Autonomic Function in Inflammatory Bowel Disease: A Narrative Review of Objective Assessment and Physiological Monitoring

Abstract

Introduction and purpose: Autonomic alterations may contribute to the physiological heterogeneity of inflammatory bowel disease (IBD). This review examines objective autonomic assessment in Crohn disease and ulcerative colitis, focusing on physiological phenotyping and longitudinal monitoring. Methods: This focused narrative review synthesizes 25 included studies. Evidence on heart rate variability (HRV), Holter monitoring, cardiovascular reflexes, orthostatic responses, baroreflex function, sudomotor testing, and wearable-derived signals was organized by modality and relationship with disease activity. Brief description of the state of knowledge: HRV was the most studied modality and was associated with clinical, biochemical, and endoscopic activity in selected cohorts. Autonomic alterations may persist during remission and do not consistently correspond to symptoms or inflammatory markers. Reduced HRV alone does not establish autonomic neuropathy. Multimodal testing assesses complementary physiological domains and may yield discordant findings. Wearables offer opportunities for repeated assessment alongside sleep and physical activity, while neuromodulation remains investigational. Heterogeneous protocols, small cohorts, and limited external validation constrain clinical interpretation. Conclusions: Objective autonomic assessment may complement established IBD evaluation in selected patients. The proposed Clinical Algorithm and Physiological Framework are hypothesis-generating and require prospective validation. Standardized multimodal protocols and longitudinal studies are needed. Current evidence does not support autonomic biomarkers as stand-alone tools for disease monitoring or exercise prescription.