Sandbox:Retropharyngeal abscess

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

Synonyms and keywords:

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 retrophayngeal abscess in adults.

Classification

There is no established classification system for retropharyngeal abscess. hsiukhiwusn

Pathophysiology

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

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

Transmission

Transmission of the infection to the retropharyngeal space could be by trauma, lymphatic spread or by direct spread.

Mode of transmission of infection to retropharyngeal space
Lymphatic spread	Retropharyngeal space consists two pair of lymphnodes, which drains nasopharynx, adenoids, posterior paranasal sinuses, middle ear, and eustachian tube. Draining infected can be infected following the upper respiratory tract infection. Lymphnode may undergo liquefaction necrosis, which my progress into retropharyngeal cellulitis, which left intreated can progress to abcess formation. However by age 4 years, these lymph node undergo spontaneous atrophy.
Direct spread/ Trauma	Adults In adults, retropahryngeal 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, or osteomyelitis of cervical spine Children In children, retropahryngeal space can be contaminated by direct trauma( to oropharynx(swallowing a foreign body or running and falling with an object in the mouth).

Immune response

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

Causes

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

Most common causes

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

• Veillonella

Less common causes

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

Epidemiology and Demographics

United States

The incidence of pediatric RPA in the United States more than doubled in the first decade of the 21^st century, according to a study of pediatric deep space neck infections. Deriving their statistics from the Kids’ Inpatient Database (KID), Novis et al found that between 2000 and 2009, the incidence of RPA increased from 0.1 cases per 10,000 to 0.22 cases per 10,000. They also found no significant change in the incidence of either peritonsillar or parapharyngeal abscess in those years. ^{null 1}

A study by Woods et al, also using the KID, reported the incidence of RPA to have risen, among children under age 20 years, from 2.98 per 100,000 population in 2003 to 4.10 per 100,000 population in 2012. ^{null 2}

A review of cases of RPA over an 11-year period at the Children's Hospital of Michigan revealed a 4.5-times increase in the incidence of RPA when compared with the previous 12 years. ^{null 3} A later review at the same hospital revealed that the incidence increased 2.8-fold between 2004 and 2010, compared with the incidence from 1993-2003. ^{null 4}

Similarly, an 11-year chart review of 162 pediatric patients with RPA at St. Louis Children's Hospital revealed that the number of RPA cases in children increased significantly from 1995 to 2006. ^{null 5}

International

A review of deep neck infections (DNI) in children over a 12-year period at a medical center in Taiwan revealed 50 children with DNI. Nine children had DNI in the retropharyngeal space, 17 in the parapharyngeal space, 21 in the peritonsillar region, and 3 were mixed. ^{null 6}

Another study from Taiwan, by Huang et al, found that out of 52 children with DNI, the retropharyngeal space was the third most common site of infection (7 patients), after the parapharyngeal space (22 patients) and the submandibular space (12 patients). ^{null 7}

A review of RPAs and parapharyngeal abscesses (PPAs) in children presenting to 2 pediatric tertiary care medical centers in Israel over an 11-year period revealed 39 children with RPA or PPA. The incidence increased during the course of the study.^{null 8}

A retrospective analysis of children diagnosed with RPA and PPA over a 9-year period in a tertiary care medical center in Spain revealed 17 children with RPA, 11 with PPA, and 3 with both. ^{null 9}

A study by Yap et al found that in Wales, hospital admissions for RPA, as well as for tonsillitis, PPA, and peritonsillar abscess, rose between 1999 and 2014. ^{null 10}

Mortality/Morbidity

Once mediastinitis occurs, mortality approaches 50%, even with antibiotic therapy. Retropharyngeal abscess can also cause internal jugular vein thrombosis, carotid artery erosion, pericarditis, and epidural abscess. In addition to invasion of contiguous structures, retropharyngeal abscess can cause sepsis and airway compromise.

Overall mortality rate was 1% in a review of deep cervical space infections in Taiwan. ^{null 11}

In a study of 234 adults with deep space infections of the neck in Germany, the mortality rate was 2.6%. The cause of death was primarily sepsis with multiorgan failure. ^{null 12}

In the United States, in 2003, a review of the Kids' Inpatient Database (KID) revealed 1321 pediatric admissions with RPA, with no fatalities. ^{null 13}

A case series from Children's National Medical Center in Washington DC presents 4 children of ages ranging from 8 months to 18 months with RPA who developed mediastinitis. All 4 were treated aggressively with antibiotics and surgical drainage of RPA, and 3 patients required thoracoscopic debridement. All 4 children survived without sequelae. ^{null 14}

Race

See the list below:

• In a 10-year review of retropharyngeal abscess cases treated at Kings County Hospital in Brooklyn, New York, 70% of patients were African American, 25% were white, and 5% were Hispanic.
• A study of pediatric patients with retropharyngeal abscess at Wayne State University in Detroit revealed 43% of cases occurred in blacks, 54% in whites, 1% in Hispanics, and 1% in biracial. ^{null 15}
• In the United States, in 2003, a review of the Kids' Inpatient Database (KID) revealed 1321 pediatric admissions with retropharyngeal abscess, of which 37.4% were white, 11.7% were African American, 11.1% were Hispanic, 2% were Asian, 3.8% were other races, and the race was not recorded in the rest of the patients. ^{null 13}

Sex

Retropharyngeal abscess is more common in males than in females, with generally reported male preponderance of 53-55%.

