Treatment

The goal of the treatment of ZD is a cricopharyngeus muscle myotomy that may be realized surgically from the longitudinal layer of the muscle up to the submucosal plane or through the cutting of the septum between the diverticulum and the esophagus (septotomy) in case of transoral techniques [10, 11].

The decision on whether to use an open or transoral approach is related to several factors including anatomy and size of the diverticulum, patient’s status and comorbidities, patient willingness, and finally local expertise.

In case of open surgery, the incision is usually performed along the anterior border of the sternocleidomastoid muscle, on the left of the neck, because the pouch expands preferentially in this location. Through this incision, the diverticulum is first exposed and then a contiguous tissue dissection is required to achieve adequate visualization of the neck of the diverticulum. At this point full-thickness careful myotomy is performed approximately 2 cm proximally into the constrictor to 5 cm distally into the proximal esophagus. The pouch is usually treated according to its size with either inversion or pexy. Only in case of large pouch (>5 cm) the diverticulum is typically resected with closure of the opening by a linear stapling device . However, open surgery may be complicated by significant rates of morbidity and mortality, particularly because most patients with the disease are elderly and already have several comorbidities [12].

Transoral approach , which entails transoral division of the septum through rigid endoscope, or flexible endoscopy, has gained increased popularity in the last 20 years.

The rationale is that a septum containing the cricopharyngeal muscle divides the diverticulum sac from the esophagus. By dividing this wall, the cricopharyngeal muscle is incised and released from its high pressure, and the diverticulum is marsupialized thus becoming a unique cavity with the esophagus and eliminating food entrapment and relieving the outflow obstruction.

Septotomy performed by a rigid endoscope, first reported simultaneously in 1993 by Collard in Belgium [13] and Martin Hirsch in England [14], is based on a transoral single-stage cut and suture technique using a laparoscopic stapler introduced through a rigid endoscope. It is considered more suitable and preferable when compared with open surgery due to quicker diet resumption, lower adverse events rates, and shorter inpatient stay [15, 16].

However, approaches using rigid endoscopy have several limitations, including the need for general anesthesia and significant rates of intraoperative failure (5–10%), mainly in cases of small diverticular size (<3 cm) or because of restricted neck mobility or inadequate jaw opening preventing the advancement of the rigid diverticuloscope into the pharynx [15].

Flexible Endoscopic Myotomy

Flexible endoscopic (FE) myotomy , published for the first time in 1995 [17, 18], is less invasive than the two former techniques, can be performed without general anesthesia (necessary in the surgical approach), and does not require neck hyperextension (necessary for the rigid endoscopic procedure) [18–20]. The procedure can be safely performed in the endoscopy suite, in the inpatient or outpatient setting. Some centers offer the FE option to all ZD symptomatic patients, although most authors recommend reserving it for selected patients, especially high-risk elderly patients, poor surgical candidates who are expected to benefit the most from this technique [21].

The obvious advantages of FE over the conventional open surgical approach are the absence of cutaneous incision, shorter operative time, reduced postoperative discomfort, faster return to oral feeding, and shorter length of hospital stay [22].

FE septotomy involves an incision of the mucosa and the muscular fibers that form the diverticular septum. Flexible endoscopy shares the same principles and rationale as rigid endoscopy: the septum between the diverticulum and the esophagus contains the cricopharyngeal muscle, and by cutting the septum and creating a common cavity, a myotomy is automatically performed (Fig. 20.2).

Unfortunately, there is a lack of agreement on who are the best candidates for flexible endoscopic treatment. As a general principle , small–medium-sized (up to 5 cm) diverticula are best approached endoscopically either with rigid or flexible technique, while small-sized ZD (up to 3 cm) may be best amenable by flexible endoscopy because of the impossibility to properly accommodate the stapler which is currently longer than 3 cm. For large diverticula there may still be space for open surgical excision, especially in younger, good surgical candidates, even though long septum typically allows for long complete flexible myotomy with excellent resolution of symptoms (personal experience, no published data).

Since its introduction, many variations of the technique have been reported and a wide array of cutting devices have been used.

Technique

Patients are placed in a left lateral decubitus position under conscious or deep sedation. Differences in the sedation approach for these patients have been recorded in the published papers with several authors still preferring to perform this technique under general anesthesia [22] and some others being more keen to use propofol-based deep sedation in the majority of patients.

Antibiotic prophylaxis is not routinely administered.

The procedure is usually done with a standard flexible scope and begins with initial endoscopic examination of the pouch, estimation of the pouch and septum, and finally suctioning of possible retained material from the diverticulum. Prior to performing the procedure, it is a common practice to introduce a nasogastric or orogastric tube via a guidewire previously endoscopically advanced in the stomach. It serves to constantly recognize the esophageal lumen during myotomy. It allows enhanced visualization of the esophageal lumen and diverticulum, and it protects the anterior esophageal wall from injury from instruments used during myotomy [23].

Most frequently, a standard transparent cap or a dedicated hood with oblique design placed on the tip of the endoscope has been used with similar intentions [24] of enhancing visualization, improving scope stability, and stretching the septum at the time of its incision.

