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.

(From Philpott CM, Selvadurai D, Banerjee AR: Paediatric retropharyngeal abscess, J Laryngol Otol 118:925, 2004.)

Figure 374-2 CT of parapharyngeal abscess in a 3 yr old child. A, Sagittal section demonstrating parapharyngeal abscess (A) and mucosal swelling (M) in the maxillary sinus. B, Coronal section of parapharyngeal abscess (A).

Retropharyngeal and lateral pharyngeal infections are most often polymicrobial; the usual pathogens include group A streptococcus (Chapter 176), oropharyngeal anaerobic bacteria (Chapter 205), and Staphylococcus aureus (Chapter 174.1). Studies have documented an increased incidence of group A streptococcus recovered from such abscesses. Other pathogens can include Haemophilus influenzae, Klebsiella, and Mycobacterium avium-intracellulare.

Treatment options include intravenous antibiotics with or without surgical drainage. A 3rd-generation cephalosporin combined with ampicillin-sulbactam or clindamycin to provide anaerobic coverage is effective. The increasing prevalence of methicillin-resistant Staphylococcus aureus can influence empiric antibiotic therapy. Studies have shown that >50% of children with retropharyngeal or lateral pharyngeal abscess as identified by CT can be successfully treated without surgical drainage. Drainage is necessary in the patient with respiratory distress or failure to improve with intravenous antibiotic treatment. The optimal duration of treatment is unknown, but therapy for several days with intravenous antibiotics until the patient has begun to improve followed by a course of oral antibiotic is typically used.

Complications of retropharyngeal or lateral pharyngeal abscess include significant upper airway obstruction, rupture leading to aspiration pneumonia, and extension to the mediastinum. Thrombophlebitis of the internal jugular vein and erosion of the carotid artery sheath can also occur.

An uncommon but characteristic infection of the parapharyngeal space is Lemierre disease, in which infection from the oropharynx extends to cause septic thrombophlebitis of the internal jugular vein and embolic abscesses in the lungs (Fig. 374-3). The causative pathogen is Fusobacterium necrophorum, an anaerobic bacterial constituent of the oropharyngeal flora. The typical presentation is that of a previously healthy adolescent or young adult with a history of recent pharyngitis who becomes acutely ill with fever, hypoxia, tachypnea, and respiratory distress. Chest radiography demonstrates multiple cavitary nodules, often bilateral and often accompanied by pleural effusion. Blood culture may be positive. Treatment involves prolonged intravenous antibiotic therapy with penicillin or cefoxitin; surgical drainage of extrapulmonary metastatic abscesses may be necessary (Chapters 373, 375).

Figure 374-3 CT of Lemierre disease. A, CT demonstrating nodular appearance of pulmonary infiltrates (arrow). B, CT of neck demonstrating thrombosis of right internal jugular vein (arrow).

(From Plymyer MR, Zoccola DC, Tallarita G: An 18 year old man presenting with sepsis following a recent pharyngeal infection, Arch Pathol Lab Med 128:813, 2004. Reprinted with permission from Archives of Pathology & Laboratory Medicine. Copyright 2004. College of American Pathologists.)

Peritonsillar Cellulitis and/or Abscess

Peritonsillar cellulitis and/or abscess, which is relatively common compared to the deep neck infections, is caused by bacterial invasion through the capsule of the tonsil, leading to cellulitis and/or abscess formation in the surrounding tissues. The typical patient with a peritonsillar abscess is an adolescent with a recent history of acute pharyngotonsillitis. Clinical manifestations include sore throat, fever, trismus, and dysphagia. Physical examination reveals an asymmetric tonsillar bulge with displacement of the uvula. An asymmetric tonsillar bulge is diagnostic, but it may be poorly visualized because of trismus. CT is helpful for revealing the abscess. Group A streptococci and mixed oropharyngeal anaerobes are the most common pathogens, with more than 4 bacterial isolates per abscess typically recovered by needle aspiration.

Treatment includes surgical drainage and antibiotic therapy effective against group A streptococci and anaerobes. Surgical drainage may be accomplished through needle aspiration, incision and drainage, or tonsillectomy. Needle aspiration can involve aspiration of the superior, middle, and inferior aspects of the tonsil to locate the abscess. General anesthesia may be required for the uncooperative patient. Approximately 95% of peritonsillar abscesses resolve after needle aspiration and antibiotic therapy. A small percentage of these patients require a repeat needle aspiration. The 5% with infections that fail to resolve after needle aspiration require incision and drainage. Tonsillectomy should be considered if there is failure to improve within 24 hours of antibiotic therapy and needle aspiration, history of recurrent peritonsillar abscess or recurrent tonsillitis, or complications from peritonsillar abscess. The feared, albeit rare, complication is rupture of the abscess, with resultant aspiration pneumonitis. There is a 10% recurrence risk for peritonsillar abscess.