Normal Aryepiglottic Fold Thickness on Radiography
The aryepiglottic folds are paired mucosal folds extending from the lateral margins of the epiglottis to the arytenoid cartilages, forming the lateral walls of the laryngeal inlet. Accurate measurement of their thickness on lateral neck radiography is essential for identifying supraglottic airway obstruction, particularly in the pediatric population where epiglottitis can be rapidly life-threatening.
Normal Reference Values
| Orientation | Measurement |
|---|---|
| Lateral | 7 mm |
Clinical Significance
On lateral neck radiography, the maximal normal aryepiglottic fold thickness is 7 mm. Thickening beyond this threshold is a reliable indicator of supraglottic inflammation or edema and should prompt urgent clinical correlation. In children, acute epiglottitis — classically caused by Haemophilus influenzae type b or, increasingly, other organisms — produces marked swelling of the epiglottis and aryepiglottic folds, creating the well-known “thumbprint sign.”
It is critical to recognize that airway assessment in a suspected epiglottitis case should never delay definitive airway management. The radiograph is confirmatory, not a prerequisite for treatment. Additional pitfalls include patient positioning (neck flexion falsely thickens folds) and under-penetrated films that obscure soft-tissue detail.
- Acute epiglottitis — bacterial or viral supraglottitis
- Angioedema — allergic or hereditary
- Thermal or caustic inhalation injury
- Supraglottic neoplasm — squamous cell carcinoma or lymphoma
- Abscess — peritonsillar or retropharyngeal extension
Reference: Donnelly LF. Pediatric Imaging, The Fundamentals. Saunders. p. 10 (2009).
Imaging Notes
Lateral neck radiography remains the primary modality for evaluating aryepiglottic fold thickness. The film should be obtained in full inspiration with the neck in neutral or mild extension to avoid artifactual soft-tissue redundancy. A true lateral projection is essential — even slight rotation can superimpose structures and misrepresent fold dimensions. Measurement is taken at the widest visible point of the fold on the lateral view.
Adequate soft-tissue technique (lower kVp, appropriate collimation) is necessary to differentiate mucosal swelling from normal anatomical structures. When radiographic findings are equivocal or advanced evaluation is required, CT of the neck with contrast provides superior delineation of the supraglottic soft tissues and can identify abscess formation or neoplastic extension.