• Clinical science

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

Overview of deep neck infections

Peritonsillar Abscess Parapharyngeal Abscess Retropharyngeal Abscess
  • Adolescents and young adults
  • Most common deep neck infection
  • Children < 5 years of age
  • Children < 5 years of age
  • Contiguous or lymphatic spread from upper respiratory tract infections (most common) or other nearby infections
  • Local penetrating pharyngeal trauma
Clinical Features
  • Features of tonsillitis
  • “Hot potato” voice
  • Trismus
  • Uvula shifted to the contralateral side
  • Inflamed ipsilateral tonsil: fluctuant, swollen, erythematous with exudates (ipsilateral bulging of the palatine arch)
  • Features of tonsillitis
  • Sometimes trismus
  • Medial displacement of the lateral pharyngeal wall and tonsil (posterior space abscess) or indurated swelling below the angle of the mandible down to the hyoid bone (anterior space abscess)
  • Features of tonsillitis
  • Sometimes trismus
  • Unilateral swelling of the posterior pharyngeal wall (possible fluctuance)
  • Neck asymmetry, with neck swelling and anterior cervical lymphadenopathy(→ inability to extend neck)
  • Clinical diagnosis
  • CT
  • Lateral x-ray: widened prevertebral (soft tissue) space
  • CT


Peritonsillar abscess


Parapharyngeal abscess

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


Retropharyngeal abscess

  • 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
  • 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

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