Clinical utility of cricopharyngeal distensibility measurements during endoscopic myotomy for Zenker's diverticulum.

BACKGROUND AND AIMS Flexible endoscopic cricopharyngeal myotomy (FECM) allows minimally invasive treatment of patients with Zenker's diverticulum (ZD); however, retreatment rates are substantial. We hypothesized that the functional lumen imaging probe (FLIP) may provide insight into ZD pathophysiology and serve as an intraprocedural guide to adequacy of myotomy. METHODS We prospectively evaluated 11 ZD patients undergoing FECM and compared the baseline cricopharyngeal distensibility with 16 controls. Intraprocedural cricopharyngeal distensibility was measured immediately pre- and postmyotomy. The cricopharyngeal-distensibility index (CP-DI) was defined as a ratio of the narrowest cross-sectional area (nCSA) and the corresponding intrabag pressure at 40 mL distension. Same-procedure myotomy extension was undertaken in a subgroup if threshold distensibility changes were not met. RESULTS ZD patients had reduced baseline nCSA and CP-DI compared with controls, (169.6 vs 227.5 mm2, p<0.001 and 3.8 vs 7.6 mm2/mm Hg, p<0.001, respectively). After cricopharyngeal myotomy, both nCSA and CP-DI increased significantly by an average of 74.2 mm2 (95% CI, 35.1 - 113.3; p=0.002) and 2.2 mm2/mm Hg (95% CI, 0.6 - 3.8; p=0.01), respectively. In the subgroup with no significant change in cricopharyngeal distensibility after initial myotomy (n=6), myotomy extension resulted in significant increases in both mean nCSA and CP-DI of 66.6mm2 (95% CI, 16.4 - 116.8; p=0.03) and 1.9 mm2/mm Hg (95% CI, 0.4 - 3.3; p=0.015), respectively. There were no adverse events. CONCLUSIONS Cricopharyngeal distensibility is reduced in ZD patients and is partially reversible by FECM. Intra-procedural FLIP cricopharyngeal distensibility measurement is safe and sensitive in detecting myotomy-induced changes. These findings support using FLIP to optimise FECM outcome. Further studies are required to derive precise metrics predictive of clinical response.