Dysphagia is a very common symptom in which patients experience difficulty in swallowing. It is not a gastrointestinal symptom but is also seen in diseases of the nervous system, some congenital conditions, collagen disorders, respiratory diseases, etc.
Although all symptoms carry clinical significance, dysphagia is important because it raises concern regarding numerous serious disorders, some of which include oesophageal or oropharyngeal carconima, myasthenia gravis, etc.
In addition, dysphagia causes malnutrition and dehydration and raises the chances of aspiration of food thus leading to aspiration pneumonia.
Pathophysiology and classification of Dysphagia:
Before you move onto learn about the causes of dysphagia, it is important to remember that the upper part of the oesophagus is made of skeletal muscle and is thus affected by skeletal muscle conditions such as myasthenia gravis and polymyositis. On the other hand, the lower part is made of smooth muscle and is affected by smooth muscle disorders such as scleroderma and achalasia. This helps us classify dysphagia into upper and lower dysphagia, a summary of both is as under:
Upper Dysphagia or Oropharyngeal Dysphagia
- It is due to neuromuscular problems of the oropharynx as well the skeletal part of the oesophagus.
- Causes include: Stroke, amyotrophic lateral sclerosis, multiple sclerosis, myasthenia gravis, polymyositis, Parkinson’s disease and myotonic dystrophy.
- It is accompanied by nasal regurgitation of oral contents or coughing due to aspiration whenever swallowing is attempted. Usually, the other symptoms of the underlying neuromuscular disorder are present in addition to the dysphagia.
Lower Dysphagia or Oesophageal Dysphagia:
- Since this part is lined by smooth muscle, any disease affecting it has to be of smooth muscle origin.
- This type of dysphagia does not present with simultaneous regurgitation or coughing and is observed with the ingestion of both solids and liquids.
- Common causes include : Esophagitis, Achalasia, Diffuse oesophageal spasm, Scleroderma, etc.
Another classification has been devised keeping the normal physiology of the swallowing act in mind:
Stage 1: This happens when you chew the food you eat and mix it up with saliva, consequently pressing it upwards against the hard palate so that this food can be moved to the back of the mouth. Right after this, the swallowing reflex is initiated by the vagus nerve. Dysphagia in this phase is usually due to diseases that affect the neuromuscular system, such as myasthenia gravis, polio, etc.
Stage 2: This is the stage of the transportation of food, which is caused due to closure of the soft palate with the pharyngeal wall in order to prevent regurgitation of the oral contents through the nose. Simultaneously, the larynx moves upwards as the vocal cords close to stop food from entering the trachea whereas breathing stops to allow the passage of food by the constriction of the muscles of the throat. Dysphagia in this region is usually due to carcinoma or spasm.
Stage 3: Stage 2 works to propel food into the oesophagus whereas stage 3 focuses on transferring this food through the oesophagus into the stomach, an action that is aided by peristalsis as well gravity. Dysphagia in this stage is due to narrowing of the oesophagus which could be due to esophagitis, diverticula, etc.
- Understanding Dysphagia (merckmanuals.com)
- Understanding Dysphagia (a part of having Myositis) (sarchasm2.wordpress.com)
- The Teen Who Can’t Swallow – What is it? (lynnawiensmd.com)