519: Time-Varying Sympathetic Index of Electrodermal Activity as an Objective Biomarker for Visceral Pain

Topic: Clinical Science
Subtopic: Pain category (ICD-11), Chronic primary visceral / pelvic pain, Electrophysiology, Assessment and Measurement of Pain/Nociception, Digital Health Technologies

Background and Aims: There are few objective biomarkers available for measuring pain. The assessment of pain, especially chronic abdominal pain relies heavily on subjective reporting [1]. Chronic pain disorders, including irritable bowel syndrome (IBS) are commonly associated with autonomic dysfunction, characterized by increased sympathetic activity and reduced parasympathetic activity [2][3]. Autonomic activities can be quantified using non-invasive, wearable bioelectrical signals, such as electrodermal activity (EDA), serving as an objective pain biomarker, facilitating the development of more effective treatments [4][5]. This preliminary study investigated the feasibility of using an EDA-derived index to observe sympathetic activity in response to experimentally induced visceral and somatic pain.

Methods: Twenty-five healthy adults completed two pain-evoking procedures while reporting pain intensity using a touchscreen visual analog scale (VAS, 0-100). Somatic pain was induced via thermal grill illusion using alternating warm (42-45°C) and cool (10-15°C) metal bars. Visceral pain was induced using a 10-ml enema of 20% glycerol. EDA was recorded from the non-dominant hand using a wearable device. We computed the time-varying sympathetic index (TVSymp) from the EDA, which is the mean spectral amplitude in the 0.08–0.24 Hz frequency band associated with sympathetic tone [6].

Results: We compared the mean TVSymp of the somatic pain (SP) and of the visceral pain across three stages of the enema test: Baseline (BL), stimulation onset (VPO, from enema holding until maximum VAS), and recovery (VPR, from maximum VAS until VAS <10). VPO exhibited an increase in sympathetic activity, with a mean TVSymp of 1.22 ± 0.65. This was higher than the values for VPR and BL (p < 0.05), which had mean TVSymps of 0.61 ± 0.65 and 0.29 ± 0.22, respectively. However, SP exhibited an overall higher mean TVSymp (1.95 ± 1.06).

Conclusions: Preliminary results demonstrate that EDA can serve as a marker of changes in sympathetic activity when visceral pain occurs. There is an increase in activity as subjects report incremental pain and a reduction in activity as pain begins to decrease. TVSymp has potential as a biomarker for visceral pain since sympathetic activity measurements show less dispersion than those generated by somatic pain. The findings could be useful for machine learning models in clinical IBS studies related to abdominal pain. The National Institute of Diabetes and Digestive and Kidney Diseases supported this study (R01DK138248).

References: [1] Gouverneur, P., Badura, A., Li, F., Bieńkowska, M., Luebke, L., Adamczyk, W. M., ... & Piętka, E. (2024). An experimental and clinical physiological signal dataset for automated pain recognition. Scientific Data, 11(1), 1051.
[2] Walker, L. S., Stone, A. L., Smith, C. A., Bruehl, S., Garber, J., Puzanovova, M., & Diedrich, A. (2017). Interacting influences of gender and chronic pain status on parasympathetically mediated heart rate variability in adolescents and young adults. Pain, 158(8), 1509-1516.
[3] Liu, Q., Wang, E. M., Yan, X. J., & Chen, S. L. (2013). Autonomic functioning in irritable bowel syndrome measured by heart rate variability: A meta‐analysis. Journal of digestive diseases, 14(12), 638-646.
[4] Kong, Y., & Chon, K. H. (2024). Electrodermal activity in pain assessment and its clinical applications. Applied Physics Reviews, 11(3).
[5] Kong, Y., Posada-Quintero, H. F., & Chon, K. H. (2021). Real-time high-level acute pain detection using a smartphone and a wrist-worn electrodermal activity sensor. Sensors, 21(12), 3956.
[6] Posada-Quintero, H. F., Florian, J. P., Orjuela-Cañón, Á. D., & Chon, K. H. (2016). Highly sensitive index of sympathetic activity based on time-frequency spectral analysis of electrodermal activity. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 311(3), R582-R591.

Presenting Author: Hugo F. Posada-Quintero
Submitting Author: Hugo Posada-Quintero

Senior Author: Hugo F. Posada-Quintero

IASP 2026 Global Year theme of Neuropathic Pain: No

• Javier O. Pinzon-Arenas: M.Sc. - University of Connecticut
• Amir Mohammad Karimi Forood: NA - University of Connecticut
• Confidence C. Francis-Edoziuno: NA - University of Connecticut
• Riley Q. McNaboe: NA - University of Connecticut
• Ariel Kamen: NA - University of Pennsylvania
• Bin Feng: PhD - University of Connecticut
• Xiaomei Cong: PhD - Yale University
• Ming-Hui Chen: PhD - University of Connecticut
• Wendy A. Henderson: PhD - University of Pennsylvania
• Hugo F. Posada-Quintero: PhD - University of Connecticut