Clinical Characteristics and Novel Manometric Features of Pseudoachalasia: Identification of Loss of Respiratory Variation in Lower Esophageal Sphincter Pressure.

Background: Pseudoachalasia closely mimics idiopathic achalasia in both symptoms and high-resolution manometry (HRM) findings, making accurate diagnosis difficult. This study aimed to clarify the clinical characteristics of pseudoachalasia encountered at our institution and identify novel manometric findings specific to this condition. Methods: This single-center retrospective study compared the clinical characteristics and HRM findings of patients diagnosed with pseudoachalasia (pseudoachalasia group) with those diagnosed with idiopathic achalasia or esophagogastric junction outflow obstruction (EGJOO), collectively defined as the idiopathic achalasia group, between April 2015 and March 2024. Pseudoachalasia was defined as cases with no mucosal abnormalities on the initial endoscopic examination, and with clinical symptoms, esophagographic findings, and HRM results consistent with achalasia. Results: Five patients were diagnosed with pseudoachalasia. Two cases were classified as Type 2 achalasia and three as EGJOO according to the Chicago Classification. Compared with the idiopathic achalasia group, the pseudoachalasia group was older, had a shorter symptom-to-diagnosis interval, and exhibited higher Eckardt scores. HRM demonstrated significantly higher integrated relaxation pressure (IRP) in the pseudoachalasia group. Loss of Respiratory Variation in LES Pressure (LRV-LES) was observed in all patients in the pseudoachalasia group, whereas it was present in 8.3% of patients in the idiopathic achalasia group. Conclusion: Pseudoachalasia was characterized by an older age at onset, a shorter interval from symptom onset to diagnosis, and higher Eckardt scores. HRM demonstrated elevated IRP, and LRV-LES was observed in all cases. LRV-LES may represent a novel manometric finding that can aid in the diagnosis of pseudoachalasia.