Retropharyngeal Abscesses

A lateral X-ray demonstrating prevertebral soft tissue swelling 
( marked by the arrow ) as seen in a person with a retropharygeal abscess.
http://en.wikipedia.org/wiki/Retropharyngeal_abscess

Retropharyngeal Abscesses

A retropharyngeal abscess, or RPA, is a deep tissue neck infection. It is a serious and occasionally life-threatening infection due to the anatomic location and the potential for obstruction of the upper airway. The retropharyngeal space is found posterior to the esophageal wall and anterior to the prevertebral fascia. Lymph nodes found in this space drain the nasopharynx, paranasal sinuses and middle ear. Often infections of these areas will lead to infection in the retropharyngeal space.  Atrophy of these lymph nodes at or before puberty has been found as an explanation of the predominance of RPAs in young children. In fact, some believe that they atrophy after 4 years of age.

Epidemiology

1. Peak age group is 2-4 years.
2. 50% of the time there is an obvious cause of the infection, such as a skin or throat.
3. Usually from nontraumatic causes, especially infection. Predominant bacteria are Strep Pyogenes, Staph Aureus, and anaerobes, and often a mix of these is found.
4. Nontraumatic causes are rarely found: trauma, foreign body ingestion, or complications of procedures

Clinical Manifestations

1. Symptoms relate to pressure and inflammation caused by the abscess on the airway or upper digestive/respiratory tract.
2. Dysphagia, drooling, odynophagia may be present.
3. Fever and irritability.
4. In extreme cases there may be stridor or tachypnea.
5. Neck rigidity and tenderness.
6. Because respiratory compromise is a rare and late finding, limited neck mobility is an important clue to diagnosis. Most often the child will refuse to extend the neck, while flexion is not difficult for him/her.
7. Consider RPA in young children with fever, limited neck movement, and fever. Do not rely on signs of respiratory distress to cause suspicion.

Complications

1. Airway compromise
2. retropharyngeal cellulitis
3. lateral space abscess

Diagnosis

1. Physical exam reveals midline or unilateral swelling in posterior pharynx. If the child doesn't cooperate by opening the mouth widely, a thorough lymph node exam is done, followed by imaging to confirm suspicion.
2. A CT exam of the neck is the preferred imaging method. It can differentiate between retropharyngeal abscess and cellulitis. Complete rim enhancement indicates an abscess.
3. A lateral neck film can also be done, although care must be taken to make sure the film is perfectly lateral, the neck extended, and the image taken at the point of complete inspiration.  These technical issues make CT scan a more reliable option.

Differential Diagnosis

1. Meningitis
2. Retropharyngeal Cellulitis
3. Epiglottitis
4. Peritonsillar Abscess
5. Lateral Space Abscess
6. Acute otitis media
7. Sinusitis
8. Pharyngitis

Treatment

1. Once the abscess is identified, a trial of antibiotic therapy is begun. If this trial fails, surgical drainage of the pus collection is the next step. Occasionally, when the CT image reveals a large hypodense area, doctors may choose an option of immediate surgical drainage and antibiotic therapy.
2. Parenteral treatment with Ampicillin-sulbactam or clindamycin IV until the patient is afebrile and showing clinical improvement, followed by a 14 day course of oral antibiotics.

References

1. Craig, Frances W. Retropharyngeal Abscess in Children: Clinical Presentation, Utility of Imaging, and Current Management. Pediatrics 2003; 111:1394-1398.
2. Wald, Ellen R. Peritonsillar and retropharyngeal abscess in children. UpToDate - October 2005. www.uptodate.com