Pediatric Retropharyngeal Abscess

Updated: Mar 25, 2019
  • Author: Vijay A Patel, MD; Chief Editor: Ravindhra G Elluru, MD, PhD  more...
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Overview

Practice Essentials

Retropharyngeal abscess (RPA) is a deep neck space infection that can pose an immediate life-threatening emergency, with potential for airway compromise and other catastrophic complications.

Signs and symptoms

Patients with an RPA are likely to experience a constellation of symptoms, including fever, malaise, decreased appetite, irritability, sore throat, dysphagia, odynophagia, trismus, or torticollis. The overall presentation can be insidious, even stemming from a recent upper respiratory tract infection that has not completely resolved. In view of the clinical ambiguity, especially early in the infectious course, it is important to maintain a high index of suspicion.

Physical examination findings that are commonly found in children with RPA include the following:

  • Fever
  • Toxic appearance
  • Tender lymphadenopathy (often unilateral)
  • Decreased or painful range of motion of the neck or jaw
  • Dysphonia ("hot potato" voice) 

Stridor and drooling are indications of possible airway compromise, which necessitate emergency intervention with respect to airway stabilization. Finally, bulging of the posterior pharyngeal wall is common and is usually asymmetric. 

The clinical course may appear unremarkable in the early stages, resembling that of uncomplicated pharyngitis. However, later stages may result in dysphagia, dysphonia, or respiratory compromise. If labored breathing or posturing is present, it is imperative to rule out airway obstruction and secure the airway if deemed clinically necessary. However, blind endotracheal intubation should be avoided because of the possibility of rupturing the abscess and causing either further airway obstruction or aspiration pneumonia. 

Diagnosis

Upon initial evaluation, patients in whom there is concern about a possible RPA should be evaluated and stabilized by both pediatric hospitalists and pediatric otolaryngologists. Blood tests typically obtained include the following:

  • Blood culture
  • Complete blood count with differential
  • Inflammatory markers

Imaging studies that may be considered include the following:

  • Lateral neck radiograph
  • Contrast-enhanced computed tomography (CT) scan of the neck

Radiography has a lower sensitivity and often precedes CT. CT is the modality of choice for identifying the abscess or determining its location.

Management

Treatment with intravenous broad-spectrum antibiotics should also be promptly initiated, typically including a penicillin plus an antipenicillinase (eg, ampicillin-sulbactam). When possible methicillin-resistant Staphylococcus aureus infection is a concern, clindamycin or vancomycin should be considered for empiric therapy. Antibiotic planning should take into account that the microbiology of RPA is likely to include multiple pathogens, most likely gram-negative rods and anaerobes.

Sole medical management is typically employed in a monitored hospital setting for up to 72 hours to determine adequacy; surgical intervention via transoral or transcervical approaches is often indicated if the clinical picture does not improve. 

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Background

Retropharyngeal abscess (RPA) is a deep neck space infection that can pose an immediate life-threatening emergency, with potential for airway compromise and other catastrophic complications. [1]

For an optimal understanding of deep-space infections, a strong knowledge of head and neck anatomy with respect to the fascial planes is necessary. Superficial and deep layers of the cervical fascia are found within the neck. Although this fascia is typically adherent to adjacent structures, potential spaces can be created when an infection intercalates between fascial layers and creates a real space, with rapid spread of infectious inflammation and purulence between fascial planes.

The retropharyngeal space is located immediately posterior to the pharynx (nasopharynx, oropharynx, and hypopharynx), larynx, and trachea. The visceral (buccopharyngeal) fascia, which surrounds the pharynx, trachea, esophagus, and thyroid, forms the anterior border of this space. Bounded posteriorly by the alar fascia, the retropharyngeal space is bounded laterally by the carotid sheaths and parapharyngeal spaces. It extends superiorly to the skull base and inferiorly to the mediastinum at the level of the tracheal bifurcation (see image below).

Schematic of neck deep space anatomy, as illustrat Schematic of neck deep space anatomy, as illustrated in lateral and cross-sectional views. Fascial planes (see color key) surround potential spaces. Anteriorly, retropharyngeal space is bounded by buccopharyngeal fascia, which invests pharynx, trachea, esophagus, and thyroid; posteriorly by alar fascia; and laterally by carotid sheaths and parapharyngeal spaces. Retropharyngeal space extends from skull base to mediastinum at level of tracheal bifurcation. Note danger space located between alar fascia and prevertebral fascia.

