Flexible endoscopic Zenker’s diverticulum treatments – too many in the tool box?Referring to Mittal C et al. p. 346–353
Treatments for Zenker’s diverticulum have evolved over the decades. The surgical approach evolved from open surgery to rigid endoscopic cricopharyngeal bar myotomy, which offered a shorter hospital stay, high efficacy, and less morbidity . Flexible endoscopic cricopharyngeal bar myotomy was reported in 1995 and was initially performed in only a limited number of centers owing to its perceived difficulty and potential complications. Over the years, however, many centers have adopted this method with success. A needle-knife, with or without a diverticuloscope  to isolate the cricopharyngeal bar, was used. More recently, endoscopic submucosal dissection knives have often been used  . In 2014, Kedia et al. reported a new method with stepwise exposure of the cricopharyngeal muscle by mucosal incision and submucosal dissection . This method offered the advantage of isolating the structures and visualizing the cricopharyngeal muscle in order to selectively and completely incise down to the bottom of the diverticulum while avoiding perforation, with the aim of improving long-term efficacy. Our group reported further details of the method with slight modification in video format , and named this method “full-exposure cricopharyngeal myotomy.”
In this issue of Endoscopy, Mittel et al. report on a retrospective study of practice patterns in Zenker’s myotomy from 12 centers, with details of tools, techniques, and outcomes . I congratulate the authors on their effort to investigate modern treatment modalities for symptomatic Zenker’s diverticulum in the United States. Not surprisingly, a variety of tools have been used over the years. Two major methods were used: traditional septotomy and submucosal dissection on the septum followed by myotomy (exposure technique). The mean Zenker’s diverticulum size was 2.7 cm (range 0.5–7 cm). The authors used the Eckardt score to assess dysphagia symptoms, with clinical success defined as an overall score of < 3 and dysphagia score of < 2. Overall technical success was 98.1 % and clinical success was 78.1 %.
“The best technique may differ among patients with different symptoms, diverticulum sizes, and comorbidities: Z-POEM may be most suitable for a smaller Zenker’s diverticulum, myectomy for a large diverticulum, and a conventional septotomy or exposure-type technique for a medium diverticulum (arguably 2–5 cm).”
The traditional method had lower clinical success (75.2 %) than the exposure technique (90.9 %), though not statistically different, which is probably due to the lower number of cases with the exposure technique (22 vs. 101). The clinical success rate was significantly higher with a hook knife than a needle- or insulated tip knife. There were no significant differences in outcomes between centers with different case volumes (cases up to 10, 11–20, > 20). The adverse event rate was 8.1 %, with a higher perforation rate for the exposure technique (12.5 %) than the traditional technique (2.9 %). This is remarkable because the exposure technique aims to reduce the risk of inadvertent perforation by visualizing each layer of the wall. Familiarity with anatomical structures comes with experience, as gastroenterologists are not usually familiar with structures in this region. It is possible that perforation occurred in the early phase of technical adaptation. Repeat intervention was required for symptoms in 15.5 % of patients, which is comparable to the rate reported in previous studies  ; however, short-term follow-up (mean 5.7 months) of only 76.4 % of the original patient cohort may have lowered the reintervention rate.
Multiple and linked confounding variables make analysis difficult in this study, such as differences between knives, techniques, and the participating medical centers. Importantly, we do not have data from individual centers with regard to case volume, techniques, tools, and success rates. Variables include tools (insulated tip knife may be inferior to other knives), technique (exposure technique may offer higher clinical success), and learning curve. The hook knife was used more frequently in the exposure technique (54.2 %) than in the traditional technique (21.9 %); the insulated tip knife was used only for the traditional technique.
Flexible endoscopic treatment of Zenker’s diverticulum has evolved over recent years. Centers with lower case volumes may have adopted the newer (exposure) technique and tools, as they may have embarked on treatment for Zenker’s diverticulum more recently, when more knowledge and technical details had become available. The traditional technique using a needle-knife and insulated tip knife is likely to have been used at the high-volume centers in the early years. Thus, treatment outcomes of centers are not solely a reflection of the learning curve. The authors have acknowledged these issues in the study limitations and subgroup analysis was not possible. Nevertheless, it is notable that centers with case volumes of 10 or less showed excellent outcomes. Despite the limitations of this study, it is safe to conclude that Zenker’s diverticulotomy is feasible and adaptable at such tertiary referral centers.
We need to standardize the flexible endoscopic technique for treatment of Zenker’s diverticulum and aim for higher clinical success rates and, more importantly, lower recurrence rates, as flexible endoscopy offers better maneuverability and visualization. The recurrence rate of 10 %–15 % was similar to that for rigid endoscopic treatment . Costamagna et al. reported the prognostic variables for clinical success with flexible endoscopic septotomy . Pretreatment diverticulum size > 50 mm, septotomy length < 25 mm, and residual diverticulum of 10 mm were prognostic indicators for recurrence. Complete cricopharyngeal bar myotomy with minimum residual cricopharyngeal bar or diverticulum reduces the risk for residual symptom or recurrence.
Other promising treatment options reported recently are peroral endoscopic myotomy for Zenker’s diverticulum (Z-POEM)   and myectomy . Z-POEM creates a submucosal tunnel in order to expose and completely cut the cricopharyngeal bar, keeping the overlying mucosa intact. However, perforation has still been reported (5 %), requiring hospital admission . Moreover, the intact mucosa that was covering the cricopharyngeal bar would become the mucosal flap and it is not clear how this mucosal flap affected patients after myotomy. Z-POEM carries a risk of possible leakage at the entry site, which could lead to abscess formation as it creates a pocket within the submucosa to adventitia or fascia. The procedure requires complete entry site closure to prevent complications, and multiple clips may involve significant discomfort, cost, and time.
Myectomy is an attractive option to reduce recurrence. Creating a wide window by removing a large area of the cricopharyngeal bar may provide long-lasting resolution of symptoms. No recurrence of symptoms was reported (0 %), although the myotomy group had a higher recurrence rate (22.7 %) than commonly reported . Larger studies would be required to confirm superiority of myectomy in reducing recurrence.
The best technique may differ among patients with different symptoms, diverticulum sizes, and comorbidities. Z-POEM has the advantage of performing complete and extended myotomy to the esophageal lumen, which may be most suitable for a smaller diverticulum with significant symptoms associated with cricopharyngeal hypertrophy. Myectomy has the advantage of removing the septum of large diverticula, for which simple cricopharyngeal bar myotomy risks higher recurrence. Conventional septotomy, or rather exposure technique, would be the standard treatment for a medium Zenker’s diverticulum (arguably 2–5 cm). Classification of clinically relevant Zenker’s diverticulum to aid selection of a treatment modality is eagerly awaited.
29 March 2021 (online)
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