Swallowing Difficulties (Dysphagia)
How often do we really THINK about the swallowing process when we eat our favourite meal, or gulp down cold water on a hot summer’s day? Swallowing is mostly automatic – or so we think… until one day we are suddenly no longer able to swallow. Is it really that complicated? Yes. In fact, swallowing is a highly complex process, involving the brain, a set of at least 50 muscles, and some of our cranial nerves just to swallow one mouth full of fluid or food. Amazing? I think so!
The Swallowing Process
The swallowing process is a very complex act, involving both our senses and muscular movement, allowing food to move safely from the mouth to the stomach. This process consists of three phases, namely the oral phase, the pharyngeal phase and the oesophageal phase. During the oral, fluid or food (called the bolus) is placed in the mouth and is manipulated by the tongue in order to swallow. The tongue then pushes the bolus to the back of the mouth. Once the bolus reaches the base of the tongue, the second phase of the swallowing process, the pharyngeal phase, initiates. In total, the pharyngeal phase of the swallowing process takes less than one second! During this phase, a number of crucial things must happen to make sure that you can swallow effortlessly and safely:
- The swallow response must be triggered – this is mediated by messages sent from the throat to your brain.
- The soft palate must seal the nasal cavity to prevent food from entering your nose whilst you swallow.
- The pharyngeal (throat) muscles must push the bolus down towards the stomach via the oesophagus.
- The airway must seal itself to prevent fluid/food from entering our lungs.
From this explanation it is easy to see that there are various ways in which dysphagia can present itself, for example:
- inability of the tongue to form a bolus or push the bolus towards the throat (food may fall out of the mouth, may get stuck on the tongue or remain stagnant in the cheeks)
- a delay in the initiating the swallowing process (you feel like you can’t “begin” the swallow)
- weakened throat muscles, unable to push a bolus down to the oesophagus (it feels like food gets stuck in your throat and it won’t go down)
- fluids or food entering the airway if not properly sealed off, called aspiration (coughing or choking during swallowing)
The oeosphageal phase of swallowing begins when the food passes through the upper oesophageal sphincter and into the oesophagus. Contractions (peristalsis) of the oesophagus then moves the food into the stomach. Oftentimes individuals may encounter difficulties such as reflux, motility problems or a painful sensation when food “gets stuck”, creating the feeling of heartburn.
The pictures below illustrate the oral, pharyngeal and oesophageal phases of the swallowing process:
Conditions That May Cause Dysphagia
Dysphagia may be caused by various reasons, being neurological, systemic, or structural. Neurological disorders such as a stroke or brain injury may result in direct damage to the parts of the brain responsible for regulating swallowing, thus causing the sudden onset of dysphagia. Many degenerative neurological conditions, such as Motor Neuron Disease and Parkinson’s Disease, may result in progressively worsening dysphagia, because it affects the brain’s control of the muscles involved in the swallowing process. Systemic diseases, for example certain auto-immune diseases like myasthenia gravis and scleroderma, can also affect swallowing over time due to muscular weakness.
ENT-specialists often deal with structural problems that may cause dysphagia, like conditions affecting the larynx (voice box), and throat. Head and Neck Cancers, such as voice, throat and tongue cancers unfortunately often result in dysphagia and voice changes, and oftentimes these are the first symptoms a patient may experience. Reduced motion or paralysis of the vocal folds fail to adequately protect the airway, and may thus also result in dysphagia. There are many other structural defects that may cause dysphagia, and are managed by ENT-specialists (including spasm of the upper oesophageal sphincter and diverticulum or pouches that may form). Since many of these conditions may result in similar clinical symptoms, it is best to consult with your ENT-specialist for a diagnosis.
Take Home Message
Dysphagia is a symptom of an underlying condition, and should be taken seriously. It is important to find the underlying cause of your dysphagia. Unmanaged dysphagia can result in several detrimental consequences, like dehydration, malnutrition, pneumonia and a decrease in quality of life. The ENT specialist is one of the professionals who can assist you in managing dysphagia. He/she usually works hand in hand with a qualified speech therapist (dysphagia therapist) who can assist with different tests and interventions to evaluate and manage your dysphagia.
Logemann, JA. 1998. Evaluation and Treatment of Swallowing Disorders. Austin, Tex: PRO-ED.
Zuercher, P, Moret, CS, Rainer, D & Schefold, JC. 2019. Dysphagia in the intensive care unit: epidemiology, mechanisms, and clinical management. Critical Care 2019, vol.23(103).