Difficulty swallowing
liquids is usually due to poor muscular control before the swallow. This is the most common cause of dysphagia in individuals
with neurologic diseases.
Difficulty swallowing solid food is usually associated with anatomic and physiologic abnormality.
For example, an alaryngeal patient has difficulty with posterior tongue movement
Oral Stage
The
oral stage is voluntary and requires control of oral structures, including the anterior position of the soft palate. Following
mastication, the food is pulled together into a cohesive mass. Next, in a second or less, the tongue propels the bolus posteriorly.
The oral stage ends once the material passes the anterior faucial arches at the back of the throat.
This posterior
tongue movement and the material passing along the anterior faucial arches help activate the involuntary or reflexive swallow
that constitutes the pharyngeal stage.
The reflex is
believed to originate in the fauces, soft palate, base of
the tongue, and posterior pharyngeal wall. Innervation is primarily
from the vagus in the brain stem, but involves cranial nerves IX through XI.
Because these
nerves exit the medulla and pass through the jugular foramen together, localized trauma and disease may damage both structures
resulting in dysarthria, dysphagia, and dyspnea.[17]
Potential problems -- The oral stage requires
adequate chewing, sealing, and transporting of the bolus. Some of the possible difficulties in this stage may arise from lip
paresis as well as reductions in buccal tension, tongue elevation and posterior carriage, range of jaw movement, and oral
sensitivity.
These may lead
to spilling or pocketing of the bolus in lateral sulci, and
may delay the swallow reflex. Problems during the oral stage
may cause food or liquid to fall into the pharynx and lead to aspiration before the swallow reflex is elicited.
Pharyngeal
Stage
This is a reflexive
stage that begins with the raising of the hyoid and larynx, and closing of the thyroarytenoid and ventricular
cords to
create a velopharyngeal seal. Next, the epiglottis tilts and the cricopharyngeus muscle, or superior esophageal sphincter,
is relaxed, opening the esophagus.
With the help
of accessory muscles, a peristaltic wave moves the bolus through the hypopharynx and into the esophagus in approximately one
second.[18]
Potential problems -- Factors that may lead to difficulties during this stage include:
Velopharyngeal insufficiency, reduced swallow reflex, poor peristalsis, reduced pharyngeal pressure, and residue in the valleculae
and piriform sinuses. Also, there may be restricted elevation of the larynx and an inadequate tilting of the epiglottis as
well as incomplete closure of the vocal cords.
Esophageal Stage
This phase begins as the superior
esophageal sphincter opens and, propelled by the peristaltic wave contractions that were started in the pharyngeal phase,
the bolus passes through the esophagus and inferior esophageal sphincter into the stomach. This stage takes from 8 to 20 seconds.[18]
Potential
problems -- The esophageal phase requires an adequate opening of the superior and inferior esophageal sphincters,
as
well as good peristaltic movement of the bolus into the stomach. Possible difficulties in this stage include a reduced
cricopharyngeal opening, resulting in some material remaining in the pharynx and posing a risk for aspiration after the swallow;
and esophageal reflux, in which material returns to the pharynx from the esophagus and poses a risk for aspiration.
==============================================
Swallowing Tests X-RAYS AND RELATED TESTS
Certain X-rays may be helpful in determining whether function of
the mouth and throat muscles is adequate for safe and effective feeding. These include upper GI (gastrointestinal) series,
nuclear scintiscan, and a video feeding study.
An upper GI series can evaluate the structure of the esophogus and stomach,
screen for GE reflux and give limited information about mouth (oromotor) and swallowing function.
A small swallow of barium is given to and a series of X-rays are
taken to visualize the pathway that the barium takes to get to the stomach.
The scintiscan is a nuclear medicine study
which can evaluate reflux that occurs through the gastroesophogeal spinchter (the inlet of the stomach), the rate of gastric
emptying through the pyloric sphincter (the outlet of the stomach), and check for aspiration into the lungs.
Radioisotope
is either swallowed by the patient or placed by nasogastric tube into the stomach, and its' return into the esophagus, appearance
in the lungs, and rate of disappearance from the stomach is assessed.
The video feeding study is a diagnostic test that incorporates the
skills of both the radiologist and the feeding therapist. The patients ability to handle foods is evaluated under X-ray (fluoroscopy)
while the therapist feeds the patient a variety of foods and liquids of different textures.
The different types of
food and liquid are observed as they pass through the mouth, throat and esophagus, and into the stomach. It is primarily a
demonstration of oromotor and swallowing function, and is very helpful
in determining the thickness and texture of foods that the patient can safely handle.
===================================================
