Zenker's Diverticulum
Zenker's Diverticulum
Transoral endoscopic therapy using a rigid endoscope cannot be performed in all patients. An open approach is required in 15% to 68% of cases when inadequate rigid endoscopic exposure of the diverticulum occurs from upper teeth protrusion, inadequate jaw opening, or insufficient neck mobility. Additionally, the risk of perforation is increased with insertion of a rigid diverticuloscope when there is insufficient protection of a small diverticulum sac by the dorsal esophageal wall.
There is a variety of techniques and methods to perform flexible endoscopic transoral cricopharyngeal myotomy. The septum (CP muscle) is commonly divided using a needle knife (normally used for endoscopic retrograde cholangiopancreatography use) or cutting devices designed for endoscopic submucosal dissection (ESD), such as a hook knife (Figure 5A–C). Other methods used to divide the septum include monopolar and bipolar forceps, argon plasma coagulation, harmonic scalpels and stapling devices, the latter two of which are passed alongside the endoscope and not through the flexible endoscope channel. The optimal cutting technique remains elusive as comparative trials in this arena are lacking. Some therapeutic endoscopists advocate for the use of a soft diverticuloscope to stabilize the septum, improve visualization, and further guide the instrument of incision. This accessory is positioned such that it straddles the septum with stabilizing flanges within the upper esophageal lumen and within the ZD, although it is not available in the United States. Other accessories used to enhance visualization include transparent hoods or caps attached to the tip of the endoscope, generally reserved for endoscopic mucosal resection. When the soft diverticuloscope is not used, the preprocedural placement of a nasogastric tube is a frequent maneuver and has a dual benefit. The tube acts as an incisional guide while also serving as a method to deliver enteral nutrition in the event of a procedural AE, such as perforation. If placed nasally, the use of a small-caliber endoscope is used to perform transnasal endoscopy and avoid transfer of the guidewire. A small hole is cut in the tip of the nasogastric tube to allow wire passage. Blind passage of a nasogastric tube is not recommended.
(Enlarge Image)
Figure 5.
Flexible endoscopic cricopharyngeal myotomy for ZD therapy. (A) Endoscopic view with short, clear cap attached to endoscope tip. Nasogastric tube is in place, and hook knife sheath is seen. (B) Midpoint of the cricopharyngeal myotomy procedure. (C) Completion myotomy.
The transoral flexible endoscopic approach to ZD was first described nearly 20 years ago. Since then several series have been published that highlight a variety of efficacious technical applications and an acceptable safety profile. This technique successfully reduces cricopharyngeal sphincter pressure and has been shown to be comparable to the use of a rigid transoral diverticuloscope in terms of efficacy and safety. Nonetheless, flexible transoral cricopharyngeal myotomy is not commonly performed in the United States. The advantages of a flexible endoscopic approach are the flexibility and smaller endoscope diameter, which are especially useful for patients with poor neck extension and/or limited jaw retraction. Additionally, this technique can also be performed without the use of general anesthesia. Flexible endoscopic intervention may be most suitable for elderly patients with comorbid medical conditions limiting surgical intervention. In rare instances, patient comorbidities limit even flexible endoscopic diverticulectomy. Injection of botulinum toxin into the diverticular apex has been described in a small series of 2 patients with satisfactory outcomes.
At the time of this writing, 18 case series have been published regarding the use flexible endoscopic therapy for the treatment of ZD (Table 1). The available studies comprise nearly 650 patients. The available data suggest that adequate treatment can be provided in 1 to 2 treatment sessions with a high rate of clinical resolution and a low rate of diverticular recurrence or persistence. The majority of the included studies report a clinical resolution rate of >90%, whereas the recurrence or persistence of clinical symptoms appears to be <20%; however, no formal definitions of clinical success exist. We believe clinical success should be based solely on improvement in symptoms and not on radiographic or endoscopic findings. The difficulty arises in regard to diversity of symptoms, which can be attributed to ZD. An additional limitation of many flexible endoscopic series is the lack of clinical follow-up. Of the 18 available studies, the length of postprocedural follow-up was not reported in nearly one-third of the studies.
