Retropharyngeal abscess

OVERVIEW: What every practitioner needs to know

Are you sure your patient has retropharyngeal abscess? What are the typical findings for this disease?

Odynophagia, fever, neck pain with movement.
Voice change, neck mass, difficulty breathing.

What other disease/condition shares some of these symptoms?

Other conditions with signs and symptoms similar to those of retropharyngeal abscess include retropharyngeal cellulitis/phlegmon (RPC), epiglottitis, peritonsillar abscess, croup, bacterial tracheitis, diphtheria, angioedema, lymphangioma, hemangioma, foreign body in the airway.

What caused this disease to develop at this time?

Retropharyngeal abscess is usually an extension of pharyngeal infection. It can also be caused by extension of vertebral osteomyelitis. In about 25% of children and adults with RPA, the infection is due to trauma to the parapharyngeal space. Young children (typically 2-4 years of age) are affected more frequently due to higher frequency of upper airway infections.

What laboratory studies should you request to help confirm the diagnosis? How should you interpret the results?

Complete blood cell count (CBC) with differential usually reveals leukocytosis with increased percentage of neutrophils and bands. Blood culture (aerobic AND anaerobic) has limited sensitivity, but is very helpful in guiding therapy when it is positive. Negative blood culture or normal CBC does not rule out RPA or retropharyngeal phlegmon.
Throat culture should be collected to identify possible group A streptococcal infection.
In a patient with airway compromise, traumatic and stressful laboratory testing procedures should be delayed until the patient’s airway is secured.
Pus is an ideal specimen for culture. Pus should be submitted for both aerobic and anaerobic cultures and stains.

Would imaging studies be helpful? If so, which ones?

A soft tissue lateral neck radiograph can be used initially and may help determine posterior pharyngeal wall thickness. This study has limitations, however, because patient positioning may make interpretation difficult, and differentiation between cellulitis and abscess is not possible unless an air/fluid level is seen.

Computed tomography (CT) with contrast is the study of choice for RPA or retropharyngeal phlegmon. It offers accurate anatomic delineation and extent of underlying pathology. It is quick and usually spares the patient from sedation. Radiation exposure, expense, and the need for sedation for select patients are the disadvantages of CT. The accuracy of CT in predicting an abscess in retropharyngeal infections in one study was 75% with a false-positive rate of 25%. CT had a low sensitivity (43%) and specificity (63%) in differentiating RPA from cellulitis among children admitted for retropharyngeal infection.

Intraoral ultrasound is non-invasive, readily available, and well-tolerated by children. Sedation or anesthesia is rarely required, but ultrasound does have limitations. The absence of contrast in ultrasound studies may limit structure identification. It also requires cooperation of the patient.

Confirming the diagnosis

Clinical assessment of retropharyngeal infections relies on presence of neck pain, neck stiffness, fever, pharyngeal swelling and external neck swelling, depending on the extent of infection. Pediatric patients presenting with airway obstruction should undergo timely and careful examination, with the airway properly secured.

Differentiation of cellulitis and lymphadenitis from an abscess is clinically difficult, and often imaging is needed. CT with contrast is the most helpful diagnostic tool. Contrast-enhanced CT can typically reveal areas of low attenuation and rim-enhancement.

Physical findings of respiratory distress, trismus, neck mass, obstruction, drooling, and odynophagia are suggestive of deep neck infection.

Neck pain or mass with torticollis in a young child with a history of upper respiratory tract infection, otitis media, or trauma should raise suspicion for deep neck infection.

Physical examination revealing midline pharyngeal swelling or bulging is diagnostic of retropharyngeal mass (e.g., lymphangioma or hemangioma), possibly abscess.

If you are able to confirm that the patient has retropharyngeal abscess, what treatment should be initiated?

Deep neck infections can progress rapidly, and patients usually require hospitalization and close observation for complications. Treatment of RPA depends on severity of presentation.

Patients with airway compromise need immediate intubation by an experienced physician. Parenteral antibiotics should be started once IV access is secured, along with otolaryngology consultation for surgical drainage. Parenteral hydration and analgesia are important adjuncts to initial care.

Patients without airway compromise should be evaluated by an otolaryngologist, started on parenteral antibiotics, hydrated, and treated adequately for pain.

