Retropharyngeal Abscess

A CASE OF RETROPHARYNGEAL ABSCESS

INTRODUCTION
Retropharyngeal abscess (RPA) produces the symptoms of sore throat, fever, neck stiffness, and stridor. Retropharyngeal abscess occurs much less commonly today than in the past because of the widespread use of antibiotics for suppurative upper respiratory infections. Retropharyngeal abscess, once almost exclusively a disease of children, is observed with increasing frequency in adults. Retropharyngeal abscess poses a diagnostic challenge for the emergency physician because of its infrequent occurrence and variable presentation.

PATHOPHYSIOLOGY

The retropharyngeal space is posterior to the pharynx, bound by the buccopharyngeal fascia anteriorly, the prevertebral fascia posteriorly, and the carotid sheaths laterally. It extends superiorly to the base of the skull and inferiorly to the mediastinum.

Abscesses in this space can be caused by the following organisms:

• Aerobic organisms, such as beta-hemolytic streptococci and Staphylococcus aureus
• Anaerobic organisms, such as species of Bacteroides and Veillonella
• Gram-negative organisms, such as Haemophilus parainfluenzae and Bartonella henselae

IMAGING STUDIES

• Widening of the retropharyngeal soft tissues is observed in 88% of patients with retropharyngeal abscess in a series that defined soft tissue swelling as more than 7 mm at C2 and more than 14 mm at C6. Most authors define retropharyngeal soft tissue swelling as more than 7 mm at C2 and more than 22 mm at C6; thus, lateral neck radiographs may be considerably less sensitive for detecting retropharyngeal abscess than this study indicates.
• Generally, the anteroposterior diameter of the prevertebral soft tissue space in children should not exceed that of the contiguous vertebral bodies.
• In addition to showing widening of the prevertebral space, the lateral neck radiograph rarely may show a gas-fluid level, gas in the tissues, or a foreign body.

TREATMENT

Prehospital Care

• Supplemental oxygen and attention to upper airway patency are the essential components of prehospital care in patients with suspected retropharyngeal abscess.
• If a child exhibits respiratory distress, the sniffing position may be beneficial.
• Occasionally, endotracheal intubation or cricothyrotomy may be required if the patient exhibits signs of upper airway obstruction.

Emergency Department Care

ED management of retropharyngeal abscess includes attention to the airway, fluid resuscitation if necessary, antibiotic treatment, and preparation for an emergency operation. Frequent vital sign checks and continuous oxygen saturation monitoring are essential.

• Airway management
  • Apply supplemental oxygen. In young children, this can be completed in a nonthreatening way by letting the parent direct blow-by oxygen at the child's face.
  • Endotracheal intubation may be required if the patient has signs of upper airway obstruction. It may be difficult because of upper airway swelling.
  • Cricothyrotomy (surgical or needle) may be required in the patient with upper airway obstruction who cannot be intubated. Tracheostomy may be required for definitive airway management.
• Intravenous fluids are required if the patient is dehydrated because of fever and difficulty swallowing.

Antibiotics

Gram-positive organisms (including beta-lactamase producing), gram-negative organisms, and anaerobes must be covered. The list of antibiotic regimens in the table below is from The Sanford Guide to Antimicrobial Therapy 2008.¹⁶

Some recommend the following regimens, which were not mentioned in The Sanford Guide to Antimicrobial Therapy: penicillin and oxacillin, second- or third-generation cephalosporin and clindamycin, penicillinase-resistant penicillin combined with either clindamycin or metronidazole, or third-generation cephalosporin in combination with clindamycin, nafcillin, or both (triple therapy).