Endoscopic Stent Treatment for Crohn’s Disease

List of Abbreviations

CD

Crohn’s disease

EBD

Endoscopic balloon dilation

FCEMS

Fully covered self-expanding metal stent

IBD

Inflammatory bowel disease

PCSEMS

Partially covered self-expanding metal stent

SEMS

Self-expandable metal stent

Introduction

Crohn’s disease (CD) is an inflammatory disorder that can be classified as stricturing, penetrating and non-stricturing, non-penetrating behavior based on the Montreal Classification. A stricture is an abnormal area of narrowing in the intestinal lumen and develops progressively over years with the growth of fibrotic tissue in a chronic inflammatory background. Stricturing events increase with the disease duration ranging from subtle to complete obstruction and stenosis. It is seen in 30%–35% of patients within 10 years of diagnosis of CD and approximately 70%–80% of patients will eventually require surgery by 20 years. Strictures are considered clinically relevant when there is a significant narrowing of the lumen with prestenotic dilation and obstructive symptoms. Diagnosis is made by imaging studies or endoscopy.

In 80% of the patients with CD, there is endoscopic evidence of recurrence at 1 year. More than 50% of the patients would need a repeat surgery after 15 years. Over 40% have a recurrence of obstructive symptoms after 4 years and probably would require severe surgical procedures in the long term.

Specific treatment is required only for symptomatic strictures irrespective of accompanying dilation on upstream imaging. Currently, the recommended treatment for CD-associated short strictures, less than 4–5 cm, is endoscopic balloon dilation (EBD) in combination with optimum medical therapy for the active luminal disease. It is a safe and effective alternative to surgery with an approximately 2% incidence of severe adverse events such as perforation and an overall success rate ranging from 44% to 67%. However, 50%–75% of patients experience a recurrence of the stricture within 1 year of EBD. In these patients, self-expanding metal stents (SEMS) would be a minimally invasive alternative to the repeat EBD or surgery.

SEMS have so far shown promising results but has also been reported with a high rate of adverse events. Removal of the stent within the first month of deployment is required to avoid intestinal impaction. Biodegradable stents have been recently introduced to overcome these drawbacks. Their initial case reports and case series have been reassuring with acceptable clinical results and no mucosal growth. Some of the results of these studies have been criticized because they included patients naive to EBD.

We will discuss the efficacy and safety of metallic and biodegradable stents and to discuss the types of the stents, their indications, and their clinical utility in CD.

Types of Stents

Based on the type of the material, stents are classified into three categories: (1) metallic; (2) plastic; and (3) biodegradable. SEMSs consist of knitted metal mesh cylinders which gradually expand until they reach their maximum fixed diameter. SEMSs are composed of stainless steel, alloys such as elgiloy and nitinol, or a combination of nitinol and silicone. Elgiloy is an alloy that is composed of cobalt, nickel, and chromium and generates high radial forces. Nitinol is an alloy composed of nickel and titanium, which increases flexibility and helps stenting sharply angulated turns with relatively lesser radial force. The stents also have a proximal and/or distal flare to allow anchorage of the stent edges to the gut wall thereby preventing migration. Since tissue ingrowth can occur in between the interstices of the metal stent, technological modifications by fully or partially covering the stent by a plastic membrane or silicone has been employed. Depending on the extent of coverage, the stents are classified as fully covered (FCSEMS) or partially covered SEMS (PCSEMS). The partially covered stents have uncovered segments at both ends to anchor to the tissue thereby reducing migration risk as compared to FCSEMS ( Fig. 15.1 ).

The biodegradable stents consisted of polydioxanone monofilament, which is expected to secure the integrity and maintenance of radial force for 6–8 weeks before degradation They are spontaneously degraded in 10–12 weeks.

Self-expanding Metal Stents

We have limited information on the efficacy and safety of SEMS in the management of CD-associated strictures. There have been a total of 12 case reports and four small case series which have been published ( Table 15.1 ).

Table 15.1

Studies of Patients With Crohn’s Disease Treated With Self-Expandable Metal Stent

Author	Number of Patients	Location	Previous Treatment	Technical Success	Clinical Success	Outcome
Matsuhashi et al.	2	Colon and ileocolonic anastomosis	EBD	Yes	Yes	Symptom free at 3 and 4.5 years
Wholey et al.	1	Colon	No	Yes	Yes	Bridge to surgery
Suzuki et al.	2	Colon	–	Yes	Yes	Surgery
Wada et al.	1	Colon	No	Yes	Yes	Perforation and fistula
Bickston et al.	1	Ileocolonic	EBD	Yes	Yes	Symptom free at 2 months
Dafnis	1	Colon	No	Yes	Yes	Death from lung cancer
Martines et al.	1	Ileocolonic	EBD	Yes	Yes	Bridge to surgery
Small et al.	1	Rectum	No	Yes	Yes	Bridge to surgery
Keränen et al.	2	Anastomotic stricture	No	Yes	Yes	Bridge to surgery and perforation
Levine et al.	5	Ileocolonic anastomosis	EBD	Yes	Yes	Symptom free in 80%
Attar et al.	11	Ileocolonic anastomosis and terminal ileum	EBD	Yes	Yes	Symptom free in 4/11 patients ≥1 year. Two adverse events
Branche et al.	7	Ileocolonic anastomosis	EBD	Yes	Yes	Symptom free in 5/7 patients, mean follow-up 10 months
Loras et al.	17	Ileocolonic anastomosis and colon	EBD	Yes	Yes	Symptom free in 11/17 patients, mean follow-up 67 weeks. One adverse event.

