Infectious Disorders – Drug Targets, 2012, 12, 291-296 291 Retropharyngeal : Diagnosis and Treatment Update

1 2,3 Brian K. Reilly * and James S. Reilly

1Children’s National Medical Center, Washington, DC; USA; 2Chair, Department of Surgery, Nemours/Alfred I. duPont Hospital for Children, Wilmington, DE, USA; 3Professor of Otolaryngology and Pediatrics, Thomas Jefferson Univer- sity, Philadelphia, PA, USA Abstract: is a deep space infection that may present in various subtle ways permitting po- tentially lethal complications to occur before appropriate diagnosis is made and expedient management undertaken. This article reviews in detail the pertinent anatomy, diagnostic pearls, and clinical recommendations to optimally manage these common infections in children. Keywords: Abscess, imaging, infection, neck, pediatric, retropharyngeal.

OVERVIEW whether purulence is obtained intra-operatively [3]. Classic findings for abscess include large fluid with central A retropharyngeal abscess (RPA) is a deep neck space hypodensity, complete ring enhancement, and scalloping infection defined by its anatomical location within the deep Fig. (1). cervical tissue planes. RPA is located behind the pharyngeal mucosa and is contained anteriorly by the buccopharyngeal fascia (around the constrictor muscles) and laterally by the carotid sheath/. Superiorly, it may ex- tend to the skull base, and inferiorly, it can travel to the me- diastinum. This “potential” retropharyngeal space, which expands with infection, is occupied by a lymph-node basin [1] that serves as the common, final drainage pathway of the nasal cavity, , nasopharynx, oropharynx, hypopharynx, and . Inadequately treated and virulent infections of these regions can cause suppuration of these nodes. Thus, retropharyngeal lymphadenitis with can progress to a cellulitis, which, if untreated, evolves to early abscess or phlegmon and then to abscess.

The diagnosis of RPA is initially based upon clinical symptoms and signs on . What compli- cates this type of deep neck space abscess is the fact that there is rarely any reported visible or palpable external neck swelling. , , and odynophagia represent a classic triad of symptoms. In addition, there are many pa- tients who have irritability with only subtle findings of head- ache, decreased oral intake, , and limited neck mo- tion. As a result, a clinician’s suspicion of RPA is best cor- roborated with computed tomography (CT) imaging with contrast. A CT scan of the neck is helpful to differentiate between retropharyngeal cellulitis, phlegmon, and abscess as well as to localize the infection to facilitate surgical drainage. As such, CT imaging can help determine the next appropriate Fig (1). A 17-year-old boy with trismus, torticollis, and odynophagia. decision in management. The main controversy is in treat- On computed tomography, he was found to have a large retropharyn- ment of abscess with solely medical versus surgical and geal abscess causing narrowing of the airway and displacement of the medical therapy. Shefelbine et al., [2] argue that a CT scan carotid space laterally. Because of its large size, scalloped appear- will help determine what subset of RPA can be successfully ance, and proximity to great vessels, the patient was taken immedi- treated with alone. Indeed, a CT scan is helpful as ately for surgical drainage via an intra-oral approach. a surgical roadmap; although, it does not always predict Although airway compromise remains a grave concern, early identification and treatment of a retropharyngeal *Address correspondence to this author at the National Children’s Medical Center, 111 Michigan Avenue, NW, Washington, DC 20010, USA; abscess lessens the rate of this complication. Regardless, Tel: 202-476-3659; Fax: 202-476-5038; E-mail: [email protected] airway monitoring in an intensive care unit (ICU) setting is

