Normalization of Gastric Emptying After Pyloroplasty in Gastroparetic Patients Can Be Achieved Despite Abnormal Smooth Muscle Histology

Introduction: Studies have demonstrated that impaired gastric motility in gastroparetic (GP) patients is related to the depletion of the interstitial cells of Cajal (ICC) in gastric smooth muscle. With surgical treatment approaches such as pyloroplasty (PP) and gastric electrical stimulation to treat patients with refractory GP there was the opportunity to obtain full-thickness gastric and pyloric smooth muscle biopsies. The aim of this study was to investigate the prevalence of changes of ICC and the degree of fibrosis affecting the antral and pyloric smooth muscles in drug refractory GP patients. Methods: Full thickness antral (A) and pyloric (P) biopsies were obtained during combined GES and PP surgery in 44 GP patients (32 diabetic [DM] and 12 idiopathic [ID]; mean age: 43years (20-78); 73% female [n=32]) who had failed all available medical therapies. Mean duration of DM was 15 years (3-50). Mean duration of GP symptoms was 5.5 years (1-20). Tissues were stained with H&E, trichrome for fibrosis and c-kit for the presence of ICC. Significant ICC depletion was defined as < 10 cells/HPF. All patients had scintigraphy gastric emptying (GE) tests done at baseline and 3 months after surgery, with retention at 4 h of >10% of the study meal being interpreted as delayed GE. Results: All 44 patients provided both antral and pyloric tissue samples. The mean number of antral ICC was 12.3±5.6, while the mean number of pyloric ICC was 7.1±5.8 (p< 0.05). 14 patients (32%) had depletion of antral ICC (< 10/ HPF), while 30 (68%) had depletion of pyloric ICC. Smooth muscle fibrosis in the antrum was observed in 45% and in 51% the pyloric biopsies. All GP patients had delayed GE before surgery, and 50% of them with < 10 antral ICC normalized GE (< 10% retention at 4th hrs). In addition, 53% of patients with < 10 pyloric ICC normalized their GE, although their antral ICC were still depleted. Conclusion: We conclude that in GP patients requiring surgery after failing all medical therapies: 1) There was significantly more pyloric ICC depletion (68%) compared to antral ICC depletion (32%); 2) After pyloroplasty gastric emptying can be normalized in GP patients despite ongoing depletion of ICC in the antrum.