Retropharyngeal Abscess, Lateral Pharyngeal (Parapharyngeal) Abscess, and Peritonsillar Cellulitis/Abscess

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Chapter 374 Retropharyngeal Abscess, Lateral Pharyngeal (Parapharyngeal) Abscess, and Peritonsillar Cellulitis/Abscess

Diane E. Pappas, J. Owen Hendley

The neck contains deeply located lymph nodes including retropharyngeal nodes and lateral pharyngeal nodes that drain the mucosal surfaces of the upper airway and digestive tracts. These nodes lie within the retropharyngeal space (located between the pharynx and the cervical vertebrae and extending down into the superior mediastinum) and the lateral pharyngeal space (bounded by the pharynx medially, the carotid sheath posteriorly, and the muscles of the styloid process laterally), which are interconnected. The lymph nodes in these deep neck spaces communicate with each other, allowing bacteria from either cellulitis or node abscess to spread to other nodes. Infection of the nodes usually occurs as a result of extension from a localized infection of the oropharynx. Retropharyngeal abscess can also result from penetrating trauma to the oropharynx, dental infection, and vertebral osteomyelitis. Once infected, the nodes may progress through three stages: cellulitis, phlegmon, and abscess. Infection in the retropharyngeal and lateral pharyngeal spaces can result in airway compromise or posterior mediastinitis, making timely diagnosis important.

Retropharyngeal and Lateral Pharyngeal Abscess

Retropharyngeal abscess occurs most commonly in children <3-4 yr of age, with boys affected more often than girls. Up to 67% of patients have a history of recent ear, nose, or throat infection. The retropharyngeal nodes involute after 5 yr of age and, therefore, infection in older children and adults is much less common.

Clinical manifestations of retropharyngeal abscess are nonspecific and include fever, irritability, decreased oral intake, and drooling. Neck stiffness, torticollis, and refusal to move the neck may also be present. The verbal child might complain of sore throat and neck pain. Other signs can include muffled voice, stridor, respiratory distress, or even obstructive sleep apnea. Physical examination can reveal bulging of the posterior pharyngeal wall, although this is present in <50% of infants with retropharyngeal abscess. Cervical lymphadenopathy may also be present. Lateral pharyngeal abscess commonly presents as fever, dysphagia, and a prominent bulge of the lateral pharyngeal wall, sometimes with medial displacement of the tonsil.

The differential diagnosis includes acute epiglottitis and foreign body aspiration. In the young child with limited neck mobility, meningitis must also be considered. Other possibilities include lymphoma, hematoma, and vertebral osteomyelitis.

Incision for drainage and culture of an abscessed node provides the definitive diagnosis, but CT can be useful in identifying the presence of a retropharyngeal, lateral pharyngeal, or parapharyngeal abscess (Figs. 374-1 and 374-2). With CT scans, deep neck infections can be accurately identified and localized, but CT accurately identifies abscess formation in only 63% of patients. Soft tissue neck films taken during inspiration with the neck extended might show increased width or an air-fluid level in the retropharyngeal space. CT with contrast medium enhancement can reveal central lucency, ring enhancement, or scalloping of the walls of a lymph node. Scalloping of the abscess wall is thought to be a late finding and predicts abscess formation.

Figure 374-1 CT of retropharyngeal abscess. A, CT image at level of epiglottis. B, Sequential CT slice exhibiting ring-enhancing lesion. C, Further sequential CT slice demonstrating inferior extent of lesion.

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