2212-3989/12 $58.00+.00 © 2012 Bentham Science Publishers 292 Infectious Disorders – Drug Targets, 2012, Vo l. 12, No. 4 Reilly and Reilly still prudent for large , young children, and for dren aged 2-6 years put this patient population at highest risk those with frank snoring/stertor; ICU care may be indicated for RPA. also after surgical drainage. In fact, Landler et al. found that the typical patient was a There are two major treatment modalities of retropharyn- five-year-old male from an urban location admitted in a non- geal abscess: 1) conservative medical management with in- elective fashion via the emergency department [4]. travenous antibiotics, sometimes including steroids, and/or Children are much more prone to the development of this 2) prompt surgical drainage. Early stages of infection, gener- condition; although, some adolescents who have either a ally cellulitis or phlegmon, are managed with antibiot- compromised immunological system or who have never had ics/steroid regimens. Advanced or refractory disease leads to a prior adenotonsillectomy can be at risk. Older children are a larger or more serious RPA. True RPA abscesses, which less likely to develop a retropharyngeal abscess because the demonstrate scalloping and measure more than 2 cm in nodes of Rouvière (located in the retropharyngeal space) diameter, or which progress in the setting of antibiotics, typically begin to involute and regress beginning at four favor prompt surgical drainage. years of age; by the time the child is six years old, the retro- Regardless of the treatment modality chosen, an RPA pharyngeal nodes have substantially regressed. Specific geo- requires close monitoring and inpatient hospital care. Chil- graphic regions or ethnic races have never been shown to be dren with an RPA can be managed by the pediatric physi- predisposed to RPA. cians. In coordination with the otolaryngology surgeons, a decision of the benefits of operative intervention should be PRESENTATION/SYMPTOMS made daily. More severely ill patients benefit from infectious disease consultants, who can help select appropriate antibi- Major criteria for probable RPA include toxic appear- otic coverage, evaluate the sensitivity to the antimicrobial ance, airway distress, high grade fever (>101°F), , agent, and determine the length of treatment. dysphagia, trismus, limited neck motion, head tilt or torticol- lis, and noisy breathing pattern including stertor. Patients with milder symptoms, suggestive of cellulitis, are non-toxic INCIDENCE in appearance, possess low grade fever (< 101°F), headache, Antitbiotics have reduced the incidence, morbidity, and irritability, and decreased oral intake. mortality of abscesses. Landler et al., performed the largest Symptoms that occur with an RPA are secondary to the national review in 2003, which showed seasonal variation in swelling of space. Neck stiffness is due to inflammation of admissions for RPA [4]. The highest percentage of admis- prevertebral muscles (i.e., longus colli). Odynophagia is sec- sions was in the spring (March, 10.7%) and lowest in the ondary to distension of the and hypopharynx. Chil- summer (August, 3.8%). Of the 1,321 national admissions dren usually present three days after developing symptoms, reviewed in this study database there were no deaths. The but can arrive between 24 hours to two weeks after the onset mean age of patients was 5.1 years. Approximately 37% of symptoms. were female and 63% were male. Additionally, a tracheal “rock maneuver” can be per- Kirse et al., showed that group A beta-hemolytic Strepto- formed on physical exam. This manipulation elicits pain coccus (GABS) has been found to be more often present in with movement of the larynx from side to side. Although this cultures during the late 1990s [5]. Because of the increased technique can help rule out RPA, when positive, this is a frequency with which children obtain CT scans, this diagno- relatively non-specific finding. When the RPA abscess is at sis, which was previously missed on exam or lateral neck X- the level of the oropharynx, a bulge of the pharyngeal wall rays, is more readily noted in the current practice of medi- can occasionally be noted with careful examination using a cine. tongue blade and headlight. Small palpable cervical adeno- phathy is common as well. COST Patients often have an antecedent history of , Although there are increased costs associated with failed , adenoiditis, otitis, and/or . Although a or prolonged medical treatment, the mortality rate secondary large review by Kirse et al., [5] did not show antecedent to this condition has dramatically fallen to nearly zero in the trauma as the cause of any retopharyngeal abscess, this find- current era of medicine. The length of stay of non- ing may be explained by the fact that many children are not surgical patients was on average 3.9 versus 4.8 days. likely to mention trauma. Certainly, children after adenoidec- Landler et al. examined admissions in 2003, and found tomy are at risk if the surgical site becomes infected secon- that less than half, or 563 (43%) patients underwent surgical darily Fig. (2). In addition, specific cases of trans-cervical drainage of their infection [4]. More importantly, the use of spinal surgery with fixation hardware placement or small CT scans and attendant surgical procedures reduces the po- mucosal excoriation from intubation could cause a small tential for spread of RPA. The average cost of treatment in injury to the pharyngeal mucosa, which ultimately leads to US dollars varies greatly from state to state: $5,126 (Utah) to cellulitis and abscess. These types of surgical complications $27,776 (California). are much less frequently reported in the literature.