Two other potential spaces (the danger space and the prevertebral space) are located in close proximity to the retropharyngeal space. The danger space is formed anteriorly by the alar fascia and posteriorly by the prevertebral fascia. The prevertebral space is bounded anteriorly by the prevertebral fascia and posteriorly by the longus colli spinal muscles.

The danger space extends down the mediastinum to the level of the diaphragm, whereas the prevertebral space continues to the insertion of the psoas muscles. These anatomic relations can allow infection of the retropharyngeal space to spread to the mediastinum, leading to potentially fatal mediastinitis.

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Pathophysiology

The retropharyngeal space can become infected in one of the following two ways:

  • Infectious spread from a contiguous area
  • Infection directly inoculated from penetrating trauma

The "classic" RPA is observed in pediatric patients occurs when an upper respiratory tract infection (URI) spreads to retropharyngeal lymph nodes, which form chains in the retropharyngeal space on either side of the superior constrictor muscle. Degeneration or suppuration of these nodes leads to abscess formation.

Of specific interest is the group of lateral retropharyngeal nodes at the skull base that bears the name of the French anatomist Henri Rouvière. The nodes of Rouvière typically are not of great clinical interest, but as the primary lymphatic drainage of the nasopharynx, they can become significant in cases of nasopharyngeal cancer. They are also pertinent to the discussion of RPA, in that they can suppurate and lead to abscess formation.

In children, RPA is usually caused by an infection which spreads to the retropharyngeal lymph nodes, with subsequent cellulitis and abscess formation. Fibrosis and atrophy start in these nodes at approximately 4 years of age; by 6 years of age, the retropharyngeal nodes typically regress. In older patients, infection of the retropharyngeal space usually occurs from penetrating trauma or direct spread from an adjacent space.

Complications of RPA arise from mass effect, abscess rupture, or infectious spread. The most urgent complication is RPA expansion against the pharynx or trachea, leading to airway compression. Abscess rupture can cause aspiration of purulent material, leading to asphyxiation or pneumonia. The spread of infection can also lead to inflammation and destruction of adjacent tissues.

Spread of infection to the mediastinum can result in mediastinitis, purulent pericarditis and tamponade, pyopneumothorax, pleuritis, empyema, or bronchial erosion. Lateral spread of infection can involve the carotid sheath and cause internal jugular vein thrombosis or carotid artery rupture. Posterior spread of infection can result in osteomyelitis and erosion of the spinal column, causing vertebral subluxation and spinal cord injury. Finally, RPA can evolve into necrotizing fasciitis, sepsis, and death.

Hence, accurate and prompt treatment of and intervention for presumed RPA are crucial to prevent significant untoward sequelae.

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Etiology

Most retropharyngeal space infections arise from drainage to the retropharyngeal nodes from primary nasopharyngeal infections. The resulting lymphadenitis can lead to cellulitis, which can then suppurate and result in abscess formation. Possible predisposing infections can include the following:

Infectious sources (eg, osteomyelitis of the spine) also can spread directly anteriorly from the prevertebral space. Retropharyngeal infections can also spread from contiguous spaces, such as the parapharyngeal space, submandibular space, or prevertebral space.

Penetrating trauma can also be involved in retropharyngeal space infection via direct seeding. Accidental lacerations are not uncommon in children who run and fall down after they have placed a sharp object in their mouths. Parents may be unaware of these predisposing events, and thus the diagnosis can be even more elusive. Foreign bodies (fishbones) have also been implicated in penetrating trauma to the retropharyngeal space.

RPA can also be iatrogenic secondary to instrumentation of the upper respiratory tract. Iatrogenic causes of inoculation to this space include instrumentation with laryngoscopy, endotracheal intubation, surgery, endoscopy, feeding tube placement, and dental procedures.

Risk factors for RPA include low socioeconomic status, poor oral hygiene, and immune dysfunction (HIV, diabetes, or immunosuppression).

The infection is often polymicrobial, with gram-positive organisms and anaerobes predominating; however, gram-negative bacteria have also been isolated. The source of bacteria is usually the oropharyngeal flora, with the most common organisms being group A beta-hemolytic streptococci. Staphylococcus aureus is also fairly common. Abdel-Haq et al noted an increasing incidence of methicillin resistance in Staphylococcus isolates (24% of all cultures and 64% of Staphylococcus-positive cultures). [2]

The most common anaerobes are Bacteroides species. Other causative agents include Haemophilus parainfluenzae, Veillonella, Peptostreptococcus, Fusobacterium, and Eikenella species.

