Retropharyngeal abscess

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Vishal Devarkonda, M.B.B.S[2]

Overview

Retropharyngeal space is a deep space in neck extending from the base of skull to the posterior mediastinum. Microorganisms can be introduced into this space either through lymphatic or direct or traumatic spread leading to cellulitis. Cellulitis may progress to form phlegmon, which in-turn progress to form mature abscess. Most common causes of retropharyngeal abscess are polymicrobial infections, beta-hemolytic streptococcus, Streptococcus pyogenes (group A streptococcus [GAS]), Staphylococcus aureus (including methicillin-resistant S. aureus [[[Methicillin resistant staphylococcus aureus infections|MRSA]]]), and respiratory anaerobes. Retropharyngeal abscess commonly affects children, median age being 4 years for children. Common complications of retropharyngeal abscess are life-threatening descending necrotizing mediastinitis, sepsis, internal jugular vein thrombophlebitis, and mediastinitis. Patients with retropharyngeal abscess may present with pain in neck, fever, sore throat, and mass in neck . Diagnosis of retropharyngeal abscess is based on clinical presentation supported by radio-graphic imaging. Management predominantly consists of empiric intravenous antibiotics or combination of surgical drainage and intravenous antibiotics.

Historical Perspective

• The exact origins of the disease is not clearly known. The term abscess is derived from latin term abscessus(meaning: act of going away)
• In 1926, Guthrie described a case of retropharyngeal abscess in childhood.
• In 1946, Davidson described a case of retropharyngeal abscess in adults.

Classification

There is no established classification system for retropharyngeal abscess.

Pathophysiology

The pathophysiology of retropharyngeal abscess can be discussed in following headings:

Anatomy of retropharyngeal space

Retropharyngeal space is a deep space of neck extending from the base of skull to the posterior mediastinum. Space is bordered anteriorly by middle layer of deep cervical fascia(buccopharyngeal fascia), posteriorly by deep layer of deep cervical fascia, laterally by carotid sheath containing carotid artery and jugular vein.

By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See "Book" section below)Bartleby.com: Gray's Anatomy, Plate 994, Public Domain, https://commons.wikimedia.org/w/index.php?curid=566933

Transmission

Transmission of microorganisms into the retropharyngeal space could be through trauma or direct spread or lymphatic spread.

Mode of transmission of infection to retropharyngeal space
Lymphatic spread	Retropharyngeal space consists two pair of lymph nodes, which drains nasopharynx, adenoids, posterior para-nasal sinuses, middle ear, and eustachian tube. Draining lymph nodes may get inflamed/infected following an upper respiratory tract infection. Lymph node may undergo liquefaction necrosis, which my progress into retropharyngeal cellulitis, which left untreated can progress to abscess formation. However by age 4 years, these lymph nodes undergo spontaneous atrophy.
Direct spread/ Trauma	Adults In adults, retropharyngeal space can be contaminated by direct trauma(eg, penetrating foreign trauma, endoscopy, dental procedures) or extension of local infection such as odontogenic infection, ludwig's angina, osteomyelitis of cervical spine. Children In children, retropharyngeal space can be contaminated by direct trauma to oropharynx(swallowing a foreign body or running and falling with an object in mouth).

Immune response

Introduction of infections into retropharyngeal space either through lymphatic or direct or traumatic spread may lead to suppurative adenitis of retropharyngeal lymph nodes or cellulitis of retropharyngeal space. Cellulitis may progress to form phlegmon, which in-turn progress to form mature abscess.

Causes

Polymicrobial infection is often responsible for retropharyngeal abscess. The other organisms involved in causing retropharyngeal abscess include:

Most common causes

• Poly-microbial infections
• Beta-hemolytic streptococcus
• Streptococcus pyogenes (group A streptococcus [GAS])
• Staphylococcus aureus (including methicillin-resistant S. aureus [MRSA])
• Prevotella

• Veillonella

Less common causes

• Haemophilus Influenzae
• Haemophilus parainfluenzae
• Neisseria species
• Bacteroides
• Fusobacterium
• Salmonella
• Mycobacterium
• Bartonella henselae
• Porphyromonas species

Epidemiology and Demographics

There are no comprehensive studies studying the epidemiology and demographics of retropharyngeal abscess worldwide.

