Purpose: Reduced counts of interstitial cells of Cajal are well-documented in patients with gastroparesis. Also, gastric enteric inflammation, observed by Tcells and macrophages, has been recently investigated. In this pilot study, we explored gastric mucosal tissue to determine any differences in mucosal nerve fiber density potentially associated with Gp pathophysiology. Methods: Gastric mucosal tissues from 5 Gp patients (mean age 53.5 yrs; 80% Caucasian, 80% female; 1 diabetic, 2 idiopathic, 2 postsurgical Gp) and 3 agematched controls were compared. For Gp patients, full thickness stomach biopsies, obtained at permanent gastric stimulator implantation, were processed, fixed in appropriate solutions, and stained using immunohistochemistry markers for inner and outer muscular ICC and S100, as well as for CD3, CD4, CD8 and CD68 in the enteric plexus. Superficial mucosal nerve fiber length density (μm/μm3) was evaluated using PGP 9.5 immunostained sections imaged by confocal microscopy and quantified with AutoNeuron®. Results were analyzed with STATA 11 software using a senior regression model. Results: Mean mucosal nerve fiber density for Gp patients, at 0.0018 as compared to 0.0024 for age-matched controls, was strongly associated with inner muscular ICC, at 12.04 μm/μm3 [2.76, 21.32] p = 0.026, and weakly associated with both CD4, at 7.49 [-1.48, 16.46] p = 0.077, and CD 68, at 6.37 [-0.90, 13.64] p = 0.068. Conclusion: Mucosal nerve fiber density is reduced in gastroparesis patients when compared to controls. Further investigation of the association between enteric inflammation and mucosal nerve fiber density should be conducted to improve our understanding of the pathogenesis of gastroparesis. Disclosure: Dr Thomas Abell, Consultant, Licensor and instructor for Medtronic Inc.Table: MUCOSAL NERVE FIBRE DENSITY in GASTROPARESIS