RISK FACTORS WORK-UP The immature immune system and the more prominent The initial clinical evaluation occurs most often in the lymphatic nodal systems in the retropharynx of young chil- setting of an emergency room. Update on Retropharyngeal Infection Infectious Disorders – Drug Targets, 2012, Vol. 12, No. 4 293

region. , which is much less common than RPA, shows the to be swollen and thickened and on x- ray is known as the “.” or laryngotra- cheal (LTB) is very common. On an x-ray, it shows the “,” a narrowing of the air column on the anteroposterior view of the neck. A confirmatory narrow- ing should be visible on the lateral neck film when LTB is present. Lastly, bacterial is an infection of the air- way, which presents on an x-ray as scalloping of the subglot- tis and cervical .

In contrast, RPA shows thickening of the prevertebral

space/tissues during a film that is taken during inspiration.

This finding is confirmed by ballooning of the pyriform si-

nuses in the hypopharynx. Measurements of the amount of

soft tissue relative to the vertebral column width, are com-

monly referenced but may be misleading in lateral neck

films obtained by faulty techniques; these include films ob-

tained during exhalation, which favors medial displacement

of the posterior pharyngeal soft tissues.

A cervical CT with intravenous contrast should be per- formed in all children in whom you suspect an RPA. Spe- cifically, the CT scan should be parallel to the hard palate, from the skull base to the thoracic inlet, and with 5-mm cuts. Fig (2). A six-year-old boy with increased neck stiffness and The key distinction is to differentiate RPA from enhanced after adenoidectomy. On computed tomography, he was found to lateral retropharyngeal lymph nodes, edematous retro- have retropharyngeal cellulitis/phlegmon after adenoidectomy. He pharyngeal lymph nodes, early abscess, retropharyngeal was treated successfully with intravenous antibiotics. cellulitis, and, ultimately, true retropharyngeal abscess. A CT for retropharyngeal cellulitis will show tissue Routine blood tests, including complete blood count or thickening and scattered small hypodensities but absence of C-reactive protein (CRP), are not diagnostic or prognostic clear central hypodensity and lack of ring enhancement. indicators but give context to the severity of the infection. A Malloy et al., found that prevertebral tissue edema does not “left-shift” with greater bands does not directly correspond correspond to the presence or severity of abscess [8]. Phleg- to the extent of infection yet can imply active infection. mon has central hypodensity and/or ring enhancement, Also, a clinician can find lymphocytic predominance in a which is not as prominent/complete as with frank pus. Round patient with mononucleosis. A white blood cell count or oval fluid is also a classic finding for phlegmon. Retro- (WBC) count is often elevated, with a mean level of pharyngeal abscess has clear hypodensity, clear ring en- 17,000/mcL. Ranges from 4,000-45,000/mcL have been re- hancement, and scalloping/irregularity of abscess wall. Rim corded. A WBC is also helpful to follow to determine re- irregularity [5] is a stronger predictor that there will be puru- sponse to medical therapy and/or satisfactory drainage; how- lence than ring enhancement alone. Rim irregularity is a late ever, this can be confounded if steroid therapy is started. finding that foreshadows rupture and free dissection in the C-reactive protein has been shown in studies to be ele- facial planes of the neck. vated in patients with RPA. In Pelaz et al., 100% of patients Often what is read as abscess on CT is a necrotic retro- with RPA had an elevated CRP, with a mean of 14.57 mg/dL pharyngeal in the early suppurative phase. In- at