Abnormalities of swallowing are surprisingly common in infants and young children. Knowledge of the physiologic and anatomic differences of swallowing of pediatric patients, as well as the radiological manifestations of swallowing dysfunction during the different phases of swallowing, allows radiologists to tailor the imaging study and take an active role in patient management.
Dr. Mercado-Deane is an Assistant Professor in the
Department of Radiology, University of Texas Houston Medical
School, Houston, TX.
Abnormalities of swallowing are a surprisingly common occurrence
in infants and young children. Swallowing dysfunction can be
defined as interference with adequate nutrition, with the transport
of food from the mouth to the stomach, or with the enjoyment of the
feeding process. Such dysfunction can be clinically occult until
serious complications occur, such as aspiration pneumonia, chronic
sinusitis, apnea, or acute life-threatening events.
During the process of evaluating swallowing dysfunction, the
videofluoroscopy or modified barium swallow study is an integral
part of the armamentarium used for a complete evaluation. This
study is performed by a radiologist, in conjunction with a speech
pathologist. Knowledge of the physiologic and anatomical
differences of swallowing of pediatric patients, as well as the
radiological manifestations of swallowing dysfunction during the
different phases of swallowing, allows the radiologist to tailor
the study and take an active role in patient management.
This article will provide an overview of the anatomy, physical
development, and normal oral-motor function, as well as
radiological and clinical manifestations of swallowing dysfunction
in infants and children.
Anatomy and development
Swallowing is a complex process that involves 5 cranial nerves
(V, VII, IX, X, XII), 5 cervical nerves, cortical and subcortical
pathways, as well as midbrain and brainstem involvement. Associated
integration of 32 groups of muscles is necessary to achieve
Also, there are anatomical differences between infants, children,
and adults that are associated with the stages of development,
resulting in more efficient feeding as the patient matures. The
infant has a small oral cavity, with a relatively large tongue that
occupies most of the cavity. Lateral sucking fat pads aid the
tongue in maintaining the milk bolus in a central canal. The
structures in the pharynx are also in close proximity, allowing
easy nasal breathing. The soft palate and arytenoids are prominent.
The larynx is located anterior and superior, under the tongue base.
The location of the larynx allows maximum airway protection during
swallowing, with minimal effort of laryngeal elevation.
As growth and maturation occur, there is a change in the anatomic
relationship of structures. The fat pads disappear and tooth
eruption occurs as the child prepares for solid meals and cup
drinking. The head and neck grow and elongate, the larynx starts to
descend, and mouth breathing becomes possible (figure 1).
In neonates and infants, there are two types of sucking
patterns: nutritive and non-nutritive. The non-nutritive pattern is
more rapid, with no cessation of breathing occurring. It is as
important as nutritive sucking in helping to preserve feeding
skills during episodes of interruption of the feeding experience
because of therapy or illness.
In nutritive sucking, a breath precedes sucking and swallowing.
Multiple sucks and swallows are possible with a single breath. In
older infants and children, once they arrive at a more adult eating
pattern that includes solids and liquids, their
swallowing/breathing pattern becomes irregular, and then swallowing
is restricted to expiration.
Swallowing is identified as early as 11 weeks gestational age
(GA). True suckling is seen from 18 to 24 weeks GA. Non-nutritive
sucking is seen at 27 to 28 weeks. A pattern 1:1:1 ratio of
breathe, suck, and swallow is seen at 34 weeks, which allows
sufficient oral feeding to meet nutritional needs. Episodes of
several sucks and swallows occurring with a single breath are seen
by 35 to 36 weeks GA.
For the purpose of imaging evaluation, the swallowing process
can be divided into 4 phases: 1) the oral preparatory phase, where
the food is chewed and mixed with saliva; 2) the oral phase, with
the bolus propelled posteriorly by the tongue; 3) the pharyngeal
phase, with elevation of the soft palate and vallecula to seal the
nasopharynx, elevation of the larynx to close the vestibule,
relaxation of the cricopharyngeal muscle, and contraction of the
lateral walls of the pharynx; and 4) the esophageal phase, during
which the cricopharyngeal muscle contracts and the bolus is
transferred through the esophagus.
In neonates and infants <6 months old, the first two phases are
one. All this occurs in a fraction of a second (figure 2).
Clinical manifestation of swallowing dysfunction
Swallowing dysfunction is recognized in patients with
neurological deficits and chronic illnesses. Awareness of different
symptoms and presentations allows diagnosis of swallowing
difficulties in the general population.