Incidence

In United states, incidence of retropharyngeal abscess in kids under age 20 years is 4.10 per 100,000 population for year 2012.

Case Fatality Rate

Case fatality rate for retropharyngeal abscess varies from study to study, it ranges from low of zero case fatalities(after reviewing the data from 1321 pediatric admissions with retropharyngeal abscess in year 2003) to high of 2.6% case fatalities(234 adults with deep space neck infections in adults).

Age

Retropharyngeal abscess commonly affects children, with median age being 4 years for children.

Gender

Retropharyngeal abscess is more commonly affects in males than in females. The gender ratio is approximately 1.63.

Race

In year 2015, a comprehensive study analysed 6233 patients admitted to US hospitals with retropharyngeal abscess from year 2003 to 2012 and reported that for year 2012, 49.5% of the admitted patients were white, 19.2% were black, 21.9 % were hispanic and 9.5% were other race.

Screening

There are no established screening guidelines to screen patients for retropharyngeal abscess.

Natural History, Complications, and Prognosis

Natural history

If left untreated or appropriate medial or surgical interventions are delayed, patients with retropharyngeal abscess may develop life threatening complications which include mediastinitis, sepsis and internal jugular vein thrombophlebitis.

Complications

Complications of retropharyngeal abscess include:

• Epidural abscess
• Mediastinitis
• Carotid artery aneurysm or erosion
• Internal jugular vein thrombophlebitis
• Septic pulmonary embolism
• Cranial nerve dysfunction (IX–XII)
• Cavernous sinus thrombosis
• Aspiration pneumonia
• Life-threatening descending necrotizing mediastinitis
• Sepsis

Prognosis

The prognosis of retropharyngeal abscess is good when detected early and appropriately treated. Relapse may occur in 1 to 5 percent of cases.

Differentiating retropharyngeal abscess from other diseases

Retropharyngeal abscess must be differentiated from other upper respiratory diseases and conditions that may cause throat pain and airway obstruction as shown in the table below:

Disease/Variable	Presentation	Causes	Physical exams findings	Age commonly affected	Imaging finding	Treatment
Peritonsillar abscess	Severe sore throat, otalgia fever, a "hot potato" or muffled voice, drooling, and trismus	Aerobic and anaerobic bacteria most common is Streptococcus pyogenes.	Contralateral deflection of the uvula, the tonsil is displaced inferiorly and medially, tender submandibular and anterior cervical lymph nodes, tonsillar hypertrophy with likely peritonsillar edema.	The highest occurrence is in adults between 20 to 40 years of age.	On ultrasound peritonsillar abscess appears as focal irregularly marginated hypoechoic area.	Ampicillin-sulbactam, Clindamycin, Vancomycin or Linezolid
Croup	Has cough and stridor but no drooling. Others are Hoarseness, Difficulty breathing, symptoms of the common cold, Runny nose, Fever	Parainfluenza virus	Suprasternal and intercostal indrawing, Inspiratory stridor, expiratory wheezing, Sternal wall retractions	Mainly 6 months and 3 years old rarely, adolescents and adults	Steeple sign on neck X-ray	Dexamethasone and nebulised epinephrine
Epiglottitis	Stridor and drooling but no cough. Other symptoms include difficulty breathing, fever, chills, difficulty swallowing, hoarseness of voice	H. influenza type b, beta-hemolytic streptococci, Staphylococcus aureus, fungi and viruses.	Cyanosis, Cervical lymphadenopathy, Inflamed epiglottis	Used to be mostly found in pediatric age group between 3 to 5 years, however, recent trend favors adults as most commonly affected individuals with a mean age of 44.94 years	Thumbprint sign on neck x-ray	Airway maintenance, parenteral Cefotaxime or Ceftriaxone in combination with Vancomycin. Adjuvant therapy includes corticosteroids and racemic Epinephrine.
Pharyngitis	Sore throat, pain on swallowing, fever, headache, abdominal pain, nausea and vomiting	Group A beta-hemolytic streptococcus.	Inflamed pharynx with or without exudate	Mostly in children and young adults, with 50% of cases identified between the ages of 5 to 24 years.	_	Antimicrobial therapy mainly penicillin-based and analgesics.
Tonsilitis	Sore throat, pain on swallowing, fever, headache, and cough	Most common cause is viral including adenovirus, rhinovirus, influenza, coronavirus, and respiratory syncytial virus. Second most common causes are bacterial; Group A streptococcal bacteria,	Fever, especially 100°F or higher.Erythema, edema and exudate of the tonsils, cervical lymphadenopathy, and Dysphonia.	Primarily affects children between 5 and 15 years old.	Intraoral or transcutaneous USG may show an abscess making CT scan unnecessary.	Antimicrobial therapy mainly penicillin-based and analgesics with tonsilectomy in selected cases.
Retropharyngeal abscess	Neck pain, stiff neck, torticollis, fever, malaise, stridor, and barking cough	Polymicrobial infection. Mostly; Streptococcus pyogenes, Staphylococcus aureus and respiratory anaerobes (example; Fusobacteria, Prevotella, and Veillonella species)	Child may be unable to open the mouth widely. May have enlarged cervical lymph nodes and neck mass.	Mostly between 2-4 years, but can occur in other age groups.	On CT scan, a mass impinging on the posterior pharyngeal wall with rim enhancement is seen	Immediate surgical drainage and antimicrobial therapy. emperic therapy involves; ampicillin-sulbactam or clindamycin.

