EDs are classified based on their anatomy (true or false) and etiology (traction or pulsion) [4]. E-EDs are often false pulsion diverticula secondary to an esophageal motility disorder [8]. Conversely, M-EDs are usually true traction diverticula that are secondary to postinflammatory scarring and are classically called Rokitansky diverticula [4]. However, our patient did not exhibit periesophageal inflammation, and the histopathology confirmed the diagnosis of a pseudodiverticulum. These findings resembling E-ED suggest a similar etiology at play. Esophageal motility disorders, which are associated with 43–100% of all E-ED cases [9, 10], are also associated with M-ED [3, 11, 12]. HRM metrics are essential for classifying esophageal motility disorders. The IRP is a measure of deglutitive relaxation based on 4 s of the lowest mean axial pressure, continuous or discontinuous, across the LES during the 10-s period after a swallow, and is an important metric to assess adequacy of EGJ relaxation. The DL is a time measurement from the start of swallow-induced UES opening to the arrival of esophageal contraction at the contractile deceleration point, the inflection point in the wavefront velocity proximal to the EGJ. A swallow is considered premature or spastic if the DL is less than 4.5 s. For example, one of the esophageal motility disorders, Type I achalasia, is diagnosed by the absence of normal esophageal peristalsis and IRP > 25 mmHg with at least 2 swallows. In the present case, the IRP was normal, and the DL was normal. Therefore, the patient did not meet the criteria for an esophageal motility disorder although the IBP was elevated, which can indirectly indicate esophageal obstruction and is associated with esophageal motility disorders [5, 13]. The fourth version of the Chicago classification has adopted IBP as a criterion for ED, although IBP is recommended for the evaluation of motility disorders only in patients with an abnormal IRP [6]. Quader et al. reported that elevated IBP indicated an obstructive process in cases where IRP is normal [7]. In the present case, the elevated IBP might be due to an obstructive issue, although the IRP was normal. This is the first case reporting a patient with M-ED in whom elevated IBP suggested an esophageal motility disorder.

The indication for surgery should be carefully considered in patients with M-ED. Those with asymptomatic ED are often followed without surgery as they do not experience clinically significant progression of symptoms [14]. On the other hand, symptoms such as dysphagia and pneumonia can lead to reduced quality of life and sometimes fatal complications, leading to the consideration of surgery. However, postoperative complications, especially leakage, are not uncommon and require attention. In one study from Mayo Clinic on one of the largest cohort studies on open surgery for ED, mortality rate was 9.1% and 18% of the all patients experienced leakage [9]. Although minimally invasive surgery, including laparoscopic and thoracoscopic approaches, has become the mainstream in recent years, the overall mortality rate of 0–7% is up to 8–24% in those with leakage [4, 10, 12, 15]. Therefore, surgery for ED is not a low-risk option even today despite significant surgical advances and indications for surgery should be carefully considered.

Patients with M-ED and esophageal motility disorder should undergo esophagomyotomy and diverticulectomy, given that diverticulectomy alone is associated with an increased rate of esophageal leak and ED recurrence [16]. However, esophagomyotomy in patients without an esophageal motility disorder remains controversial; some surgeons argue that myotomy should not be added to the surgical approach as it may increase the risk of leakage from unnecessary myotomy [3, 12], while others propose that myotomy should be performed in all cases because they consider that the patients have an underlying esophageal motility disorder not noted in the Chicago classification [10]. In the present case, although the patient did not meet the criteria for an esophageal motility disorder, elevated IBP indicated an esophageal motility disorder, and myotomy was performed in addition to diverticulectomy, leading to the successfully symptomatic resolution without recurrence.