Deep neck infections

Deep neck infections include peritonsillar abscess, parapharyngeal abscess (PPA), and retropharyngeal abscess (RPA). While uncommon, deep neck infections are clinically significant because of their potentially life-threatening complications, including the spread of infection to vital nearby structures and airway compromise. Early recognition, broad-spectrum IV antibiotic therapy, aggressive airway management, and urgent ENT consultation reduce the risk of complications and death from sepsis or airway compromise.

Epidemiology ^[3]

• Most frequently occurs in adults aged 20–40 years
• The most common deep neck infection
• Increased risk of airway obstruction in children with peritonsillar abscess

Etiology ^[4][5]

• Pathogens: Streptococcus pyogenes (most common), Streptococcus anginosus, viridans streptococci, Staphylococcus aureus, and Haemophilus species, often in a polymicrobial environment
• Acute bacterial tonsillitis (see acute tonsillitis)

Clinical features ^[5][6]

• Features of tonsillitis: fever, malaise, severe sore throat, dysphagia, and odynophagia
• “Hot potato” voice (muffled speech), drooling, or halitosis
• Trismus
• Uvula shifted to the contralateral side, with inferior and medial displacement of tonsil
• Unilateral fluctuant, swollen, erythematous tonsil with exudates (ipsilateral bulging of the palatine arch)
• Ipsilateral ear pain
• Ipsilateral cervical lymphadenopathy (and neck swelling)

Diagnostics ^[3][7]

Diagnosis is usually clinical. Obtain imaging if there is diagnostic uncertainty or concern for complications.

Microbiological studies

• Bacterial culture of abscess aspirate can help to direct therapy for the causative pathogen.
• Obtain a rapid group A streptococcus antigen detection test. ^[8]
• Consider a monospot test to rule out infectious mononucleosis.

Evidence of pus on needle aspiration confirms the diagnosis.

Imaging ^[3]

• Ultrasound neck (intraoral or transcutaneous) ^[9]
  • Indication: diagnostic uncertainty
  • Findings: irregular hypoechoic cavity with a defined circumference
• CT or MRI neck with IV contrast ^[10]
  • Indication: clinical suspicion of other diagnoses or complications
  • Findings
    • Fluid collection adjacent to tonsil with rim enhancement
    • Uvula deviation
    • May show extension of abscess beyond the peritonsillar space ^[3]
    • May show complications (e.g., internal jugular thrombosis, carotid sheath abscess erosion)

Treatment ^[3][7]

• Patients with respiratory distress: prompt airway management
• Systemic antibiotics (IV or oral) with abscess drainage are the mainstay of therapy.
• Consult ENT and/or oral maxillofacial surgery for consideration of abscess drainage.
• Provide supportive care (e.g., pain management, antipyretic therapy, IV fluid therapy)
• Consider corticosteroids (e.g., dexamethasone ) to reduce inflammation. ^[3][11]

Antibiotic therapy ^[3]

• Start empiric antibiotic therapy for deep neck infections.
  • Target coverage for aerobes (e.g., Streptococcus spp.) and anaerobes.
  • E.g., clindamycin; or ampicillin/sulbactam ) ^[3]
• Tailor to culture and sensitivity results.
• Duration: 10–14 days

Abscess drainage ^[3]

• Indication: most patients (unless the abscess is < 1 cm and there is no drooling, trismus, or muffled voice)
• Method
  • Preferred: incision and drainage or needle aspiration
  • Tonsillectomy: Consider for abscesses unresponsive to drainage and antibiotics or if complications occur.

Complications ^[12][13]

• Can become life-threatening due to airway compromise
• Further spread of infection into the parapharyngeal space (PPA), retropharyngeal space (RPA), mediastinum (mediastinitis), or fascia (necrotizing fasciitis)
• Aspiration pneumonia
• Internal jugular vein thrombosis or thrombophlebitis
• Bacteremia and sepsis

Disposition ^[11][14]

• Outpatient management may be appropriate, unless there are risks for complications or previous outpatient therapy was unsuccessful

Epidemiology ^[15]

• Most common in children < 5 years of age
• ♂ > ♀

Etiology ^[4]