Mycobacterium tuberculosis, Bartonella henselae, and Coccidia should be suspected in patients who may be predisposed (immunosuppressed individuals or recent immigrants), especially if they are not responding to conventional therapies.

Finally, another consideration in the evaluation of these patients is the possibility of Lemierre syndrome (septic thrombophlebitis of the internal jugular vein secondary to RPA). This infection is classically associated with Fusobacterium necrophorum, an anaerobic gram-negative rod. [3] Surgical intervention, with adjunctive medical treatment that includes antibiotic therapy and anticoagulation, may be warranted in complicated RPA secondary to Lemierre syndrome.

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Epidemiology

United States statistics

In an analysis of a large national database of pediatric admissions in the United States, [4]  Lander et al found 1321 cases of RPA in 2003. A large retrospective review of pediatric head and neck infections at the University of Mississippi Medical Center, published in 2006, [5] found that of the 1010 documented pediatric head and neck infections, 26 were RPA.

In a 2014 study, Novis et al used the Kids' Inpatient Database (KID) to evaluate the incidence, demographics, and outcomes of deep neck space infections in North American children between 2000-2009. [6] The incidence of pediatric RPA increased significantly, but there were no concurrent increases in combined deep neck space infections, peritonsillar abscesses, or parapharyngeal abscesses. Management of RPA changed over this period (decreased operative intervention and shorter average hospital stay).

International statistics

With less access to health care and decreased availability of antibiotics, deep neck space infections are a more common complication of URI in developing nations. Pathogens not typically seen in the United States are also noted in this population (tuberculosis) and should be considered.

A tertiary hospital in Freiburg, Germany, studied deep neck infections occurring over 8 years. [7] Of the 234 documented infections, 15 (6.4%) were RPA. Although no subgroup analysis was specifically performed for RPA, one interesting finding was a higher-than-expected rate of B henselae infection (catscratch disease) and cervical tuberculosis. Thus, the treating physician should consider all infectious etiologies when evaluating patients in whom atypical infections are a concern.

A study from India also described a socioeconomic correlation with deep neck abscesses. [8] Most patients with RPA were of low socioeconomic status, which was theorized to contribute to the incidence of abscesses in addition to poor dental hygiene and a lack of healthcare access.

Age- and sex-related demographics

RPA is almost exclusively a pediatric diagnosis. Most occur in children aged 6 months to 6 years (mean age, 3-5 years). [4, 5, 9, 9] Other deep neck abscesses (eg, parapharyngeal and peritonsillar) are observed more frequently in adults and older children.

Although no sex predilection has been described in the literature, several studies have noted a higher incidence of deep neck infections in boys. In a large national database, 63% of patients were male. [4]

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Prognosis

In uncomplicated cases of RPA in a relatively healthy patient, the prognosis for complete recovery without sequelae is excellent, though complicated cases may be associated with significant mortality and morbidity. In patients with complications such as carotid artery infection, jugular vein thrombosis, or mediastinitis, mortality can approach 20-60%.

Total hospital stays for both conservative and surgical management tend to be, on average, in the range of 3-6 days, though some stays have been reported to exceed 30 days. [10, 11]  There are also studies that reported statistical insignificance with respect to length of stay and management type. Except in the most severe or complicated cases, patients are treated with intravenous antibiotics alone or surgery and can return home shortly thereafter without significant morbidity.

In a study of 2181 children with cervical abscesses, Harounian et al found that major contributors to length of stay included operating time, days of postoperative ventilation, and length of time from admission to surgery. [12] Younger children (< 2 years) had both a longer wait time until surgery (1.4 vs 1.1 days) and a prolonged length of stay (4.3 vs. 3.4 days).

Finally, the overall recurrence rate has been estimated to be in the range of 1-5%; in those circumstances, further management must be pursued. [13]

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Patient Education

Advise a follow-up appointment for parents or caregivers of children diagnosed with URIs that do not follow an appropriate course of resolution.

Advise parents or caregivers to return immediately if the patient develops clinical manifestations of deep neck space infection, such as difficulty swallowing, swelling in the back of throat or neck, muffled voice, jaw or neck stiffness, or worsening of symptoms.

Advise parents to remain especially alert for signs of airway compromise, such as shortness of breath, drooling, or noisy breathing.

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