The exact definition of dysphagia varies, but, in brief, dysphagia is difficulty with the act of swallowing solids or liquids. It may be subjective or objective and can refer to the sensation of not being able to swallow, food "sticking" or not passing, choking episodes, or aspiration of food and/or liquids. It should be distinguished from odynophagia (pain on swallowing) and globus sensation (sensation of a lump in the throat between meals). Dysphagia can be caused by functional or structural abnormalities of the oral cavity, pharynx, esophagus, or gastric cardia. 
One in 17 people will develop dysphagia in their lifetime.  The condition is reported to occur in 13% of the general population ages 65 years and older.  However, rates of 50% or more have been reported in older individuals in residential care.    Dysphagia affects 40% to 70% of people with stroke. 
Dysphagia may be treated by various specialties or ideally by a multispecialty team. The core of such a team includes the patient’s primary care physician, otolaryngologists, speech and swallowing therapists, gastroenterologists, and radiologists. In addition, neurologists, dieticians, oncologists, general surgeons, and thoracic surgeons are often involved in the patient’s care.
Swallowing and therefore difficulty swallowing can be anatomically and physiologically divided easily into three distinct parts: the oral phase, the pharyngeal phase, and the esophageal phase.
The oral phase (sometimes referred to as the preparatory phase) is the voluntary phase that occurs in the oral cavity. Mastication with salivary lubrication and tongue movement prepare the bolus to be thrust posteriorly into the pharynx.
The pharyngeal phase involuntarily transfers the bolus of food and/or liquid from the mouth to the esophagus. Its coordinated contractions not only are necessary to propel the bolus but are crucial in protecting the larynx and upper airway from aspiration of material into the airway and lung.
The esophageal phase is the involuntary phase that utilizes peristalsis to propagate the food/liquid bolus through the esophagus into the stomach. The esophagus is bound by upper and lower sphincters (the upper formed by the cricopharyngeus muscle), which prevent retrograde flow of stomach contents into the esophagus.
Clinical Professor of Otolaryngology - Head and Neck Surgery
Loyola University Medical Center
SJC declares that he has no competing interests.
Dr Steven J. Charous would like to gratefully acknowledge Dr Michael F. Vaezi and Dr Farnoosh Farrokhi, the previous contributors to this monograph. MFV and FF are authors of references cited in this monograph.
Instructor in Medicine
Harvard Medical School
Director of Clinical Research
The Celiac Center
Beth Israel Deaconess Medical Center
DL declares that he has no competing interests.
Associate Professor of Otolaryngology and Pediatrics
Division of Otolaryngology
Children's National Medical Center
Otolaryngology and Pediatrics
George Washington University School of Medicine and Health Sciences
RKS declares that he has no competing interests.
Professor of Otolaryngology - Head and Neck Surgery
Honorary Consultant Otolaryngologist
JW declares that she has no competing interests.
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