Introduction
Esophageal strictures (ES) are circumscribed narrowing of the esophageal lumen to
a diameter < 13 mm which lead to dysphagia, difficulty in swallowing. Benign esophageal
strictures (ES) are more common and can be due to various etiologies like corrosive
ingestion, peptic disease, radiotherapy for head and neck cancers, and postoperative
strictures. Endo-therapy is also first-line management for benign strictures. Dilation
by bougie or balloon dilators has been the standard treatment for benign ES and generally
the simple ones respond adequately to one to three dilations [1]. Complex strictures, however, are difficult to treat being longer (> 2 cm), angulated
or with severely stenosed lumen [2]. Approximately 20 % to 30 % of benign strictures can become refractory to endoscopic
dilation, and as many as 50 % in cases of corrosive strictures [3]. Factors determining response to endo-therapy have been the point of much research.
Techniques that have been studied to predict response to endoscopic dilations include
contrast-enhanced computed tomography (CECT) scans and endoscopic ultrasound (EUS).
Esophageal wall thickness (EWT) on CECT has been found to correlate with response
to dilation in one study [4] but not in another [5]. EUS, using radial probe, placed at the proximal margin of the stricture, has been
used to predict response to dilation based on the depth of tissue injury, i. e. the
number of layers of esophageal wall involved [6]. The main drawback of the radial EUS probe is that it may not generally be negotiable
across the stricture segment, and hence, may result in inadequate characterization
of esophageal wall involvement.
EUS mini-probes (EUS-M) are high-frequency (12 – 20 MHz) three-dimensional (3 D) catheter
probes that can be easily negotiated across the stricture segment without dilation,
enabling high-frequency image acquisition. There is only one study of EUS-M in patients
with benign ES, wherein the authors showed that mucosal involvement required fewer
endoscopic dilation sessions compared to deeper involvement [7] .
With a lack of data on use of EUS-M in evaluation and prediction of response of benign
ES to dilation therapy, this study was planned as a proof-of-concept to analyze benign
ES with EUS-M and identify characteristics that can help in predicting its response
to dilation therapy.
Patients and methods
This was a prospective study of all consecutive patients with benign ES who presented
to the Department of Gastroenterology in a tertiary care center with dysphagia between
June 2019 and December 2019. Patients who had esophageal webs, stricture length > 6 cm,
malignant or post-radiation strictures or who had undergone prior endoscopic intervention
were excluded. Written informed consent were obtained from all patients. The study
was approved by the Institute ethics committee (ethics clearance number INT/IEC/2019/001416,
dated 16.07.2019).
Baseline evaluation
All patients underwent barium esophagography to assess the site, number, and length
of stricture(s) and associated gastric involvement. Each patient also underwent an
esophagogastroduodenoscopy (EGD) evaluation using a gastroscope (Olympus GIF-H180;
outer diameter 9.9 mm.) for stricture site, number, length, and presence of ulceration.
Stricture diameter was assessed by the size of the first balloon dilator used for
dilation. The esophagus was divided into upper one-third (upper esophageal sphincter
to 23 cm), middle third (23 – 31 cm) and lower third (31 cm to lower esophageal sphincter).
An EUS mini-probe (Olympus UM-DG20–31 R, freq. 20 MHz; diameter 2.2 mm) was used to
evaluate the stricture. Under direct endoscopic vision, the mini-probe was passed
through the lumen of the stricture. If the probe could not be passed across the stricture
initially, a guidewire (0.025, 270 cm, Visiglide, Olympus, United States) was inserted
first using a standard cannula (Olympus, United States) and then the probe was inserted
over the guidewire. Assessment of the stricture was done by direct contact method.
EUS-M evaluation was carried out by a single experienced operator (JS) with experience
of performing > 3,500 EUS procedures. Initially, the probe was passed across the length
of the stricture, and then gradually pulled proximally. Layers of the esophagus, namely
the mucosa, submucosa, muscularis and the outer adventitial layers, were identified
and the stratification, thickness, symmetric or asymmetric thickening, and depth of
the stricture was noted in terms of involvement of the layers ([Fig. 1]). The segment of the stricture with the maximum wall thickness was considered for
evaluation of the characteristics and measurements.
Fig. 1 Schematic diagram of the layers of the esophagus on EUS assessment.
Measurements were taken for total EWT and thickness of the involved part of the wall.
