An x-ray of the soft tissues of the neck can be useful for diagnosing various conditions. The presence of air in the prevertebral space indicates a dilated esophagus. In children, this suggests achalasia as the cause of esophageal dilation, while in adults it typically indicates a malignant stricture that is causing proximal dilation of the esophagus. The x-ray finding of air in the prevertebral space consistently indicates an enlarged esophagus.