There are four types of hiatal hernias. However, the sliding hiatal hernia (type 1) is the most common and accounts for up to 95% of all hiatal hernias. Type 1 hiatal hernias solely involve "sliding" of the gastroesophageal (GE) junction into the thoracic cavity. Type 2 to 4 hiatal hernias are true paraesophageal hernias (PEHs) and are classified based upon on location of the GE junction as well as what has herniated into the thoracic cavity. A type 2 hiatal hernia has a GE junction in the normal anatomic position, but a portion of the stomach, most often the fundus, has herniated through the hiatus. Type 3, like type 2, have a portion of the stomach that has herniated through the hiatus, but also have an abnormal position of the GE junction in the thoracic cavity. Type 4 has an abnormal GE junction position like type 1 and 3. However, another organ, most often a portion of the colon, has herniated into the thoracic cavity.
In sliding hiatal hernias, the GE junction migrates above the diaphragm secondary to increased laxity of the phrenoesophageal ligament. The ligament remains intact, and the GE junction migrates into the posterior mediastinum. With less amount of esophagus intra-abdominally, this predisposes the GE junction to malfunction leading to reflux. Regarding type 2 to 4, there is not one predominant theory to explain them all, and thus most PEHs are multifactorial in etiology. PEHs most often are associated with, but not limited to the widening of the esophageal hiatus or congenital versus acquired, such as prior history of surgical dissection, trauma, persistent increases in intra-abdominal pressure, or esophageal shortening due to fibrosis or scarring from repeated exposure to noxious content.
The prevalence of sliding hiatal hernias ranges from 10% to 60%. Sliding hiatal hernias represent 95% of all hiatal hernias with paraesophageal hernias making the remaining. Older individuals are affected more commonly than those younger than the age of 50. There is an increased preponderance among obese patients and those who suffer from conditions that increase intra-abdominal pressure, for example, chronic constipation or excessive vomiting. Of the paraesophageal hernias, the most and least frequent are type 3 and 2, respectively. The term "giant hiatal hernia" refers to a hiatal hernia that has 30% or more of the stomach superior to the hiatus and in the thoracic cavity.
Sliding hernias are thought to develop secondary to progressive disruption of the GE junction, which leads to a widening and circumferential laxity of the phrenoesophageal membrane. Herniation results in an alteration of the physiologic anatomy of the GE junction by decreasing the amount of intra-abdominal esophagus thus allowing reflux of gastric contents. It has been shown the susceptibility of the esophagus to reflux during abdominal straining was directly proportional to the size of a sliding hernia. Sliding hernias predispose to reflux by altering both the competence of the GE junction as well as decreasing the clearance of contents in the distal esophagus. Sliding hiatal hernias impair clearance in the distal esophagus by a phenomenon called "re-reflux." It occurs predominantly during inspiration and is most pronounced in the recumbent position. The crural diaphragm is thought to pinch off the distal esophagus and act as a one-way valve. In the setting of type 1 sliding hiatal hernia, the GE junction is no longer intra-abdominal and has subsequently migrated superiorly through the hiatus and above the crural diaphragm. As mentioned earlier, type 2 to 4 hiatal hernias are not clearly understood and thought to be from multiple contributing risk factors. Most often the combination of an increased diameter of the hiatus in the setting of persistent increased intra-abdominal pressure set the stage to develop a paraesophageal hernia.
Patients can develop esophageal mucosal ulcerations called Cameron ulcers. These most often are seen in type 1 hiatal hernias. Otherwise, there are no other histopathological changes associated with hiatal hernias.
Most patients with sliding hernias (type 1) are generally asymptomatic. However if symptoms are present, they are usually nonspecific and consist of epigastric abdominal pain, fullness, and usually, have a history of GERD. As mentioned earlier, this is a consequence of the inadequate length of the intraabdominal esophagus leading to reflux of gastric contents. Patients with PEHs can develop symptoms of obstruction. If the obstruction occurs at the level of the GE junction, then dysphagia is the most common symptom. If any contents remain in the distal esophagus, then regurgitation will occur. However, if the distal stomach becomes obstructed, the resulting proximal gastric distention will lead to nausea and vomiting and in some cases chest pain that radiates to the back. Patients that develop Cameron ulcers can show signs and symptoms of anemia such as pallor and fatigue if there is ongoing occult blood loss.
Diagnosis is based primarily on radiographic findings, upper endoscopy, and esophageal manometry. An upper gastrointestinal (GI) series remains a mainstay in the diagnoses of hiatal hernias. The study can show the location of the GE junction, size of the hernia defect, and the orientation of the stomach. Upper endoscopy can evaluate for the presence of Cameron ulcers as well as directly visualize the amount of stomach that has herniated into the chest. High-resolution manometry (HRM) and esophageal pressure topography (EPT) has been shown to reliably detect hiatal hernias, which is characterized by a pressure trough located between the crural hiatus and GE junction. This modality provides information on intraluminal pressure, lower esophageal sphincter function, and coordinated contractile movements of the esophagus. This is important in surgical planning in determining which antireflux procedure would be needed if the repair was indicated.
Patients with a type 1, sliding hernia, do not require surgical management. Medical management of reflux disease with proton-pump inhibitors and H-2 blockers is the mainstay of therapy. Surgical management of asymptomatic patients with paraesophageal hernias also remains controversial. Most experts do not recommend surgical management in asymptomatic patients because the annual risk of developing symptoms in which emergent surgical intervention is necessary is around 2%, yet the mortality rate for elective repair is approximately 1.5%. While consensus is not clear on asymptomatic patients, there is unanimous agreement symptomatic patients benefit from elective surgical repair. The standard of care is laparoscopic repair consisting of four key elements: excision of the hernia sac, maintaining the adequate length of the intra-abdominal esophagus, repair of the hiatal defect, and gastric fixation with the antireflux procedure.