Thickness was measured from the luminal mucosal layer to the outer layer of the esophagus
for total wall thickness and up to the outer margin of the stricture for involved
part thickness. The percentage of the esophageal wall involved by the stricture ({involved
part thickness/total wall thickness} *100) also was calculated.
Endoscopic dilation
Endoscopic dilation was done after informed consent and as an outpatient procedure
([Fig. 2]). Patients underwent sedation with intravenous midazolam (initially 0.5 – 1 mg,
dose titrated to effect with cumulative dose < 5 mg) with/without intravenous (IV)
pentazocine (20 – 30 mg) before dilation. Dilation was performed using balloon dilators
(CRE balloon, Boston Scientific, Marlborough, Massachusetts, United States). The diameter
of the balloon was determined on the basis of the endoscopist’s subjective assessment
and imaging findings. The balloon was negotiated across the narrowed segment under
endoscopic vision and was positioned approximately equally on either side of the narrowing
and inflated by a saline-filled pressure gun (Alliance inflation device; Boston Scientifc
Corp, Marlborough, Massachusetts, United States) as per manufacturer’s instructions.
The balloon was inflated to incremental diameters, for 60 seconds at each diameter.
Fig. 2 Study design.
After each dilation, patients were observed for 4 hours with specific attention to
the occurrence of chest pain, abdominal pain, and difficulty in breathing and hemodynamic
status. Patients were discharged home the same day with instructions to immediately
report if they developed any fever, chest pain, or shortness of breath. They were
followed up for a period of 48 hours post-procedure via telephone calls. In the event
of suspected perforation, a water-soluble contrast study was performed to document
any leak, and urgent surgical consultation was sought. Patients with peptic strictures
were prescribed proton pump inhibitors (PPI) besides dilation.
Dilation was repeated at 2 – to 3-week intervals until a target diameter of 15 mm
was achieved. Patients with refractory strictures were considered for endoscopic injection
of steroids into the stricture. Triamcinolone acetonide (80 mg, diluted 1:1 with saline
solution) was injected with a 23-gauge, 5-mm-long sclerotherapy needle in aliquots
of 0.5 mL each as described in detail elsewhere [8].
Definitions
-
Dysphagia was graded on a scale of 0 to 4. [9]
-
Clinical success (responders) was defined as resolution of difficulty in deglutition
with symptomatic improvement to a dysphagia score of less than 2 and achievement of
15-mm dilation [10].
-
Refractory stricture (RS) was defined if even after five sessions of dilation, the
patient still remained symptomatic or the stricture could not be dilated to a diameter
of 15 mm [10].
Follow-up imaging
All patients underwent repeat EUS-M assessment after the initial maximum of five sessions
of dilations and were assessed for the same parameters as mentioned above.
Data analysis
Very limited data exist on the role of EUS-M in esophageal strictures, hence this
study was conducted as a proof-of-concept. Patients were grouped into responders and
refractory stricture after the initial sessions (maximum five dilations). Assessment
of response was done by PD and RK, who were blinded to the EUS findings. JS was blinded
regarding the response.
Outcome measures
The primary outcome measure was to compare the responder and the refractory groups
for EUS-M characteristics such as total esophageal wall thickness, involved esophageal
wall thickness, and layers of esophageal wall involvement for their effects on response
to dilation. EUS-M characteristics of the strictures based on etiology were also noted
and their impact on the final outcome. The change in the involved esophageal wall
thickness after the five sessions of dilation were also compared between responders
and refractory group.
Statistical analysis
Data were entered in Microsoft Excel and analyzed using SPSS software version 23.0
(SPSS Inc., Chicago, Illinois, United States). Quantitative variables were represented
using measures of central location like mean/median/measures of dispersion (standard
deviation or standard error). Continuous variables were compared using the Student’s
t test. Dichotomous variables were compared using Chi squared test. P < 0.05 was considered statistically significant. Repeated measurement of ANOVA was
used for relationship between EUS-M layers of esophageal wall involvement and outcome.
A receiver operating characteristic curve was plotted and a cut-off of the involved
wall thickness for predicting response to dilation was calculated. Based on a previous
study [6], the dilation requirement for strictures involving muscularis propria and those not involving it were 6.30 vs 2.67 sessions. Thus, with 80 % power and
alpha error estimation of 5 %, a sample size of 14, with seven having muscularis involvement and seven without, was estimated.
