The opening that connects the esophagus with the stomach is controlled by a series of muscles. If these weaken, stomach acids can flow into the esophagus and cause inflammation or even cause part of it to penetrate into the abdomen, causing a hiatal hernia.Chronic pain is one of the most complex phenomena in medicine. It is so important that specialists from many areas participate in its approach, from anesthesiology to psychiatry. Many factors intervene in its origin and evolution that professionals must take into account to find the precise treatment for each person.