Retropharyngeal Abscess

Background

• A retropharyngeal abscess is a deep neck infection of the retropharyngeal space with the potential for airway compromise and other life-threatening complications.
  • The retropharyngeal space is contained anteriorly by the buccopharyngeal fascia (encasing the pharyngeal constrictor muscles), posteriorly by the prevertebral fascia, and laterally by the carotid sheath/parapharyngeal space, and it extends superiorly to the skull base and inferiorly to the mediastinum.
  • In children, the retropharyngeal space (which expands with infection) has a lymph node basin that serves as a station in the lymphatic drainage pathway of the nasal cavity, paranasal sinuses, nasopharynx, oropharynx, and hypopharynx. Inadequately treated or virulent infections of these regions can result in retropharyngeal lymphadenitis with edema, which may progress to suppuration and abscess formation if left untreated.
• A retropharyngeal abscess usually affects children < 5 years old, because retropharyngeal lymph nodes tend to regress by about age 6 years. It is more common in boys than girls. It is rare in adults.
• In children, a retropharyngeal abscess is usually caused by complicated bacterial upper respiratory infections with suppurative lymphadenitis of the retropharyngeal lymph nodes leading to the development of a purulent collection.
• A retropharyngeal abscess can also develop due to a local trauma (most common cause in adults), including:
  • foreign body ingestion (such as a chicken or fish bone)
  • instrumental procedures, such as
    • laryngoscopy
    • endotracheal intubation
    • feeding tube placement
    • oropharyngeal suctioning

Evaluation

• Suspect the diagnosis based on clinical features, such as:
  • a history of fever, pain, neck stiffness, neck swelling, dysphagia, or dyspnea
  • physical exam showing torticollis, posterior pharyngeal edema, and occasionally oropharyngeal bulging, with or without cervical adenopathy
  • additional findings suggestive of retropharyngeal abscess
    • toxic appearance
    • airway distress or stertor
    • high-grade fever (> 101 degrees F [38.3 degrees C])
    • drooling
    • dysphagia
    • trismus
    • patient in a "sniffing position" in an effort to maximize the airway (with head tilted back)
• Cultures:
  • Consider a needle aspiration (performed at the time of surgical drainage) to obtain fluid for cultures and sensitivities.
  • In children, throat cultures and nasopharyngeal swabs may help guide appropriate choice of antibiotics.
• Imaging studies:
  • Imaging should not delay the care in patients with a suspected retropharyngeal abscess and respiratory distress or an impending airway compromise, as early treatment is associated with improved outcomes.
  • Contrast-enhanced computed tomography (CT) is the standard for diagnostic imaging of deep neck abscesses; findings suggestive of retropharyngeal abscess include:
    • a large fluid collection with central hypodensity
    • a complete ring enhancement and scalloping
  • Other imaging studies may include:
    • lateral neck x-ray
    • ultrasound
    • magnetic resonance imaging
• Blood tests (such as complete blood count with differential) may help determine the severity of the infection, but do not necessarily indicate the presence of an abscess.

Management

• Begin an immediate airway evaluation and management with rapid airway stabilization and surgical management if the airway is compromised.
• Start empiric broad-spectrum antibiotics as soon as possible. This is an emergency condition, and infection in this region is associated with airway compromise and morbidity.
  • Continue parenteral antibiotics until the patient is afebrile for at least 48 hours, then transition to an oral therapy with amoxicillin-clavulanate, clindamycin, ciprofloxacin, trimethoprim-sulfamethoxazole, or metronidazole (as based on culture sensitivities, if possible).
  • Continue the antibiotics postoperatively in patients having surgical drainage.
  • Steroids are often used in conjunction with antibiotics for treatment of retropharyngeal abscess.
• There is no consensus regarding medical (empiric antibiotics with or without steroids) vs. surgical (drainage) approaches for the first-line treatment of an retropharyngeal abscess. The patient's airway and clinical presentation should dictate the approach.
  • Most children with an retropharyngeal abscess are reported to respond to conservative management (antibiotics without surgical drainage).
    • Options for initial empiric parenteral antibiotic therapy to target pathogens such as Streptococcus viridans, Klebsiella pneumoniae, and Staphylococcus aureus include:
      • penicillin plus beta-lactamase inhibitor
      • beta-lactamase-resistant antibiotic plus drug effective against most anaerobes
      • metronidazole plus third-generation cephalosporin (such as cefotaxime, ceftriaxone)
      • carbapenem (such as imipenem-cilastatin, meropenem)
      • cephamycin (such as cefotetan, cefoxitin)
      • clindamycin plus quinolone
      • vancomycin if:
        • S. aureus is considered the likely pathogen (methicillin sensitive or resistant).
        • The patient uses IV drugs and is at risk for infection with methicillin-resistant S. aureus (MRSA).
        • The patient has profound neutropenia or immune dysfunction.
    • The factors associated with an increased risk for antibiotic failure and need for surgical intervention include:
      • age at admission < 3 years
      • symptoms > 3 days before starting IV antibiotics
      • leukocyte count > 22,000/mm³
      • hypodense core on CT scan ≥ 20 mm
  • Surgical drainage is the traditional method for treating deep neck abscesses, and is widely used for treatment of a complicated and/or severe deep neck infection.
    • There is no consensus on what size abscess requires surgical management, or how long to give medical therapy prior to using surgical intervention.
    • Immediate surgical drainage (in conjunction with antibiotic treatment) is usually suggested for an abscess characterized by either of the following:
      • ≥ 20 mm in diameter with scalloping (detected on CT scan)
      • no clinical improvement with parenteral antibiotics for 48 hours
    • Other indications for surgery include:
      • significant airway compromise
      • septicemia
      • mediastinitis, resulting from downward extension of infection
      • diabetes.