The lateral neck x-ray shows-

There is significant widening of prevertebral soft tissue space anterior to upper cervical vertebrae (C1-C5). The cervical vertebral alignment is abnormal but this is likely secondary to marked prevertebral swelling and associated paravertebral muscle spasm.

Negative findings are – no foreign body visible. No gas locules/air fluid levels seen.

With a strong clinical suspicion for retropharyngeal abscess, the patient went on to have a CT scan of the neck which confirmed a retropharyngeal abscess.

The normal limit of soft tissue width in paediatric population should be less than 7mm in front of C2 and 14 mm in front of C6.

Caveat: The prevertebral space may falsely appear wide when the lateral neck x-ray is obtained when the child is crying/exhaling with neck held in flexion.

Reference: www.expertconsultbook.com