admission and 1.4 mg/dL at discharge [6]. deed, it takes at least 48 hours for a phlegmonous node to develop into an abscess. Thus, children who are taken early CULTURES for drainage and who do have turbid fluid or purulence are When dealing with critically ill children, throat cultures having preemptive drainage performed. Many surgeons de- and nasopharyngeal swabs can guide an appropriate choice cide to operate based on whether there is retropharyngeal of antibiotics. The majority of abscesses are polymicrobial, adenitis, which is readily treated with antibiotics, as opposed with Streptococcus, Staphylococcus, and anaerobes consti- to a retropharyngeal abscess, which can require longer dura- tuting the “big three.” Group A beta-hemolytic Streptococ- tion of antibiotics or immediate surgical drainage. cus is one of the most commonly found pathogens, and Plain-film radiography, which performs a quick survey of investigation by Cottichia et al. has shown a slight increase the anatomy of the neck soft tissue, does not adequately in resistance over the past decade [7]. Clindamycin resis- make this distinction between phlegmon and abscess. There tance is noted with the anaerobe Eikenella corrodens. are recent papers that note that contained abscesses can be treated exclusively with intravenous antibiotics; however, in IMAGING our opinion, drainage is well tolerated and can eliminate the Soft-tissue lateral cervical radiographs can be helpful in need for prolonged courses of antibiotics. Ultrasound can be quickly differentiating among the infections of the cervical difficult to obtain and requires an experienced radiologist for 294 Infectious Disorders – Drug Targets, 2012, Vo l. 12, No. 4 Reilly and Reilly interpretation. CT has been suggested as a means of separat- 5 to 21 days, with a median duration of 10 days [5]. McClay ing into medical and surgical treatment groups, but it has et al., examined a series of patients with non-complicated, limitations that include exposure to radiation, need for seda- small abscesses who were treated successfully with clin- tion, and absence of therapeutic benefits. damycin with or without cefuroxime [9]. If methicillin- Delayed images are helpful in differentiating between resistant Staphylococcus aureus (MRSA) is suspected, the clinician should consult infectious disease and start the pa- edematous nodes and abscess. In certain cases, however, a tient on IV vancomycin. CT can still be indeterminate. Therefore, a clinical decision must be made on whether to operate or continue antibiotics. Thus, early surgical intervention (e.g., incision and drainage STEROID MANAGEMENT with/without adenoidectomy) is essential to prevent spread Many clinicians will start a patient on steroids, methyl- of infection unless there is prompt and complete response to prednisolone/prednisone/dexamethasone (1mg/kg up to medical therapy (less than 48 hours; Fig. (3)). 12mg), for 12-24 hours to improve inflammation and help with torticollis and post-operative nausea.

BACTERIOLOGICAL FINDINGS

Coticchia et al., found that S. aureus is more prone in

children younger than 1 year (79%) [7]. In contrast, GABS is more frequently found in children older than 1 year (29%). The majority of infections were polymicrobial. There has been a dramatic increase in the incidence of GABS over the past few years. MRSA has also been rarely uncovered in deep neck space infections as microbial resis- tance rises.

MANAGEMENT Some studies argue in favor of prompt early surgical management while others argue in favor of conservative management with IV antibiotics. There is no true consensus

on what size abscess to operate on and how long to give

medical therapy a chance to work before surgical interven- tion is appropriate.

