Introduction
Oropharyngeal dysphagia, commonly referred to as a swallowing disorder, presents a significant challenge for affected individuals. This condition arises due to a malfunction in the intricate network of muscles and nerves involved in swallowing, which thereby impacts the passage of food and fluids from the mouth to the stomach. This article will delve into the physiological complexities of oropharyngeal dysphagia and discuss the diverse array of treatment modalities available to enhance the lives of those grappling with this disorder.
What Is Oropharyngeal Dysphagia?
Oral or oropharyngeal dysphagia, or simply difficulty in swallowing foods and drinks, occurs due to dysfunction in one or more parts of the swallowing apparatus. The swallowing apparatus starts from the mouth (including the lips, tongue, and oral cavity) and extends to the pharynx, the upper airway, and the esophagus, along with its sphincters, which include both the upper and lower esophageal sphincters. Abnormalities that affect the upper esophageal sphincter, pharynx, larynx, or tongue, either separately or in combination, can cause oropharyngeal dysphagia.
This condition interferes with the normal transit or airway-protective functions of the oropharyngeal axis. On the other hand, diseases affecting the esophagus result in deranged transit functions. Symptoms in dysphagic patients reflect either transit or airway protection abnormalities. The physiology and the detailed phases of swallowing are discussed further. Any obstruction or impediment at these levels can cause changes and potential oropharyngeal diseases that result in dysphagia.
What Is the Swallowing Reflex?
Swallowing is a reflex sequence that occurs naturally in humans, which is a directed or guided sequence of muscle contractions that moves food from the mouth into the stomach. Swallowing also serves a protective function in the human body by clearing the upper respiratory tract of any potential or trapped foreign material. This physiological process is a naturally timed sequence of muscular contraction and relaxation, considered in medical literature as a spatiotemporal sequence. The initiation of swallowing is therefore an entirely automated event series.
There are four major phases of swallowing: preparatory, oral, pharyngeal, and esophageal. The preparatory phase begins in the oral cavity, where the food bolus forms. Food is moved into the oral cavity, pharynx, and esophagus through positive pressure waves. These waves are generated by the tongue's piston-like action and rhythmic peristaltic contracting movements in the esophagus. The sphincters between the oral and nasal cavities, as well as at the upper and lower ends of the esophagus, direct these pressure waves in an orderly direction to guide the bolus passage into the digestive tract.
What Are the Physiology and Phases of Swallowing?
The swallowing sequence starts with both the pressure in the mouth as well as the pharynx which is almost close to atmospheric pressure. The oral, pharyngeal, and esophageal phases then occur as follows:
The oral cavity is where the pressure changes occur during swallowing. Through the piston-like action of the tongue, as mentioned previously, the pressure increases eventually during this phase of swallowing after the nasopharyngeal sphincter closes. This produces muscle contractions or relaxations that travel through the oral cavity and the pharynx towards the upper esophageal sphincter. The upper esophageal sphincter closes when the resting pressure of water (H2O) is between 16 and 60 cm, while the lower esophageal sphincter closes at a pressure of 10 cm H2O. Once the food bolus passes into the stomach after repetitive swallows, the lower esophageal sphincter eventually relaxes and remains relaxed until the completion of the last swallow and bolus conversion.
The preparatory and oral phases of swallowing are under the voluntary control of the nervous system, whereas the pharyngeal and esophageal phases are completely involuntary. The motor sequence of swallowing is an organized activity in the neurons of the human brainstem, which has a well-defined functional swallowing center. The interneuron network in the brain center is responsible for the organization and sequence of the swallowing phases, involving rhythmic muscular contraction sequences.
What Are the Treatment Modalities for Oropharyngeal Dysphagia?
Though there is no single curative modality or direct drug for treating dysphagia, the causative or common underlying systemic conditions such as hypothyroidism (a condition in which the thyroid gland does not make enough thyroid hormones to meet the body's needs), oropharyngeal disease, or obstructive disorders of the upper respiratory tract should first be treated medically. Addressing these conditions can aid in a better prognosis and, in turn, alleviate swallowing difficulties. Pharmacotherapy to regenerate the nerves or to strengthen the affected muscles specifically so as to obtain relief from dysphagia does not exist.
Patients suffering from dysphagia may receive dietary recommendations, involving modifications in the preparation and type of food consumed. For instance, a nutritionist or registered dietitian can prescribe a suitable diet based on the patient's underlying health condition, which might be a cause of dysphagia. Dietary changes, suggested by healthcare providers, nutritionists, or dietitians, should focus on alleviating difficulties during swallowing while ensuring adequate nutrition for the patient.
Physical therapy regimens recommended by physicians or oral surgeons can help, which mainly focus on muscle relaxation and strengthening of the orofacial cavity. These exercises tone and enhance muscle functions essential for swallowing. Various techniques are used to strengthen the swallowing force, such as:
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Multiple Dry Swallow Protocol: This includes a series of swallows to enhance pharyngeal closure and reduce any retained pharyngeal residue.
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Supraglottic Swallow: In this technique, the patient breathes deeply, and bears down while swallowing food, followed by a cough. This is done to close the airway and reduce the potential problem of food aspiration.
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Mendelsohn’s Maneuver: The patient is asked to maintain the laryngeal and hyoid bone in an elevated position after swallowing food. This prolongs the upper esophageal sphincter opening, which enhances emptying.
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Shaker Exercise: This involves a series of traction forces, isotonic, and isometric head raises with the patient in a supine position (face up position), applying traction to the suprahyoid muscles, thereby easing dysphagia. Healthcare providers may also suggest several postural techniques or changes to relieve dysphagia, such as chin-tuck, chin-up, head or neck tilting, and rotation.
Conclusion
In conclusion, swallowing is a complex reflex process in human physiology. In the medical context, it manifests as oropharyngeal dysphagia, which can be a painful or uncomfortable experience for patients. Proper investigation by healthcare providers, dentists or oral surgeons, or physicians is essential to diagnose the local or systemic factors that cause the condition. Treatment regimens depend on dietary alterations and appropriate maneuvers or exercises that aim to relieve the discomfort.
