Paediatric Imaging

Retropharyngeal abscess

Rupture of an infected retropharyngeal node may lead to local suppuration and abscess formation. Infection of the node is due to associated infection of the adenoids and tonsils, both of which drain into the retropharyngeal nodes, most commonly Staphylococcus aureus. Other causes include perforation of the retropharynx by a foreign body which may be iatrogenic occurring during intubation or passage of a nasogastric tube, or be caused nonaccidentally by the forcible passage of a spoon or a finger into the retropharynx. Accidental perforation classically occurs when the child who has a sharp object in the mouth, such as a pencil, suddenly has an arm jolted. Rarely, a retropharyngeal abscess may result from vertebral osteomyelitis.

Clinically, the child presents with fever, neck pain, drooling at the mouth due to inability to swallow saliva, and as obstruction progresses, stridor and airways obstruction.

The radiological diagnosis can usually be made on a lateral radiograph of the postnasal space. There is widening of the prevertebral soft tissue with loss of the normal cervical lordosis. (Fig.1). An airfluid level may be seen if there is perforation of the retropharynx. If this is present, a contrast swallow using a water-soluble contrast agent will show the distal extent of the abscess track. Rarely, a foreign body may be seen in the soft tissues. Contrast-enhanced CT of the retropharynx will confirm the diagnosis of an abscess (Fig.2) if there is clinical doubt.

A complication of retropharyngeal inflammation is Grisels syndrome. The inflammation leads to laxity of the spinal ligaments which may result in subluxation of the cervical spine, and torticollis, or more rarely rotatory fixation.

HC

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Fig.1

Lateral neck radiography of a child with loss of the normal cervical lordosis and marked prevertebral soft tissue swelling due to a large retropharyngeal abscess.
Retropharyngeal abscess, Fig.1
Retropharyngeal abscess, Fig.2