More rarely, instead of the orogastric tube, some experts use a soft diverticuloscope (Zenker’s diverticulum overtube, ZDO-22-30; Cook Medical, Winston-Salem, North Carolina) to stabilize and visualize the septum (Fig. 20.3). The diverticuloscope is placed as an overtube on the endoscope and contains two distal flaps that serve to straddle the septum and safeguard the anterior esophageal wall and posterior diverticular wall.

Even though diverticuloscope may potentially improve the maneuverability with lower complication rates compared with the use of a transparent cap or no device, there are no significant differences in clinical outcomes with the use of one or other accessories [24–27].

However, it is worth noting that the diverticuloscope is only commercially available in Canada and Europe.

Regardless of different accessories that can be selected to improve septum exposure, different cutting techniques and devices can be used (needle knife, hook knife, monopolar forceps, argon plasma coagulation) depending on physicians’ personal experience and preferences. The most commonly used devices are hook knife and the needle knife (Olympus Medical, Tokyo, Japan) [11, 17, 20, 25, 27, 28]. The technique with the needle knife of a single incision alongside the midline of the diverticular septum, through blended current coagulation, is shown in Video 20.1. The incision is distally directed toward the bottom of the pouch, by moving the tip of the endoscope, hence the tip of the needle.

Nevertheless using the hook knife (Olympus Medical, Tokyo, Japan), a potentially more complete myotomy can be achieved since the muscular fibers at the bottom of the septum may be gently pulled upward using the hook part of the knife before cutting, allowing very precise dissection [11, 29] (Fig. 20.4).

At the end of the cut, one or more endoclips are placed to prevent delayed perforation or bleeding.

Additional approaches used to divide the septum include monopolar and bipolar forceps, argon plasma coagulation, harmonic scalpels, and stapling devices, the latter two of which are advanced alongside the scope and not through the working channel of the scope. The optimal cutting technique remains quite elusive because of the lack of comparative trials among different endoscopic techniques.

More recently, some researchers reported a number of technique modifications such as the use of a stag beetle knife (SB Knife, Sumitomo Bakelite, Tokyo, Japan) with two insulated monopolar blades, which facilitates the procedure of “grasp and cut ” [30], or using a stag beetle knife where two parallel incisions on the septum are performed to dissect the mucosa and the horizontal fibers of the cricopharyngeal muscle and the septum in between is removed with the aid of a polypectomy snare [31, 32].

Outcome

Available data from previous series suggest that adequate treatment can be provided in one to two treatment sessions with a quite high rate of clinical resolution of symptoms and a low rate of diverticular recurrence. Most of the studies report a clinical resolution rate of about 90%. However most of these studies are retrospective and comparison among different studies is biased by the lack of universally agreed formal definitions of clinical success.

Improvement in symptoms can be evaluated through different scores which try to include the different symptoms related to the diverticulum and make more reliable and standardized the evaluation of clinical outcome especially in the long term [33–35].

A recent meta-analysis showed that FE myotomy for ZD is effective and safe. The overall initial treatment success rate ranged from 56.4% to 100%, whereas the success rate of studies where a comprehensive evaluation of ZD symptoms was carried out ranged from 56.4% to 96.6% [36].

In particular the meta-regression analyses for overall safety show that the cutting device, diverticulum size, or sedation was not associated with the outcomes of the procedure.

Adverse event rates ranged from 0% to 36.4%, with a median of 14.1%. The most frequently reported adverse event was perforation which occurred in 41 patients overall (6.5%).

Other common adverse events include hemorrhage, pneumonia, fever, emphysema, bleeding, and neck abscess.

Flexible endoscopy is associated with a clinical recurrence rate ranging from 0% to 32%, with a random effects pooled rate estimate of 11% [36]. The risk of recurrence of the symptoms is mainly related to the lack of the completeness of the incision which leaves a substantial amount of muscle active and responsible of recurrent symptoms. Changes in the motor activity of the esophagus (hypertonus), individual anatomical features of the diverticulum (such as a wide and deep diverticulum), and the diverticulum’s relationship to the esophageal wall (a semi-lateral or lateral location) may also contribute to the likelihood of the disease recurrence.

Repeat endoscopic treatment, in case of treatment failure or symptoms recurrence, can easily and successfully be achieved with significant improvement in the majority of treated patients.

However, with the available literature, it is challenging to analyze the real recurrence rate since there exists a high heterogeneity across studies, with a mean follow-up duration which ranges from 7 months to 43 months [36].

Z-POEM

Recent advances in natural orifice transluminal endoscopic surgery (NOTES) have given rise to novel myotomy techniques including peroral endoscopic myotomy (POEM) [37].

Recently, some authors have reported a novel technique called the submucosal tunneling endoscopic septum division (STESD) [38–40] or so-called Z-POEM, inspired by the POEM technique.

The theoretical advantage is to completely dissect the muscular septum through a submucosal tunnel while maintaining the mucosal integrity. This procedure has the potential to reduce the risk of perforation and mediastinitis and the rate of recurrence [38].