The clinical manifestations that prompt referrals for evaluation
are not specific responses to an underlying cause. These include
pulmonary signs and symptoms including recurrent pneumonias,
difficult-to-control asthma, congestion and cough with feedings,
apparent life-threatening episode, apnea, bradycardia, cyanosis
with feedings, and persistent oxygen requirements. Gastrointestinal
symptoms include poor weight gain and growth. Generalized
manifestations of oral dysfunction include drooling and gagging,
refusal to feed, messy eating, and tongue thrusting.
Radiological evaluation of swallowing
Usually patients that present with respiratory and
gastrointestinal symptoms will be referred initially for an upper
gastrointestinal (UGI) study. This study evaluates the esophagus,
stomach, and proximal duodenum, including assessing any evidence of
reflux or its consequences, such as esophagitis or strictures. It
is not designed for close evaluation of the swallowing phase.
However, it can be used as a screening tool, looking for
nasopharyngeal reflux (NPR), laryngeal penetration, and tracheal
aspiration. In a recent article, Friedman et al
suggest that deep laryngeal penetration, into the lower third of
the laryngeal vestibule, during swallowing is a predictor of
aspiration later into the feedings and warrants full
The modified barium swallow study (MBSS) is the radiological
method of choice for the evaluation of swallowing.
The MBSS is a diagnostic tool, concentrating on the oral and
pharyngeal phases of swallowing. It provides a dynamic assessment
of the phases of swallowing in real time.
The handling of the bolus is visualized from the time it enters the
oral cavity through its transit through the pharynx and its
entrance into the esophagus. Other procedures, such as direct
nasopharyngoscopy and cervical real-time ultrasound, have been
advocated, due to the lack of ionizing radiation, but both have
their limitations. The most important limitation is the inability
to identify episodes of tracheal aspiration, which occur with
Traditionally, the MBSS is performed in conjunction with a speech
pathologist and is videotaped with the patient in a semi-recumbent,
lateral position for fluoroscopy of the airway. Videotaping permits
additional review of the study and facilitates therapy
recommendations. Pulsed fluoroscopy (<30 frames/sec) is not
recommended because the episodes of laryngeal penetration and
aspiration occur in a fraction of a second
and can be missed.
Different age-appropriate consistencies are given to ascertain the
degree of dysfunction and evaluate therapeutic options.
Different consistencies of food and liquids, mixed with barium,
are offered to the patient. This includes thin liquids with the
consistency of nectar and honey, pureed food, and soft and hard
solid food. A minimum of 3 swallows per type of liquid and solid
food is observed, and the swallowing mechanism is recorded.
Radiological manifestations of swallowing
In the oral phase, the radiological manifestations are similar
to those seen clinically: spillage of contrast outside of the mouth
due to poor lip seal, spillage of the bolus under the tongue,
tongue tremors, and small bolus formation requiring multiple sucks
per swallow due to tongue weakness and incomplete tongue elevation.
Early spillage of contrast into the vallecula, prior to initiating
swallow, reflects poor bolus control (figure 3).
The manifestations of pharyngeal dysfunction include
nasopharyngeal reflux, laryngeal penetration, and aspiration.
Reflux of the bolus into the nasopharynx (figure 4) is due to
incomplete closure of the nasopharynx by the soft palate. Laryngeal
penetration (figure 5) refers to penetration of the bolus into the
vestibule of the larynx without aspiration, caused by delayed
elevation of the larynx. Tracheal aspiration with penetration of
contrast into the airway below the level of the vocal cords (figure
6) can result from delayed elevation of the larynx, delayed
pharyngeal transit time of the bolus, decreased clearance of bolus
(with residual noted in the vallecula and pyriform sinuses [figure
7]), and spillage of this residual into the larynx and trachea
Cricopharyngeal muscle achalasia/dysfunction represents failure of
relaxation or incoordinated relaxation of the cricopharyngeal
muscle with swallowing. This dysfunction will cause either reflux
of the bolus into the oropharynx or pooling of bolus in the
pyriform sinuses, allowing spillage into the trachea and
The handling of each consistency given should be documented, as
well as the behavior of the patients. Documentation of any episode
of refusal, associated cough or silent aspirations with swallowing,
apneas, and bradycardias, if the patient is on a monitor, should be
made. This will provide real-time information to the clinicians.
Review of the recorded videofluoroscopic study with the speech
pathologist is recommended.
Swallowing is a complex process, divided into three phases: the
oral-preparatory, oral pharyngeal, and esophageal phase. Swallowing
dysfunction can occur at different levels, due to immaturity,
underlying central nervous system abnormalities, prolonged illness,
or as a complication of gastroesoph-ageal reflux. It can occur in
children with no underlying chronic illness or neurological
disease. Swallowing dysfunction should be considered as one of the
causes of exacerbation of respiratory illnesses. An upper
gastrointestinal study can be used as a screening tool for
identification of swallowing dysfunction, and the MBSS evaluates
and provides therapeutic alternatives.