Retropharyngeal Abscess

  • Etiology: pharyngitis or upper respiratory infection -> retropharyngeal adenitis -> abscess, bacterial
  • Imaging: normal prevertebral space is < 1/2 vertebral body at C2, soft tissue thickening of > 1 cervical vertebral body, to diagnose retropharyngeal mass need inspiratory image taken in extension, measurements less important than whether retropharynx changes with respiration
  • DDX: physiological tracheal buckling which can be seen on lateral neck images obtained on expiration + flexion – so beware of false positives due to expiration / flexion – airway radiograph should always be taken in inspiration + extension
  • Complications: airway compression, arteritis, jugular vein occlusion (Lemierre syndrome), atlanto-axial rotatory subluxation, extension into mediastinum
  • Clinical: seen in infancy and young children – 6 months to 6 years (older children + adults have peritonsillar + parapharyngeal abscess), 50% cases between 6-12 months, fever / stiff neck / dysphagia / stridor

Cases of Retropharyngeal Abscess

Radiograph of retropharyngeal abscess
Lateral radiograph of the airway taken in inspiration and extension shows massive thickening of the prevertebral soft tissues.
CT of atlanto-axial rotatory subluxation due to retropharyngeal abscess
Axial images with bone windows from a CT with contrast of the neck shows the C1 vertebral body (above left) rotated approximately 30 degrees to the right in relation to the C2 vertebral body (above right). Axial image with soft tissue windows (below) from the same CT shows a low density fluid collection with an enhancing rim to the left of midline in the retropharyngeal space.