Retropharyngeal abscess must be differentiated from other causes of dysphagia and fever.

Variable		Croup	Epiglottitis	Pharyngitis	Bacterial tracheitis	Tonsilitis	Retropharyngeal abscess	Subglottic stenosis
Presentation	Cough	✔	—	Sore throat, pain on swallowing, fever, headache, abdominal pain, nausea and vomiting	Barking cough, stridor, fever, chest pain, ear pain, difficulty breathing, headache, dizziness.	Sore throat, pain on swallowing, fever, headache, cough	Neck pain, stiff neck, torticollis fever, malaise, stridor, and barking cough	Depends on severity. May have respiratory distress at birth, exercise-induced dyspnea, intermittent wheezing. Inspiratory stridor.
	Stridor	✔	✔
	Drooling	—	✔
	Others are Hoarseness, Difficulty breathing, symptoms of the common cold, Runny nose, Fever		Other symptoms include difficulty breathing, fever, chills, difficulty swallowing, hoarseness of voice
Causes	Parainfluenza virus		H. influenza type b, beta-hemolytic streptococci, Staphylococcus aureus, fungi and viruses.	Group A beta-hemolytic streptococcus.	Staphylococcus aureus	Most common cause is viral including adenovirus, rhinovirus, influenza, coronavirus, and respiratory syncytial virus. Second most common causes are bacterial; Group A streptococcal bacteria,	Polymicrobial infection. Mostly; Streptococcus pyogenes, Staphylococcus aureus and respiratory anaerobes (example; Fusobacteria, Prevotella, and Veillonella species)	Congenital, trauma
Physical exams findings	Suprasternal and intercostal indrawing, Inspiratory stridor, expiratory wheezing, Sternal wall retractions		Cyanosis, Cervical lymphadenopathy, Inflammed epiglottis	Inflammed pharynx with or without exudate	Subglottic narrowing with purulent secretions in the trachea	Fever, especially 100°F or higher.Erythema, edema and Exudate of the tonsils. cervical lymphadenopathy, Dysphonia.	Child may be unable to open the mouth widely. May have enlarged cervical lymph nodes and neck mass.	Signs of respiratory distress, intermittent wheezing. Inspiratory stridor.
Age commonly affected	Mainly 6 months and 3 years old rarely, adolescents and adults		Used to be mostly found in pediatric age group between 3 to 5 years, however, recent trend favors adults as most commonly affected individuals with a mean age of 44.94 years.	Mostly in children and young adults, with 50% of cases identified between the ages of 5 to 24 years.	Mostly during the first six years of life	Primarily affects children between 5 and 15 years old.	Mostly between 2-4 years, but can occur in other age groups.	May be congenital congenital or acquired. Mean age in acquired is 54.1 years
Imaging finding	Steeple sign on neck X-ray		Thumbprint sign on neck x-ray	—	Lateral neck xray shows intraluminal membranes and tracheal wall irregularity.	Intraoral or transcutaneous USG may show an abscess making CT scan unnecessary.	On CT scan, a mass impinging on the posterior pharyngeal wall with rim enhancement is seen	Bronchoscopy reveals subglottic stenosis. Computed tomography may reveal a concentric stenotic tracheal segment.
Treatment	Dexamethasone and nebulised epinephrine		Airway maintenance, parenteral Cefotaxime or Ceftriaxone in combination with Vancomycin. Adjuvant therapy includes corticosteroids and racemic Epinephrine.	Antimicrobial therapy mainly penicillin-based and analgesics.	Airway maintenance and antibiotics	Antimicrobial therapy mainly penicillin-based and analgesics with tonsilectomy in selected cases.	Immediate surgical drainage and antimicrobial therapy. emperic therapy involves; ampicillin-sulbactam or clindamycin.	Endoscopic balloon dilation for patients with low-grade subglottic stenosis, glucocorticoid injections, and resection.

