs on the cervical vertebrae
- Narrowing of the esophagus
- Tumors of the tissues surrounding the esophagus or the pharynx
- Schatzki's rings at the lower end of the esophagus
- Eosinophilic esophagitis
- Herniations through the walls of the esophagus or the pharynx
- Degenerative diseases of the brain (Parkinson's disease, Lou Gehrig's disease, multiple sclerosis)
- Degenerative diseases of the motor nerves
- Tumors of the brainstem
- Inflammation of the skeletal muscle of the pharynx
- Myasthenia gravis
- Muscular dystrophies (production of abnormal proteins by skeletal muscle cells that cause degeneration of the muscle cells and their replacement with scar tissue)
- Metabolic myopathies (reduced activity of the enzymes in skeletal muscle cells that adversely affects the generation of energy for contraction of the muscle)
- Reduced production of saliva
Some of the symptoms that might be felt by people affected by oropharyngeal dysphagia include:
- Difficulty initiating a swallow
- Inability to control food or saliva in the mouth
- Having food or liquids dripping out of the mouth
- A sensation of food sticking in the throat
- Coughing during swallowing
- Coughing after swallowing
- Wet/gurgly voice with eating or drinking
- Regurgitation of food
- Recurring pneumonia
- Unexplained weight loss
The symptoms of esophageal dysphagia might include:
- Inability to swallow solid food
- Feeling of food being stuck in the chest
- Regurgitation of food
- Inability to swallow liquids (in case of achalasia)
It must be noted that painful swallowing may or may not occur with dysphagia. Odynophagia might not always be caused due to the inadequacies of the swallowing mechanism. There's no denying the fact that one might find it difficult to distinguish between odynophagia and dysphagia. Individuals affected by dysphagia might equate the discomfort caused by the sensation of food being stuck in the pharynx or esophagus to pain. Moreover, pain could also coexist with difficulty. However, the common contributing factors for odynophagia usually include:
- Gastroesophageal reflux disease (Regurgitation of gastric contents towards the esophagus)
- Damage to the mucous lining of the esophagus
- Ulceration due to intake of very hot beverages or food
- Immunodeficiency disorders
- Infections caused by Candida albicans, Herpes virus, orCytomegalovirus
- Exposure to radiation
- Esophagitis induced by pills
- Esophageal spasms
- Inflammation of the epiglottis
In some cases, the pain might be due to carcinoma. Therefore, doctors may take a sample of the tissues from the affected area and perform a biopsy to confirm or rule out carcinoma as the causal factor. More often than not, endoscopy done on individuals affected by painful swallowing reveals ulcerations on the surface of mucosa. In case of GERD, the pain or burning sensation is attributed to the passage of food through the inflamed section of the esophagus. Besides pain, the affected individual is likely to experience the following symptoms:
- Burning sensation
- A stabbing pain that radiates to the back
Diagnosis and Treatment
Since several conditions could cause difficulty or pain while swallowing, the treatment can be determined only after identifying the underlying cause. The diagnostic tests that might be conducted include:
- Flexible Endoscopic Evaluation of Swallowing with Sensory Testing (a lighted endoscope is used to examine the swallowing mechanism in response to stimuli such as food, liquids, or a puff of air)
- Videofluoroscopic swallow study (examination of a videotaped X-ray of the entire swallowing process after consumption of food/liquids and mineral barium)
Other tests might also be conducted to identify the causal agent in case an infection is the suspected cause. Similarly, imaging studies or biopsy might be conducted, if the doctors want to identify or rule out cancer.
The treatment of dysphagia and odynophagia would vary, depending on the underlying cause. The treatment options might include drug therapy (the use of muscle relaxers, anti-microbial drugs, immunosuppressants), withdrawal of offending food or drugs, dietary modification (taking small bites, changing the consistency of the food, adding thickeners to liquids for achalasia), alternative forms of feeding (if the patient cannot consume food/liquids by mouth), compensatory techniques, optimal positioning, exercises for strengthening and coordination of oral muscles, chemotherapy and radiotherapy (for cancer), etc. In some cases, surgery might be recommended.
On a concluding note, dysphagia and odynophagia are different medical conditions, but it is hard for the patient to differentiate between them. At times, these could also coexist. The goal of dysphagia rehabilitation can be achieved when the reason behind the difficulty while swallowing is identified. On the other hand, the treatment of odynophagia can be initiated if the contributing factor for painful swallowing has been ascertained. Pain while swallowing may or may not occur with difficulty while swallowing. Thus, the treatment will involve treating the underlying cause or correcting abnormalities related to feeding and swallowing mechanism.
Disclaimer: The information provided in this article is solely for educating the reader. It is not intended to be a substitute for the advice of a medical expert.