**4.1 Prevertebral soft tissue swelling**

Prevertebral soft tissue swelling is result of hemorrhage or intraoperative soft tissue trauma which leads to oedema which may cause transient dysfunction of the esophageal movement by impairing the upper esophageal sphincters. Nevertheless, Kang et al. failed to find a significant correlation between the thickness of prevertebral soft tissue and the incidence of dysphagia [27, 28].
