Achalasia is a swallowing disorder that affects the esophagus, the muscular tube connecting the mouth to the stomach. Esophageal manometry is a diagnostic test used to evaluate the function of the esophagus and its sphincters. This procedure provides valuable insights into how the esophageal muscles contract and relax, helping to identify various conditions that impair swallowing. The diagnosis offered by manometry is important for guiding appropriate treatment strategies.
Understanding Achalasia
Achalasia is a rare disorder characterized by the esophagus’s inability to move food effectively into the stomach. This condition results from damaged nerves in the esophageal wall, which leads to two primary issues. First, the muscles of the esophagus lose their coordinated wave-like contractions, known as peristalsis, that normally push food downward. Second, the lower esophageal sphincter (LES), a ring of muscle at the junction of the esophagus and stomach, fails to relax properly during swallowing.
The impaired movement of food and the constricted LES cause food and liquids to accumulate in the esophagus. This accumulation often leads to common symptoms such as dysphagia, which is difficulty swallowing for both solids and liquids. Patients may also experience regurgitation of undigested food, chest pain, coughing fits, and gradual weight loss due to inadequate nutrient intake.
What Esophageal Manometry Involves
Esophageal manometry is a procedure that measures the pressure and coordination of muscle contractions within the esophagus and the lower esophageal sphincter. Before the test, patients are asked to fast, usually for six hours, to ensure the esophagus is empty.
The procedure begins with the patient sitting upright, and a thin, flexible catheter is inserted through one nostril. A numbing gel or spray is applied to the nostril and back of the throat to minimize discomfort and suppress the gag reflex. As the catheter advances down the throat and into the esophagus, patients may experience a sensation of gagging or discomfort.
Once the catheter is in place, the patient is asked to swallow small sips of water. These swallows are performed at specific intervals, allowing the sensors to record the pressure changes as the esophageal muscles contract and the LES relaxes. The data collected is then transmitted to a computer, which creates a detailed map of the esophageal motility patterns. The entire procedure takes about 15 minutes, after which the catheter is removed.
Interpreting Manometry Findings for Achalasia
Esophageal manometry is the preferred diagnostic test for achalasia, providing specific patterns that confirm and classify the disorder. A key finding in achalasia is the absence of esophageal peristalsis.
Another hallmark of achalasia is the incomplete relaxation of the lower esophageal sphincter (LES) during swallowing, often accompanied by an elevated LES pressure. This incomplete relaxation is quantified by an abnormal median integrated relaxation pressure (IRP). An IRP value greater than 12 mmHg indicates outflow obstruction at the esophagogastric junction.
The Chicago Classification 4.0 is the standardized framework used to interpret high-resolution manometry findings and classify achalasia into distinct types. Type I achalasia is characterized by an abnormal median IRP and complete absence of esophageal peristalsis, with no significant esophageal pressurization. Type II achalasia also presents with an abnormal median IRP and absent contractility, but it is distinguished by panesophageal pressurization in at least 20% of swallows.
Type III achalasia is identified by an abnormal median IRP, absent peristalsis, and premature or spastic contractions in the esophageal body. Differentiating between these types of achalasia is important for guiding treatment decisions, as each type may respond differently to various interventions. For inconclusive manometry diagnoses, Chicago Classification version 4.0 recommends additional tests such as a timed barium esophagram or functional lumen imaging probe (FLIP).