Deep neck infections

Deep neck infections include peritonsillar abscess (PTA), parapharyngeal abscess (PPA), and retropharyngeal abscess (RPA). PTA commonly occurs in adolescents or young adults as a complication of acute tonstillitis. Clinical features include fever, sore throat, dysphagia, a “hot-potato” voice, and trismus (lockjaw). Diagnosis is primarily based on examination of the pharynx, which demonstrates a characteristic fluctuant, enlarged tonsil and contralateral deviation of the uvula. Antibiotics and incision and drainage of the abscess are the mainstay of treatment. PPA and RPA are more common in children < 5 years of age, and typically occur secondary to dental infections or upper respiratory infections, respectively. PPA and RPA both present with nonspecific features of tonsillitis. In addition, PPA may lead to medial displacement of the lateral pharyngeal wall and tonsil, while RPA may lead to unilateral swelling of the posterior pharyngeal wall. The diagnosis of PPA is made with CT, while RPA is usually confirmed with either lateral x-ray, which shows widening of the prevertebral space, or CT if x-ray is non-diagnostic. In both PPA and RPA, IV empiric antibiotic therapy is routinely administered and surgery may be necessary in certain cases. 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.

Basic anatomy of the neck

• Two major fascial layers: superficial cervical and deep cervical fascia
• The deep cervical fascia is divided into 3 layers: investing, pretracheal and prevertebral layers.
  • The carotid sheath consists of fascia from all three deep layers and surrounds the common carotid artery, internal jugular vein, and vagus nerve.
• Deep neck spaces are spaces between these deep layers.
  • The retropharyngeal space communicates laterally with the parapharyngeal space and may drain into the prevertebral space.
  • The danger space extends from the skull base to the posterior mediastinum and is posterior to the retropharyngeal space.

Overview of deep neck infections

References:^[1][2][3]

• Epidemiology
  • Most common deep neck infection
  • Most common in adolescents and young adults
• Etiology
  • 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
  • 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 cervical lymphadenopathy (and neck swelling)
• Diagnosis
  • Usually a clinical diagnosis
  • Gram stain and culture of aspirated abscess fluid, and throat culture to identify causative pathogen
  • Contrast-enhanced CT if there is a clinical suspicion of other diagnoses or complications
• Treatment
  • Airway management is always the first step!
  • IV antibiotics with good gram-positive and anaerobic coverage: empiric clindamycin or ampicillin-sulbactam .
  • Incision and drainage or needle aspiration (surgical drainage): risk of airway obstruction, complications, or immunodeficiency.
  • Tonsillectomy indicated if:
    • Unresponsive to drainage and antibiotics
    • Recurrent tonsillitis or peritonsillar abscess, or other complications occur
    • Airway obstruction is present
• Complications
  • 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

References:^{[3][4][5][6][7][8][9][10][11]}

• Epidemiology
  • Most common in children < 5 years of age
  • ♂ > ♀
• Etiology
  • 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 into the parapharyngeal space
    • Pharyngeal or salivary gland infections
• Clinical features
  • 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
• Diagnosis
  • Gram stain and culture of aspirated abscess fluid, and throat culture to identify causative pathogen
  • CT
    • Confirms diagnosis
    • Determines extent of infection
    • Enables CT-guided abscess aspiration, or drainage
• Treatment
  • Airway management is always the first step!
  • IV broad-spectrum antibiotics: ampicillin-sulbactam, penicillin G or ceftriaxone plus metronidazole, or clindamycin.
  • Surgical drainage
• Complications
  • 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!