A transoral approach to these abscesses is recommended unless there is extension lateral to the great vessels. The ma- Fig (3). A five-year old boy with torticollis, stiff neck, and voice jority of these RPA can be managed transorally. Those that changes. On computed tomography, he was found to have a left 8 x extend to the parapharyngeal space are drained internally or 8 x 4-mm hypodense fluid collection with rim enhancement just externally Fig. (4). Patients who do not improve after drain- medial to the carotid space, consistent with retropharyngeal space age may require return to the operating to break up addi- abscess. The are mildly enlarged. He was treated success- tional loculations/pockets when these findings are confirmed fully with intravenous antibiotics without the need for surgical by repeat contrast cervical CT. drainage. Post-operative airway management rarely mandates that the child remains intubated after the procedure. These chil- DURATION OF MEDICAL THERAPY dren tend to be younger with corresponding small anatomy or airways compromised by enlarged or other soft- There is no standard agreement in the literature about the tissue swellings. For the rare child with post-procedure respi- first line antibiotics or the necessary duration of antibiotic ratory distress, the child may be kept intubated for only 1-2 therapy. All patients should be placed initially on intrave- days while the swelling subsides. Occasionally, a bedside nous (IV) antibiotics with broad spectrum coverage for respi- direct laryngoscopy can be accomplished to confirm reduc- ratory bacteria and monitored for clinical improvement in tion of swelling prior to extubation. symptoms/clinical status before being transitioned to enteral antibiotics. COMPLICATIONS ANTIBIOTIC CHOICES Pediatric retropharyngeal abscesses develop from within and are initially contained by the wall of suppurative lymph Most children can be treated with a single antibiotic, ei- nodes. If untreated, these lymph node capsules can rupture, ther Unasyn (ampicillin/sulbactam) or clindamycin when spilling infection into cervical deep tissue fascial planes with penicillin allergic or when there is concern for penicillin ensuing complications from spread of the infection. resistance. In some settings, coverage can be broadened with cefuroxime, flagyl, or Zosyn (piperacillin/tazobactam). Kirse Retropharyngeal abscesses can have life threatening et al., studied the duration of antibiotics, which ranged from complications; although, these have become much less Update on Retropharyngeal Infection Infectious Disorders – Drug Targets, 2012, Vol. 12, No. 4 295 likely. The most immediate complication to assess is the These complications are rare in children in the antibiotic safety/patency of the airway. A large retropharyngeal ab- era. In older children and adults, the disease spreads directly scess left untreated can impinge on the airway and will mani- into the larger fascial planes and more often must receive fest in drooling, tripoding, or stertorous breathing. Such a immediate surgical treatment. patient should have the airway secured in the operating room and should undergo immediate drainage.

Fig (5). Computed tomography demonstrates the “bulge” into the airway as the infection tracks down the prevertebral space. This patient remained intubated after surgical drainage.

CONCLUSIONS Retropharyngeal abscess is an increasingly common in- fection that leads to admissions to pediatric care facilities.

The increase is due to a change in the bacterial profile with increased drug resistance; however, a second factor includes earlier diagnosis by contrast enhanced CT of the cervical region, particularly when evaluated in the emergency de- partment. A CT Scan permits elucidation between the spectrum of possible retropharyngeal processes ranging, from cellulitis to phlegmon to micro-abscesses to consolidated RPA. Treat-