Results
Forty patients with benign ES were screened to be enrolled in this study. Of the 40
patients screened, eight were excluded (6 had strictures > 6 cm in length and 2 had
esophageal webs). Finally, 30 patients with 32 strictures were included in the study
([Fig. 2]).
Of the 30 patients, 17 were females; the age ranged from 19 to 71 yr (mean 47.16 ± 15.88
yr). The etiology was anastomotic (after esophago-gastric or esophago-colonic anastomosis),
n = 14 (13 for carcinoma esophagus and 1 for corrosive injury); caustic, n = 6 with
eight strictures; peptic, n = 7 and drug-induced (nonsteroidal anti-inflammatory drugs
[NSAIDS]), n = 2. Median time from symptom onset to endoscopic assessment was 3 months
(IQR 10). Of the seven cases of peptic stricture, three had ulceration and the remaining
four did not. None of the other strictures had hyperemia or ulceration. Mean length
of strictures on barium esophagography was 3.45 cm (standard deviation 4.6 cm.), without
any ulceration or intra-mural pseudo-diverticula. The most common site of stricture
was the upper esophagus (14; 45.2 %) followed by middle and lower third of the esophagus
(6 each; 19.4 %).
After the initial phase of a maximum of five sessions of dilations as described above,
23 patients were classified as responders and eight had refractory strictures. One
patient expired due to an unrelated cause and was excluded from the final analysis.
Of the eight refractory strictures, six improved after an additional three to five
sessions of dilation with intralesional triamcinolone, while one underwent surgery
and one was lost to follow up ([Fig. 2]). The response to dilation is summarized in [Table 1].
Table 1
Response of dilations according to etiology.
|
Type of Stricture
|
No. of Patients/Strictures
|
Responders (%)
|
No. of Dilations to 15 mm (mean no. to reach 15 mm)
|
Complications
|
|
Anastomotic
|
13/13
|
8 (61.5 %)
|
4.28
|
nil
|
|
Corrosive
|
6/8
|
6 (75 %)
|
4
|
nil
|
|
Peptic
|
7/7
|
100 %
|
2.42
|
nil
|
|
NSAIDs
|
2/2
|
50 %
|
1.5
|
nil
|
NSAIDs, non-steroidal anti-inflammatory drugs
EUS mini-probe assessment
Of the 30 patients with 32 strictures, EUS-M stricture assessment was done in 31 strictures.
This included two patients with two strictures each, whose individual strictures were
analyzed separately at the start of intervention and on follow-up. In one patient,
EUS-M assessment could not be done as the patient did not give consent for the same.
EUS mini-probe characteristics based on etiology of stricture
[Table 2] shows details of EUS-M evaluation in patients with different etiology. Corrosive
strictures had the highest total esophageal wall thickness (4.66 ± 1.34 mm) followed
by anastomotic (4.00 ± 1.54 mm) and peptic strictures (3.44 ± 1.3 mm); P = 0.275. The two patients with NSAID-induced strictures had wall thickness of 9.2 mm
and 3.2 mm. Patients with corrosive strictures had the most involved esophageal wall
thickness and percentage of the esophageal wall involved followed by anastomotic and
peptic strictures (P = 0.026 and P = 0.021, respectively).
Table 2
Comparison of EUS findings in esophageal strictures based on etiology.
|
EUS mini-probe Findings[*]
|
Anastomotic stricture (n = 13)
|
Corrosive stricture (n = 8)
|
Peptic stricture (n = 7)
|
P value
|
|
Total esophageal wall thickness (mean ± SD in mm)
|
4.00 ± 1.54
|
4.66 ± 1.34
|
3.44 ± 1.3
|
0.275
|
|
Involved esophageal wall thickness (mean ± SD in mm)
|
2.73 ± 1.7
|
3.51 ± 1.36
|
1.39 ± 0.62
|
0.026
|
|
Percentage of esophageal wall involved by the stricture (mean ± SD in percentage)
|
65.54 ± 25.4
|
76.38 ± 26.2
|
40.71 ± 14.6
|
0.021
|
EUS, endoscopic ultrasound; SD, standard deviation.
* Two patients had nonsteroidal anti-inflammatory drug-related stricture and are not
shown in this table.
