An 18 month old female presented to the Emergency 
Department with a history of fever, noisy breathing, a 
harsh cough, and drooling.  The fever and coughing 
began yesterday, but tonight the fever is higher and the 
cough sounds very harsh.  The sound of this cough was 
alarming to the parents.  The highest temperature 
measured was 39.5 degrees rectally.  She was noted to 
be drooling more than usual, but this was attributed to 
teething.  Her cry was more raspy than her normal cry.  
She was not taking in solids well, but she was taking 
liquids well.
     Exam:  VS T39.1 degrees rectally, P170, R28, BP 
100/66.  She appeared alert, awake, not toxic, in no 
acute distress.  She did not appear to prefer an upright 
or a forward leaning position.  Skin was warm & moist,
without rash.  No head or sinus tenderness were noted.  
Tympanic membranes were normal.  The oral pharynx 
was clear and the mucosa was moist.  Excessive 
drooling was not noticed by the examiner.  The neck
was supple with small lymph nodes bilaterally.  Heart
regular without murmurs.  Lungs clear when resting.
However, when she was crying, mild inspiratory stridor
was noted.  An occasional croupy cough was noted.  
The abdominal exam was unremarkable.  Color and
perfusion were good.  A soft tissue lateral neck 
radiograph was ordered.

View lateral neck radiograph.


Is this radiograph consistent with croup?

     The epiglottis is normal in shape.  The pre-epiglottic 
(vallecular) space is preserved.  The airway is patent.  
There is pre-vertebral soft tissue swelling noted.  This 
radiograph is consistent with a retropharygeal abscess, 
not croup.

Discussion and teaching points:
     The retropharyngeal space is a pocket of connective 
tissue that extends from the base of the skull 
approximately to the tracheal carina.  It harbors two 
chains of lymphoid tissue that drain the nasopharynx, 
adenoids, and posterior paranasal sinuses.  Bacterial 
infections of the areas drained may result in 
suppuration of the nodes and abscess formation.  
These lymphatic chains begin to atrophy about the third 
or fourth year of life.  Thus, 50% of the cases of 
retropharyngeal abscess occur between 6 and 12 
months of age, and 96% of cases occur in children 
under 6 years of age (prior to lymphatic atrophy).  
Staph aureus and group A beta-hemolytic streptococci 
are the most common pathogens; however, 
Hemophilus influenza and anaerobes have also 
been recovered.  
     There is usually a prodromal nasopharyngitis or 
pharyngitis with dysphagia, refusal of feeding, severe 
throat pain, hyperextension of the head, and noisy 
respirations.  Previous trauma or evidence of 
associated infectious conditions should be sought.  
Respirations may be labored.  There may be drooling, 
stridor, a raspy voice (cry), and a croupy cough.  A 
bulge in the retropharynx may be visible.  Meningismus 
may result from irritation of the paravertebral ligaments.  
Pain in the back of the neck or shoulder may be 
precipitated by swallowing.  However, in many cases, a 
retropharyngeal abscess may be difficult to clinicially 
distinguish from croup.  
     A lateral view of the soft tissues of the neck is 
frequently helpful in making the diagnosis, 
demonstrating the retropharyngeal mass in the stable 
patient.  Normal prevertebral spaces are as follows:
     Anterior to C2:  Less than or equal to 7mm in 
children and adults.
     Anterior to C3 and C4:  less than 5mm in children or 
adults or less than 40% of the AP diameter of the C3 
and C4 vertebral bodies.
     To simplify things, others suggest that the upper 
pre-vertebral soft tissue should be no wider than one 
vertebral body width.
     Adequate hyperextension of the head and neck is 
necessary in order to properly interpret the film if there 
is no history of trauma.  If the head and neck are not 
properly positioned, the pre-vertebral space will appear 
to be widened because the neck is not extended 
enough.  Repeating the radiograph with proper 
positioning may resolve this problem.  If proper 
positioning is not possible or if the clinician is unsure if 
plain films are definitive, CT of this area can more 
accurately define any abnormalities of this region.
     Most patients presenting with symptoms of croup 
have viral croup.  While epiglottitis is usually not
difficult to distinguish clinically from croup, an early 
retropharyngeal abscess may be difficult to distinguish 
from croup.  A lateral neck radiograph may reveal this 
occult diagnosis in selected cases, such as those with 
high fever, unexpected lymphadenopathy, or those wit
h a suspicious bulge in the pharynx. 
    Other causes of partial upper airway obstruction 
include epiglottitis, croup, peritonsillar abscess, severe 
tonsillitis, infectious mononucleosis, cystic hygroma, 
hemangioma, or neoplasms.  Retained upper 
esophageal foreign bodies, trauma to the retropharynx 
from foreign body ingestion, instrumentation, and 
C-spine injury can also cause localized swelling or 
obstruction.

View another cause of stridor.


     This radiograph shows evidence of epiglottitis (also 
called supraglottitis).  The epiglottis is thumb-like in 
appearance (instead of triangular or flat in shape) and 
the aryepiglottic folds are thickened.  The pre-epiglottic 
space is preserved to some degree, but it is not as 
large as it should be.  In many cases of epiglottitis, the 
pre-epiglottic space is obliterated (replaced by 
edematous tissue).  The retropharyngeal space 
(pre-vertebral tissue) is not widened.

View another cause of stridor.


     This radiograph looks normal except for a mild 
degree of subglottic airway narrowing.  This type of  
pattern correlates best with patients presenting with 
viral croup.

References
     Fleisher GR.  Infectious Disease Emergencies.  In:  
Fleisher GR, Ludwig S (eds).  Textbook of Pediatric 
Emergency Medicine, third edition.  Baltimore, Williams 
& Wilkins, 1993, pp. 613-621.
     Santamaria J, Abrunzo TJ.  Ear, Nose, and Throat.  
In:  Barkin R (ed).  Pediatric Emergency Medicine 
Concepts and Clinical Practice.  Chicago, Mosby Year 
Book, 1992, pp. 680-682.