ments, therefore, need to be tailored to the clinical symptoms

and signs, appropriate lab and radiological tests, and the ef- Fig (4). An eight-month-old boy with severe dyspnea, dysphagia, fectiveness of the medical interventions. Prompt intravenous and croup-like symptoms. On computed tomography, he was found antimicrobial agents effective against gram positive organ- to have a large retopharyngeal abscess with extension to the isms should be given with close monitoring for the first 48 parapharyngeal space. He required emergent intubation, both intra- hours of therapy. Longer periods of observation are indicated oral and external drainage with over 60 ml of purulence, prolonged when there is prompt medical response. intravenous antibiotics for methicillin-resistant Staphylococcus aureas, and a return to operating room for further drainage of reac- Surgical drainage is very simple, quick (less than 20 cumulated pus. minutes), and effective but requires general anesthesia. The mainstay procedure is a trans-oral incision and drainage and Complications also stem from spread of infection either may include adenoidectomy if the RPA is high in the naso- via the so-called danger space, the prevertebral space pharynx or if the RPA is more lateral in the Fig. (5), or the parapharyngeal space with resultant medi- oropharynx. Most importantly, the pharyngeal and laryngeal astinitis, septic thrombophlebitis, and carotid artery aneu- airway can be completely assessed. Malloy et al., found that rysm. Systemic spread of infection can result in , dis- 88% of patients taken to the operating room had purulence seminated intravascular coagulopathy (DIC), and sepsis with [8]. The vast majority promptly respond with routine recov- multi-organ failure. ery in the post-anesthesia care unit followed by overnight antibiotics and discharge home in the morning on oral anti- Extension posteriorly into the prevertebral musculature biotics. can cause laxity of the transverse ligament and, if significant stress is placed, ultimately atlanto-occipital separation. This Delays in surgical interventions may lead to spread of is known as Grisel’s syndrome and is a non-traumatic sub- RPA infections into the adjacent spaces of the cervical re- luxation of the atlanto-axial joint caused by inflammation of gion into the chest and lead to severe sepsis and even death. the adjacent tissues. Poor outcomes are very rare in modern pediatric medical and 296 Infectious Disorders – Drug Targets, 2012, Vo l. 12, No. 4 Reilly and Reilly surgical care, unless the child has a compromised immu- fections in children: the Toronto experience. Int. J. Pediatr. nological system or is in an economically deprived area with Otorhinolaryngol., 2005, 69(1), 81-86. [4] Lander, L.; Lu, S.; Shah, R.K. Pediatric retropharyngeal abscesses: poor access to health care/medical support system. a national perspective. Int. J. Pediatr. Otorhinolaryngol., 2008, 72(12), 1837-1843. CONFLICT OF INTEREST [5] Kirse, D.J.; Roberson, D.W. Surgical management of retropharyn- geal space infections in children. Laryngoscope, 2001, 111(8), Neither author has any conflict of interest to disclose. 1413-1422. [6] Pelaz, A.C.; Allende, A.V.; Llorente Pendás, J.L.; Nieto, C.S. Con- servative treatment of retropharyngeal and parapharyngeal abscess ACKNOWLEDGEMENTS in children. Craniofac. Surg., 2009, 20(4), 1178-1181. Neither author has any source of funding to disclose. [7] Coticchia, J.M.; Getnick, G.S.; Yun, R.D.; Arnold, J.E. Age-, site-, and time-specific differences in pediatric deep neck abscesses. Arch. Otolaryngol. Head Neck Surg., 2004, 130(2), 201-207. REFERENCES [8] Malloy, K.M.; Christenson, T.; Meyer, J.S.; Tai, S.; Deutsch, E.S.; Barth, P.C.; O'Reilly, R.C. Lack of association of CT findings and [1] Rouviere, H. Anatomy of the Human Lymphatic System. Tobias, surgical drainage in pediatric neck abscesses. Int. J. Pediatr. Oto- M.J., Trans.; Edward Brothers: Ann Arbor, MI, 1938. laryngol., 2008, 72(2), 235-239. [2] Shefelbine, S.E.; Mancuso, A.A.; Gajewski, B.J.; Ojiri, H.; [9] McClay, J.E.; Murray, A.D.; Booth, T. Intravenous antibiotic ther- Stringer, S.; Sedwick, J.D. Pediatric retropharyngeal lymphadeni- apy for deep neck abscesses defined by computed tomogra- tis: differentiation from retropharyngeal abscess and treatment im- phy. Arch. Otolaryngol. Head Neck Surg., 2003, 129(11), 1207- plications. Otolaryngol. Head Neck Surg., 2007, 136(2), 182-188. 1212. [3] Daya, H.; Lo, S.; Papsin, B.C.; Zachariasova, A.; Murray, H.; Pirie, J.; Laughlin, S.; Blaser, S. Retropharyngeal and parapharyngeal in-

Received: November 29, 2010 Revised: October 28, 2011 Accepted: December 08, 2011