EBD , endoscopic balloon dilation.

The initial experience with the use of SEMS was published as case reports. It included a total of 12 cases with the placement of 20 stents. There was a wide heterogeneity among the patients and the type of stent used. Also, in 50% of the patients, the stents were used as a bridge to surgery making it difficult to interpret the results.

One of the first retrospective series reported a total of five patients with refractory ileocolonic postoperative anastomotic strictures. Uncovered SEMS was used in this series and hence were not removed. The procedure was considered successful in four patients, with long-term follow-up in two of them. The fifth patient experienced delayed stent occlusion with subsequent resection and removal of the stent.

Subsequently, in a larger series of 11 patients of which nine patients had previous ileocolonic or ileocecal resection and two were naive to surgery, FCSEMS was placed. The procedure was completely satisfactory (stent removal with a disappearance of obstructive symptoms) in only one patient. In another three patients with spontaneous migration of the stent, patients were symptom free for more than 1 year. In two cases, urgent surgery was required because of stent migration. Stent migration can lead to impaction, perforation, and a need for additional surgery, which suggests that stent movement in a controlled pattern is necessary to lower the risks.

Due to poor results related to stent migration, the same group conducted another study using PCSEMS. It involved seven patients with previous ileocolonic anastomosis (<5 cm). They were treated with PCSEMS that was removed at 7 days. Around 72% of patients remained asymptomatic at the median follow-up of 10 months without any stent migration or adhesion. The largest case series of CD patients treated with SEMS was published recently. It was a retrospective Spanish cohort study involving six centers. They evaluated the efficacy and safety of SEMS for the treatment of CD-associated symptomatic strictures refractory to medical and or endoscopic treatment. A total of 25 stents (4 PCSEMS and 21 FCSEMS) were placed in 17 patients with stenosis (<8 cm) in the colon and ileocolonic anastomosis. Out of 17 patients, 13 had prior surgeries before the stent placement and 14 had a history of unsuccessful endoscopic dilation. Clinical success was defined as remaining free of obstructive symptoms at the end of the follow-up of at least 1 year after the procedure, without major complications. Clinical success was achieved in 11/17 patients (64.7%) over a mean follow-up period of 67 weeks (11–272). The technical success rate for stent placement was achieved with 23 of 25 stents (92%). The removal of the stent was technically difficult in 2 out of 4 PCSEMS (50%) and 2 out of 21 FCSEMS (9.5%); in these cases, SEMS were maintained for 8 and 16 weeks, respectively, and this long period was probably responsible for their adherence. Spontaneous stent migration was observed in 13 of 25 stents (52%) and was believed to be due to the resolution of stenosis in 11 of 13 patients (84.6%). One patient developed severe complication due to proximal stent migration during insertion. Its endoscopic removal was not possible due to colonic angulations and therefore another stent was inserted during the same procedure. He underwent a surgical removal of the stent 4 months later and remained asymptomatic during this time.

Biodegradable Stents

Biodegradable polydioxanone stents were developed and licensed for the treatment of refractory benign esophageal strictures. In a study which included 21 patients with benign esophageal strictures, biodegradable stents were used, and an efficacy of 45% (9 of 21 patients) was observed over a mean follow-up of 53 weeks (25–88). Although they were initially used in the left side of the colon, a custom-made system is now available to facilitate stent deployment in the proximal colon, ileum, or duodenum. Regarding the use of biodegradable stents in CD patients, to date, only one small series of patients (n = 11) and two case reports have been published.

A study involved using biodegradable stents in 11 patients with CD having short stenosis (<50 mm) at various locations (small intestine, colon, ileocolonic anastomosis). They had one faulty insertion, three migrations (2 of them in 2 days), one relapse at 4 months requiring placement of a new stent, and one stent shortening. The mean time to stent degradation in the other seven patients was 4 months. No immediate adverse events including perforation occurred in this study. Overall success rate of 54%–63% was observed over a median follow-up of 17 months (12–29 months).

In recently published case reports, biodegradable stent was successfully placed in a woman with CD and colonic stenosis of 6 cm length. Similarly, in a man with an inflamed 12-cm small bowel stricture in the ascending limb of an ileoanal J-pouch, a biodegradable stent was successfully placed with successful outcome. In a study by Karstensen et al., six patients with CD were included. Out of them, three patients had native strictures, one had an ileocolonic postoperative stricture, and other two had duodenal or postcolectomy strictures. They used biodegradable stent after a mean of 5.5 sessions of balloon dilation. Technical success was observed in five out of six patients. However, there was no clinical success. Stent migration was noted in one patient.

Severe mucosal hyperplastic reaction leading to obstruction after biodegradable stenting has been reported in esophageal strictures but not in the intestinal strictures so far. Most of them were successfully treated with single balloon dilation and have been resolved after stent degradation.

In conclusion, biodegradable polydioxanone stents represent a new therapeutic option for CD patients with strictures in which EBD is unsuccessful or for refractory bowel strictures. Further studies are necessary to fully assess their long-term efficacy and safety.

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