Diagnosis

Diagnosis is based on clinical presentation supported by radio-graphic imaging:

History and symptoms

Patients with retropharyngeal abscess may present with:

• Pain in neck
• Fever
• Sore throat
• Mass in neck
• Respiratory distress(stridor)
• Difficulty swallowing (dysphagia)
• Pain with swallowing (odynophagia)
• Unwillingness to move the neck(torticollis)
• Change in voice
• reduced opening of the jaws(Trismus)
• Chest pain

Physical examination

Role of physical examination in diagnosing retropharyngeal abscess is limited, as most of the patients aren't able to open the mouth widely.

Patients with suspected retropharyngeal abscess should be examined in a head-down position(trendelenburg) position. It is recommended to perform examination in an operation room as it permits to place an artificial airway, if necessary. A midline or unilateral swelling of the posterior pharyngeal wall may be appreciated.

Appearance of the Patient

• They are usually acutely-ill looking.

Vital Signs

• High temperature

HEENT

• Change in voice
• Trismus

Neck

• Tenderness of anterior neck
• Tender submandibular and anterior cervical lymph nodes
• Tender anterior cervical lymphadenopathy
• Palpable neck mass

Laboratory findings

Laboratory findings may show non-specific leukocytosis.

Imaging

Diagnosis of retropharyngeal abscess should be ultimately supported by radio-graphic imaging. In suspected patients, an initial lateral and anterio-posterior X-ray of neck should be ordered, which is usually followed with CT scan of the neck with IV contrast. CT scan not only helps in diagnosing the retropharyngeal abscess but also helps in identifying the position of carotid artery and internal jugular vein in relation to infectious process.

Plain X-ray

Lateral neck X ray demonstrate thickening of soft tissue with possible gas-fluid levels in pre-vertebral cervical space.

Pathological widening of retropharyngeal space should be considered, if it is greater than 22 mm at C6 in adults and 7 mm at C2 or 14 mm at C6 in children.

Other X ray findings include:

• Reversal of normal cervical lordosis
• Radiopaque foreign body
• Soft-tissue mass

By James Heilman, MD - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10379664

CT scan

Patients with retropharyngeal abscess, abscess may appear as

• Mass impinging on the posterior pharyngeal wall
• Complete rim enhancement with scalloping is indicative of an abscess
• Low density core, soft tissue swelling, obliterated fat planes are other common CT scan findings associated with retropharyngeal abscess

Retropharyngeal abscess CT-axial CT of the neck demonstrates an extensive multi-loculated collection located posterior and to the right of the pharynx. The oropharynx and hypopharynx are both distorted, narrowed and displaced anteriorly and towards the left. - Case courtesy of A.Prof Frank Gaillard, Radiopaedia.org, rID: 5344

Management

There are no comprehensive randomized controlled studies evaluating the management of retropharyngeal infections. Patients should be ideally hospitalized in a setting where intubation or tracheotomy are easily accessible, in case if there is any respiratory compromise. Management predominantly consists of empiric intravenous antibiotics or combination of surgical drainage and intravenous antibiotics. During hospitalization patient should be regularly monitored for airway patency, hydration status, and potential complications.