Initial parenteral antibiotics should provide treatment for common pathogens causing RPA, including group A Streptococcus, Staphylococcus aureus and respiratory anaerobes. Empiric therapy can then be modified based on perioperative pus culture (aerobic and anaerobic) and Gram stain results. In general, RPAs are polymicrobial infections, and the isolation of respiratory anaerobes is limited by the collection technique and laboratory handling of the specimen.

The following parenteral antibiotics will provide adequate initial coverage: clindamycin (25-40 mg/kg/day IV divided every 6-8 hours) or ampicillin-sulbactam (200 mg ampicillin/kg/day IV divided every 6 hours). Imipenem (60-100 mg/kg/day IV divided every 6 hours) or meropenem (60 mg/kg/dose IV divided every 8 hours) are suitable, although they are more expensive alternatives with no clear additional benefit.

Oral antibiotics are reserved for outpatient management of RPC and a drained RPA. Amoxicillin-clavulanic acid (45 mg/kg/day – amoxicillin component- PO divided every 12 hours, 875 mg PO every 12 hours in adults) or clindamycin 30 mg/kg/day PO divided every 8 hours, 450 mg PO every 8 hours in adults.

Patients found to be infected with MRSA should be treated with vancomycin (60 mg/kg/day IV divided every 6 hours) or clindamycin (40 mg/kg/day IV divided every 8 hours). Clindamycin should only be used if the MRSA isolate is susceptible to clindamycin, or local epidemiology supports its empiric use (clindamycin resistance < 10%). Oral linezolid is an expensive alternative for outpatient management of documented MRSA infection. The dose depends on age and weight of the patient : children <5 years: 30 mg/kg/day PO divided every 8 hours, children 5-11 years: 20 mg/kg/ day PO divided every 12 hours, children ≥12 years and adolescents: 600 mg PO every 12 hours.

The decision to switch to oral antibiotics is based on clinical course and appropriate when patient is afebrile, and able to swallow pills and liquids.

Surgery is required for all abscesses that do not initially respond to antibiotics, are >2 cm, or result in airway compromise. Most otolaryngologists will advocate trans-oral drainage if the infection is located medially to major vessels. A transcervical approach may be necessary for abscesses lateral to great vessels.

Clinical improvement of pain and fever is observed within 24-48 hrs after antibiotic therapy and/or surgical intervention. Patients who do not improve with antibiotics alone should be evaluated for presence of abscess and need for surgical intervention.

Patients who had an abscess drained and continue to be febrile or in pain should be carefully evaluated for complications such as partial drainage of the RPA, reaccumulation of pus, extension of infection to surrounding structures, or septic jugular thrombophlebitis.

Appropriate duration of antimicrobial therapy has not been well studied. In general, 14 days of antibiotics from successful drainage should be sufficient.

What are the adverse effects associated with each treatment option?

Antibiotic therapy is safe in general. Documented side effects of antibiotic therapy include rashes, nausea, abdominal pain, diarrhea, bone marrow suppression, Stevens-Johnson syndrome, anaphylaxis, ototoxicity and nephrotoxicity (vancomycin), AST and ALT elevation, pseudomembranous colitis, and headache.

Risks associated with surgical drainage include bleeding, as well as risks associated with general anesthetic. Surgical incision and drainage by a trans-oral approach carries a low risk of morbidity or mortality.

What are the possible outcomes of retropharyngeal abscess?

The prognosis of RPA is good if the condition is recognized and treated early.

Antibiotic therapy is safe and rarely results in serious side effects. Both general anesthetic and surgical incision and drainage by a trans-oral approach carry a low risk of morbidity or mortality.

What causes this disease and how frequent is it?

There is no documented seasonal variation for RPA. Younger children are more commonly affected. Its incidence is declining because of the widespread use of antibiotics and improvement in medical care. Boys have a higher risk of developing RPA than girls. In general, RPAs are not considered contagious.
There are no known environmental triggers to RPA, and there is no known genetic predisposition to RPA.

How do these pathogens/genes/exposures cause the disease?

The retropharyngeal space extends from the base of the skull to the mediastinum at the level of the first or second thoracic vertebrae. In children, retropharyngeal phlegmon and abscess usually follow an upper respiratory tract infection with suppuration of the retropharyngeal lymph nodes. These lymph nodes usually atrophy by 3 to 4 years of age.

After the age of 5 years, retropharyngeal infection becomes less frequent. Older children and adults presenting with RPA often have a history of foreign body ingestion, external trauma, or instrumentation, such as intubation or esophagoscopy.

Other clinical manifestations that might help with diagnosis and management

What complications might you expect from the disease or treatment of the disease?

