Abscess, Retropharyngeal

Article Author:
Thomas Knorr
Article Editor:
Virteeka Sinha
Updated:
10/27/2018 12:31:50 PM
PubMed Link:
Abscess, Retropharyngeal

Introduction

A retropharyngeal abscess is an uncommon but potentially life-threatening diagnosis. This disease is most common in children under the age of five but also occurs in adults. Typically patients under the age of five have an antecedent upper respiratory tract infection leading to suppurative cervical lymphadenitis and eventually retropharyngeal abscess. In older children and adults, a retropharyngeal abscess is caused by trauma to the posterior pharynx which leads to inoculation of the retropharyngeal space and results in abscess formation. As a retropharyngeal abscess grows in size, it can lead to upper airway obstruction and asphyxiation. Treatment of retropharyngeal abscess ranges from prolonged courses of intravenous antibiotics to surgical incision and drainage.[1][2][3]

Etiology

The anatomy of the deep neck is as follows:

There are three fascial layers and three spaces where hematoma or infection can collect and lead to airway compromise. These layers and spaces, listed in anterior to posterior order, are (1) buccopharyngeal fascia, retropharyngeal space, (2) alar fascia, alar “danger” space, and (3) prevertebral fascia, prevertebral space. 

The retropharyngeal space extends craniocaudally from the base of the skull to the posterior mediastinum and is enclosed by the buccopharyngeal and alar fascia. Retropharyngeal abscess is suppurative collections within this space. Although infections of the prevertebral and alar spaces also can occur, infections of these anatomic spaces will not be discussed here.

The retropharyngeal space contains chains of lymph nodes that drain the nasopharynx, adenoids, posterior paranasal sinuses, and middle ear. These lymph node chains are present in young children, but atrophy and involute typically by age four to five years old. In one-half of cases of retropharyngeal abscess patients report an antecedent upper respiratory tract infection. Upper respiratory tract infections result in suppurative adenitis of these retropharyngeal lymph nodes and eventual abscess formation.

Trauma to the posterior pharynx resulting in retropharyngeal infection and eventual abscess formation is typically the etiology of retropharyngeal abscess in adults and older children. One-fourth of retropharyngeal abscesses is attributed to the trauma of the posterior pharynx resulting in inoculation of the retropharyngeal space, cellulitis, phlegmon formation, and eventually, retropharyngeal abscess.[4][5][6]

Epidemiology

Retropharyngeal abscess typically occurs in children between the ages of two and four years but can occur at any age.

Half of retropharyngeal abscesses are believed to be attributed to antecedent upper respiratory tract infections leading to retropharyngeal suppurative lymphadenitis and eventual abscess formation.

One-fourth of retropharyngeal abscesses is attributed to retropharyngeal trauma which results in inoculation of the retropharyngeal space resulting in abscess formation.

Although an uncommon diagnosis, the incidence of retropharyngeal abscess has been increasing in recent years according to data collected from 2000 through 2009.[1][7]

Pathophysiology

In children younger than five years old, the retropharyngeal space contains chains of lymph nodes that drain the nasopharynx, adenoids, posterior paranasal sinuses, and middle ear. An antecedent upper respiratory tract infection can result in suppurative adenitis of these retropharyngeal lymph nodes and eventual abscess formation. As these retropharyngeal lymph nodes atrophy and involute during normal development, antecedent upper respiratory tract infection resulting in retropharyngeal abscess becomes less likely. In older children and adults, trauma to the posterior pharynx resulting in retropharyngeal infection is the more likely mechanism through which retropharyngeal abscess originates.

After suppurative adenitis or trauma results in the seeding of the retropharyngeal space, cellulitis results and eventually leads to phlegmon and abscess formation in the retropharyngeal space. Retropharyngeal abscesses are often polymicrobial infections. Bacteria which commonly contribute to these infections include Group A Streptococcus pyrogens, Staphylococcus aureusFusobacteriumHaemophilus species, and other respiratory anaerobic organisms.

As the retropharyngeal abscess grows in size, it results in gradual upper airway obstruction and eventually to asphyxiation if left untreated. Although mortality from sepsis does occur in these patients, the number one cause of death in patients with retropharyngeal abscess remains upper airway occlusion.[8][9]

History and Physical

Early retropharyngeal abscess presents similarly to uncomplicated pharyngitis. Aspects of a patient's history that are concerning for early retropharyngeal abscess would be antecedent upper respiratory tract infection or trauma to the posterior pharynx. As this infection progresses, symptoms related to upper aerodigestive obstruction become more prominent and typically progress over days. The following are red flags in a patient’s history which should be concerning for upper aerodigestive obstruction:

  • Dysphagia
  • Odynophagia
  • Inability to tolerate oral secretions
  • Neck stiffness
  • Torticollis
  • Refusal to extend neck due to pain or discomfort
  • Change in voice, “hot potato voice,” muffled voice
  • Trismus
  • Neck swelling, cervical lymphadenopathy
  • Chest pain (mediastinal extension)
  • Respiratory distress (stridor, tachypnea, retractions).

Patients who present with retropharyngeal abscess typically are febrile and ill appearing. Early in the illness, patients may only have mild to moderate pharyngeal erythema and refusal to tolerate anything by mouth. As the disease progresses, pharyngeal erythema and swelling will become more prominent, and patients will be unable to tolerate even their oral secretions. Patients typically will have extreme discomfort with neck extension and often will prefer to hold their necks in flexion, as opposed to epiglottitis where patients will preferentially hold their necks in extension.

