Peroral Endoscopic Myotomy with EndoFLIP and Double-Endoscope: Novel Techniques for Achalasia in Pediatric Population

Introduction

Achalasia is a rare esophageal motility disorder in pediatric population with an incidence of 0.11 cases per 100,000 children. ¹ Diagnosis is established manometrically with characteristic findings of impaired esophagogastric junction (EGJ) relaxation and esophageal aperistalsis after exclusion of pseudoachalasia or mechanical obstruction. Pharmacological treatments in children including calcium channel blockers (nifedipine) and intrasphincteric injection of botulinum toxin have only short-term clinical response. ² Endoscopic pneumatic balloon dilatation and laparoscopic Heller myotomy (LHM) with partial fundoplication have been shown to be safe and effective as definitive management of pediatric achalasia.^3,4 Since the introduction of peroral endoscopic myotomy (POEM) in 2010, increasing number of studies have found satisfactory short- and long-term outcomes in adults.^5,6 However, experience of POEM for treatment of achalasia in pediatric population is limited. We herein describe the first case of pediatric achalasia managed with POEM incorporated with novel techniques using combination of EndoFLIP^® (Endoluminal Functional Lumen Imaging Probe) and double endoscope for intraoperative assessment of adequacy of myotomy.

Patient Presentation

A 11-year-old boy, who enjoyed good past health, presented with 4-month history of progressive dysphagia, repeated vomiting of undigested food, and weight loss. Regurgitation occurred shortly after ingestion and he developed progressive intolerance to both solid and liquid food with holdup sensation at retrosternal level and sometimes heartburn. He experienced marked weight loss of 9 kg in 4 months time. Physical examination was unremarkable except both the weight-for-height and body mass index-for-age dropped from 50th percentile to below 3rd percentile in months.

Esophagogastroscopy showed dilated esophagus with retained saliva and food residue (Fig. 1a) and tapered narrowing at EGJ (Fig. 1b). There was no mechanical obstruction. Barium swallow revealed dilated lower esophagus with decreased primary peristalsis but preserved tertiary contractions. Characteristic bird beak sign with pooling and stasis of barium was noted (Fig. 1c). Esophageal high-resolution manometry (HRM) revealed impaired EGJ relaxation with median integrated relaxation pressure of 31.5 mmHg for 10 test swallows and panesophageal pressurization representative of achalasia type II pattern according to Chicago classification (Fig. 1d). ⁷ Eckardt symptoms score was 9 (2 for weight loss; 3 for both dysphagia and regurgitation; 1 for retrosternal pain). ⁸

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FIG. 1.

(a) Esophagogastroscopy showed dilated esophagus with pooling of saliva and food residue at lower esophagus. (b) Dilated esophagus with tapered narrowing at EGJ. (c) Barium swallow showed characteristic bird beak sign with pooling of barium in the absence of distal obstruction. (d) HRM revealed impaired EGJ relaxation and panesophageal pressurization. HRM, high-resolution manometry; EGJ, esophagogastric junction.

Operative technique

POEM was performed under general anesthesia. A 9.9-mm-diameter forward-viewing gastroscope (Olympus GIF-HQ190) was used. EGJ was identified at 36 cm from incisor. EndoFLIP was used intraoperatively before and after POEM. EndoFLIP involved a balloon catheter containing an array of electrodes and pressure transducers that measured impedance at different levels, which was inversely proportional to the cross-sectional area at that locus. The balloon was inflated to 30 mL to hourglass shape with the narrowest cross-sectional area at the level of EGJ. EGJ distensibility could, therefore, be calculated with this impedance planimetry technique by using the formula of narrowest cross-sectional area in mm²/intraballoon pressure in mmHg.^9,10 Before POEM, the EGJ distensibility index was 1.7 mm²/mmHg, intraballoon pressure was 27.3 mmHg, and the minimal EGJ diameter was 8.5 mm. Submucosal injection of saline mixing with 0.3% indigo carmine and adrenaline (500:5:1 mL) using ERBE HybridKnife^® was performed at 10 o'clock over anterior wall of the midesophagus at 28 cm level. Mucosa was opened longitudinally using ENDO CUT^® Q mode of ERBE VIO^® 300S machine (Fig. 2a). A submucosal tunnel was created from the mucosal entry site down and ∼3 cm beyond the EGJ (Fig. 2b), of which the position was confirmed by identifying the palisading vessels within the submucosal layer at the EGJ (Fig. 2c) and bluish discoloration of the gastric cardia mucosa on retroflexed endoscopic view in stomach (Fig. 2d). Anterior myotomy cutting the circular muscle layer while preserving the longitudinal muscle was performed with combination of End cut Q (effect 3, cut duration 1 or 2, cut interval 4) and coagulation mode (40 watts, effect 2) at 12 o'clock from 30 cm level toward the EGJ and 2 cm beyond (Fig. 2e). Double-endoscope technique was used to confirm the adequacy of myotomy by inserting a 5-mm-diameter endoscope (Olympus GIF-XP260 N) through nostril into stomach and observing the transillumination of first endoscope at the end of submucosal tunnel. After POEM, repeat EndoFLIP measurements revealed increased minimal EGJ diameter to 11.2 mm, decreased intraballoon pressure to 17.5 mmHg, and increased distensibility index from 1.7 to 6.0 mm²/mmHg (Fig. 2f). Mucosal opening was closed with hemostatic clips (Olympus EZ clips 90 degrees) (Fig. 2g). Endoscopic examination at the end of the procedure showed widely patent EGJ before decompression of stomach (Fig. 2h).

