Normal Prevertebral Soft Tissue C2 Thickness Radiography CT
The prevertebral soft tissues at C2 represent the retropharyngeal space anterior to the cervical vertebral bodies, and accurate measurement on lateral projections is a cornerstone of cervical spine evaluation. Swelling of this space can indicate serious underlying pathology including hemorrhage, abscess, or ligamentous injury. Because normal thickness varies significantly with patient age and imaging modality, age-stratified reference values are essential for correct interpretation.
Normal Reference Values
| Orientation | Age | Measurement |
|---|---|---|
| Lateral | 0-2 y/o | 7.6 mm |
| Lateral | 3-6 y/o | 8.4 mm |
| Lateral | 7-15 y/o | 6.8 mm |
| Lateral | 0-2 y/o | 9 mm |
| Lateral | 3-6 y/o | 9.8 mm |
| Lateral | 7-10 y/o | 12.1 mm |
| Lateral | 11-15 y/o | 14.5 mm |
Clinical Significance
Prevertebral soft tissue thickening at C2 raises concern for retropharyngeal pathology or cervical spine injury. In pediatric patients, physiologic variation is wide — particularly in young children where the space can appear prominent due to normal lymphoid tissue and patient positioning. Expiratory phase or neck flexion can falsely increase apparent thickness, making technique verification critical before attributing swelling to pathology.
Measurements exceeding the published upper limits for a given age group should prompt clinical correlation and, where appropriate, advanced cross-sectional imaging. CT provides more accurate delineation of soft tissue extent, fluid collections, and osseous injury than plain radiography alone.
- Retropharyngeal abscess — most common cause of marked thickening in young children
- Retropharyngeal hematoma — associated with trauma or coagulopathy
- Cervical spine fracture or ligamentous injury — especially after high-energy trauma
- Calcific tendinitis (longus colli) — acute onset, calcium deposits on CT
- Neoplasm or adenopathy — consider lymphoma, metastatic disease, or primary bone tumor
Reference: Vermess D, Rojas CA, Shaheen F et al. Normal pediatric prevertebral soft-tissue thickness on MDCT. AJR Am J Roentgenol. 2012;199(1):W130-3.
Imaging Notes
On lateral radiography, prevertebral thickness at C2 is measured from the anterior cortex of the C2 vertebral body to the posterior pharyngeal airway wall. The image should be obtained in full inspiration with the neck in neutral extension; flexion and expiration are the most common causes of spurious thickening. Adequate lateral positioning without rotation is mandatory for reliable measurement.
On CT (MDCT), measurements are obtained on sagittal reformats in the lateral plane, similarly from the anterior C2 cortex to the posterior pharyngeal mucosal surface. CT eliminates the issues of respiratory phase and positioning variability seen on radiography and allows characterization of tissue density — distinguishing fluid, fat, or hemorrhage — making it the preferred modality when plain radiograph findings are equivocal or clinical suspicion remains high.