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:

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).

Microbiology

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

• Beta-hemolytic streptococcus
• Streptococcus pyogenes (group A streptococcus [GAS])
• Staphylococcus aureus (including methicillin-resistant S. aureus [MRSA]),
• Fusobacteria
• Prevotella
• Veillonella
• Haemophilus Influenzae
• Neisseria species
• Bacteroides
• Fusoabcterium
• Salmonella

Infections in these areas may lead to suppurative adenitis of the retropharyngeal lymph nodes [1,2,5,6]. Retropharyngeal abscess is associated with antecedent upper respiratory tract infection in approximately one-half of cases [7].

In approximately one-fourth of cases (usually in older children or adults), retropharyngeal infection is secondary to pharyngeal trauma (eg, penetrating foreign body, endoscopy, intubation attempt, dental procedures) [1,5,7-11]. It also may occur in association with pharyngitis, vertebral body osteomyelitis, and petrositis.

Retropharyngeal infections progress from cellulitis to organized phlegmon to mature abscess [1]. Early institution of appropriate antimicrobial therapy may halt progression to mature abscess [12].

Immune response

Retropharyngeal infections progress from cellulitis to organized phlegmon to mature abscess [1]. Early institution of appropriate antimicrobial therapy may halt progression to mature abscess

Screening

There are no established guidelines to screen patient for

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