EUS mini-probe characteristics and outcome
EUS-M findings of 30 strictures were compared between responders and non- responders
([Table 3]). [Table 3] shows that baseline EUS features of the strictures such as total esophageal wall
thickness and involved esophageal wall thickness did not differ between those who
improved compared to those who did not. The percentage of esophageal wall involved
by stricture showed a trend towards significance with a higher percentage involvement
seen in those patients who developed refractory strictures.
Table 3
Comparison of EUS mini-probe findings between responders versus refractory strictures.
|
EUS mini-probe findings
|
Responders (n = 22)
|
Refractory (n = 8)
|
P value
|
|
Total esophageal wall thickness (mean ± SD in mm)
|
4.30 ± 1.91
|
3.78 ± 0.92
|
.474
|
|
Involved esophageal wall thickness (mean ± SD in mm)
|
2.51 ± 1.82
|
2.87 ± 1.44
|
.613
|
|
Percentage of esophageal wall involved by the stricture (mean ± SD in percentage)
|
55.23 ± 23.23
|
72.50 ± 27.87
|
.098
|
EUS, endoscopic ultrasound; SD, standard deviation.
However, when a cut-off of 2.85 mm of the involved wall thickness was used, there
was a statistically significant difference in mean number of dilations needed for
stricture resolution ([Fig. 3]). Strictures with involved wall thickness ≥ 2.85 mm required a mean of 5.10 dilations
compared to 2.83 for those < 2.85 mm (P = 0.011). The cut-off of 2.85 mm for involved wall thickness had a sensitivity of
67 % and specificity of 73 % for predicting requirement of more than five sessions
of intervention for stricture resolution.
Fig. 3 Comparison of mean number of dilations needed for stricture resolution when a cut-off
of involved esophageal wall thickness of 2.85 mm is used.
Patients were categorized into two groups based on EUS-M assessment of percentage
esophageal wall involvement by the stricture ([Fig. 4]). Using a cut-off of 70 % for percentage of esophageal wall involved by stricture,
there was a statistically significant difference between responders and non-responders.
While 85.7 % patients with < 70 % involvement responded to five sessions of dilation,
response was seen in only 44.4 % for those with involvement ≥ 70 % (P = 0.019).
Fig. 4 Comparison of percentage of wall involvement between improved strictures and refractory
strictures.
Impact of esophageal wall layer involvement by stricture on outcome
Depth of esophageal wall involved by the stricture was assessed by EUS-M in terms
of number of layers affected before start of intervention. Only mucosal involvement
was noted in 15 strictures, mucosal and submucosal involvement in nine and all three
layers involved in six ([Fig. 5]). We analyzed response based on the layers of involvement. More dilations were needed
for symptom resolution with increasing depth of involvement of esophageal layers from
mucosa to muscularis propria ([Table 4]). The responder group had more strictures with only mucosal involvement (13; 59.1 %
vs. 2; 25 %) and fewer with all layer involvement (3; 13.6 % vs. 3; 37.5 %) compared
to refractory group although the difference did not reach significance (P = 0.077).
Fig. 5 EUS mini-probe images of strictures. a Corrosive stricture involving all layers of the esophageal wall, D1 is the involved
wall thickness-3.1 mm. b Corrosive stricture with involvement till the submucosa, D2 is the involved esophageal
wall thickness –2.2 mm. and D1 is the total wall thickness –4.8 mm. c Peptic stricture involving the mucosa, involved wall thickness is D2 – 1.9 mm. and
D3 is total esophageal wall thickness –4.6 mm.
Table 4
Number of dilations needed for clinical response according to the layers of esophageal
wall involved.
|
EUS mini-probe layers of esophageal wall involvement
|
Total number
|
Mean number of dilations for clinical response (± SD)
|
P value
|
|
Layer 1 = only mucosa (no.)
|
15
|
2.14 (± 1.83)
|
.001
|
|
Layer 2 = mucosa + submucosa (no.)
|
9
|
4.78 (± 1.85)
|
|
Layer 3 = mucosa + submucosa + muscularis propria (no.)
|
6
|
5.80 (± 1.64)
|
EUS, endoscopic ultrasound; SD, standard deviation.
Change in the esophageal wall layer thickness after dilation
Change in EWT was assessed by EUS-M after five sessions of intervention. Repeat EUS
assessment was available for 20 strictures and comparison between those who responded
and those who were refractory is shown in [Table 5]. Mean change in total EWT was significantly higher in the responder group compared
to the refractory group (1.32 vs 0.200; P = 0.023) with greater percentage change in the wall thickness (29.1 % vs 5.7 %; P = 0.003).