References:^{[1][3][6][12][13][14][15]}

• Epidemiology
  • Generally the most dangerous deep neck infection
  • Most common in children < 5 years of age
  • ♂ > ♀
  • Overall incidence in the U.S. has increased.
• Etiology
  • 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
  • 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.
• Diagnosis
  • Contrast-enhanced CT: shows hypodense lesion in retropharyngeal space, soft-tissue swelling, peripheral ring enhancement, mass effect
    • Initial step if in no signs of respiratory compromise
    • Confirms diagnosis in patients with a suspicion of RPA and with a negative x-ray
    • Determine extent of infection to other spaces and presence of foreign bodies
    • Differentiate between cellulitis and abscess
  • Gram stain and culture of aspirated abscess fluid and blood to identify causative pathogen
  • Lateral neck x-ray: shows a widened prevertebral (soft tissue) space (gas in the retropharyngeal space and lordosis) ^[16]
• Differential diagnosis
  • Other deep neck infections
  • Trauma
  • Other causes of neck swelling or respiratory distress: anaphylaxis or angioedema, retropharyngeal tumors
  • Other causes of neck stiffness: meningitis, cervical spine osteomyelitis, dystonia
• Treatment
  • Airway management is always the first step if the patient has signs of respiratory distress
  • Hospitalization for all children and any patient with respiratory compromise
  • IV broad-spectrum antibiotics: empiric options include ampicillin-sulbactam or clindamycin.
  • Needle aspiration or incision and drainage of abscess (surgical drainage) should be performed immediately in patients with a compromised airway or other life-threatening complications
• Complications
  • Airway obstruction
  • Spread of infection to carotid sheath; (internal carotid artery erosion, jugular vein thrombophlebitis) and then mediastinum (acute necrotizing mediastinitis with widened mediastinum on chest x-ray )
  • Infection can spread and enter the skull base (epidural abscess) or the posterior mediastinum (pericarditis).
  • Aspiration pneumonia
  • Atlantoaxial dislocation
  • Bacteremia and sepsis

In patients with airway compromise, airway management should be performed before any other diagnostic or treatment measures!

References:^{[3][13][17][18][19][20][21][22][23]}

• There are no currently established guidelines available for the optimal empiric therapy for deep neck infections. ^[24]
• Empiric coverage should cover the gram-positive (e.g., Staphylococcus aureus, Streptococcus spp., viridans streptococci), gram-negative (Haemophilus influenzae), and anaerobic (e.g., Porphyromonas, Fusobacterium, Prevotella, Bacteroides, and Peptostreptococcus spp.) bacteria most commonly found in the oropharyngeal and odontogenic spaces.
• An individualized approach should take the following into account:
  • Local bacterial resistance patterns
  • Suspected focus of infection
  • Prior antibiotic treatment
  • Severity of the infection
• Possible regimens (for adults)
  • Amoxicillin-clavulanic acid PLUS metronidazole ^[25]
  • Ceftriaxone PLUS clindamycin ^[26]
  • Ceftriaxone PLUS metronidazole ^[26]
  • Cefuroxime PLUS clindamycin ^[27]
  • Penicillin G PLUS clindamycin PLUS gentamicin ^[26]
  • Piperacillin-tazobactam ^[24]
  • Meropenem ^[24]
  • Imipenem/cilastatin ^[24]
• If MRSA infection is suspected or the patient is immunosuppressed, consider the addition of one of the following: ^[24]
  • Vancomycin
  • Linezolid

• Secure airway
  • Anesthesia and/or ENT consult
  • Prepare for difficult airway
  • Consider steroids (e.g., dexamethasone ) if airway edema is present
  • Consider nebulized racemic epinephrine in patients with respiratory distress ^[28]
• IV access and obtain blood cultures (2 sets)
• Consider rapid test for group A streptococcus (for peritonsillar abscess).
• Start broad-spectrum antibiotics (see empiric antibiotic therapy for deep neck infections).
• ENT consultation to evaluate the need for ultrasound-guided needle aspiration, surgical drainage, or tonsillectomy.
• Dental consultation for evaluation of teeth as a potential source of infection
• Antipyretic therapy
• Pain management
• Continuous pulse oximetry
• Consider ICU admission for airway monitoring.

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