Major complications of RPA include mediastinitis, Lemierre’s syndrome (thrombophlebitis of a deep neck vein), carotid artery rupture, septicemia, airway compromise, osteomyelitis, and pneumonia.

Are additional laboratory studies available; even some that are not widely available?

How can retropharyngeal abscess be prevented?

There are no vaccines available to protect children from RPA; however, since RPA frequently results from a complication of upper respiratory tract infection, routine influenza vaccination is recommended for all healthy and high-risk children > 6 months of age. There are no known behavioral risk factors predisposing to RPA.

What is the Evidence?

Goldstein, NA., Hammerschlag, MR., Feigin, RD, Cherry, JD, Demmler-Harrison, GJ, Kaplan, SL. “Peritonsillar, retropharyngeal, and parapharyngeal abscesses”. Feigin and Cherry's textbook of pediatric infectious diseases. 2009. pp. 177-84.

Schwartz, RH., Long, SS, Pickering, LK, Prober, CG. “Infections related to the upper and middle airways”. Principles and practice of pediatric infectious diseases. 2003. pp. 213

Al-Sabah, B, Bin Salleen, H, Hagr, A. “Retropharyngeal abscess in children: 10-year study”. J Otolaryngol. vol. 33. 2004. pp. 352-5. (Pediatric study looking into controversy between medical and surgical approach to treatment of RPA. The study showed that children with fewer initial symptoms were more likely to respond to medical therapy alone. The study did not detail the CT findings, therefore possibly over-representing patients with retropharyngeal phlegmon alone.)

Brook, I.. “Microbiology and management of peritonsillar, retropharyngeal, and parapharyngeal abscesses”. J Oral Maxillofac Surg. vol. 62. 2004. pp. 1545-50. (Review of pediatric deep neck infections; focuses on microbiology and management.)

Malloy, KM, Christenson, T, Meyer, JS. “Lack of association of CT findings and surgical drainage in pediatric neck abscesses”. Inter J Pediatr Otorhinolaryngol. vol. 72. 2008. pp. 235-9. (Interesting retrospective study of 43 children, showing no correlation between CT findings and presence of pus at surgery. The study cautions clinicians not to rely on CT findings alone when recommending surgical intervention, but to use it in conjunction with clinical acumen.)

Courtney, MJ, Mahadevan, M, Miteff, A.. “Management of paediatric retropharyngeal infections: non-surgical versus surgical”. ANZ J Surg. vol. 77. 2007. pp. 985-7. (A study of 24 children with retropharyngeal cellulitis, early and fully developed abscess, comparing medical to surgical management. The authors support conservative (medical) treatment of retropharyngeal infections. Limitations of the study include its small size, lack of CT definition of early abscess, and CT size of abscess.)

Page, NC, Bauer, EM, Lieu, JE.. “Clinical features and treatment of retropharyngeal abscess in children”. Otolaryngol Head Neck Surg. vol. 138. 2008. pp. 300-6. (Large retrospective study of 162 children with RTA. The study describes factors that are helpful in selecting patients for surgical drainage.)

Grisaru-Soen, G, Komisar, O, Aizenstein, O. “Retropharyngeal and parapharyngeal abscess in children–epidemiology, clinical features and treatment”. Inter J Pediatr Otorhinolaryngol. vol. 74. 2010. pp. 1016-20.

Cramer, JD, Purkey, MR, Smith, SS, Schroeder, JW. “The impact of delayed surgical drainage of deep neck abscesses in adult and pediatric populations”. Laryngoscope. 2016 Apr 8. (This is a prospective cohort comparing the importance of timing of RPA drainage among children and adults.)

Ongoing controversies regarding etiology, diagnosis, treatment

There is ongoing debate regarding the usefulness of CT scan in establishing the diagnosis of RPA. However, until better imaging options are available, it remains the study of choice for patients who cannot be evaluated by intra-oral ultrasound.

Medical treatment of RPA vs surgical drainage remains an area of controversy. Some studies of children with retropharyngeal infection showed that medical treatment (antibiotics alone) did not prolong the hospital stay or result in any complications. However, the size of the abscesses among those children was not documented. It is possible that certain children with small abscesses can be treated with antibiotics alone without compromising morbidity, mortality, or other parameters such as duration of hospital stay. It is our recommendation to use all clinical information and clinical appearances in conjunction with imaging studies when making a decision regarding surgical intervention.

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