Table 5
Comparison of change in esophageal wall thickness with intervention between responder
and refractory groups.
|
EUS mini-probe findings
|
Responder N = 14
|
Refractory N = 6
|
P value
|
|
Mean change in total esophageal wall thickness in mm (± SD)
|
1.32 ± 1.1
|
0.200 ± 0.12
(± 1.08)
|
0.023
|
|
Mean Percentage change in esophageal wall thickness in % (± SD)
|
29.1 ± 16.3
|
5.7 ± 3.13
|
0.003
|
EUS, endoscopic ultrasound, SD, standard deviation.
Discussion
In this study, we assessed the utility of EUS-M in predicting response of esophageal
strictures to endoscopic dilation in a cohort of 28 patients with 30 strictures. Although
total EWT on EUS among different etiologies of stricture did not differ, but there
were significant differences based on involved wall thickness and percentage of esophageal
wall involvement. Corrosive strictures had the most involvement of wall thickness
and percentage of esophageal wall involvement followed by anastomotic strictures,
while peptic strictures had the lowest value. Mean number of dilations required for
stricture resolution was found to be significantly dependent on the layers of the
wall involved.
Stricture formation occurs due to fibrous tissue production and collagen deposition
in the esophageal wall, leading to narrowing of the esophageal lumen. Both circumferential
and longitudinal collagen deposition has been demonstrated after corrosive esophageal
injury [11]. The esophageal wall gets markedly thickened secondary to this deposition [4]. Similarly, anastomotic strictures develop from the ischemic injury incurred, leading
to similar collagen deposition and fibrosis [12]. Ulceration, hyperemia, and other factors can confound the findings of wall thickness
or involvement. However, only three patients with peptic strictures in the current
study had ulceration. None of the patients in the corrosive or anastomotic group had
ulceration. In fact, corrosive and anastomotic strictures are known to be complex
strictures. Earlier studies using EUS did show that corrosive and post-radiation strictures
have thicker EWT compared to peptic strictures [6]
[7]. Using EUS-M, we found that while the total EWT was no different among patients
with different etiologies, the involved EWT was higher in corrosive strictures (3.51 ± 1.36 mm)
than in anastomotic strictures (2.73 ± 1.7 mm) and peptic strictures (1.39 ± 0.62 mm).
The percentage of involved EWT was also highest in corrosive strictures followed by
anastomotic and peptic strictures.
Prediction of stricture resolution following dilation has been the subject of much
interest as it may be helpful in predicting outcome and counselling patients. Moreover,
rescue measures used for refractory strictures could be employed upfront in predicted
poor responders. Lahoti et al evaluated the role of CT imaging in prognosticating
corrosive esophageal strictures in 21 patients [4]. They found that patients with maximal wall thickness ≥ 9 mm required more dilations.
However, a recent study of 64 patients with corrosive strictures showed that median
CT esophageal wall thickness was 7 mm (range 3 – 22 mm) and that it did not predict
technical or clinical success, refractory or recurrent strictures and adverse events
of endoscopic dilation [5]. CT can evaluate overall wall thickness, but it cannot delineate the wall layers
and hence their degree of involvement. Therefore, the role of EUS is important because
it can image layers of the wall of the esophagus and thus the depth and degree of
involvement.
Radial EUS has been used to assess benign ES in 27 patients [6] in one study and it was found that corrosive and post-radiation strictures had significantly
greater wall thickness compared to peptic strictures. Moreover, depth of wall involvement
on EUS predicted endoscopic dilation response. However, this assessment could be done
only from the mouth of the stricture. Adequate examination of the whole length of
the stricture is needed for effective measurement of the EWT and the layers involved
as evidently these strictures need not be uniform in their depth of involvement along
the longitudinal axis. For that to be done with radial EUS, the stricture has to be
dilated. That might not only distort the subsequent image acquisition, but even after
dilation, the sturdy echoendoscope might not be successfully maneuvered across the
stricture. EUS-M has clear advantages in this regard, as it can be easily passed across
tight strictures without dilation. In a recent study, EUS-M was used to assess indeterminate
strictures wherein only total wall thickness was assessed and the conclusion was that
wall thickness ≥ 9 mm was suggestive of malignancy [13]. In the only other study of EUS-M for benign ES, the authors only looked into maximum
EWT and layers of the wall involved. Both those parameters were found to correlate
with increased requirement for dilation [7].