The oropharynx of a patient with a suspected retropharyngeal abscess only should be thoroughly examined with palpation or probing by clinicians who are experienced in emergent airway management. Abscess rupture can occur during the examination of the posterior pharynx, leading to aspiration and potential asphyxiation. It has been suggested that this exam should be performed with patients in the Trendelenburg position to prevent aspiration in case of abscess rupture, and suction equipment should be readily available.

Evaluation

Labs including complete blood count, blood cultures, and preoperative labs are necessary if a retropharyngeal abscess is suspected. However, obtaining these labs should be delayed if phlebotomy will cause additional distress to the patient. This additional distress to the patient can cause early upper airway obstruction to become complete upper airway obstruction, especially in younger children. Both aerobic and anaerobic blood cultures should be obtained. In patients with retropharyngeal abscess white blood cell counts are greater than 12,000 in 91% of individuals.[3][10][11]

Lateral neck radiographs are typically the imaging study of choice in the initial evaluation of suspected retropharyngeal abscess, especially in young children. Lateral neck radiographs have the benefit of lower radiation exposure and tend to be better tolerated by patients who are exhibiting signs of airway compromise. Lateral neck x-rays should be obtained during inspiration with the neck held in normal extension. Improper technique in obtaining this imaging study can result in false positives for retropharyngeal infection.  When retropharyngeal infection is present, the depth of the prevertebral space will be increased on the lateral neck x-ray. In healthy individuals, the upper limit of normal of the prevertebral space is 7 mm at C2 and 14 mm at C6 in children. In healthy adults, the upper limit of normal of the prevertebral space is 7 mm at C2 and 2 mm at C6.

Additionally, patients who are presenting with a concerning story for retropharyngeal abscess which is also endorsing chest pain should have a chest x-ray obtained to investigate for mediastinal involvement.

CT of the neck with intravenous contrast is the best imaging study to evaluate patients with a retropharyngeal abscess. If there is a concern for airway compromise in these patients, a clinician who is trained in emergency airway management should be present while the CT scan is being obtained. Patients may require an emergent surgical airway if upper airway obstruction occurs. The sensitivity of CT scan for detecting retropharyngeal abscess varies in the literature ranging from 64% to 100%.

Treatment / Management

All patients presenting with a confirmed diagnosis of retropharyngeal infection require hospital admission, intravenous antibiotics, and otolaryngology consultation. Antibiotic therapy should cover upper respiratory organisms including anaerobic organisms. Patients presenting airway compromise should have immediate surgical incision and drainage performed to relieve their upper airway obstruction.[12][13][14]

In patients not presenting with severe respiratory distress or airway compromise, management typically begins with a 24 to 48 hour trial of intravenous antibiotic therapy. After 24 to 48 hours of antibiotic therapy, the need for surgical incision and drainage will be reevaluated by a trained otolaryngologist. Factors which have been associated with an increased need for surgical incision and drainage include an abscess with a cross-sectional area greater than 2 cm2 and symptoms for greater than 2 days. There is no evidence that patients presenting with mature abscesses greater than 3 cm2 benefit from surgical intervention before 24 to 48 hours of antibiotic therapy.

All patients must have careful airway monitoring when undergoing treatment of retropharyngeal abscess especially during the first 24 to 48 hours of therapy.

Initial antibiotic therapy should include either ampicillin-sulbactam (50 mg/kg every 6 hours) or clindamycin (15 mg/kg every 8 hours). If patients appear septic or do not respond to initial antibiotic therapy, vancomycin or linezolid also should be administered. Parenteral antibiotics should be continued until patients are clinically improved and afebrile for 24 hours. After patients demonstrate clinical improvement and remain afebrile, they may be transitioned to oral antibiotics. Amoxicillin-clavulanate (45 mg/kg every 12 hours) or Clindamycin (13 mg/kg every 8 hours) are acceptable oral regimens. Oral antibiotics should be prescribed for 14 days, and the patient may be discharged home with strict return precautions.

Differential Diagnosis

  • Foreign body in airways
  • Pneumonia
  • Mediastinitis
  • Epidural abscess
  • Oral cavity infections
  • Epiglottitis
  • Pharyngitis

Complications

Consultations

  • ENT surgeon
  • Dental surgeon
  • Anesthesia
  • Critical care specialist

Deterrence and Patient Education

Maintain good oral hygiene

Regular dental checkups

Enhancing Healthcare Team Outcomes

Retropharyngeal abscess is a life-threatening disorder which can quickly result in airway compromise and death. In view of the very high morbidity and mortality, a multidisciplinary approach to diagnosis and treatment is recommended. The triage nurse should be familiar with the symptoms and not mistake it for a simple upper respiratory tract infection. Once the ER physician is notified, the radiologist should be consulted for the appropriate imaging test. The patient should be monitored by the critical care specialist, thoracic and ENT surgeon. Besides delivering ICU care, the nurse also plays a vital role in patient and family education. In order to prevent the disorder, the patient should be educated on proper maintenance of oral hygiene and getting regular dental checkups. More important the patient should be told that he or she has symptoms of dysphagia or dyspnea and a fever, immediate medical care should be sought. Way too many people delay seeking medical care thinking that they only have a URTI. Finally, the pharmacist should instruct the patient to discontinue smoking, eat healthy, maintain a healthy weight, and abstain from alcohol. [15][16][17] (Level III)

Outcomes

When the diagnosis is made early and treatment instituted, the prognosis is good. But the patient needs aggressive treatment, preferably in the ICU. If there is any delay in treatment, complications are common and the disorder carries a mortality rate of over 40%.[2][18] (Level V)