Endoscopic implantation of Plexiglas (PMMA) microspheres for the treatment of GERD Christos Feretis, MD, Paul Benakis, MD, Christos Dimopoulos, MD, Apostolos Dailianas, MD, Panayotis Filalithis, MD, Konstantinos M. Stamou, MD, Andreas Manouras, MD, Nickolaos Apostolidis, MD Athens, Greece Background: A gelatinous implant containing polymethylmethacrylate (PMMA) beads is success- fully used to augment the diminished thickness of the chorium in patients with skin defects and wrinkles. The aim of the present study was to determine whether submucosal injection of PMMA microspheres into the lower esophageal folds decreases the severity of symptoms and acid reflux in patients with GERD. Methods: Endoscopic submucosal implantation of PMMA was carried out in 10 patients with GERD who were either refractory to or dependent on proton pump inhibitors. Symptom severity score, 24-hour pH monitoring, upper GI endoscopy, and EUS were performed to evaluate the effi- cacy of implantation. Results: A significant decrease in the symptom severity score and mean total time with esophageal pH less than 4 was noted after the implantation of PMMA (p < 0.05). Seven of 10 patients were taking no medication after PMMA implantation. There were no serious procedure- related complications. Conclusions: Endoscopic implantation of PMMA into the submucosa of the lower esophageal folds may be a new method for treating GERD. Further studies are required to determine the long- term efficacy of the procedure. (Gastrointest Endosc 2001;53:423-6.) VOLUME 53, NO. 4, 2001 GASTROINTESTINAL ENDOSCOPY 423 Received August 28, 2000. For revision November 8, 2000. Accepted January 3, 2001. From the Department of Therapeutic Endoscopy and the Department of Internal Medicine, “Hygeja” Hospital, Athens, and the Department of Propaedeutic Surgery, Hippokrateion Hospital, Athens Medical School, Athens, Greece. Reprint requests: Konstantinos M. Stamou, MD, 20 Potamianou St, 115 28, Athens, Greece. Copyright © 2001 by the American Society for Gastrointestinal Endoscopy 0016-5107/2001/$35.00 + 0 37/1/113912 doi:10.1067/mge.2001.113912 The use of biocompatible materials as tissue aug- menting factors is an established procedure in urological and plastic surgery. Implantation of poly- dimethylsiloxane and polytetrafluoroethylene parti- cles has been successfully used to treat intrinsic ure- thral sphincter deficiency, 1,2 vesico-ureteral reflux, 3 and incontinence 4 after radical prostatectomy. Implant-related complications such as granulo- matous reaction 5 and migration 6 as well as concerns about the association of silicone fluid with connec- tive tissue disorder 7 have given impetus for the development of a better implant. The ideal implant should be biologically and chemically inert, non- migrating, durable, and should induce a negligible foreign-body reaction. Polymethylmethacrylate (PMMA) was first used in human applications in 1936 for dental prostheses. Through continuous improvements in manufacturing, it has taken on many of the properties of an ideal implant. Hence, it is successfully used in plastic surgery to augment the diminished thickness of the chorium in cases of skin defects and wrinkles. Apart from its well-documented biocompability, 8 PMMA microspheres of 100μ have a smooth, com- pletely round surface that permits injection through a needle, hinders phagocytosis and migration from the implantation site, and evokes negligible foreign body reaction. 9 The substance used as a carrier for PMMA is a heated 3.5% bovine spongious encephali- tis-free gelatin solution, characterized by the removal of gelatin’s allergenic ends. The prepared implant is a 1:3 suspension of PMMA in gelatin solution. After implantation, the gelatin (75% of total volume) is phagocytized by macrophages within 3 months and replaced by fibroblasts and col- lagen fibers, a reaction that is stimulated by PMMA spheres (25% of total volume). 10,11 The spheres are encapsulated by connective tissue, which replaces 50% of the gelatin volume as demonstrated by histo- logic assessment. 12 Thus, at least two thirds of the total volume of the implant remains at the site of injection. There are no detectable changes in the his- tologic picture of the implant and surrounding tissue complex after 4 months. These properties of PMMA implant render it an attractive tissue bulking factor. Therefore, our hypothesis was that the submucosal injection of PMMA into the lower esophageal folds 13 could reduce gastroesophageal acid reflux and symp- toms of GERD.