Our study, using EUS-M, demonstrated that rather than the total wall thickness, it
is the depth of esophageal wall involved by the stricture that is predictive of treatment
response. We looked at total EWT, involved EWT, and percentage of the wall involved
in patients who responded and those who had refractory strictures. There was no difference
in any of the three measurements between the two groups although there was a trend
towards a higher percentage of esophageal wall involved in the refractory strictures.
Moreover, > 70 % esophageal wall involvement correlated with number of dilations required.
Analyzing further, we found that depth of wall involvement in terms of the layers
of wall did correlate with the outcome. Patients with only mucosal fibrosis had the
best response while those with involvement of muscularis propria had the worst. This observation could only be made by using EUS-M and not with any
other imaging. Esophageal wall edema can confound the findings on wall thickness.
However, all patients in the current study were in chronic phase (> 3 months) and
thus had fibrotic strictures, evident from the scarred tissue on endoscopy, rather
than edema. Moreover, edema can be delineated on EUS as hypoechoic areas within the
layers, which was not present in any of the cases in the current study. Thus, we believe
that edema did not contribute to esophageal wall involvement in any of our patients.
This relates to the fact that depth of involvement of a stricture, which is an indirect
clue to the depth of injury, determines the “refractoriness” of the stricture. The
deeper the involvement, the greater the fibrosis and more difficult it is to break
it. Corrosive strictures are known to be refractory due to the deeper tissue injury,
a fact that has been highlighted in the current study. Anastomotic stricture, being
ischemic in nature, corresponds to similar deep involvement [12]. Peptic strictures, on the other hand, are usually short (< 1 cm) and start with
edema associated with chronic inflammation and eventually lead to fibro-collagen deposition
[14]. They are usually simple strictures and rarely tends to be refractory [2].
An interesting observation was repeat imaging in 20 patients that showed greater change
in total EWT and percentage change in EWT in responders as compared to refractory
strictures. The major factor contributing to the thickness of the involved segment
was the extent of fibrosis. More effective breakage of this fibrotic tissue leads
to better treatment response and indirectly reflects greater change in wall thickness
after dilation. Our study is the first to demonstrate this phenomenon objectively,
that is, greater change in wall thickness occurs among responders compared to those
who are refractory.
This was the first study to include a detailed evaluation of EUS-M in patients with
benign ES in terms of total EWT, involved EWT, and depth of involvement, its impact
on the outcome and also to compare the three different etiologies influencing characteristics
of strictures. Moreover, the dynamics of the stricture characteristics before and
after dilation and its impact were demonstrated. In a sense, in patients with deeper
involvement, as assessed on EUS-M, and thus expected poor outcome with conventional
dilation techniques, additional measures such as stents or surgery can be undertaken
up front. Moreover, recent advances in management of difficult strictures and complete
esophageal obstruction involve techniques such as open per-oral endoscopic myotomy
(O-POEM) and per-oral endoscopic tunneling for restoration of esophagus (POETRE) [15]. In these situations, involvement of muscle layer by EUS-M can help predict the
feasibility of these techniques [16]. We propose that, with adequate validation, the concept of EWT assessment prior
to subjecting patients to dilation can be incorporated in an algorithm to guide optimum
management of ES, thus avoiding the tedious route of initial conventional dilation
regimens.
The limitations of this study were that the sample size was small. Moreover, repeat
EUS-M evaluation was available only for 20 strictures. Larger studies are needed to
consolidate the findings of the current study. Our study did not include radiation
strictures, which is an important cohort of refractory cases and warrants further
study along the same lines. Stricture diameter assessment requires more objective
measurement, such as with a barium pill.
Conclusion
In conclusion, this was the largest study to evaluate the role of EUS-M for predicting
response of benign ES to endo-therapy. EUS-M, which can be negotiated across the stricture
segment, provides high-resolution images and is a useful tool for adequately assessing
stricture dynamics. Corrosive and anastomotic strictures have greater depth involvement
compared to peptic strictures, hence their expected refractoriness to therapy. Depth
of involvement by a stricture and the layers of the esophageal wall involved rather
than the esophageal wall thickness predict whether a stricture will respond to endo-therapy.