• Pathogens: streptococci (viridans streptococci, S. pneumoniae), staphylococci (including MRSA), Haemophilus influenzae, oral anaerobes (peptostreptococci, Bacteroides species), often in a polymicrobial environment
• Oropharyngeal infections
  • Dental infections (most commonly)
  • Acute tonsillitis
  • Peritonsillar abscess through the superior constrictor muscle into the parapharyngeal space
  • Pharyngeal or salivary gland infections

Clinical features ^[16]

• Features of peritonsillar abscess, especially trismus
• Posterior space abscess: medial displacement of the lateral pharyngeal wall and tonsil
• Anterior space abscess: indurated swelling below the angle of the mandible down to the hyoid bone
• Respiratory distress: dyspnea, stridor
• Limited cervical neck extension

Diagnostics ^[2][11]

• Imaging: required for diagnostic confirmation ^[17]
  • CT neck with IV contrast (preferred) may show: ^[17][18]
    • Hypodense collection with rim enhancement in the lateral pharyngeal space
    • Single or multiloculated lesion with central fluid and/or air
  • MRI neck ^[2]
    • Indication: concern for complications
    • Findings: similar to CT but with better visualization of soft tissue (e.g., for cellulitis) ^[11]
• Microbiological studies (e.g., bacterial culture of abscess aspirate): can help to direct therapy for the causative pathogen

Treatment ^[18][19]

Systemic IV antibiotics with abscess drainage and supportive care are the mainstays of therapy.

• Patients with respiratory distress: prompt airway management
• Start empiric IV broad-spectrum antibiotics: see “Empiric antibiotic therapy for deep neck infections” for more detail and dosing.
• Switch to targeted antibiotics based on culture and sensitivity results.
• Most patients require surgical drainage or image-guided drainage: Consult ENT and/or oral maxillofacial surgery.
• Provide supportive care (e.g., pain management, antipyretic therapy, IV fluid therapy)
• Consider corticosteroids (e.g., dexamethasone ) to reduce inflammation. ^[3][11]
• Consult dentistry for abscesses with an odontogenic source for possible removal of the infected tooth.
• Patients should be managed as inpatients.

Conservative treatment with IV antibiotics alone may be considered in select patients (e.g., clinically stable patients with a small abscess).

Complications ^[4]

• Airway obstruction
• Spread of infection to retropharyngeal space, carotid sheath (presents with torticollis) and then mediastinum (internal carotid artery erosion jugular vein thrombophlebitis, and mediastinitis), or cranial nerves (Horner syndrome, hoarseness, unilateral paresis of the tongue, and other neurologic deficits)
• Aspiration pneumonia with spontaneous pus drainage
• Bacteremia and sepsis

Parapharyngeal infections can become life-threatening because of their proximity to the retropharyngeal space, carotid sheath, and airway!

Epidemiology ^[15][20]

• Generally the most dangerous deep neck infection
• Most common in children < 5 years of age
• ♂ > ♀
• Overall incidence in the U.S. has increased.

Etiology ^[21]

• Pathogen: streptococci (viridans streptococci, S. pneumoniae), staphylococci (including MRSA), Haemophilus influenzae, oral anaerobes (peptostreptococci, Bacteroides species), often in a polymicrobial environment
• Direct or indirect causes
  • Contiguous or lymphatic spread from oral (most common) or upper respiratory tract infections
  • Local penetrating pharyngeal trauma; (e.g., from small bones such as of fish or chicken, or medical instruments)
  • Spread from other deep neck infections (nasopharynx, sinuses, adenoids)

Clinical features ^[22]

• Features of tonsillitis and trismus (minimal)
• Neck asymmetry with unilateral swelling of the posterior pharyngeal wall; (possible fluctuance) → inability to extend neck
• Torticollis
• Anterior cervical lymphadenopathy
• Respiratory distress
• Infants may also present with lethargy, cough, poor intake, rhinorrhea, and agitation.

Diagnostics ^[23]

Imaging is required for diagnostic confirmation. Microbiological studies can help identify the causative pathogen.