Management of retropharyngeal abscess in children and adults follows:

Children

Combination of surgical drainage and intravenous antibiotics

Widely accepted indications for surgical drainage of abscess include: airway compromise, or failure to response after 24-24 hrs administration of empiric anti microbial therapy, or CT scan showing large (>3 cm2) hypodense area(indicative of mature abscess) or life-threatening complications. Drainage fluid should be sent for culture and sensitivity, for choosing appropriate antibiotics for further management.

Medical therapy

Trail of antimicrobial therapy for initial 24 to 48 hours without surgical drainage should be considered in patients who do not have airway compromise, CT scan showing cross-sectional hypodense area between <2 to 3 cm2 and no life-threatening complications.

Empiric intravenous antibiotic include:

• Ampicillin-sulbactam (50 mg/kg 6 h IV) or Clindamycin (15 mg/kg per dose [maximum single dose 900 mg]every 8 h IV).
• In patients with moderate or severe disease who do not respond to empiric therapy, additional intravenous Vancomycin (40 to 60 mg/kg per day divided in three to four doses; maximum daily dose 2 to 4 g or Linezolid (<12 years: 30 mg/kg per day divided in three doses; ≥12 years: 20 mg/kg per day in two doses; maximum daily dose 1200 mg) should be considered to optimize the coverage against Gram-positive cocci.
• Once the patients is afebrile and shows signs of clinical improvement, a 14 day oral antimicrobial therapy with either Amoxicillin-clavulanate (45 mg/kg per dose 12 h oral) or Clindamycin (13 mg/kg 8 h oral) should be prescribed.
• Antimicrobial therapy should be adequately supplemented with analgesics, antipyretics and intravenous fluids.

Adults

Combination of surgical drainage and intravenous antibiotics

Widely accepted indications for surgical drainage of abscess include: airway compromise or failure to response after 24-24 hrs administration of empiric antimicrobial therapy or CT scan showing large volume abscess or life-threatening complication. Drainage fluid should be sent for culture and sensitivity, for choosing appropriate antibiotics for further management.

Medical therapy

Trail of antimicrobial therapy for initial 24 to 48 hours without surgical drainage should be considered in patients who do not have airway compromise, CT scan showing small volume abscess, and no life-threatening complications.

Antibiotics regimen coverage for deep neck space infections
Antibiotics regimen	Coverage rate (%)
Ceftriaxone, clindamycin	76.40%
Ceftriaxone, metronidazole	70.79%
Cefuroxime, clindamycin	61.80%
Penicillin G, metronidazole	16.85%
Penicillin, gentamicin, clindamycin	67.42%

Preferred medical therapies

Preferred regimen

Ampicillin-sulbactam 3 g/6h IV

Alternative regimens

• Penicillin G 2 to 4 MU/6h IV every four to six hours plus metronidazole  500 mg/6h IV OR
• Clindamycin  600 mg/6h IV OR
• Ceftriaxone 1 g/24 h plus metronidazole 500 mg/6 h IV OR
• Ciprofloxacin 400 mg/12 h IV plus clindamycin 600 mg/6h IV

In patients with moderate or severe disease or having MRSA risk factors(higher incidence of MRSA in hospital and community, IV drug abuse or co-morbid conditions like diabetes mellitus, living in crowed places) or who do not respond to empiric therapy, additional intravenous vancomycin (15 to 20 mg/kg/12 h IV) or linezolid (600 mg/12 h IV) should be considered to optimize the coverage against gram-positive cocci.

Antimicrobial therapy should be adequately supplemented with analgesics, antipyretics and intravenous fluids.

Duration

Once the patients is afebrile and shows signs of clinical improvement IV antibiotics can be replaced with oral antibiotics. Oral antibiotics should be continued for 2-3 weeks after discharge to prevent recurrence or complications.

Discharge instructions

Patients should be asked to report to the health care provider if they notice any new onset of enlarging mass, difficulty in breathing, worsening pain, fever and any stiffness in neck.

Prevention

Primary Prevention

There are no established primary preventive measures for preventing retropharyngeal abscess.

Secondary prevention

There are no established secondary prevention measures, but early detection and appropriate medical and surgical intervention can help in early recovery and prevention of complications.