AEs following flexible endoscopic therapy range from inconsequential to life threatening. In our appraisal of the available studies, we identified a median overall AE rate of 6% (range 0%–38%) in the 16 studies with available data. Bleeding is the most common intraprocedural event occurring in a minority of cases (<5%). This can generally be controlled endoscopically using a variety of electrocautery devices or endoclips. Postprocedural throat pain is nearly uniform and often requires narcotic medications. Uncomplicated subcutaneous emphysema may represent microperforation; however, this finding does not mandate surgical intervention and may occur in asymptomatic patients. Clinically relevant and potentially the most severe AE is perforation, which can be documented by extravasation of oral water-soluble contrast (Supplementary Video 2 http://www.cghjournal.org/cms/attachment/2019475005/2039575870/mmc1.mp4%20/cms/attachment/2019475005/2039575877/mmc1.flv). Fortunately, this is relatively uncommon when flexible endoscopic therapy is performed by skilled endoscopists. A recent review by Dzeletovic et al identified a median rate of perforation and/or leak of 4% (range, 0%–27%). Unfortunately, the definition and reporting of AEs have not been standardized, and we strongly recommend the use of a standardized lexicon so that meaningful comparisons between and within disciplines can be made.
Issues pertinent to reluctance of gastroenterologists to performing ZD therapy likely include referral patterns, procedural risks, medicolegal issues, and the complex nature of the procedure. However, the techniques used are now increasingly practiced during many other advanced therapeutic endoscopic procedures.
There is still no consensus on the technical details when ZD therapy is performed using a flexible endoscope. One cannot underestimate the technical expertise involved in this treatment. We believe endoscopists with training in advanced endoscopy and experience in advanced endoscopic techniques, especially in the use of electrocautery devices, ESD, and possibly endoscopic retrograde cholangiopancreatography (because the use of needle-knife therapy is common), should perform ZD therapy. Some authors have noted an average of 60 minutes required to perform flexible cricopharyngeal myotomy.
Endoscopic cricopharyngeal myotomy shares common techniques and tools that can be borrowed from those used to perform ESD and per oral endoscopic myotomy. With advancements and increased utilization of these techniques, experienced therapeutic endoscopists are poised to perform transoral flexible endoscopic therapy of ZD.
Selected expert therapeutic endoscopists may carefully consider developing and offering this therapy for their patients. For those advanced endoscopists planning to incorporate this technique into clinical practice, we recommend utilizing animal models to gain familiarity with the procedure. An animal model using domestic pigs has been previously described in the literature. Pigs are ideal because of a normal anatomic pharyngeal pouch that resembles a ZD and permits diverticulotomy using the devices described above.
Flexible Endoscopic Approach
Transoral endoscopic therapy using a rigid endoscope cannot be performed in all patients. An open approach is required in 15% to 68% of cases when inadequate rigid endoscopic exposure of the diverticulum occurs from upper teeth protrusion, inadequate jaw opening, or insufficient neck mobility. Additionally, the risk of perforation is increased with insertion of a rigid diverticuloscope when there is insufficient protection of a small diverticulum sac by the dorsal esophageal wall.
There is a variety of techniques and methods to perform flexible endoscopic transoral cricopharyngeal myotomy. The septum (CP muscle) is commonly divided using a needle knife (normally used for endoscopic retrograde cholangiopancreatography use) or cutting devices designed for endoscopic submucosal dissection (ESD), such as a hook knife (Figure 5A–C). Other methods used to divide the septum include monopolar and bipolar forceps, argon plasma coagulation, harmonic scalpels and stapling devices, the latter two of which are passed alongside the endoscope and not through the flexible endoscope channel. The optimal cutting technique remains elusive as comparative trials in this arena are lacking. Some therapeutic endoscopists advocate for the use of a soft diverticuloscope to stabilize the septum, improve visualization, and further guide the instrument of incision. This accessory is positioned such that it straddles the septum with stabilizing flanges within the upper esophageal lumen and within the ZD, although it is not available in the United States. Other accessories used to enhance visualization include transparent hoods or caps attached to the tip of the endoscope, generally reserved for endoscopic mucosal resection. When the soft diverticuloscope is not used, the preprocedural placement of a nasogastric tube is a frequent maneuver and has a dual benefit. The tube acts as an incisional guide while also serving as a method to deliver enteral nutrition in the event of a procedural AE, such as perforation. If placed nasally, the use of a small-caliber endoscope is used to perform transnasal endoscopy and avoid transfer of the guidewire. A small hole is cut in the tip of the nasogastric tube to allow wire passage. Blind passage of a nasogastric tube is not recommended.
(Enlarge Image)
Figure 5.
Flexible endoscopic cricopharyngeal myotomy for ZD therapy. (A) Endoscopic view with short, clear cap attached to endoscope tip. Nasogastric tube is in place, and hook knife sheath is seen. (B) Midpoint of the cricopharyngeal myotomy procedure. (C) Completion myotomy.