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FIG. 2.

(a) Submucosal dissection with injection of indigo carmine–saline. (b) Submucosal tunnel created (arrow) and true lumen of esophagus (asterisk). (c) Presence of palisading vessels within the submucosal layer at EGJ. (d) Identification of EGJ with bluish discoloration at the gastric cardia on retroflexed endoscopic view in stomach. (e) Anterior myotomy cutting the circular fibers (f) EndoFLIP^® measurements of distensibility index before (left) and after (right) POEM. The hourglass-shape balloon with the narrowest area corresponding to the level of EGJ (g) Mucosal closure with hemostatic clips. (h) Widely patent EGJ after POEM on air sufflation. EndoFLIP, Endoluminal Functional Lumen Imaging Probe; POEM, peroral endoscopic myotomy.

Gastrografin esophagogram was performed on postoperative day 1 and showed smooth passage of contrast without leakage. He tolerated fluid diet well without dysphagia or regurgitation and was fit for discharge on postoperative day 3. Antibiotics and proton pump inhibitors (PPIs) were prescribed for 1 week and 1 month, respectively. At 1-week follow-up after POEM, Eckardt symptoms score improved from 9 to 0 though he experienced mild nocturnal heartburn sensation, which was alleviated with PPI. At 7-month post-POEM, Eckardt symptoms score remained zero with weight gain of >11 kg and weight-for-height regained to 50th percentile since POEM. He had been asymptomatic and not requiring any PPIs. Reassessment esophagoscopy showed widely open EGJ with easy passage of endoscope with no esophagitis (Fig. 3a), and esophageal HRM revealed normal lower esophageal sphincter resting tone and residual pressure with median integrated relaxation pressure of 3.5 mmHg (Fig. 3b). Esophageal 24-hour pH–impedance study showed no significant reflux with DeMeester score of 12.3 (Fig. 3c).

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FIG. 3.

(a) Esophagogastroscopy showed patent EGJ with easy passage of endoscope and no esophagitis. (b) Esophageal HRM showed aperistalsis but normalized LES resting tone and residual pressure with median integrated relaxation pressure of 3.5 mmHg. (c) Esophageal 24-hour pH–impedance study showed no significant reflux with DeMeester score of 12.3. LES, lower esophageal sphincter.

Discussion

Experience of POEM for treatment of achalasia in pediatric population is limited. Maselli et al. first reported successful POEM in a 3-year-old girl with Down syndrome and achalasia and showed satisfactory treatment outcomes at 1-year follow-up in 2012. ¹¹ Recently, Caldaro et al. compared the outcomes of 9 children who underwent POEM with another 9 patients who underwent LHM. ¹² The authors concluded that the POEM group had shorter operation time, longer myotomy, and shorter hospital stay than the LHM group with no differences in clinical and manometric parameters on follow-up. The largest POEM study by far included 27 pediatric patients with POEM, in which 1 patient failed submucosal tunneling due to severe adhesion. ¹³ The clinical and manometric outcomes were satisfactory on 2-year follow-up.

The technique of POEM, however, has been modified in different centers. The accurate extent of submucosal tunneling into the gastric cardia and the length of myotomy are the important determining factors to success of POEM. Majority of the studies in pediatric population described the submucosal injection of indigo carmine–saline for identification of bluish discoloration at gastric cardia; however, this method is rather crude and inaccurate. In our case, we introduced the intraoperative use of EndoFLIP system using impedance planimetry during volumetric distension, which allows real-time assessment of the distensibility of EGJ and immediate evaluation of the treatment effects after POEM. ¹⁴ This technology has been found in adult population that the intraoperative EGJ cross-sectional area during POEM for achalasia correlated with postoperative symptomatic outcomes and reflux.^15,16 Petrosyan et al. recently also described their use of EndoFLIP during both LHM and POEM, which aid in identifying the adequacy of myotomy. ¹⁷ Incorporation of double-endoscope POEM was first described in our pediatric patient for ensuring complete gastric myotomy by observing the transillumination of the dissecting endoscope at the submucosal tunnel with retroflexed view of gastric cardia using second endoscope. This double-endoscope technique has been found to result in more complete gastric myotomy with high rates of technical and clinical success in an adult study. ¹⁸ However, we have to acknowledge that this technique may not be universally applicable for smaller children or infants as the esophageal lumen might be too small to accommodate two endoscopes at the same time.

From currently available literatures, POEM for achalasia in pediatric population appears to have encouraging results similar to adult patients. However, larger case series with long-term follow-up and multicenter randomized trials are needed to establish the efficacy and safety of POEM in the pediatric population.