Endoscopic mucosal incision and muscle interruption (MIMI) for the treatment of Zenker’s diverticulum

Background: In peroral endoscopic myotomy for Zenker’s diverticulum (Z-POEM), the cricopharyngeus muscle is divided within a submucosal tunnel started in the hypopharynx. We aimed to evaluate the safety and preliminary outcomes in patients who underwent a modified version of the Z-POEM where the tunnel is made directly overlying the cricopharyngeus, the mucosal incision and muscular interruption (MIMI) approach, and to compare these with patients who underwent a non-tunneled flexible endoscopic approach. Methods: All patients with ZD who were treated by flexible endoscopy at our institution between January 2015 and February 2020 were identified by a retrospective chart review. Dysphagia symptoms were assessed using a validated scoring system. Results: Nineteen patients with ZD underwent MIMI (mean age 76.1 years, 68.1% male) and seven patients underwent non-tunneled flexible endoscopic approach (mean age 64.4 years, 85.7% male) during the study period. Mean ZD size was 2.8 cm in the MIMI group and 1.9 cm in the non-tunneled group (p = 0.03). Clinical success was achieved in 17/19(89.5%) MIMI patients and 7/7(100%) of non-tunneled flexible endoscopic patients (p = 0.101). Dysphagia scores improved in both groups, although this difference was only significant in the MIMI group (p ≤ 0.001). Recurrence occurred in 2/17(11.7%) MIMI patients and 3/7(42.9%) non-tunneled flexible endoscopic patients (p = 0.096). There were 4 complications, including one pharyngeal perforation requiring open surgical repair in a patient with a small ZD with an associated cricopharyngeal bar in the MIMI group. Median length of follow-up was 290 [142; 465] days in the MIMI group and 1056 [258; 1206] days in the non-tunneled group (p = 0.094). Conclusions: MIMI is a technically feasible and effective treatment for ZD. Care should be taken in patients with a cricopharyngeal bar and small ZD, as this may increase the risk of perforation. Larger studies with long-term follow-up are needed to determine if MIMI reduces the risk of symptom recurrence when compared to non-tunneled flexible endoscopic approaches.