Imaging Case of the Week 7

A 64 year old man presents with fever, throat pain and difficulty swallowing. He is unable to swallow his own saliva. On examination, he has a soft stridor. You suspect a retropharyngeal abscess with epiglottitis as a differential. What does the lateral neck xray show?

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The xray shows swelling of the epiglottis, suggestive of epiglottitis which is an ENT emergency.

Two important radiological signs of epiglottitis are clearly present in this xray.

1. Thumbprinting sign – Swollen epiglottis causes this sign.

2. Vallecula sign – Vallecula is the pre-epiglottic space. It is visible on plain radiographs as a deep air pocket at the level of hyoid anterior to the epiglottis. It is normally parallel to the pharyngotracheal air column. If vallecular sign is present, instead of a deep linear space, a V shaped shallow space is seen.

A normal lateral neck xray showing deep vallecular space is presented below for comparison. Red outline demonstrates vallecula and blue outline demonstrates epiglottis.

Note – epiglottitis is largely a clinical diagnosis in ED and lateral neck xray is not a routine investigation, especially in children. Patients should never be positioned supine for the xray as this may close off the airway.