P85 | ALTERATION OF SUBMUCOSAL AND MYENTERIC GANGLIA IN SEVERE GUT DYSMOTILITY: A QUANTITATIVE MORPHOMETRIC ANALYSIS

H. Yaghi¹, E. Boschetti¹, S. Blando¹, I. Neri¹, C. Malagelada², R. De Giorgio³, L. Manzoli¹, S. Ratti¹ | ¹Center of Clinical Surgical Molecular and Experimental Anatomy Alma Mater Studiorum, University of Bologna, Bologna, Italy; ²Departament de Medicina, Universitat Autonoma de Barcelona, Barcelona, Spain; ³Department of Translational Medicine, Università di Ferrara, Ferrara, Italy

Severe gut dysmotility (SD) is marked by impaired gut propulsion and distinct histopathological features, including fewer myenteric and submucosal neurons per ganglion and increased interganglionic distance. However, neurons counting remains complex and time-consuming, even with simplified protocols. The aim of this study is therefore to assess whether the number of ganglia in the submucosal and myenteric plexuses may serve as practical and discriminative indices for distinguishing patients from controls and supporting the diagnosis. The study included 39 patients and 8 controls. Patients were analyzed as a group or by histochemical phenotype: apparently normal (AN), inflammatory neuromyopathy (INF), and degenerative neuromyopathy (DEG). Formalin-fixed, paraffin embedded jejunal sections were immunolabelled for Neuron Specific Enolase (NSE) as pan neuronal marker. Following the neuromuscular ridge from right to left, all consecutive fields containing the myenteric plexus (≥8 fields) were analyzed and normalized to the plexus length (in mm), while all fields including the submucosal plexus were analyzed and normalized to the area of submucosa examined. The analysis of myenteric ganglia revealed a significant reduction in the number of ganglia per mm of myenteric ridge in SD patients (p = 0.0002), with 87% of patients falling below the threshold defined by the lowest value observed in controls. This reduction remained consistent across histopathological subgroups (AN: p = 0.0032; INF: p =0.0145; and DEG: p =0.0004). Although the analysis of the submucosal plexus revealed a significant reduction in the number of ganglia per mm² of submucosa in SD patients (p = 0.0410), only 26% of cases fell below the threshold defined by the lowest value observed in controls. This reduction remained consistent only in the AN and DEG subgroups. While requiring further validation, this study provides proof of concept for a new diagnostic algorithm for SD, based on the stepwise assessment of morphometric indices, with a focus on the myenteric plexus. Future analyses will consider ganglion volume, sex-related differences, and will expand the investigation from the jejunum to the colon.