• Children's Hospital of Michigan reports 54% of cases of RPA in males in a 2012 study. ^{null 4}
• A study of children with retropharyngeal abscess in Toronto reported 67% of cases in males.
• A study of retropharyngeal abscess in children in Detroit found 56% of cases in males. ^{null 15}
• A study of adults with deep space infections of the neck in Germany revealed that 56% of patients were male and 44% were female. ^{null 12}
• A study of cases in Nigeria found a male-to-female ratio of 1:1. ^{null 16}
• In the United States, in 2003, a review of the Kids' Inpatient Database (KID) revealed 1321 pediatric admissions with retropharyngeal abscess, of which 63% were male. ^{null 13}

Age

Initially, retropharyngeal abscess was thought to be a disease limited to children, but now it is being encountered with increasing frequency in adults.

• A review of adults with deep space infections of the neck in Germany revealed a mean age (±standard deviation) of 44.5 (±21.8) years.
• A review of retropharyngeal abscess cases at the Hospital for Sick Children in Toronto revealed that 66% of pediatric cases occurred in children younger than 6 years.
• A review of 30 cases of retropharyngeal abscess over an 11-year period in Nigeria found the median age to be 21 months, and 77% of patients were younger than 5 years. Eighty-three percent of retropharyngeal abscesses occurred in children, and 17% occurred in adults. ^{null 16}
• A 10-year review at Kings County Hospital in Brooklyn, New York, revealed that 30% of the cases were in pediatric patients aged 16 months to 8 years and 70% were in adults aged 21-64 years.
• A 35-year review of cases involving children who were treated for retropharyngeal abscess at the Children's Hospital of Los Angeles revealed that 50% of patients were younger than 3 years and 71% were younger than 6 years.
• A review or retropharyngeal abscess in children in Detroit found a mean age of 4.1 years, with a range from 2 months to 18 years.
• A review in Sydney, Australia, found that, in 55% of pediatric cases of retropharyngeal abscess, the children were younger than 1 year, with 10% diagnosed in the neonatal period.
• A review of RPA cases in children in Albuquerque revealed a median age of 36 months, with 75% of patients younger than 5 years and 16% of patients younger than 1 year. ^{null 17}
• In the United States, in 2003, a review of the Kids' Inpatient Database (KID) revealed 1321 pediatric admissions with retropharyngeal abscess, with an average age of 5.1 years (SD, 4.4). ^{null 13}
• An 11-year chart review of 162 pediatric patients with retropharyngeal abscess at St. Louis Children's Hospital revealed an average age of 4.9 years (range, 6 d to 17 y). ^{null 5}
• A 5-year review of 11 children with parapharyngeal abscess in Portugal revealed an average age of 3.3 years (range, 0-12 y). ^{null 18}
• A 12-year retrospective review of 50 pediatric patients with deep neck infections in Taipei revealed that all of the retropharyngeal abscesses occurred in children younger than 10 years. ^{null 6}

Screening

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

Natural History, Complications, and Prognosis

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

Diagnosis

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 the retro pharyngeal 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 operation room as it permits to place an aritifical airway if necessary. A midline or unilateral swelling of the posterior pharyngeal wall can be appreciated.

Other physical examination findings include

• 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 radiographic 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 the infectious process.

Plain X-ray

Lateral neck X ray demonstrate thickening of soft tissue with possible gas-fluid levels in the 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 the normal cervical lordosis
• Radiopaque foreign body
• Soft-tissue mass

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 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.

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 easily accessible in case if there is a 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 for potential complications.

Combination of surgical drainage and intravenous antibiotics

Widely accepted indications for surgical drainage include: airway compromise, or failure to response after 24-24 hrs of administration of empiric anti microbial therapy, or CT scan showing large (>3 cm2)hypodense area(Indicative of mature abscess) or life-threatening complication.

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 per dose every six hours intravenously), or Clindamycin (15 mg/kg per dose [maximum single dose 900 mg]every eight hours intravenously). 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 converage againist 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 every 12 hours), or Clindamycin (13 mg/kg per dose every 8 hours) should be prescribed. Antimicrobial therapy should be adequately supplemented with analgesics, antipyretics and intravenous fluids.

Discharge instructions

Patients should be asked to report to the health care provider if the 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.