The transoral flexible endoscopic approach to ZD was first described nearly 20 years ago. Since then several series have been published that highlight a variety of efficacious technical applications and an acceptable safety profile. This technique successfully reduces cricopharyngeal sphincter pressure and has been shown to be comparable to the use of a rigid transoral diverticuloscope in terms of efficacy and safety. Nonetheless, flexible transoral cricopharyngeal myotomy is not commonly performed in the United States. The advantages of a flexible endoscopic approach are the flexibility and smaller endoscope diameter, which are especially useful for patients with poor neck extension and/or limited jaw retraction. Additionally, this technique can also be performed without the use of general anesthesia. Flexible endoscopic intervention may be most suitable for elderly patients with comorbid medical conditions limiting surgical intervention. In rare instances, patient comorbidities limit even flexible endoscopic diverticulectomy. Injection of botulinum toxin into the diverticular apex has been described in a small series of 2 patients with satisfactory outcomes.
Outcome of Flexible Endoscopic Cricopharyngeal Myotomy
At the time of this writing, 18 case series have been published regarding the use flexible endoscopic therapy for the treatment of ZD (Table 1). The available studies comprise nearly 650 patients. The available data suggest that adequate treatment can be provided in 1 to 2 treatment sessions with a high rate of clinical resolution and a low rate of diverticular recurrence or persistence. The majority of the included studies report a clinical resolution rate of >90%, whereas the recurrence or persistence of clinical symptoms appears to be <20%; however, no formal definitions of clinical success exist. We believe clinical success should be based solely on improvement in symptoms and not on radiographic or endoscopic findings. The difficulty arises in regard to diversity of symptoms, which can be attributed to ZD. An additional limitation of many flexible endoscopic series is the lack of clinical follow-up. Of the 18 available studies, the length of postprocedural follow-up was not reported in nearly one-third of the studies.
AEs following flexible endoscopic therapy range from inconsequential to life threatening. In our appraisal of the available studies, we identified a median overall AE rate of 6% (range 0%–38%) in the 16 studies with available data. Bleeding is the most common intraprocedural event occurring in a minority of cases (<5%). This can generally be controlled endoscopically using a variety of electrocautery devices or endoclips. Postprocedural throat pain is nearly uniform and often requires narcotic medications. Uncomplicated subcutaneous emphysema may represent microperforation; however, this finding does not mandate surgical intervention and may occur in asymptomatic patients. Clinically relevant and potentially the most severe AE is perforation, which can be documented by extravasation of oral water-soluble contrast (Supplementary Video 2 http://www.cghjournal.org/cms/attachment/2019475005/2039575870/mmc1.mp4%20/cms/attachment/2019475005/2039575877/mmc1.flv). Fortunately, this is relatively uncommon when flexible endoscopic therapy is performed by skilled endoscopists. A recent review by Dzeletovic et al identified a median rate of perforation and/or leak of 4% (range, 0%–27%). Unfortunately, the definition and reporting of AEs have not been standardized, and we strongly recommend the use of a standardized lexicon so that meaningful comparisons between and within disciplines can be made.
Who Should be Performing Flexible Endoscopic Cricopharyngeal Myotomy?
Issues pertinent to reluctance of gastroenterologists to performing ZD therapy likely include referral patterns, procedural risks, medicolegal issues, and the complex nature of the procedure. However, the techniques used are now increasingly practiced during many other advanced therapeutic endoscopic procedures.
There is still no consensus on the technical details when ZD therapy is performed using a flexible endoscope. One cannot underestimate the technical expertise involved in this treatment. We believe endoscopists with training in advanced endoscopy and experience in advanced endoscopic techniques, especially in the use of electrocautery devices, ESD, and possibly endoscopic retrograde cholangiopancreatography (because the use of needle-knife therapy is common), should perform ZD therapy. Some authors have noted an average of 60 minutes required to perform flexible cricopharyngeal myotomy.
Endoscopic cricopharyngeal myotomy shares common techniques and tools that can be borrowed from those used to perform ESD and per oral endoscopic myotomy. With advancements and increased utilization of these techniques, experienced therapeutic endoscopists are poised to perform transoral flexible endoscopic therapy of ZD.
Selected expert therapeutic endoscopists may carefully consider developing and offering this therapy for their patients. For those advanced endoscopists planning to incorporate this technique into clinical practice, we recommend utilizing animal models to gain familiarity with the procedure. An animal model using domestic pigs has been previously described in the literature. Pigs are ideal because of a normal anatomic pharyngeal pouch that resembles a ZD and permits diverticulotomy using the devices described above.
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