Esophageal stricture is a narrowing along the swallowing tube; it may occur anywhere along the esophagus, but usually at the lower end. At the LES, this may be due to acid reflux and require balloon dilation.
Occasionally, the dysfunction occurs at the upper, or UES, sphincter. This is often at the cricopharyngeal muscle location.
Recently, with more aggressive treatment of tumors, using combined chemo and radiation therapy, severe mucositis may occur and this perhaps can lead to a stricture around the UES. Early muscular exercises especially with the help of E-stim and swallowing therapy, as well as earlier esophageal dilation may help.