High-resolution endoluminal sonography in achalasia

Background: Imaging of the lower esophageal sphincter in patients with achalasia using 7.5 and 12 MHz ultrasound transducers has shown variable results. Methods: A 20 MHz radial ultrasound transducer was used to quantitatively compare the lower esophageal sphincter in patients with achalasia to that of normal volunteers. The transducer, housed in a 6.2F catheter, was placed at the level of the lower esophageal sphincter in 29 patients with achalasia and 19 normal subjects. Videotaped images from the lower esophageal sphincter were digitized and the width of the circular smooth muscle, longitudinal smooth muscle, and total muscularis propria were measured. A mean width for each muscle layer was calculated. Results: All muscle layers were found to be significantly thickened at the lower esophageal sphincter in patients with achalasia when compared with those in normal subjects: circular smooth muscle (0.206 cm ± 0.137 cm vs 0.124 cm ± 0.038 cm, p < 0.017); longitudinal smooth muscle (0.128 cm ± 0.077 cm vs 0.088 cm ± 0.028 cm, p < .041); and total muscle thickness (0.317 ± 0.180 cm vs 0.224 cm ± 0.049 cm, p < 0.033). Conclusion: Although high-resolution endoluminal sonography cannot be used to differentiate patients with achalasia from normal controls, this study quantitatively demonstrates that both the mean longitudinal and mean circular smooth muscle layers at the lower esophageal sphincter are wider in patients with achalasia than in a group of normal subjects. (Gastrointest Endosc 1995;42:545-9.)