• CT neck with IV contrast (preferred study) ^[17]
  • Indication: suspicion of RPA with a negative x-ray
  • Findings ^[24]
    • Hypodense fluid collection with ring enhancement in the retropharyngeal space
    • Posterior pharynx wall with anterior displacement
    • May detect spread of infection to other spaces and the presence of foreign bodies
    • Differentiates between cellulitis and abscess
• Lateral x-ray neck ^[24][25]
  • Indication: initial screening study in patients with airway compromise or if there is a low level of suspicion for RPA
  • Findings
    • Widened prevertebral (soft tissue) space with gas or air-fluid levels
    • Lordosis
    • Evidence of foreign body, if present
• MRI neck ^[2][11]
  • Indication: contraindication to CT
  • Findings are similar to CT with improved detection of:
    • Soft tissue changes (e.g., necrosis)
    • Complications (e.g., extension of abscess to prevertebral space)
• Microbiological studies (e.g., bacterial culture of abscess aspirate): can help to direct therapy for the causative pathogen

Treatment ^[11][14][23]

Systemic IV antibiotics with abscess drainage and supportive care are the mainstays of therapy.

• Patients with respiratory distress: prompt airway management
• Start broad-spectrum empiric antibiotics (e.g., clindamycin; or ampicillin/sulbactam ): See “Empiric antibiotic therapy for deep neck infections.”
• Switch to targeted antibiotics based on culture and sensitivity results. ^[23]
• Adult patients usually require needle aspiration or surgical drainage: Consult ENT and/or maxillofacial surgery. ^[11][23][26]
• Consult dentistry for abscesses with an odontogenic source for possible removal of the infected tooth.
• Provide supportive care (e.g., pain management, antipyretic therapy, IV fluid therapy)
• Consider corticosteroids (e.g., dexamethasone ) to reduce inflammation. ^[3][11]
• Patients should be managed as inpatients.

Airway management is always the first step if the patient has signs of respiratory distress.

Complications ^[27]

• Airway obstruction
• Spread of infection to carotid sheath including internal carotid artery erosion and jugular vein thrombophlebitis (Lemierre syndrome)
• Descending mediastinitis (acute necrotizing mediastinitis); . May be visible on chest x-ray as a widened mediastinum +/- bilateral pleural effusions
• Infection can spread and enter the skull base (epidural abscess) or the posterior mediastinum (pericarditis).
• Aspiration pneumonia
• Atlantoaxial dislocation
• Bacteremia and sepsis

• Throat pain
  • Tonsillitis
  • Pharyngitis
  • Epiglottitis
• Painful neck mass ^[28]
  • Cervical adenitis
  • Cat-scratch disease
  • Acute purulent sialadenitis
• Neck swelling or respiratory distress
  • Anaphylaxis or angioedema
  • Retropharyngeal tumors
• Neck stiffness
  • Meningitis
  • Cervical spine osteomyelitis
  • Dystonia

The differential diagnoses listed here are not exhaustive.

General principles

• Infections are typically polymicrobial.
• There are currently no guidelines on optimal empiric therapy for deep neck infections; Follow local protocols and consider early specialist consultation. ^[3][29]
• Switch to targeted antibiotics once culture and sensitivity results are available.

Most common pathogens ^[29]

• Gram-positive: e.g., Staphylococcus aureus, Streptococcus spp., viridans streptococci
• Gram-negative: e.g., Haemophilus influenzae
• Anaerobic: e.g., Porphyromonas, Fusobacterium, Prevotella, Bacteroides, and Peptostreptococcus spp.

Example regimens (for adults) ^[3]

• Immunocompetent patients
  • Amoxicillin/clavulanic acid ^[3]
  • Ampicillin/sulbactam ^[3]
  • Ceftriaxone PLUS metronidazole ^[3]
  • Penicillin allergy: clindamycin
• Suspected MRSA infection ^[3]
  • Vancomycin OR linezolid
  • PLUS metronidazole
• Severe disease, concern for MDRO, and/or immunocompromised patients ^[3][29]
  • Vancomycin
  • PLUS piperacillin/tazobactam OR meropenem

Empiric antibiotic therapy should be tailored to local antibiograms, suspected focus of infection, prior antibiotics, and disease severity.

• Secure airway: See “Airway management.”
• Secure IV access and obtain blood cultures (2 sets).
• Start empiric antibiotic therapy for deep neck infections
• Obtain imaging if diagnosis is uncertain or to help plan surgical intervention.
• Consult ENT and/or maxillofacial surgery to evaluate the need for ultrasound-guided needle aspiration, surgical drainage, or tonsillectomy.
• Consult dentistry for evaluation of teeth as a potential source of infection.
• Antipyretic therapy
• Pain management
• Continuous pulse oximetry
• Consider ICU admission for airway monitoring.