Swallowing is a complex process which must accomplish two main objectives: transporting the food from the oral cavity to the oesophagus,
and protecting the entrance of the airway while this transport occurs.
The principal anatomical structures that take part on it are shown in the Fig. 1.
The swallowing is divided into four stages (Fig. 2):
- Oral preparatory phase: The bolus is located in the oral cavity,
between the tongue and the palate.
The glossopharyngeal junction remains sealed so it cannot go into the pharynx.
- Oral propulsive phase: The tongue moves in an anterosuperior direction pressing against the palate,
which causes a backwards movement of the bolus toward the oropharyngeal junction.
- Pharyngeal phase: Hyolaryngeal complex moves in an anterosuperior direction to prevent the entrance of the airway from being into the trajectory of the bolus and,
moreover,
to make the cricopharyngeus muscle (upper oesophageal sphincter) open.
Larynx and velopharyngeal junction also get closed.
A wave of contraction with a vertical direction (from upper to lower constrictor muscles) occurs,
which eases the bolus clearance towards the oesophagus.
- Oesophageal phase: When the bolus crosses the upper oesophageal sphincter into the cervical oesophagus,
the sphincter closes and the structures of the pharynx and larynx return to their initial position.
Airway opens again.
We can divide the pathology of swallowing into two disease groups,
depending on which of the two previously mentioned functions of the process fails:
- Efficacy disorders: A portion of the bolus (or the entire bolus) fails to arrive to the oesophagus.
- Safety disorders: Part of the bolus (or the entire bolus) enters the airway.
Approaching the diagnosis: Role of videofluoroscopy
Evaluation begins by asking the patient about his medical history,
which usually helps to define the possible causes of his problem.
The following step is an accurate clinical examination. Then there can be used some instrumental techniques,
where the videofluoroscopic swallowing exam (VFSE) plays an important part.
It provides live imaging of the four phases of the swallowing process that allow the assessment of the width and speed of movement of the anatomical structures as well as their coordination,
so we can subsequently establish the specific stage and location of the problem.
Using both clinical and radiologic data,
we usually are able to establish the diagnosis.
Sometimes the pathology is caused by some specific food consistencies,
while a more or less thick same food quantity is well tolerated.
Performing a VFSE provides us with not only the anatomic structures where the problem takes place and the kind of pathology,
but also the food consistency that triggers it.
This,
besides for diagnosis,
is paramount when we need to approach the proper nutrition for the patient,
because we will know which consistencies we are able to administer without any risks.
In the next lines we will present the technique and the main,
both physiological and pathological,
findings on a VFSE.